Medicine, Faculty of
Non UBC
Surgery, Department of
DSpace
Audiology Research 14 (6): 939-957 (2024)
University of British Columbia. Otolaryngology
Stella, Irene
Perrin, Philippe
Casteran, Matthieu
Joud, Anthony
Mallinson, Art
Klein, Olivier
(1) Background: Surgery for Chiari I malformation (CMI) is indicated when typical clinic-radiological features (syringomyelia, exertional headaches, sleep apnea syndrome, and tetraparesis) are present. Sometimes, patients have atypical complaints suggestive of otolaryngological (ENT) involvement, and it is sometimes difficult for the neurosurgeon to determine if these complaints are related to the CMI. Our aim was to describe postural control patterns in children with CMI using computerized dynamic posturography. To our knowledge, this is the first study addressing postural instability in pediatric CMI patients. (2) Methods: Twenty-eight children aged 6 to 17 years with both radiologically confirmed CMI and clinical ENT complaints were included. The children were separated into two groups, operated and non-operated patients, based on neurosurgical indication. Epidemiologic and posturographic results (CDP—Equitest®) were compared between both groups, as well as pre- and postoperatively in Group 2. (3) Results: In Group 2 patients, significant improvement of global SOT was found after intervention. When the three sensorial aspects of postural control calculated by the system were independently assessed, the greatest improvement was in the vestibular ratio. We also observed an altered CoG pattern (“lateral deviation”) in the Group 2 patients, which significantly differed from those in Group 1. Lateral deviation was significantly reduced postoperatively in the Group 2 patients. A correspondence between preoperative MRI and the side of lateralization on posturography was found in four children, but this cannot be regarded as significant due to the low number of patients. (4) Conclusions: Postural control seems to improve after surgery for CMI in children, mostly due to the improvement in vestibular function. There is a correspondence between the side of lateral deviation and the side of greatest tonsillar descent on MRI and perioperatively. Further studies are needed to support these results and to confirm the utility of CDP in CMI patients.
Citation: Stella, I.; Perrin, P.; Casteran,M.; Joud, A.; Mallinson, A.; Klein, O.Utilization of Vestibular Informationfor Balance Control in Children withChiari I Malformation. Audiol. Res.2024, 14, 939–957. https://doi.org/10.3390/audiolres14060079Academic Editor: Giacinto AsprellaLibonatiReceived: 4 September 2024Revised: 25 October 2024Accepted: 30 October 2024Published: 31 October 2024Copyright: © 2024 by the authors.Licensee MDPI, Basel, Switzerland.This article is an open access articledistributed under the terms andconditions of the Creative CommonsAttribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).ArticleUtilization of Vestibular Information for Balance Control inChildren with Chiari I MalformationIrene Stella 1,2,3,* , Philippe Perrin 2,3,4,5, Matthieu Casteran 2,5,6 , Anthony Joud 1, Art Mallinson 7and Olivier Klein 1,21 Department of Paediatric Neurosurgery, University Hospital of Nancy, 54011 Vandoeuvre-lès-Nancy, France2 Research Unit DevAH—Development, Adaptation and Handicap, Faculty of Medicine,University of Lorraine, 54511 Vandoeuvre-lès-Nancy, France; philippe.perrin@univ-lorraine.fr (P.P.);matthieu.casteran@univ-lorraine.fr (M.C.)3 Laboratory for the Analysis of Posture, Equilibrium and Motor Function (LAPEM),University Hospital of Nancy, 54011 Vandoeuvre-lès-Nancy, France4 Department of Paediatric Otolaryngology, Children Hospital, University Hospital of Nancy,54500 Vandoeuvre-lès-Nancy, France5 Faculty of Science and Techniques of Physical and Sport Activities, University of Lorraine,54600 Villers-lès-Nancy, France6 Research Unit 2LPN, Psychology and Neuroscience Lab, University of Lorraine, 54000 Nancy, France7 Division of Otolaryngology, Department of Surgery, Faculty of Medicine, University of British Columbia,Vancouver, BC V6T 1Z4, Canada; art@mallinson.ca* Correspondence: i.stella@chru-nancy.fr; Tel./Fax: +33-383-155-211Abstract: (1) Background: Surgery for Chiari I malformation (CMI) is indicated when typical clinic-radiological features (syringomyelia, exertional headaches, sleep apnea syndrome, and tetraparesis)are present. Sometimes, patients have atypical complaints suggestive of otolaryngological (ENT)involvement, and it is sometimes difficult for the neurosurgeon to determine if these complaintsare related to the CMI. Our aim was to describe postural control patterns in children with CMIusing computerized dynamic posturography. To our knowledge, this is the first study address-ing postural instability in pediatric CMI patients. (2) Methods: Twenty-eight children aged 6 to17 years with both radiologically confirmed CMI and clinical ENT complaints were included. Thechildren were separated into two groups, operated and non-operated patients, based on neurosurgicalindication. Epidemiologic and posturographic results (CDP—Equitest®) were compared betweenboth groups, as well as pre- and postoperatively in Group 2. (3) Results: In Group 2 patients, signifi-cant improvement of global SOT was found after intervention. When the three sensorial aspects ofpostural control calculated by the system were independently assessed, the greatest improvementwas in the vestibular ratio. We also observed an altered CoG pattern (“lateral deviation”) in the Group2 patients, which significantly differed from those in Group 1. Lateral deviation was significantlyreduced postoperatively in the Group 2 patients. A correspondence between preoperative MRI andthe side of lateralization on posturography was found in four children, but this cannot be regarded assignificant due to the low number of patients. (4) Conclusions: Postural control seems to improveafter surgery for CMI in children, mostly due to the improvement in vestibular function. There is acorrespondence between the side of lateral deviation and the side of greatest tonsillar descent on MRIand perioperatively. Further studies are needed to support these results and to confirm the utility ofCDP in CMI patients.Keywords: Chiari I malformation; pediatric neurosurgery; posturography; balance1. IntroductionInitial reports about audiovestibular symptoms in patients with Chiari I malformation(CMI) date back to 1971, when Rydell and Pulec [1] described a series of 29 patients present-ing otoneurological symptoms in a population of 130 subjects with CMI, explored at theAudiol. Res. 2024, 14, 939–957. https://doi.org/10.3390/audiolres14060079 https://www.mdpi.com/journal/audiolresAudiol. Res. 2024, 14 940Mayo Clinic (Rochester, MN, USA). The most frequent symptoms were hearing loss, tinni-tus, vertigo, and imbalance. Imbalance was reported as the chief clinical complaint in 30%of adult CMI patients in another paper published soon after by the same group [2]. Sincethat time, otolaryngologists have maintained their interest in exploring audiovestibularinvolvement in CMI, stressing the importance of this relationship.Chiari I malformation (CM1) is a structural abnormality characterized by cerebellartonsillar descent of at least 5 mm below the level of the foramen magnum [3], or of Mc Rae’sline, into the vertebral canal. Once classified as a rare disease, it is increasingly diagnoseddue to the improvements in cerebral imaging. Although the true prevalence in the generalpopulation is difficult to establish, the imaging incidence in children younger than 18 yearshas been reported to be between 0.4 to 3.6% [4,5].The symptoms related to CMI have been classically divided into four categories [2,3,6,7],as follows:(1) Exertional nuchal pain and headaches;(2) Symptoms related to brainstem and lower cranial nerve dysfunction;(3) Symptoms related to syringomyelia, occurring in 45–75% of CMI patients [2,8];(4) Cerebellar symptoms. A clinical difference between adults and children is the in-creased occurrence in children of central sleep apnea syndrome (CSAS). Feedingproblems and oropharyngeal symptoms are also more frequent in children under3 years of age [4]. Traditionally, the decision about surgical management of CMI beingnecessary was made regarding the presence of syrinx, central apnea syndrome, orsymptoms believed to be characteristic for CMI, such as exertion headache, exertionalneck pain, pyramidal signs, and tetraparesis.Although, from an anatomical point of view, it is possible that audiovestibular dis-orders might arise from a crowded posterior cranial fossa, where the brainstem, the floc-culonodular lobe of the cerebellum, and cranial nerves may be compressed or distorted,rarely are these symptoms alone sufficient to justify surgical intervention. It is the presenceof nystagmus, particularly downbeat nystagmus (DBN), that has largely been associatedwith CMI [1,9–22]. Although many neurosurgeons accept DBN as a presenting symptomof CMI [6,7], ENT evaluation is not systematically required prior to occipito-cervical de-compression, and surgical intervention does not rely on it. In the literature, there is noconsensus on the precise anatomical substrate of audiovestibular signs and symptoms seenin CMI patients, as these symptoms are classified as cerebellar in some studies [6,15], oras originating from brainstem compression or lower cranial nerves in others [3,7]. Therecognition of the relationship between audiovestibular symptoms or signs and CMI be-come fundamental in the process of the selection of surgical candidates in patients whodo not have other criteria for intervention (i.e., syringomyelia or CSAS) but have atypicalheadaches or, in some cases, are defined as “asymptomatic”.Given the fact that nystagmus has already been largely described in the literature, wedecided to focus our attention on imbalance, which is another frequently reported, but lessstudied, symptom. The term “imbalance”, also known as disequilibrium or gait ataxia,suggests a lack of movement coordination in the