Computed tomography multi-planar and 3D image assessment protocol for detailed analysis of inner ear malformations in patients undergoing cochlear implantation counseling.

<b><br>Introduction:</b> Congenital inner ear malformations resulting from embryogenesis may be visualized in radiological scans. Many attempts have been made to describe and classify the defects of the inner ear based on anatomical and radiological findings.</br> <b><br>Aim:</b> The aim was to propose and discuss computed tomography multi-planar and 3D image assessment protocols for detailed analysis of inner ear malformations in patients undergoing cochlear implantation counseling.</br> <b><br>Material and methods:</b> A retrospective analysis of 22 malformed inner ears. CT scans were analyzed using the Multi-Planar Reconstruction (MPR) option and 3D reconstruction.</br> <b><br>Results:</b> The protocol of image interpretation was developed to allow reproducibility for evaluating each set of images. The following malformations were identified: common cavity, cochlear hypoplasia type II, III, and IV, incomplete partition type II and III, and various combinations of vestibule labyrinth malformations. All anomalies have been presented and highlighted in figures with appropriate descriptions for easier identification. Figures of normal inner ears were also included for comparison. 3D reconstructions for each malformation were presented, adding clinical value to the detailed analysis.</br> <b><br>Conclusions:</b> Properly analyzing CT scans in cochlear implantation counseling is a necessary and beneficial tool for appropriate candidate selection and preparation for surgery. As proposed in this study, the unified scans evaluation scheme simplifies the identification of malformations and reduces the risk of omitting particular anomalies. Multi-planar assessment of scans provides most of the necessary details. The 3D reconstruction technique is valuable in addition to diagnostics influencing the decision-making process. It can minimize the risk of misdiagnosis. Disclosure of the inner ear defect and its precise imaging provides detailed anatomical knowledge of each ear, enabling the selection of the appropriate cochlear implant electrode and the optimal surgical technique.</br>.

[Clinical features of congenitally enlarged bony portion of Eustachian tube].

Objective:To investigate the clinical features of patients with congenitally enlarged bony portions of the Eustachian tube（ET）. Methods:The medical history, physical examination, hearing test, temporal bone high resolution computed tomography（HRCT） of six patients（nine ears） with congenitally enlarged bony portion of the ET were retrospectively analyzed. Results:Four patients were men and two were women. The minimum, maximum, and average ages were 5, 21, and（14.7±6.4） years, respectively. Three malformations were bilateral and three were left-sided. Three ears had conductive hearing loss（average bone and air conduction thresholds were 13.7 dB and 71.3 dB）, three had mixed hearing loss（average bone and air conduction thresholds were 27.7 dB and 83.7 dB）, and one had extremely severe sensorineural hearing loss. The average maximum length and width of the enlarged bony ET on temporal bone HRCT were（22.61±2.94） mm and（6.50±2.33） mm, respectively. The enlargement was combined with an external auditory canal malformation in six ears, narrow tympanic cavity in six, tympanic antrum malformation in five, ossicular chain malformation in seven, cochlear malformation in six, helicotrema malformation in three, vestibule widening in two, semicircular canal malformation in three, vestibular window malformation in six, facial nerve abnormality in five, internal auditory meatus malformation in two, low middle cranial fossa in eight, and severe internal carotid artery malformation in one. Conclusion:Bony ET enlargement is a rare congenital middle ear malformation which could combined with other ear malformations. Patients can have no ET dysfunction but different patterns of hearing loss. The defect is usually found unintentionally during imaging, and the HRCT of temporal bone is significant.

[Clinical features and temporal CT findings in patients with Branchio-Oto-Renal or Branchio-Oto Syndrome].

Objective: To assess the clinical features and CT diagnostic characteristics of Branchio-Oto-Renal or Branchio-Oto Syndrome. Methods: The temporal CT findings and clinical features observations of 13 patients with Branchio-Oto-Renal Syndrome (BORS) or Branchio-Oto Syndrome(BOS) confirmed by genetic testing were retrospectively analyzed. There were 8 males and 5 females, aged from 1 to 39 years, with a median age of 9 years, in which 3 pairs (6 cases) were parent-child relationship. Results: All of 13 cases had hearing loss and preauricular fistula, 11 cases accompanied by 2nd branchial fistulas. There were 20 ears of mixed hearing loss, 3 ears of sensorineural hearing loss, and 2 ears of conductive hearing loss. The mutation point of gene testing was located in EYA1 in 12 cases and SIX1 in 1 case. Twenty ears showed gradually narrowing of the diameter of basal turn, with hypoplasia in the second turn and aplasia in apical turn. There were irregular wall of vestibule and horizontal semicircular canal in 10 ears,widened vestibular in 7 ears, and vestibular fusion with horizontal semicircular canal in 3 ears. Three ears had an enlarged vestibular aqueduct, 8 ears showed enlargement of internal auditory canal. Seventeen ears had adhesion of malleolus to tympanic cavity. Six ears could not measured the incudostapedial joint angle by reason of tympanic inflammatory cover, 3 ears could not show incudostapedial joint, and 8 ears showed the incudostapedial joint angle more than 122°. Six ears showed poor oval window, and 1 ear had poor round window. Eighteen ears showed distended eustachian tube, and accompanied by tympanic or mastoiditis in 11 ears. Anterolateral shift of tympanum was found in 22 ears, 17 ears had low middle cranial fossa, and 3 ears had stenotic external auditory canal. Conclusions: Cochlear dysplasia, ossicular chain malformation and distended eustachian tube comprise the characteristic CT signs of BOS/BORS, which possesses versatile and complex CT findings. Temporal CT can accurately assess the important structures such as cochlea, ossicles, vestibule, semicircular canal, vestibular aqueduct and internal auditory canal. Combing with the clinical characteristics of bilateral, mixed hearing loss, preauricular fistula and branchial fistula can provide valuable information for early diagnosis and treatment.

[Comparison of efficacy between short-term personalized vestibular rehabilitation supervised by special personnel and fixed vestibular rehabilitation on recurrent peripheral vertigo].

Objective: To explore the efficacy of short-term personalized vestibular rehabilitation supervised by special personnel (ST-PVR) versus fixed vestibular rehabilitation (FVR) on decompensated recurrent peripheral vertigo. Methods: A randomized controlled trial was carried out. Patients diagnosed with decompensated recurrent vertigo in the clinic of Eye & ENT Hospital, Fudan University from January to December 2018 were randomly allocated into FVR and ST-PVR groups via computer-generated randomization. The FVR group received fixed scheme involving gaze stabilization exercises, habituation exercises, balance and gait training, while the ST-PVR group received individualized training programs based on symptoms and vestibular function examination results, with adjustments made according to the progress of recovery. Patient symptoms and vestibular function improvement were assessed using the dizziness handicap inventory (DHI), activities-specific balance confidence (ABC), self-rating anxiety scale (SAS), caloric test, and sensory organization test (SOT) at 2, 4, and 8 weeks of treatment. Results: A total of 44 patients were included, including 16 males and 28 females, with an average age of (50.6±13.5) years. There were 21 cases in the FVR group and 23 cases in the ST-PVR group. In the ST-PVR group, DHI score (49.5±26.8 vs 61.3±21.4, P=0.046) and SAS score (39.1±7.8 vs 44.3±6.6, P=0.021) significantly improved after 2 weeks of treatment, while significant improvement occurred only after 8 weeks of treatment in the FVR group (DHI score: 28.1±15.9 vs 53.1±18.5, P=0.001; SAS score: 35.3±6.7 vs 43.1±8.4, P=0.010). There was no significant change of ABC score in the FVR group after 8 weeks of treatment (86.5±12.9 vs 83.4±18.1, P=0.373), while a significant improvement was observed in the ST-PVR group after 4 weeks of treatment (83.6±15.2 vs 78.4±15.1, P=0.015). The caloric test results showed that after 8 weeks of treatment, the proportion of patients with unilateral weakness<25% increased in both groups [FVR group: 57.1% (12/21) vs 9.5% (2/21), P=0.001; ST-PVR group: 52.2% (12/23) vs 17.4% (4/23), P=0.014]. In the ST-PVR group, the proportion of patients with dominant preference≤25% significantly increased [91.3% (21/23) vs 60.9% (14/23), P=0.016], while there was no significant change in the FVR group [61.9 (13/21) vs 57.1% (12/21), P=0.500]. The proportion of patients with SOT score≥70 in the ST-PVR group increased significantly after 2 weeks of treatment [69.6% (16/23) vs 30.4% (7/23), P=0.009], while the FVR group showed a significant increase only after 8 weeks of treatment [81.0% (17/21) vs 42.9% (9/21), P=0.012]. Conclusion: Both FVR and ST-PVR effectively promote vestibular compensation by improving objective vestibular functions and relieving subjective symptoms and anxiety of the patients with decompensation recurrent vertigo, while ST-PVR might shorten the recovery time and increase balance confidence.