movements of the voluntary muscles.In the literature, it is often included as part of the general and more widely used term“dizziness”, referring to a sense of disorientation in space. “Vertigo” is a more specific term,which is defined as a sensation of rotation of oneself or of surrounding objects [23–25].There are different types of ataxia that are described [26], depending on the site of lesion.Balance disorders in CMI patients manifest with gait ataxia. To assess the real etiologyof gait instability in CMI patients, it is necessary to perform a more precise investigation,as the clinical picture is often poor, and might not provide answers. One of the mostquantitative and reliable methods of assessing postural control is dynamic posturogra-phy [27]. At our institution, computerized dynamic posturography (Equitest®, NeuroCom,Clackamas, OR, USA) (CDP) at the Laboratory for the Analysis of Posture, Equilibrium,and Motor Function (LAPEM)—University Hospital of Nancy, can be performed after ENTexamination.Audiol. Res. 2024, 14 941The aims of this study were as follows:■ To define the presence of imbalance in children with a diagnosis of CMI;■ To explore the etiologic mechanisms underlying imbalance in these patients;■ To determine if surgery has any impact on balance control;■ To explore the usefulness of ENT examination and the use of CDP in the surgicalmanagement of CMI children.The details of our study’s protocol have been already published [28] and will besummarized in this manuscript.To the best of our knowledge, there are few studies in the literature describing balancecontrol patterns in CMI patients [29,30], and this is the first study about balance controlanalysis in a pediatric CMI cohort using Equitest® (computerized dynamic posturography,or CDP).2. Patients and Methods2.1. PatientsBetween September 2019 and September 2023, 48 children with a diagnosis of CMIwere seen at our institution. The radiologic criterion for the diagnosis of CMI was thepresence of a caudal displacement of cerebellar tonsils of at least 5 mm under McRae’sline [3]. The inclusion criteria for this study were the following: children aged from6 to 18 years with radiologically confirmed CMI, presenting clinical features suggestingENT involvement (dizziness, nystagmus, gait impairment, motion sickness, malaise, andatypical migraine, which could not be directly attributed to the CMI).Patients with tonsillar ectopia secondary to other complex pathology (e.g., craniosteno-sis, craniocervical malformation, intracranial hypertension, and posterior fossa tumor) werenot included in this study, as tonsillar ectopia in these cases might not fall into the diagnosisof CMI. Children with pre-existing vestibular pathology, children unable to stand on theplatform (due to cerebral palsy, severe behavioral troubles, severe visual impairment, orassociated orthopedic pathologies), and children and/or parents who refused to participatein this study were also excluded. In our population of 48 patients,8 patients were not included in the study because they did not meet the inclusioncriteria, as follows:■ A total of 2 patients were less than 6 years of age;■ A total of 1 patient had severe visual impairment;■ A total of 2 patients had cognitive impairment;■ A total of 2 patients were operated for craniocervical decompression for cerebellarptosis secondary to craniostenosis;■ A total of 1 patient had already been operated on in the past for Chiari I malformation.In addition, 5 patients refused to be enrolled.The 35 remaining patients, who all agreed to be included in this study, were dividedinto two groups, independent of the ongoing results of this study. The first group included21 patients for whom there was no indication for surgery, and the second one was a groupof 14 patients who would have benefited from surgical intervention. The criteria that ledthe neurosurgeon to decide on surgical intervention are represented by the presence of atleast one of the following aspects: characteristic symptomatology (most of all, exertionalheadaches, usually occipito-cervical, but also of frontal location; and presence of symptomsof brainstem compression); syringomyelia; and central sleep apnea syndrome. One op-erated girl missed her definitive postoperative posturographic assessment; in two cases,the results could not be analyzed; and, at the time of this paper, data are not available forfour children yet. In total, data are available for 28 patients, including 18 non-operated and10 operated ones (Figure 1).Audiol. Res. 2024, 14 942Audiol. Res. 2024, 14, FOR PEER REVIEW 4 the neurosurgeon to decide on surgical intervention are represented by the presence of at least one of the following aspects: characteristic symptomatology (most of all, exertional headaches, usually occipito-cervical, but also of frontal location; and presence of symptoms of brainstem compression); syringomyelia; and central sleep apnea syndrome. One operated girl missed her definitive postoperative posturographic assessment; in two cases, the results could not be analyzed; and, at the time of this paper, data are not avail-able for four children yet. In total, data are available for 28 patients, including 18 non-operated and 10 operated ones (Figure 1). Figure 1. Flow chart diagram according to PRISMA 2020 guidelines. CM1: type 1 Chiari malfor-mation. 2.2. Methods All patients benefited from a complete clinical evaluation and in-depth history tak-ing, recorded in a survey, a medullary MRI to check for syringomyelia, and a poly-somnographic recording to look for sleep apnea syndrome. The patients enrolled in this study were all referred for ENT assessment, including neuro-otological examination and CDP with Equitest®. This evaluation was conducted in a blind fashion, as the ENT specialist (Ph.P.) did not know whether or not the patients were surgical candidates. The ENT assessment consisted of a neuro-otological examination and clinical vestib-ular assessment, if deemed necessary. The aims of the neuro-otological examination were to detect and differentiate cerebellar from vestibular signs, identify segmental or axial de-viations, and rule out confounding associated factors. Other evaluated factors included vergence insufficiency, refraction disorders, and other visual corrections. Vertigo or diz-ziness were accurately assessed, as well as complaints of tinnitus. Otoscopic examination was also carried out, with tympanometry and acoustic reflex test recordings (Interacous-tics, Middelfart, Denmark) and determining hearing thresholds (pure-tone air and bone-Figure 1. Flow chart diagram according to PRISMA 2020 guidelines. CM1: type 1 Chiari malformation.2.2. MethodsAll patients benefited from a complete clinical evaluation and in-depth history taking,recorded in a survey, a me ullary MRI to che k for syringomyeli , and a polysomnographicrecording to look for sle p apnea synd ome.The patients enrolled in this study were ll referred for ENT assessment, includingneuro-otological examinatio and CDP with Equit st®. This evaluation was conducted in ablind fashi n, s the ENT specialist (Ph.P.) did no know whether or ot the patien s weresurgical candidates.The ENT assessm nt consisted of a neuro-otological examination and clinical vestibu-lar assessment, if deemed nece sary. The aims of the neuro-otological examin tion wereto detect and differ ntiate c r bellar from vestibular signs, identify seg ental or axialdeviations, and rul out confounding associa ed f ctors. Other evaluated fact s inc udederge ce i sufficiency, refraction disorders, and o her visual corrections. Vertigo or izzi-n ss were accurately assessed, as well as complaints of tinnitus. Otoscopic examination wasalso carri d out, wi h tympanometry and acoustic reflex test recordings (Interacoustics, Mid-delfart, Denmark) and deter ining hea ing thresholds (pure-tone air and bone-conductionhresholds) in tone audiometry (from 250 Hz to 8000 Hz) and intelligibility in speech tests(Interacoustics).After that, CDP (computerized dynamic posturography) was carried out to determinebalance control performances.CDP assesses the global balance performance and relative weight of sensory infor-mation (visual, vestibular, and somatosensory) involved in balance control. The Equitest®balance system consisted of a dual platform with two footplates connected with a pin joint.The footplates were supported with five force transducers. The computer calculated thecenter of foot pressure (CoP) and the vertical component of the center of gravity (CoG),using the subject’s height entered by the operator. When a subject stands with their anklescentered over the stripe on the dual platform, with feet an equal distance laterally from theAudiol. Res. 2024, 14 943center line, this position is called the “electrical zero position” and serves as a referencepoint for the calculation of sway angles. The sensory organization test (SOT) consistedof three 20 s trials under six different sensory conditions, in which the surface and/orvisual surroundings (i.e., sensory inputs) were systematically manipulated (so-called “swayreferencing”) [27,31–33]. (Table 1).Table 1. Computerized dynamic posturography. Sensory organization test (Equitest®, NeuroCom,Clackamas, OR, USA). Determination of the six conditions. SR, sway-referenced [27,31–33].Postural Control TestName Situation Sensory ConsequencesCondition 1 Fixed support, eyes open -Condition 2 Fixed support, eyes closed Vision absentCondition 3 Fixed support, SR surround Altered visionCondition 4 SR support, eyes open Altered proprioceptionCondition 5 SR support, eyes closed Vision absent, altered proprioceptionCondition 6 SR support, SR surround Altered vision and proprioceptionTo protect against falls, the patients wore a safety harness connected to the ceiling andan operator stood within reaching distance. The equilibrium score (ES) was calculated bycomparing the subject’s anterior–posterior sway during each 20 s SOT trial to the maximaltheoretical sway limits of stability, which was based on the individual’s height and the sizeof