Efficacy of vestibular rehabilitation program in children with balance disorders and sensorineural hearing loss.

OBJECTIVE: Asses the efficacy of a Vestibular-balance rehabilitation program to minimize or reverse balance disability in children with sensorineural hearing loss. METHOD: Forty-five hearing-impaired children with balance deficits (i.e., variable degrees of sensorineural hearing loss or auditory neuropathy). Thirty-five were rehabilitated with cochlear implants, and ten with hearing aids. Their age ranged from 4 to 10 years old. A Pre-rehab evaluation was done using questionnaires, neuromuscular evaluation, vestibular and balance office testing, and vestibular lab testing (using cVEMP and caloric test). Customized balances, as well as vestibular rehabilitation exercises, have been applied for three months. That was followed by post-rehab assessment, including the Arabic DHI questionnaire, PBS, BESS, HTT, and DVA test. RESULTS: There was a statistically significant difference in all measured parameters (including the Arabic DHI questionnaire, PBS, BESS, HTT, and DVA test) after rehabilitation. CONCLUSIONS: Vestibular-balance rehabilitation intervention positively impacts vestibular and balance functions in hearing-impaired children.

Cochleovestibular Phenotype in a Rare Genetic MED13L Mutation.

The gene MED13 participates in transcription. The MED13L gene is a paralog of MED13 that is involved in developmental gene expression. Mutations in the gene have been shown to result in a heterogenous phenotype affecting several physiological systems. Hearing loss has been reported very rarely, and vestibular weakness has never been reported in the condition. In this report, we present a mutation of MED13L in c.1162A > T (p.Arg388Ter), where we detail and describe a cochleovestibular phenotype with objective vestibulometry for the first time. The child showed bilateral sloping sensorineural hearing loss, a bilateral vestibular weakness, and an inner ear vestibular structural abnormality on imaging. Early intervention with hearing aids and vestibular rehabilitation led to a favorable outcome in terms of speech, communication, and balance. We emphasize the importance of comprehensive audiovestibular assessment in children diagnosed with MED13L mutations for effective management of these children.

Frailty of the.

Vestibular frailty and presbyvestibulopathy, including benign paroxysmal positional vertigo (BPPV), can cause dizziness among elderly patients. Vestibular frailty and presbyvestibulopathy may contribute to the onset of the vicious circle of falling-bone fracture-prolonged bedridden status-senile dementia. Treatment interventions for vestibular frailty and presbyvestibulopathy should be based on vestibular rehabilitation rather than vestibular implantation or regeneration. In acute BPPV, the otolith repositioning maneuver can be used to return otolithic debris to the utricle. At the chronic remission stage, there are nutritional guidelines for improving bone density in otolith organs and rehabilitation guidelines for activating otolith organs to prevent exfoliation. Moreover, sleeping in the head-up position can prevent free-floating debris from entering the semicircular canal. Throughout their old age, the psychiatric care/support is also indispensable to keep their initiative against vestibular frailty.

Vestibulospinal reflexes elicited with a tone burst method are dependent on spatial orientation.