the base of support. It represents the angle (8.0 anteriorly and 4.5 posteriorly) at whichthe subject could lean in any direction before the center of gravity would move beyond apoint that allowed him/her to remain upright (i.e., point of falling). The following formulawas used to calculate the ES:Equilibrium = 12.5◦ − (Θmax − Θmin)/12.5◦ × 100where Θmax indicates the greatest antero-posterior CoG sway angle, and Θmin indicatesthe lowest antero-posterior CoG sway angle. Lower sways lead to a higher ES, indicating abetter balance control performance (a score of 100 represents no sway, while 0 indicatessway that exceeds the limit of stability, resulting in a fall). Table 2 shows the CES andsensory ratios calculation method.Table 2. Computerized dynamic posturography. Sensory organization test (Equitest®, NeuroCom,Clackamas, OR, USA). Significance of composite score and sensory ratios.Name Equation SignificanceComposite score [C1 + C2 + 3 (C3 + C4 + C5 + C6)]/14 Evaluate global balance performance. A low score represents poorpostural control.Somatosensory ratio C2/C1Ability to use somatosensory input to maintain balance (even whenvisual cues are removed).A low score suggests poor use of somatosensory references.Visual ratio C4/C1Ability to use visual input to maintain balance (even whensomatosensory cues are altered). A low score suggests poor use ofvisual references.Vestibular ratio C5/C1Ability to use vestibular input system to maintain balance (even whenvisual cues are removed and somatosensory cues are altered).A low score suggests poor use of vestibular cues or that vestibularinformation is unavailable.Visual preference ratio C3 + C6/C2 + C5Degree to which patient relies on visual information to maintainbalance (correct/incorrect information).A low score suggests reliance on visual cues even whenthey are inaccurate.Audiol. Res. 2024, 14 944The platform is also designed to register medio-lateral sways, i.e., to appreciate bodymovements in the coronal plane (“lateral deviation”). When the patient shifts the center ofthe body medio-laterally from the “zero position”, it is possible to state that the quality ofhis/her postural control is not optimal due to a deficit of the ipsilateral vestibular system.Even though it is suggested that CDP cannot definitively define the site of lesion [27,34] ingait ataxia, some authors have attempted to distinguish a cerebellar lesion from a vestibularlesion, depending on the posturographic sway pattern [35–37], relying primarily on thedirection of sway. Maki et al. [35] reported that lateral deviation is predictive of fallsin the elderly population. Given this, we decided to also analyze lateral deviation inour population.CDP also allows us to analyze the strategy adopted by a patient to maintain posturalcontrol. The rapid reflex response, which allows the human body to stand up and movewith respect to gravity, consists of a muscular reaction in the trunk and legs. In response toan event of equilibrium perturbation, the integration of the three sensorineural afferencesproduces an organized trunk and leg agonist and antagonist muscles contraction, whichmaintain the stand-up position [38]. Trunk and leg muscles enable the movement of rigidsegments around the ankle, knee, and hip joints. The most ergonomic muscular schema isselected by a healthy human body, and it is preferably driven in an “ascendant direction”,which first implicates the activation of ankle contractions, followed by knee and hip. Weconsider this strategy as “appropriate”, as oppposed to with “descending strategy”, whichinvolves an initial hip jerk rather than ankle control.Equitest has been validated as a useful tool to assess balance in children, with a goodtest–retest reliability [39]. Six years of age is a cut off that has been already identified [40]for the reliability of posturographic examination in the pediatric population.Group 1 data were compared with the preoperative data from Group 2 to look for anydifference between the two populations. Afterward, longitudinal analyses were performed,comparing the preoperative and postoperative data of Group 2 patients.The parameters of evaluation were as follows: demographic, antenatal and birth data,past medical history, level of schooling, and other everyday life parameters (e.g., abilityto ride a bike and confidence on stairs). The subjects also underwent clinical ENT andneurological assessment, MRI, polysomnographic and posturographic tests. They werealso asked about any history of headaches or vertigo. In Group 2 children, we comparedheadaches and vertigo both preoperatively and postoperatively, as this represented thebest parameter of postoperative improvement with regard to quality of life. These datawere collected using a postoperative written survey.2.3. StatisticsData analysis was presented as the median with 25th and 75th percentiles (median(interquartile range)) for continuous variables, whereas categorical variables were pre-sented as numbers and percentages. Comparisons of baseline characteristics accordingto the surgery performed were conducted by using Wilcoxon or Kruskal–Wallis tests forcontinuous variables and the Fisher exact test or χ2 test for categorical variables. Statisticalanalyses were performed using R, version 4.3.1 (6 June 2016) (R Foundation for StatisticalComputing, Vienna, Austria) and Jamovi version 2.4, with a critical level for statisticalsignificance was set at 5%. Significance is expressed on figures and tables as follows:* = p < 0.05; ** = p < 0.01; *** = p < 0.001; NS = p > 0.05.3. ResultsA total of 28 children (18 boys and 10 girls) aged 6 to 17 years (mean age 11 y) fulfilledthe inclusion criteria and were recruited in our study. There were 18 children (5 girls and13 boys) in Group 1 (non-operated patients) aged between 6 and 17 years. There were10 children (5 girls and 5 boys) in Group 2 (operated patients) aged between 6 and 16 years.No significant differences were found in age (p = 0.904) or sex distribution (p = 0.412).Table 3 reports the epidemiological data of the enrolled patients.Audiol. Res. 2024, 14 945Table 3. Epidemiological and basic medical information of the 18 included patients. In some cases,data are lacking for one patient. Fisher’s exact test was utilized for statistical analysis for all variablesexcept the wearing of glasses (Chi square test). Significance is expressed as follows: * = p < 0.05.Variable Total Population (n = 28/27) Group 1 (n = 18/17) Group 2 (BeforeOperation) (n = 10) p-ValueGenre male 18 (64%) 13 (72%) 5 (50%) 0.26Age 10.0 (8.0–14.0) 10.0 (8.0–13.0) 10.0 (8.0–15.0) 0.90Normal scholarship 22/28 (79%) 14/18 (78%) 8/10 (80%) 1.00Chronic non-neurologic illness 6/28 (21%) 5/18 (28%) 1/10 (10%) 0.37Non-chronic, non-neurologicanterior medical history 4/27 (15%) 1/17 (6%) 3/10 (30%) 0.13Non-chronic, non-neurologicanterior surgery 6/27 (22%) 3/17 (18%) 3/10 (30%) 0.64Genetic pathology 2/27 (7%) 1/17 (6%) 1/10 (10%) 1.00Neurologic pathology 1/27 (4%) 1/17 (6%) 0/10 (0%) 1.00ENT non-vestibular pathology 1/28 (4%) 1/17 (6%) 0/10 (0%) 1.00Orthopedic pathology 1/28 (4%) 1/17 (6%) 0/10 (0%) 1.00Respiratory pathology 2/28 (7%) 2/17 (11%) 0/10 (0%) 0.52Strabismus 5/28 (18%) 3/17 (17%) 2/10 (20%) 1.00Speech difficulties/Speech therapy 15/27 (56%) 8/17 (47%) 7/10 (70%) 0.42Glasses 14/27 (50%) 8/17 (44%) 6/10 (60%) 0.43Bicycle driving difficulties 24/28 (89%) 18/18 (100%) 7/10 (70%) 0.041 *Only 1 patient in Group 2 was born prematurely (i.e., before 37 weeks gestation)and none had a serious prenatal history; and 16 patients (58%) had associated medicalpathology unrelated to their CMI, which did not impact their posturographic results.Twenty-two patients (79%) attended regular school. A total of 15 children (56%) had ahistory of speech difficulty, necessitating specific therapy; 14 (50%) wore corrective lenses;and 5 (18%) had a previous history of strabismus. Only one child presented with scoliosis;however, no specific radiologic exam has been systematically realized to check for Cobb’sangles. As shown in Table 3, no significant difference between the two groups was found inany of their histories, aside from the ability to ride a bicycle. All of the children in Group 1were able to ride a bicycle, but 70% of Group 2 patients reported difficulties doing so. Thiswas independent of age (p = 0.04).Three patients (11%) reported a Chiari I malformation history in relatives; however,we did not explore heredity nor genetic aspects.In seven patients (25%), CMI was discovered serendipitously from a CT scan or-dered for minor head trauma. In two patients (7%), it was discovered after a cerebralMRI for developmental delay. In two other patients (7%), it was discovered after MRIordered for episodic faintness. Twelve children (43%) underwent cerebral imaging forrecurrent headaches and two (7%) for nuchal pain. Two children (7%) were investigated foroculomotor trouble and one (4%) for neurological deficit (sensory motor impairment).Dizziness and scoliosis were not reported as presenting symptoms or signs in anyof our cases; however, one patient with headaches reported vertigo as a main presentingsymptom, and two patients (7%) had scoliosis found at the initial examination. No patientsneeded to be treated for scoliosis and none of the aforementioned presenting aspects werefound to be significantly different between the two groups (see Table 4).Audiol. Res. 2024, 14 946Table 4. Presenting symptoms of enrolled patients, leading to cerebral imaging. The first presentingsymptom was headache, but the second most important way to diagnose was accidental finding(Fisher’s exact test).Presenting Symptom Total Population(n = 28)Group 1(n = 18)Group 2(Before Operation)(n = 10)p-ValueHeadaches 12 (43%) 6 (33%) 6 (60%) 0.24Accidental 7 (25%) 4 (22%) 3 (30%) 0.67Developmental delay 2 (7%) 2 (11%) 0 (0%) 0.52Malaise 2 (7%) 2 (11%) 0 (0%) 0.52Nuchal pain 2 (7%) 1 (6%) 1 (10%) 1.00Oculomotor deficit 2 (7%) 2 (11%) 0 (0%) 0.52Sensory-motor deficit 1 (4%) 1 (6%) 0 (0%) 1.00All but five children complained of headaches, with only one patient