Balance involves several sensory modalities including vision, proprioception and the vestibular system. This study aims to investigate vestibulospinal activation elicited by tone burst stimulation in various muscles and how head position influences these responses. We recorded electromyogram (EMG) responses in different muscles (sternocleidomastoid-SCM, cervical erector spinae-ES-C, lumbar erector spinae-ES-L, gastrocnemius-G, and tibialis anterior-TA) of healthy participants using tone burst stimulation applied to the vestibular system. We also evaluated how head position affected the responses. Tone burst stimulation elicited reproducible vestibulospinal reflexes in the SCM and ES-C muscles, while responses in the distal muscles (ES-L, G, and TA) were less consistent among participants. The magnitude and polarity of the responses were influenced by the head position relative to the cervical spine. When the head was rotated or tilted, the polarity of the vestibulospinal responses changed, indicating the integration of vestibular and proprioceptive inputs in generating these reflexes. Overall, our study provides valuable insights into the complexity of vestibulospinal reflexes and their modulation by head position. However, the high variability in responses in some muscles limits their clinical application. These findings may have implications for future research in understanding vestibular function and its role in posture and movement control.

Impact of sensory reweighting strategies on postural control using the sensory organization test in older adults with and without fall risks.

BACKGROUND: The Sensory Organization Test (SOT), an integral part of computerized dynamic posturography, plays a crucial role in evaluating postural stability under various altered sensory conditions. Despite its importance, there have been noted inconsistencies in the results pertaining to equilibrium and sensory system evaluations. This study aimed to compare four sensory analysis scores and equilibrium indices between older adults with and without fall risks. METHODS: The study included 34 participants identified as being at risk of falls and 42 control subjects. To categorize individuals between the two groups, we performed area under the receiver operating characteristic curve analyses. This classification was based on scores from the Modified Falls Efficacy Scale (MFES) and the composite scores obtained from the SOT. In addition, we used the Tampa Scale for Kinesiophobia (TSK) as well as the level of disability. RESULTS: The fall risk group demonstrated significantly higher TSK scores (39.39 ± 15.24 for control group vs. 54.65 ± 10.70 for fall risk group; t = -5.09, p = 0.001). The groups demonstrated a significant interaction on the equilibrium index (F = 4.59, p = 0.03), which was lower in the fall risk group in Condition 6 with a moving surface and surround and eyes open (t = 2.29, p = 0.01). The fall risk group demonstrated a higher somatosensory score (t = -1.73, p = 0.04). CONCLUSIONS: The fall risk group had a lower equilibrium index score in Condition six of the SOT, which was useful for identifying deficits in vestibular function to integrate sensory information under challenging conditions for postural adaptation. This strategy suggested that the fall risk group could compensate for their risk of falls by utilizing more effective somatosensory reweighting strategies compared with the control group.

[Research advances in the mechanism of vestibular compensation and treatment].

Unlike other sensory systems, since the vestibular system maintains the tension balance of the entire system in a"push-pull" mode, local dysfunction in the system will cause the balance of the entire system to collapse. Unilateral peripheral vestibular dysfunction will cause severe vestibular symptoms, but it can recover spontaneously within a few days to several weeks. This phenomenon is called "vestibular compensation"（VC）. Since the peripheral vestibular impact in most cases is irreversible, it is widely believed that the central mechanism plays a key role in the vestibular compensation process. Static symptom is fully compensated within a few weeks, which is in parallel with the restored balance in the resting discharge of the vestibular nucleus on both sides; the incomplete compensation of dynamic deficits takes longer and is achieved mainly through the mechanism of sensory substitution and behavioral substitution. Here we briefly reviewed the mechanism of vestibular compensation and treatment in order to provide an insight into further study and clinical treatment strategies.

[Vestibular rehabilitation for peripheral vestibular hypofunction: an interdisciplinary consensus]. / Vestibulyarnaya reabilitatsiya pri perifericheskoi vestibulyarnoi gipofunktsii: mezhdistsiplinarnyi konsensus.