describingexertional pain. In 9/28 children (32%), pain was localized to the occipito-cervical region,while all other patients described frontal, fronto-temporal, or holocranial pain. All operatedchildren complained of headaches, but none described exertional ones. The frequency wasmostly weekly, without significant difference for any parameter. Nineteen children (68%)had a family history of migraine.Twelve patients (43%) described having vertigo with different frequencies and characteris-tics. Interestingly, we found a significant result (p = 0.013) comparing the presence of vertigo inthe operated versus non-operated patients (respectively, 50% and 6%), with occasional vertigobeing more common in the operated patients. These aspects are shown in Table 5.Table 5. Headaches and vertigo characteristics in the enrolled patients. Results based on patients’survey. Globally, headaches are declared by 82% of the enrolled patients, and in all operated children.No patients but one Group 1 patient declared exertional headaches. No significant differences werefound between the two groups. Concerning vertigo, prevalence in the total population was 43%, being60% in Group 2. Significant difference is noted in vertigo frequency (Fisher’s exact test). Significanceis expressed as follows: * = p < 0.05.Headaches and Vertigo TotalPopulation Not Operated Operated p-ValueHeadachesGlobal 23/28 (82%) 13/18 (72%) 10/10 (100%) 0.128Occipital headaches 9/28 (32%) 5/18 (28%) 4/10 (40%) 0.68Non-occipital headaches 14/28 (50%) 9/18 (6%) 6/10 (60%) 1.00Exertional headaches 1/28 (4%) 1/18 (6%) 0/10 (0%) 1.00Weekly headaches 17/28 (61%) 10/18 (56%) 7/10 (70%) 0.69Monthly headaches 6/28 (21%) 3/18 (17%) 3/10 (30%) 0.63Drugs resolving headaches 12/27 (44%) 6/17 (35%) 6/10 (60%) 0.26Rest and dark resolving headaches 4/27 (15%) 2/17 (12%) 2/10 (20%) 0.61Family migraine 19/28 (68%) 12/18 (67%) 7/10 (70%) 1.00Associated vomiting 6/27 (22%) 3/17 (18%) 3/10 (30%) 0.64VertigoGlobal 12/28 (43%) 6/18 (33%) 6/10 (60%) 0.24Weekly vertigo 6/28 (21%) 5/18 (28%) 1/10 (10%) 0.37Monthly vertigo 6/28 (21%) 1/18 (6%) 5/10 (50%) 0.013 *Positional vertigo 7/28 (25%) 4/18 (22%) 3/10 (30%) 0.67Exertional vertigo 4/28 (14%) 1/18 (6%) 3/10 (30%) 0.12Vision-related vertigo 1/28 (4%) 1/18 (6%) 0/10 (0%) 1.00Motion sickness 7/28 (25%) 5/18 (28%) 2/10 (20%) 1.00Audiol. Res. 2024, 14 947The evolution of headaches and vertigo in Group 2 patients was evaluated at postop-erative follow up, at which time three patients declared a complete resolution of headachesafter intervention, with a very low p-value (=0.052), even if not significant. It was the num-ber of patients who had “non-nuchal” headaches that better improved, with low p-value aswell. Two patients had persisting vertigo at the postoperative follow up, compared to sixbefore the intervention; moreover, even if any of the results are statistically significant, itis interesting to notice that positional vertigo disappeared completely after the operation(Table 6).Table 6. Evolution of headaches and vertigo after the intervention in Group 2 patients. Even if any ofthe results are significant from a statistical point of view, we found a really low p-value comparingpreoperative and postoperative headaches (p = 0.052), especially for non-nuchal pain (p = 0.059).Group 2 Before Intervention After Intervention p-ValueHeadaches 10/10 (100%) 7/10 (70%) p = 0.052Nuchal 4/10 (40%) 1/7 (14%) p = 0.527Non-nuchal 6/10 (60%) 6/7 (71%) p = 0.059Vertigo 6/10 (60%) 2/10 (20%) p = 0.593Positional 3/10 (30%) 0/2 p = 0.655Exertional 3/10 (30%) 1/2 (50%) p = 0.317Brutal 0/10 1/2 (50%) p = 0.317Generally, all operated patients reported a better quality of life after surgery at thefollow-up meetings, due to a reduction or disappearance of such symptoms.In Table 7, we report data concerning the degrees of cerebral ptosis and polysomno-graphic results. At cerebral MRI, 12 patients (42%) had a more than 10 mm cerebellar ptosis,1 patient (3.5%) had ventriculomegaly, and 3 patients (10.5%) had syringomyelia at diagnosis.Seven Group 2 patients (70%) had greater than one-centimeter-sized tonsillar ptosis. Thisdifference is significant. However, one can suggest that the greater the ptosis, the greaterthe possibility of having a CSF circulation problem at the craniocervical junction. The fourchildren in the series (15% of total population) presenting with central sleep apnea syndromewere operated on, as respiratory problems related to brainstem compression is an absolutecriterion for decompressive surgery. For this reason, comparison between the two groups isnot useful. Two of them presented a central apnea index superior to 5/h. Fifteen children(56%) presented with obstructive apnea syndrome (OSAS), which is significantly higherthan the prevalence in the pediatric age group previously reported by Rydel et al. (10.3% ina population of 399 infants and adolescents from 2 to 18 years of age) [41]. However, furtherconsideration about these two topics is beyond the scope of our paper.Twelve patients (43%) described having vertigo with different frequencies and charac-teristics. Interestingly, we found a significant result (p = 0.013) comparing the presence ofvertigo in operated versus non-operated patients (respectively, 50% and 6%), with occa-sional vertigo being more common in patients who will be operated on. These aspects areshown in Table 5.Given the frequent association of audiovestibular symptoms in CMI patients, asdiscussed above, an ENT assessment was carried out in all children.The clinical evaluation made by the first author, a neurosurgeon (I.S.), revealed normalneurological status in 13 (72%) Group 1 patients and 3 (30%) Group 2 patients (Table 8).This difference is significant (p = 0.049); however, we found that these results may be relatedto the fact that symptomatology is one of the criteria for surgical intervention. Two children(10%) in Group 2, but none in Group 1, presented with disorders of coordination (ataxia inthe upper limbs). Balance disorders were diagnosed by widening of the support polygon,inferior limb ataxia, a positive Romberg’s test, or a history of frequent falls. They wereAudiol. Res. 2024, 14 948found in two Group 1 patients (11%) and in two Group 2 patients (10%) (not significant).Pyramidal signs were slightly less frequent in Group 1 (18%) than in Group 2 (22%).Table 7. (A) Radiologic details concerning the degree of cerebellar ptosis and presence of syringomyelia.(B) Polysomnography results. Significant difference is obviously found, because syringomyelia andCSAS are absolute criteria to operate (Fisher’s exact test). In the same manner, the most important factoris the degree of tonsillar ptosis. A higher degree is related to an increased probability of the patientdeveloping CSF circulation pathology at the craniocervical junction. In Group 1, polysomnographic dataare missing for one patient. AHI: Apnea-hypopnea index; OAHI: Obstructive Apnea-hypopnea index.Significance is expressed as follows: * = p < 0.05 and ** = p < 0.01.Variable Total Population(n = 28/27)Group 1(n = 18/17)Group 2 (BeforeOperation) (n = 10) p-ValueATonsillar ptosis > 1 cm 12/28 (43%) 5/18 (28%) 7/10 (70%) 0.049 *Syringomyelia 4/28 (14%) 0 (0%) 4/10 (40%) 0.010 **BCentral apnea syndrome 4/27 (15%) 0/17 (0%) 4/10 (40%) 0.012 *AHI > 5/h 2/27 (7%) 0/17 (0%) 2/10 (20%) 0.13Obstructive apnea syndrome 15/27 (56%) 9/17 (53%) 6/10 (60%) 1.00OAHI > 5 2/27 (7%) 2/17 (12%) 0/10 (0%) 0.52Table 8. Neurologic and audiovestibular findings in the enrolled patients. In the group of operatedpatients, data are lacking for one patient. Neurological examination was carried out by the firstauthor (I.S.), while ENT assessment was realized by the second author (Ph.P.). A significant differencewas found when comparing the two groups with regard to the presence of sensory disorders, and alow p-value was shown when comparing the presence of dizziness between the two groups (Fisher’sexact test). Significance is expressed as follows: * = p < 0.05 and ** = p < 0.01.Variable Total Population(n = 28/27)Group 1(n = 18/17)Group 2(Before Operation)(n = 10)p-ValueNeurologicalNormal 16/28 (57%) 13/18 (72%) 3/10 (30%) 0.049 *Coordination disorders 2/28 (7%) 0/18 (0%) 2/10 (20%) 0.12Balance disorders (ataxia) 4/28 (14%) 2/18 (11%) 2/10 (20%) 0.60OTR anomalies 6/28 (21%) 4/18 (22%) 2/10 (20%) 1.00Sensitive disorders 4/28 (14%) 0/18 (0%) 4/10 (40%) 0.010 **Oculomotor trouble 1/28 (4%) 0/18 (0%) 1/10 (10%) 0.36ENTNormal 12/27 (44%) 10/18 (56%) 2/9 (22%) 0.22Vestibular deficit 1/27 (4%) 1/18 (6%) 0/9 (0%) 1.00Nystagmus 1/27 (4%) 0/18 (0%) 1/9 (11%) 0.33Saccadic eye movements 7/27 (26%) 3/18 (17%) 4/9 (44%) 0.18Dizziness 4/27 (15%) 1/18 (6%) 3/9 (33%) 0.093Hearing loss 7/27 (26%) 4/18 (22%) 3/9 (33%) 0.65Tinnitus 3/27 (11%) 1/18 (6%) 2/9 (22%) 0.25From the ENT point of view, 10 patients (56%) in Group 1 and 2 patients in Group 2(22%) had normal otoneurological examinations. Data are lacking for one operated patient(n◦ 9), as shown in Table 7, which shows neuro-otological findings. Only one patient inGroup 1 presented with clinical vestibular disease. Nystagmus was found in only onepatient (11%) in Group 2, while saccadic pursuit was observed in three Group 1 patientsAudiol. Res. 2024, 14 949(17%) and four Group 2 patients (44%). Although not technically significant, a slightlylow p-value (0.093) was found comparing the presence of dizziness (33%). Subnormalthresholds in pure-tone conventional audiometry were noted in four patients in Group 1(22%) and two patients in Group 2 (33%). These results are not statistically different.Equitest® dynamic posturographic evaluation has been utilized as a complement toENT investigations. The mean SOT in the whole population was 65.6 (range 65.3–76.5); inaddition, when the two groups are separately evaluated, the mean SOT in Group 1 was 66(64.0–76.0), and in Group 2 it was 62.3 (66.0–77.5), without statistical differences (p = 0.655),as shown in Table 9.Table 9. Posturographic results of Group 1 patients and Group 2 patients before the intervention. Nosignificant