The literature review presents approaches to the management of patients with vestibular disorders. The principles of organization of vestibular rehabilitation in peripheral vestibular hypofunction, indications for appointment, factors influencing its implementation, technique, methods of evaluating effectiveness are considered in detail. Attention is drawn to the fact that the selection of exercises and the duration of vestibular rehabilitation is carried out individually and depends on many factors, including the nature of vestibular deficiency and the specific characteristics of the patient. The possibilities of using additional pharmacological therapy with histamine preparations, which can accelerate the onset of vestibular compensation, are shown. It is noted that vestibular rehabilitation is a safe and effective method of treating peripheral vestibular hypofunction and should be recommended to patients of all ages with vestibular disorders leading to limited social and physical activity.

Effects of galvanic vestibular stimulation on postural righting reactions in hemiplegia.

Patients with post-stroke hemiplegia often exhibit reduced ability to maintain sitting balance, a crucial factor for predicting prognosis. Galvanic vestibular stimulation (GVS) influences postural control by stimulating vestibular organ. Although several studies have focused on GVS in static postures, no studies have demonstrated the influence of GVS on righting reactions. Therefore, we aimed to investigate the effects of GVS on postural righting reactions in seated patients with stroke-induced hemiplegia. Using a vertical board (VB), righting reactions were induced by tilting the VB at 10° after patients sat for 1 min. Patients adjusted their bodies until feeling vertical upon prompt. Twenty-two left hemiplegic patients with cerebrovascular disease participated, divided into two groups undergoing right cathode GVS (RC-GVS) followed by left cathode GVS or vice versa, preceded by sham stimulation. Centre of pressure and the joint angle were measured. During the postural righting reactions towards the paralysed side, RC-GVS enhanced the righting reactions and moved the mean position on the x-axis (COPx) to the right and the mean position on the y-axis (COPy) to the front. During the postural righting reaction towards the right side, RC-GVS induced resistance against the righting reaction, COPx was deflected to the right, COPy was deflected backward, and the angle of the neck tilt increased. The findings revealed that GVS with anodal stimulation on the paralysed side could promote righting reactions in patients with post-stroke hemiplegia. SIGNIFICANCE STATEMENT: The study findings suggest that using the contralesional placement of the anode promotes righting reactions, and galvanic vestibular stimulation can induce joint movements in the neck and trunk by polarising it to act as resistance against righting reactions.

Changing Management of Intravestibular Schwannomas in the Era of Cochlear Implantation for Single-Sided Deafness.

OBJECTIVE: Intralabyrinthine schwannomas (ILSs) are a rare cause of deafness. Patients with ILS confined to the semicircular canals and the vestibule (intravestibular schwannomas) are potential candidates for cochlear implantation for hearing rehabilitation, a new option for patients with unilateral hearing loss since the 2019 FDA approval of cochlear implant (CI) for single-sided deafness. In this report, we describe an evolving management approach for ILSs causing hearing loss. PATIENTS: Adults (≥18 years) who underwent simultaneous ILS resection and CI between January 2019 and June 2023 (n = 3). INTERVENTION: Transmastoid labyrinthectomy with simultaneous cochlear implantation. MAIN OUTCOME MEASURES: Hearing performance with cochlear implantation measured as CNC Word Recognition scores and AzBio Sentence scores. RESULTS: Three patients with ILS confined to the semicircular canals and vestibule underwent simultaneous tumor resection via labyrinthectomy with CI placement. In all cases, complete tumor resection and full CI insertion were achieved. No patients experienced postoperative complications. Patients 1 and 2 underwent 6- and 9-month postactivation testing, respectively, with CNC scores 64% to 80% and AzBio 81% to 99% in the implanted ears. Patient 3 scored 0% on CNC and AzBio testing at 3 months and deferred her 6-month audiometry. CONCLUSIONS: Patients with ILS confined to the vestibule and semicircular canals can be considered for simultaneous tumor resection and CI placement.

A 3-hour time interval may not be sufficient for delayed enhancement magnetic resonance imaging with intravenous gadoteridol injection based on 3d-real IR sequence of the inner ear in Meniere's disease patient.