difference is found comparing global SOT and the 3 ratios. On the contrary, lateral CoGdeviation is significantly different between the 2 groups (Wilcoxon–Mann–Whitney test; §: Fisher’sexact test).Variable Total Population (n = 28) Group 1 (n = 18) Group 2 (BeforeOperation) (n = 10) p-ValueSOT 65.6 (65.3–76.5) 66 (64–76) 62.3 (66–77.5) 0.655 §Somesthetic Ratio 97.0 (91.5–98.5) 97.5 (95.0–98.0) 85.7 (73.5–98.5) 0.37 §Visual Ratio 85.5 (74.5–91.5) 86.0 (79.0–91.0) 73.1 (68.5–94.3) 0.98Vestibular Ratio 60.0 (40.5–69.0) 61.0 (41.0–69.0) 49.5 (42–63) 0.41Lateral deviation 9 (32%) 3 (17%) 6 (60%) 0.35Inappropriate strategy 11 (39%) 6 (33%) 5 (50%) 0.44Interestingly, we found significant results comparing lateral deviation attitude duringposturography, with 17% of abnormal lateral CoG deviation in Group 1, versus 60% inGroup 2.When the same parameters were studied in Group 2, comparing pre and post surgery,a significant difference was seen in the global SOT results (p = 0.007). In particular, wefound that the sensorineural component of postural control that improved the most wasthe vestibular one, with a p = 0.007 (see Table 10). Low p-values were found comparingsomesthetic and visual ratios.Table 10. Preoperative and postoperative posturographic results in the Group 2 patients. Significantdifferences were found comparing global SOT and vestibular ratio. Interestingly, low p-values werefound when comparing somesthetic and visual ones. In the same way, lateral CoG deviation is alsosignificantly different (Wilcoxon–Mann–Whitney test; §: Fisher’s exact test). Significance is expressedas follows: * = p < 0.05 and ** = p < 0.01.Group 2 (n = 10) Before Surgery After Surgery p-ValueSOT 62.3 (66–77.5) 73.9 (67–80.8) 0.007 § **Somesthetic ratio 85.7 (73.5–98.5) 97.6 (95.3–99.5) 0.096 §Visual ratio 73.1 (68.5–94.3) 85.1 (74.8–93.5) 0.084 §Vestibular ratio 49.5 (42–63) 65.3 (60.5–77.5) 0.005 § **Lateral deviation 6/10 (60%) 0/10 (0%) 0.011 *Inappropriate strategy 5/10 (50%) 1/10 (10%) 0.141A graphic representation of such results is reported in Figure 2.Audiol. Res. 2024, 14 950Audiol. Res. 2024, 14, FOR PEER REVIEW 12 Figure 2. Graphic representation of posturographic results. Global SOT and vestibular ratio improve significantly after surgery. Significance is expressed as follows: ** = p < 0.01. Also, lateral deviation improves significantly after surgery (p = 0.01), as graphically reported in Figure 3. Figure 3. Graphic representation of lateral deviation comparison and significant postoperative dif-ference. Comparison between the two groups did not find any significant difference; p = 0.35. On the contrary, real improvement was noticed between before and after the intervention; p = 0.011. Significance is expressed as follows: * = p < 0.05 and NS = p > 0.05 Lateral deviation also improved significantly after surgery (p = 0.01), as illustrated in Figure 2. In order to further our knowledge about this finding, we retrospectively checked the preoperative MRI and surgical reports of the operated patients. Although we cannot establish any significant correlation, we found that, in four patients, there was a perfect correspondence between the side of posturography lateralization, MRI 3D FLAIR signal tonsillar anomaly, and the side of tonsillectomy (which normally corresponds to the greater descending tonsil on MRI). Figure 4 shows the pre- and postoperative results of Figure 2. Graphic representation of posturographic results. Global SOT and vestibular ratio improvesignificantly after surgery. Significance is expressed as follows: ** = p < 0.01.Also, lateral deviation improves significantly after surgery (p = 0.01), as graphicallyreported in Figure 3.Lateral deviation also improved significantly after surgery (p = 0.01), as illustrated inFigure 2. In order to further our knowledge about this finding, we retrospectively checkedthe preoperative MRI and surgical reports of the operated patients. Although we cannotestablish any significant correlation, we found that, in four patients, there was a perfectcorrespondence between the side of posturography lateralization, MRI 3D FLAIR signaltonsillar anomaly, and the side of tonsillectomy (which normally corresponds to the greaterdescending tonsil on MRI). Figure 4 shows the pre- and postoperative results of one of thepatients. Two other patients, who presented a little MRI FLAIR bilateral tonsillar anomaly,had a normal CoG without any lateralization, and one of them benefited from minimalbilateral tonsillar coagulation.Audiol. Res. 2024, 14, FOR PEER REVIEW 12 Figure 2. Graphic representation of posturographic results. Global SOT and vestibular ratio improve significantly after surgery. Significance is expressed as follows: ** = p < 0.01. Also, lateral deviation improves significantly after surgery (p = 0.01), as graphically reported in Figure 3. Figure 3. Graphic representation of lateral deviation comparison and significant postoperative dif-ference. Comparison between the two groups did not find any significant difference; p = 0.35. On the contrary, real improvement was noticed between before and after the interv ntion; p = 0.011. Significance is expressed as follows: * = p < 0.05 and NS = p > 0.05 Lateral deviation also improved significantly after surgery (p = 0.01), as illustrated in Figure 2. In order to further our knowledge about this finding, we retrospectively checked the preoperative MRI and surgical reports of the operated patients. Although we cannot establish any significant correlation, we found that, in four patients, there was a perfect correspondence between the side of posturography lateralization, MRI 3D FLAIR signal tonsillar anomaly, and the side of tonsillectomy (which normally corresponds to the greater descending tonsil on MRI). Figure 4 shows the pre- and postoperative results of Figure 3. Graphic representation of lateral deviation comparison and significant postoperativedifference. Comparison between the two groups did not find any significant difference; p = 0.35.On the contrary, real improvement was noticed between before and after the intervention; p = 0.011.Significance is expressed as follows: * = p < 0.05 and NS = p > 0.05.Audiol. Res. 2024, 14 951Audiol. Res. 2024, 14, FOR PEER REVIEW 13 one of the patients. Two other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without any lateralization, and one of them benefited from minimal bilateral tonsillar coagulation. Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly and lateral deviation on posturography was found in four patients of Group 2. (A) FLAIR axial images at craniovertebral junction of patient number 26, showing sufferance signal of left tonsil, going toward the median line. (B) Posturographic results showed a deviation of CoG toward the left side (alignment du CDG: center of gravity alignment; CoG: center of gravity). Each shape in subfigure B corresponds to each sensory condition: : condition 1; : condition 2; : condition 3; condition 4; : con-dition 5; condition 6. However, the small number of patients included in our series did not allow us to perform a statistical analysis for this aspect. We are increasing the number of patients in our study to try and confirm our speculations. 4. Discussion The results showed a significant improvement of global SOT after intervention (p = 0.007), leading us to believe that surgical treatment of Chiari malformation improves pos-tural control in the pediatric population. When the three sensorial afferences determining postural control were independently considered, comparison between pre and post inter-vention showed low p-values for somesthetic and visual ratios, but a significant difference (p = 0.005) for the vestibular one. These data suggest that the most impacted system in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on the preoperative CDP in the Group 2 patients, which significantly differed from that of Group 1 patients. This lateral deviation reduced significantly after intervention in the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that there is a correspondence between the direction of lateral deviation and the side of tonsil-lar signal anomaly on 3D FLAIR sequences. If such a correspondence can be confirmed, axial 3D FLAIR images and CDP could be included in the standardized workup of CMI patients, as it would be of help in making a surgical decision. Further work is needed to corroborate this finding, as our numbers are too low to show significance. From a neurosurgical point of view, it is crucial for us to know what might be related to CMI in order to assure the best care for our patients. In CMI patients who manifest Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly and lateral deviation onposturography was found in four patients of Group 2. (A) FLAIR axial images at craniovertebraljunction of patient number 26, showing sufferance signal of left tonsil, going toward the medianline. (B) Posturographic results sho ed a deviation of CoG to ard the left side (align ent du CDG:center of gravity align ent; CoG: center of gravity). Each shape in subfigure B cor esponds to eachsensory condition:Audiol. Res. 2024, 14, FOR PEER REVIEW 13 one of the patients. Two other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without any lateralization, and one of them benefited from minimal bilateral tonsillar coagulation. Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly and lateral deviation on posturography was found in four patients of Group 2. (A) FLAIR axial images at craniovertebral juncti n of patient numbe 26, showing sufferance signal of left tonsil, going toward t e m dian line. (B) Posturographic results showed a deviation of CoG toward the left side (alignment du CDG: center of gravity alignment; CoG: center of gravity). Each shape in subfigure B corresponds to each sensory condition: : condition 1; : condition 2; : condition 3; ndition 4; : con-dition 5; condition 6. However, the small number of patients included in our series did not allow us to perform a statistical analysis for this aspect. We are increasing the number of patients in our study to try and confirm our speculations. 4. Discussion The results showed a significant improvement of global SOT after intervention (p = 0.007), leading us to believe that surgical treatment of Chiari malformation improves pos-tural control in the pediatric population. When the three sensorial afferences determining postural control were independently considered, comparison between pre and post inter-vention showed low p-values for somesthetic and visual ratios, but a significant difference (p = 0.005) for the vestibular one. These data suggest that the most impacted system in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on the preoperative CDP in the Group 2 patients, which significantly differed from that of Group 1 patients. This lateral deviation reduced significantly after intervention in the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that there is a correspondence between the direction of lateral deviation and the side of tonsil-lar signal anomaly on 3D FLAIR sequences. If such a correspondence can be confirmed, axial 3D FLAIR images and CDP could be included in the standardized workup of CMI patients, as it would be of help in making a surgical decision. Further work is needed to corrobora e this finding, as our numbers are too low to show significance. From a neurosurgical point of view, it is crucial for us to know what might be related to CMI in order to assure the best care for our patients. In CMI patients who manifest : condition 1;Audiol. Res. 2024, 14, FO P ER REVIEW 13 one of the patients. Two other patients, who pr sented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without ny lateralization, a d one of th m benefited from inim l bilateral tonsill r coagulation. Figure 4. Correspondence between FLAIR MRI ton illar signal nomaly and lat ral deviation on posturography was found in four patients f Group 2. ( ) FLAIR axial images at craniovertebral junction of patient number 26, s owing suff rance signal of left tonsil, g ing toward the me ian line. (B) Posturographic results show d deviation of CoG toward the left side (alignment du CDG: center of gr vity alignment; CoG: center of gravity). Each shape in subfigure B corresponds to each se sory c dition: : c diti 1; : c dition 2; : c dition 3; c dition 4; : con-dition 5; c dition 6. Howev r, the small number of patients included in our series did n t allow us to perform a statistic l analysis for this aspect. We are increasing the number of patients in our study to try a d confirm our speculations. 4. Discussion The re ults showed a sig ificant improvement of global SOT aft intervention (p = 0.007), leading us to believe that surgic l tr atment of Chi ri malformation improves pos-tural control in the pediatric population. W n the three sensorial aff rences determining postural control wer independently considered, comparison betwe n pre and post inter-venti n showed low p-value for omesthetic and visual ratios, but a sig ificant diff rence (p = 0.005) for the vestibular on . These data suggest t at the most impacted syste in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on the preoperative CDP in the Group 2 patients, which sig ificantly differed from that f Group 1 patients. This lateral deviation r uced sig ificantly aft intervention in the Group 2 patie ts, increasing the value of our findings. This finding may be of particular importance, as it suggests that there is a correspondence betwe n the direction of lateral deviation and the side of tonsil-lar sig al anomaly on 3D FLAIR sequences. If su h a correspondence can be confirmed, axial 3D FLAIR im ges and CDP could be included in the standardized workup of CMI patients, as it would be of help in making a surgical decision. Further work is needed to c rroborate this finding, as our numbers are too low to show sig ificance. From a neurosurgical point of view, it is crucial for us to know what might be related to CMI in order to assure the best care for our patie ts. In CMI patients who manifest : condition 2;Audiol. Res. 2024, 14, FOR PEER REVIEW 13 one of the patients. Two other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without any lateralization, and one of them benefited from minimal bilateral tonsillar coagulation. Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly and lateral deviation on posturography was found in four patients of Group 2. (A) FLAIR axial images at craniovertebral junction of patient number 26, showing sufferance signal of left tonsil, going toward the median line. (B) Posturographic results showed a deviation of CoG toward the left side (alignment du CDG: center of ravity alignment; CoG: center of ravity). Each shape in subfigure B corresponds to each sensory condition: : condition 1; : condition 2; : condition 3; condition 4; : con-dition 5; condition 6. However, the small number of patients included in our series did not allow us to perform a statistical analysis for this aspect. We are increasing the number of patients in our study to try and confirm our speculations. 4. Discussion The results showed a significant improvement of global SOT after intervention (p = 0.007), leading us to believe that surgical treatment of Chiari malformation improves pos-tural control in the pediatric population. When the three sensorial afferences determining postural control were independently considered, comparison between pre and post inter-vention showed low p-values for somesthetic and visual ratios, but a significant difference (p = 0.005) for the vestibular one. These data suggest that the most i pacted system in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on the preoperative CDP in the G oup 2 patients, which significantly differed from that of Group 1 patients. This lateral deviation reduced significantly after intervention in the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that there is a correspondence between the direction of lateral deviation and the side of tonsil-lar signal anomaly on 3D FLAIR sequences. If such a correspondence can be confirmed, axial 3D FLAIR images and CDP could be included in the standardized workup of CMI patients, as it would be of help in making a surgical decision. Further work is needed to corroborate this finding, as our numbers are too low to show significance. From a neurosurgical point of view, it is crucial for us to know what might be related to CMI in order to assure the best care for our patients. In CMI patients who manifest : condition 3;Audiol. Res. 2024, 14, FOR PEER REVIEW 13 ne of the patients. Two other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG wi hout any lateralization, a d ne of them benefited from inimal bilateral tonsillar co gulation. Figure 4. Correspondence b tween FLAI MRI tonsillar sig al anomaly nd lateral deviation on p sturography was found in four patients of Group 2. (A) FLAIR axi l im ges at craniovertebral ju ction of patient number 26, showing sufferance signal of left tons l, going toward the median line. (B) P sturographic re ults showed a deviation of CoG toward the left side (alignment du CDG: center of grav ty alignment; CoG: center of gravity). Ea shape in s bfig re B corresponds to each sens ry condition: : condition 1; : condition 2; : condition 3; condition 4; : con-dition 5; condition 6. However, the small number of patie ts included in our eries did not allow us to perform a atistical analysis for this aspect. We are increasing the number of patie ts in o r study to try and confirm our speculations. 4. Di cussion The results showed a significant improvement f g obal SOT after intervention (p = 0.007), leading us to b lieve that surgical treatment of Chiari malformation improves pos-tural c ntrol in the pediatric population. When th three sensorial afferences determining postural c ntrol were independently consi ered, comparison b tween pre and post inter-vention showed low p-values for som sthetic and visual ratios, but a significant difference (p = 0.005) for the vestibular one. These data suggest t at the most impacted system in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on th reoperative CDP in the Group 2 patients, wh ch significantly diffe ed from that of Gr up 1 patients. This lateral deviation re uced significantly after intervention in the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that ere is a correspondenc b twe n th d rection of lateral deviation and th side of tonsil-lar signal anomaly on 3D FLAIR sequence . If such a correspondence can be confirmed, axial 3D FLAIR images and CDP could be included in the standar ized workup of CMI patients, as it would be of help in making a surgical decision. Furthe work is needed to cor oborate this finding, as o r numbers are too l w t show significance. From a ne osurgical p int of view, it is crucial for us t know what might be related to CMI in order to assure the best care fo our patients. In CMI patients who manifest : condition 4;Audiol. es. 2024, 14, FOR PEER REVIEW 13 one f the ti t . Tw other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without any lateralization, and one of them benefited from minimal bilateral tonsillar coagulation. Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly a d lateral deviation on posturography was f und in four patients of Group 2. (A) FLAIR axial images at craniovertebral junction of patient number 26, show ng sufferance signal of left tonsil, going tow rd the median lin . (B) Posturographic results showed a deviation of CoG toward the left side (alignment du CDG: center of gravity alignment; CoG: center of gravity). Each shape i subfigure B corresponds to each sensory condition: : condition 1; : condition 2; : condition 3; condition 4; : con-dition 5; condition 6. However, the small number of patients inclu ed in our series did not allow us to perform a statistical analysis for this pect. We are increasing the number of patients in our study to try and c firm our speculations. 