BACKGROUND: Magnetic resonance imaging (MRI) can be applied to visualize endolymphatic hydrops (EH). AIMS/OBJECTIVES: To explore whether a 3-h time interval was feasible for clinical practice. MATERIALS AND METHODS: We prospectively enrolled 15 patients with unilateral Meniere's disease, each of whom underwent delayed enhancement MRI scan of the inner ear after intravenous gadoteridol injection at a 3-h interval. The ears of these patients were divided into two groups (group A: the affected ears; group B: the unaffected ears). Among the two groups, the signal intensity in perilymphatic area of the basal turn of cochlea, the results of visual evaluations in the vestibule, cochlea and semicircular canal and the detection results of EH were compared. RESULTS: Regarding the signal intensity, a difference was found between group A and group B (p = .016). Besides, no difference was found between the visual evaluations in the vestibule, cochlea and semicircular canal of the two groups. Regarding the detection results of EH, group A (6 vestibules were undiagnosable; 8 cochleae were undiagnosable); group B (9 vestibules were undiagnosable; 10 cochleae were undiagnosable). CONCLUSIONS AND SIGNIFICANCE: In the clinical application of gadoteridol for the inner ear, 3-h delayed MR imaging may not be sufficient.

Comparing the effects of different circular vection stimuli on upright stance.

BACKGROUND: Upright quiet stance is maintained through the complex integration of sensory information from the visual, vestibular, and somatosensory systems [1]. Virtual reality (VR) is a well-established tool that has been used to study sensory contributions to balance and induce visual perturbations. Previous assessments of virtual environments have suggested that VR can be used to create various visual stimuli that affect balance [2]; however, there is limited work examining which dynamic visual stimulus, in the form of circular vection (CV), is the most effective at inducing whole body lean. RESEARCH QUESTION: Therefore, this study assessed the effects of two visual stimuli using VR to better understand their effects on postural control. METHODS: 33 healthy young adults between the ages of 18-40, free of neurological impairments, stood quietly on a force plate for 30 s while wearing a head-mounted display. Participants were exposed to a field of random white dots (DOTS) or a black and white striped tunnel (TUNNEL) that rotated in the roll plane at 60°/s clockwise or counterclockwise. Amplitude was calculated from head orientation data recorded from a head-mounted display, and centre of pressure (COP). RESULTS: Independent of visual stimuli, postural lean was in the same direction as the stimulus. The DOTS stimulus increased Head orientation and COP position compared to the TUNNEL stimulus. There was no significant main effect or interaction with direction for Head or COP data. SIGNIFICANCE: When comparing the effect of stimulus design on postural sway, a DOTS stimulus was most effective at inducing direction-modulated postural sway This study builds on our understanding of the VR-related destabilizing effects on postural control and shows evidence that a DOTS stimulus has a stronger effect than a TUNNEL stimulus. Overall, it is important to consider the design of visual stimuli when examining VR effects on upright stance.

Is activation of the vestibular system by electromagnetic induction a possibility in an MRI context?

In recent years, an increasing number of studies have discussed the mechanisms of vestibular activation in strong magnetic field settings such as occur in a magnetic resonance imaging scanner environment. Amid the different hypotheses, the Lorentz force explanation currently stands out as the most plausible mechanism, as evidenced by activation of the vestibulo-ocular reflex. Other hypotheses have largely been discarded. Nonetheless, both human data and computational modeling suggest that electromagnetic induction could be a valid mechanism which may coexist alongside the Lorentz force. To further investigate the induction hypothesis, we provide, herein, a first of its kind dosimetric analysis to estimate the induced electric fields at the vestibular system and compare them with what galvanic vestibular stimulation would generate. We found that electric fields strengths from induction match galvanic vestibular stimulation strengths generating vestibular responses. This review examines the evidence in support of electromagnetic induction of vestibular responses, and whether movement-induced time-varying magnetic fields should be further considered and investigated.

CHD7 and SOX2 act in a common gene regulatory network during mammalian semicircular canal and cochlear development.

Inner ear morphogenesis requires tightly regulated epigenetic and transcriptional control of gene expression. CHD7, an ATP-dependent chromodomain helicase DNA-binding protein, and SOX2, an SRY-related HMG box pioneer transcription factor, are known to contribute to vestibular and auditory system development, but their genetic interactions in the ear have not been explored. Here, we analyzed inner ear development and the transcriptional regulatory landscapes in mice with variable dosages of Chd7 and/or Sox2. We show that combined haploinsufficiency for Chd7 and Sox2 results in reduced otic cell proliferation, severe malformations of semicircular canals, and shortened cochleae with ectopic hair cells. Examination of mice with conditional, inducible Chd7 loss by Sox2CreER reveals a critical period (~E9.5) of susceptibility in the inner ear to combined Chd7 and Sox2 loss. Data from genome-wide RNA-sequencing and CUT&Tag studies in the otocyst show that CHD7 regulates Sox2 expression and acts early in a gene regulatory network to control expression of key otic patterning genes, including Pax2 and Otx2. CHD7 and SOX2 directly bind independently and cooperatively at transcription start sites and enhancers to regulate otic progenitor cell gene expression. Together, our findings reveal essential roles for Chd7 and Sox2 in early inner ear development and may be applicable for syndromic and other forms of hearing or balance disorders.

Effect of vestibular loss on head-on-trunk stability in individuals with vestibular schwannoma.

The vestibulo-collic reflex generates neck motor commands to produce head-on-trunk movements that are essential for stabilizing the head relative to space. Here we examined the effects of vestibular loss on head-on-trunk kinematics during voluntary behavior. Head and trunk movements were measured in individuals with vestibular schwannoma before and then 6 weeks after unilateral vestibular deafferentation via surgical resection of the tumor. Movements were recorded in 6 dimensions (i.e., 3 axes of rotation and 3 axes of translation) using small light-weight inertial measurement units while participants performed balance and gait tasks. Kinematic measures differed between individuals with vestibular schwannoma (at both time points) and healthy controls for the more challenging exercises, namely those performed in tandem position or on an unstable surface without visual input. Quantitative assessment of the vestibulo-ocular reflex (VOR) revealed a reduction in VOR gain for individuals with vestibular schwannoma compared to control subjects, that was further reduced following surgery. These findings indicated that the impairment caused by either the tumor or subsequent surgical tumor resection altered head-on-trunk kinematics in a manner that is not normalized by central compensation. In contrast, we further found that head-on-trunk kinematics in individuals with vestibular schwannoma were actually comparable before and after surgery. Thus, taken together, our results indicate that vestibular loss impacts head-on-trunk kinematics during voluntary balance and gait behaviors, and suggest that the neural mechanisms mediating adaptation alter the motion strategies even before surgery in a manner that may be maladaptive for long-term compensation.

The Vestibular Nuclei: A Cerebral Reservoir of Stem Cells Involved in Balance Function in Normal and Pathological Conditions.

In this review, we explore the intriguing realm of neurogenesis in the vestibular nuclei-a critical brainstem region governing balance and spatial orientation. We retrace almost 20 years of research into vestibular neurogenesis, from its discovery in the feline model in 2007 to the recent discovery of a vestibular neural stem cell niche. We explore the reasons why neurogenesis is important in the vestibular nuclei and the triggers for activating the vestibular neurogenic niche. We develop the symbiotic relationship between neurogenesis and gliogenesis to promote vestibular compensation. Finally, we examine the potential impact of reactive neurogenesis on vestibular compensation, highlighting its role in restoring balance through various mechanisms.

Measuring Optokinetic Reflex and Vestibulo-Ocular Reflex in Unilateral Vestibular Organ Damage Model of Zebrafish.

One-sided vestibular disorders are common in clinical practice; however, their models have not been fully established. We investigated the effect of unilateral or bilateral deficits in the vestibular organs on the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) of zebrafish using in-house equipment. For physical dislodgement of the otoliths in the utricles of zebrafish larvae, one or both utricles were separated from the surrounding tissue using glass capillaries. The video data from VOR and OKR tests with the larvae was collected and processed using digital signal processing techniques such as fast Fourier transform and low-pass filters. The results showed that unilateral and bilateral damage to the vestibular system significantly reduced VOR and OKR. In contrast, no significant difference was observed between unilateral and bilateral damage. This study confirmed that VOR and OKR were significantly reduced in zebrafish with unilateral and bilateral vestibular damage. Follow-up studies on unilateral vestibular disorders can be conducted using this tool.