4. Discussion The results showed a sig ificant improvement of global SOT after intervention (p = 0.007), leading us to believe that surgical treat ent of Chiari alformation improves pos-tural control in the pediatric populatio . When the thr e s nsorial afferences determining postural control were ind pendently c sidered, comparison betw en pre and post inter-vention h wed low p-values for somesthetic and visual ratios, but a significant difference (p = 0.005) for t vestibular one. These data uggest that the most impacted system in CMI children is the vestibular system. Intere tingly, we also observed lateral deviation on the preoperative CDP in the Group 2 pati ts, which significantly differed from that f Group 1 patients. This lateral deviation reduced significantly aft r intervention i the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that ther is a correspondence between the direction of lateral eviation and the side of tonsil-lar signal anomaly on 3D FLAIR sequ nces. If such a correspond nce can be confirmed, axial 3D FLAIR imag s and CDP could be includ in the standardized workup of CMI patients, as it would be of help in making a surgical deci ion. Further work is needed to corroborate this findi g, as our numbers are too low to show significance. From a neurosurgical point f view, it is cruci l for us to know what might be related to CMI in order to assure the b st care for our patients. In CMI patients who manifest : condition 5;Audiol. Res. 2024, 14, FOR PEER REVIEW 13 one of the patients. Two other patients, who presented a little MRI FLAIR bilateral tonsil-lar anomaly, had a normal CoG without any lateralization, and one of them benefited from minimal bilateral tonsillar coagulation. Figure 4. Correspondence between FLAIR MRI tonsillar signal anomaly and lateral deviation on posturography was found in four patients of Group 2. (A) FLAIR axial images at craniovertebral junction of patient number 26, showing sufferance signal of left tonsil, going toward the median line. (B) Posturographic esults showed a devia ion f CoG toward the left side (alignment du CDG: center of gravity alignment; CoG: center of gravity). Each shape in subfigure B corresponds to each sensory conditi n: : conditi n 1; : condition 2; : conditi n 3; condition 4; : con-dition 5; condition 6. However, the small number of patients included in our series did not allow us to perform a statistical analysis for this aspect. We are increasing the number of patients in our study to try and confirm our speculations. 4. Discussion The results showed a significant improvement of global SOT after intervention (p = 0.007), leading us to believe that surgical treatment of Chiari malformation improves pos-tural control in the pediatric population. When the three sensorial afferences determining postural control were independently considered, compariso between pre and post inter-vention showed low p-values for somesthetic and visual ratios, but a significant difference (p = 0.005) for the vestibular one. These data suggest that the most impacted system in CMI children is the vestibular system. Interestingly, we also observed lateral deviation on the preoperative CDP in the Group 2 patients, which significantly differed from that of Group 1 patients. This lateral deviation reduced significantly after intervention in the Group 2 patients, increasing the value of our findings. This finding may be of particular importance, as it suggests that there is a correspondence between the direction of lateral deviation and the side of tonsil-lar signal anomaly on 3D FLAIR sequences. If such a correspondence can be confirmed, axial 3D FLAIR images and CDP could be included in the standardized workup of CMI patients, as it would be of help in making a surgical decision. Further work is needed to corroborate this finding, as our numbers are too low to show significance. From a neurosurgical point of view, it is rucial for us to know what might be related to CMI in order to assure the best care for our patients. In CMI patients who manifest : condition 6.o e r, the all nu ber of patients incl e i our series did not allo us toperfor a statistical analysis for this aspect. e are increasing the nu ber of patients inour study to try and confirm our speculations.4. isc ssioTh res lts s e a significant i provement of global SOT after interve tion(p = 0.007), leading us to b lieve that surgic l treat ent of Chiar malfor ation improvespostural ontrol i t pedi tric pop lation. When the three sensorial afferences deter-mining postural control re i depen ntly considered, com arison between pre andpost intervention sh we ow p-valu s for som st etic and visual ratios, but a significantdiffere ce (p = 0.005) for the vestibula one. These dat suggest that the most impactedsystem in CMI children is the vestibular sy tem.Interestingly, we al o observ lateral devia ion o the preoperative CDP in theGroup 2 patients, wh ch sig ificantly diffe ed from tha of Group 1 patients. This lateraldeviation reduced si nific ntly aft r interventio in t e Group 2 pati nts, increasing thevalu of o findings. This finding may be of particular importance, as it suggests thatthere is a correspondence between the direction of lateral deviation and the side of tonsillarsignal anomaly on 3D FLAIR sequences. If such a correspondence can be confirmed, axial3D FLAIR images and CDP could be included in the standardized workup of CMI patients,as it would be of help in making a surgical decision. Further work is needed to corroboratethis finding, as our numbers are too low to show significance.From a neurosurgical point of view, it is crucial for us to know what might be relatedto CMI in order to assure the best care for our patients. In CMI patients who manifestsigns or symptoms clearly related to the malformation (i.e., central sleep apnea syndrome,syringomyelia, effort headaches, and tetra paresis), the need for surgical treatment is rapidlyestablished. However, vestibular assessment may become an essential assessment in acategory of CMI patients called “asymptomatic” or “oligo symptomatic”, because of theAudiol. Res. 2024, 14 952absence of typical CMI symptoms. Many papers have been published on this subject, butthe cause and effect relationship between the otoneurological signs and symptoms andCMI still remains a source of debate in the neurosurgical community [42]; in addition, thiscan create controversy regarding surgical management, as these symptoms and signs arenot historically directly attributed to the presence of CMI [43] and do not provide sufficientinformation for the neurosurgeon to make a decision about surgical intervention. However,in a recent special journal issue, these ENT symptoms have been reported as possible CMImanifestations and have been defined as ‘atypical’ symptoms by Novegno et al. [44]. Forthis reason, an ENT assessment should be required for all CMI patients.In the literature, we found only two papers [29,30] that studied the relationshipbetween CMI and posturographic assessment; however, neither study reported any infor-mation about the lateral sway pattern, which suggests that our study is the first one to lookat lateral deviation in children with CMI.Famili [29] studied Equitest® results in a cohort of 24 CMI adults (21/24 females, agedfrom 20 to 61 years) who complained about dizziness symptoms. The data suggested asignificantly lower use of somatosensory information, but a peripheral vestibular lesionwas found in only 8% of patients, suggesting a central origin of dizziness in this population.It is difficult to determine (especially in the pediatric population) whether the vestibu-lar impairment in CMI results from damage to afferent fibers of the spinocerebellar bundle,from cranial nerve dysfunction (in the central or peripheral portion), or from the cerebellarvestibular nuclei. The vestibular system is a complex neuronal pathway whose central com-ponent is situated mostly in the posterior fossa, at the level of the craniocervical junction(Figure 5). It includes the cerebellar nuclei and cranial nerve nuclei in the brainstem. Theperipheral portion of the vestibular system includes the VIIth cranial nerve, which leavesthe brainstem to reach its destination through the acoustic pore.Audiol. Res. 2024, 14, FOR PEER REVIEW 14 signs or symptoms clearly related to the malformation (i.e., central sleep apnea syndrome, syringomyelia, effort headaches, and tetra paresis), the need for surgical treatment is rap-idly established. However, vestibular assessment may become an essential assessment in a category of CMI patients called “asymptomatic” or “oligo symptomatic,” because of the absence of typical CMI symptoms. Many papers have been published on this subject, but the cause and effect relationship between the otoneurological signs and symptoms and CMI still remains a source of debate in the neurosurgical community [42]; in addition, this can create controversy regarding surgical management, as these symptoms and signs are not historically directly attributed to the presence of CMI [43] and do not provide suffi-cient information for the neurosurgeon to make a decision about surgical intervention. However, in a recent special journal issue, these ENT symptoms have been reported as possible CMI manifestations and have b en defined as ‘atypical symptoms by Novegno et al. [44]. For this reason, an ENT assessment should be required for all CMI patients. In the literature, we found only two papers [29,30] that studied the relationship be-tween CMI and posturographic ass ssment; however, neither study reported any infor-mation about the lateral sway pattern, which suggests that our study is the first one to look at lateral deviation in children with CMI. Famili [29] studied Eq itest® results in a cohort of 24 CMI adults (21/24 females, aged from 20 to 61 years) who complained about dizziness symptoms. The data suggested a significantly lower use of somatosensory information, but a peripheral vestibular lesion was found in o ly 8% of patients, suggesting a central origin of dizziness in this popula-tion. It is difficult to determine (especially in the pediatric population) whether the vestib-ular impairment in CMI results from damage to afferent fibers of the spinocerebellar bun-dle, from ranial nerv dysfunction (in the centr l or peripheral portion), or from the cer-ebellar vestibular nuclei. The vestibular system is a complex neuronal pathway whose central component is situated mostly in the posterior fossa, at the level of the craniocervi-cal junction (Figure 5). It includes the cerebellar nuclei and cranial nerve nuclei in the brainstem. The peripheral portion of the vestibular system includes the VIIth cranial nerve, which leaves the brainstem to reach its destination through the acoustic pore. Figure 5. Schematic reconstruction of the neural pathway implicated in the sensory neural integra-tion for postural control. Direct compression on the flocculo-nodular lobe, spinocerebellar and cerebello-ves-tibular tracts, or vestibular nuclei, or distortion of vestibular nerves could produce balance Figure 5. Schematic reconstruction of the neural pathway implicated in the sensory neural integrationfor postural control.Direct compression on the flocculo-nodular lobe, spinocerebellar and cerebello-vestibulartracts, or vestibular nuclei, or distortion of vestibular nerves could produce balance problemsAudiol. Res. 2024, 14 953and ataxia. In addition, at the same level, olivary nuclei are interlaced in the pretectal flocculo-nodular pathway, which is implicated in the modulation of the visual information that isessential for balance control (e.g., optokinetic nystagmus and ocular pursuit) [45].A hypothesis has been proposed [9] that a central origin of vestibular impairmentin CMI patients is most likely. This is consistent with other reports [29,46]. Monchoet al. [42,47] showed an abnormal brainstem auditory-evoked potential (BAEP) in a cohortof 200 CMI adult patients, mainly at the retrocochlear level, suggesting the implicationof CMI-related brainstem distortion (i.e., a central origin). A recent study of patientswith endolymphatic hydrops (i.e., a peripheral vestibulopathy) showed problems withperilymph–CSF dynamics due to CSF hydrodynamic alterations at the foramen magnumlevel and suggested that this may be a possible mechanism of ENT-related symptoms inCMI patients [20].In our study, a complete neuro-otological examination, accompanied by audiometryand further management, if deemed necessary, was carried out on all of the children.However, given the limited cooperation of children, we did not include systematic complexinstrumental ENT examination, even though that would have helped us to delineatebrainstem involvement from peripheral vestibular involvement [17]. A lack of cooperation,mental disability, behavioral trouble, orthopedic disease, and visual impairment are allfactors that might influence the CPD results. For this reason, children presenting with anyof these issues were not included in this study.Children generally have fewer comorbidities than adults, and they do not normallypresent with degenerative body issues that might also affect postural control. In our study,none of the operated children showed clinical vestibular impairment before intervention, thusreinforcing the idea that postoperative vestibular improvement detected on CPD is directlylinked to craniovertebral junction decompression rather than from other confounding factors.A lack of cooperation is one of the most important limiting factors in a clinical studyin children of this age, as it narrows the wide spectrum of available tests for the study ofthe vestibular system, which reduces the precision of the assessment in such a population.In addition, we feel it is important in this discussion to outline the specificity of thedevelopment of the vestibular system in the pediatric population. This will also help us tocome to some conclusions regarding our results.Sensory inputs utilized by the balance system (somesthetic, visual, and proprioceptiveinputs) change progressively during development [40,48–51]. Sinno et al. [51] recentlystudied 120 healthy children utilizing Equitest®, reported SOT normative data throughoutchildhood and adolescence, and outlined how postural abilities change during develop-ment. Compared to adults, younger children utilize more somatosensory inputs. Eventhough the vestibular system is the first system to develop and is morphologically com-plete at birth, vestibular maturity is reached later, as it entails a higher processing centerof neurosensory inputs utilized for postural control. In addition, balance performancedeclines not only between the young and the elderly, but also from decade to decade, asdemonstrated by the Polish team of Pierchala et al. [52].The age difference may be one of the reasons for the fact that our results are in contrastwith the posturographic results in adults reported by Famili [29]. In addition, that studywas characterized by a high prevalence of females (90%), and one might suggest that thisgender distribution imbalance might have influenced their results. In our study, genderdistribution was equal in Group 2, although there was a slight female prevalence (66%) inthe overall population. There are few papers directly addressing gender influence on CDPresults [53], but some studies [48–50,54] have also reported this information, while focusingprimarily on aged-related modifications. It is generally assumed that, with increasing age,scores worsen in both males and females in more difficult CDP conditions (Conditions 5and 6) [55,56]. In a study conducted by Faraldo-Garcia et al. [53], females seemed to bebetter at integrating sensory vestibular information than males, as well as at dealing withvisual conflict.Audiol. Res. 2024, 14 954One may also ask if learning phenomena or age-related bias might influence ourresults. Given the structure of our study [28], age-related improvement is not a factor, asposturographies were performed 2 to 3 months before and 3 to 4 months after surgicalintervention. This laps of time is not enough to observe dramatic improvement of complexsensory integration ability due to the child’s growth. In the same way, it is too long tosignificantly impact memory, so it cannot explain SOT postoperative improvement.In our study, the SOT and vestibular ratio improvement observed after surgery forCM1 leads us to believe that posterior fossa overcrowding in this disorder disturbs thepostural abilities, predominantly affecting the vestibular system. As the most significantlimit of our study is the small sample size, we are continuing our study so that our samplesize can be increased.5. ConclusionsThe surgical indication for CMI patients may be obvious when concerning symptomsand signs, such as syringomyelia or sleep apnea syndrome, are present. However, decisionsmade regarding surgical management may be more controversial when patients are asymp-tomatic or when they present with “atypical” symptoms and signs, such as vestibularand postural complaints. Due to the increasing awareness about the existence of theseatypical symptoms in CMI, a specific ENT evaluation is highly recommended as part of apreoperative workup. This is particularly important in children, as it is even more difficultto determine the presence of symptoms linked to CMI, and also more difficult to take anaccurate history to clarify their signs and symptoms.Computerized dynamic posturography may be a good solution to examine ataxia andpostural patterns in children with CMI over 6 years of age, as it is a safe and sensitivemeasuring tool. However, further studies with a greater number of patients are necessaryto better elucidate the role of CDP in the workup of CMI patients.Author Contributions: Conceptualization: I.S., O.K. and P.P.; methodology: I.S. and M.C.; validation:P.P. and O.K.; formal analysis: M.C.; investigation: I.S. and P.P.; resources: I.S., O.K. and A.J.; datacuration: I.S.; writing—original draft preparation: I.S.; writing—review and editing: I.S., P.P. andA.M.; visualization: O.K., A.J., M.C. and A.M.; supervision: P.P. and O.K.; funding acquisition: I.S.All authors have read and agreed to the published version of the manuscript and have conceived anddesigned this study.Funding: This project won a financial award from Neurosphynx rare diseases healthcare network,which nationally coordinates the Reference Center for Chiari malformation and rare vertebro-medullary diseases (PIH n◦5 AAP Neurosphynx 2021/APHP Necker–CHRU Nancy).Institutional Review Board Statement: This protocol received ethical approval from the ClinicalResearch Delegation of Nancy University Hospital, in accordance with the National Commission onInformatics and Liberties (Commission Nationale de l’Informatique et des Libertés) (protocol number2019PI256-107).Informed Consent Statement: Informed consent was obtained from all subjects involved in thisstudy. Our data treatment was in accordance with the methodology of reference MR-004 specificationfor data policy. This protocol has been registered on Clinicaltrials with the following registrationnumber: NCT04679792 (17 December 2020). The study findings will be disseminated via peer-reviewedpublications and conference presentations, especially for Neurosphynx’s rare disease healthcare network.Data Availability Statement: Data are available on the Nancy Regional Hospital Center databaseand are only known by the principal investigator due to the CNIL privacy policy.Acknowledgments: The authors acknowledge Arnaud Wiedeman-Fode (Pediatric Intensive CareUnit—University Hospital of Nancy) for their contribution to statistical analysis.Conflicts of Interest: The authors declare no conflicts of interest. The funders had no role in thedesign of this study; in the collection, analyses, or interpretation of the data; in the writing of themanuscript; or in the decision to publish the results.Audiol. 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Chiari I malformation
pediatric neurosurgery
posturography
balance
Utilization of Vestibular Information for Balance Control in Children with Chiari I Malformation
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