Normal Vestibular Function Research Articles

Motor Proficiency Associated with Vestibular Deficits in Children with Hearing Impairments

The purpose of this study was to investigate the relationship of vestibular function to motor proficiency, including balance, in children with hearing impairments. Thirteen children with normal hearing and 29 children with hearing impairments, ranging in age from 7 to 13 years, were classified into categories based on vestibular function using neuro-otologic measures (ie, vestibulo-ocular reflex function and posturography). Children in each category were tested for motor proficiency using clinical assessment measures (eg, balance, muscle tone, and coordination). The test results indicated that the children with hearing impairments and normal peripheral vestibular function (n = 7) exhibited normal motor proficiency, including balance. The children with hearing impairments and loss of peripheral vestibular sensitivity (n = 19) also demonstrated normal motor proficiency, except for balance ability. The children with hearing impairments and sensory organization deficits (n = 3), however, exhibited motor deficits in many areas. The results of this study indicate that motor proficiency in children with hearing impairments depends on vestibular function. Interventions for motor deficits in children with hearing impairments, therefore, must consider vestibular function as well as motor performance.

Analyses of prognostic factors relevant to acute low-tone sensorineural hearing loss

Objective: To investigate the prognostic factors relevant to acute low-tone sensorineural hearing loss (ALHL). Methods: 196 adult ALHL patients, including 82 males and 114 females with mean age of (43.1±14.3)years old were included. All patients received the same therapy and were evaluated the curative effect. To evaluate the impact factors on the prognosis of hearing, inclusive of age, gender, time delay before the first visit, degree of deafness, vestibular function, electrocochleogram, and the serum levels of thyroxines by SPSS 18.0 software. Results: Of those 196 patients with ALHL, 124(63.3%) were recovery, 5(2.6%) were excellent better, 42(21.4%) were better, and 25 (12.8%) were poor, with a total effective rate of 87.2%. Among 15 (12.1%) who recurred the hearing loss, 2 developed into Meniere's disease during the follow-up. The mean age of patients with poor hearing effect was significantly older than that of other patients (P<0.05). No relativity was found between gender and hearing curative effect. There existed a statistical difference in total effective rate among subjects with different histories (P<0.05). In addition, the recovery rate was significantly different between groups, i. e., the course of disease was less than 14 days, between 14 days and 6 months, and between 6 months and 2 years (P<0.05). There was no statistical significance in total effective rate among different degrees of deafness (P>0.05). However, in term of the recovery rate, the difference was statistical significance (P<0.05). The recovery rate in patients with mild hearing loss was higher than that in middle or heavy hearing loss (both P<0.05). Among patients with mild deafness, the recovery rate in patients whose history was less than 3 months was significantly higher than that more than 3 months (P<0.05). For moderate deafness patients, the recovery rate in patients whose history was less than 7 days was significantly higher than that more than 1 month (P<0.05). There were statistical differences in hearing effect of 130 (66.3%) patients with abnormal vestibular function in comparison to that with normal vestibular function (χ2=15.1, P<0.05). There were 17(8.7%) patients with abnormal electrocochleogram combined with abnormal vestibular function, and the hearing effects were all poor. There were 45 (23.0%) patients with abnormal thyroxine levels in serum, which was significant higher than that in health adults of 5.9%(χ2=7.26, P<0.01). There was no significant difference in hearing prognosis between patients with abnormal and normal thyroxine levels (χ2=2.51, P>0.05). Conclusions: With respect to ALHL, the hearing effect is associated significantly with the history. The severity of hearing loss is negative prognostic factor for hearing recovery. Age, vestibular function, and electrocochleogram might predict hearing recovery. Gender and thyroxine levels couldn't predict the hearing prognosis, although there is a high incidence rate in patients with ALHL.

Using Balance Function to Screen for Vestibular Impairment in Children With Sensorineural Hearing Loss and Cochlear Implants.

1) To determine if bilateral vestibular dysfunction can be predicted by performance on standardized balance tasks in children with sensorineural hearing loss (SNHL) and cochlear implants (CI). 2) To provide clinical recommendations for screening for vestibular impairment in children with SNHL. Retrospective cohort study. Tertiary care pediatric implant center. Pediatric patients (4.8-18.6 years) with profound SNHL using CIs. Vestibular end-organ (horizontal canal and otoliths), and balance assessment. Comparison of balance skills, measured by the Bruininks Oseretsky Test of Motor Proficiency II (BOT-2), was performed between two groups of children with SNHL and CI: 1) total bilateral vestibular loss (TBVL) (n = 45), and 2) normal bilateral vestibular function (n = 20). Sensitivity, specificity, and suitability of each task as a screening tool for the detection of TBVL were assessed. Balance as measured by the BOT-2 balance subtest was significantly poorer in children with TBVL then those with normal vestibular function (p < 0.0001). "Eyes closed" tasks best identified children with TBVL having the highest sensitivity and specificity. One-foot standing eyes closed was found to have the best performance as a screening tool for TBVL using a timed cutoff of 4 seconds. A brief in-office screen of balance function using one of the BOT-2 balance subtest tasks, one-foot standing eyes closed, is able to identify children at risk of TBVL with excellent sensitivity and specificity and should be used to screen for TBVL in all children presenting with SNHL.

Reliability and Normative Data for the Dynamic Visual Acuity Test for Vestibular Screening.

The purpose of this study was to determine reliability of computerized dynamic visual acuity (DVA) testing and to determine reference values for younger and older adults. A primary function of the vestibular system is to maintain gaze stability during head motion. The DVA test quantifies gaze stabilization with the head moving versus stationary. Commercially available computerized systems allow clinicians to incorporate DVA into their assessment; however, information regarding reliability and normative values of these systems is sparse. Forty-six healthy adults, grouped by age, with normal vestibular function were recruited. Each participant completed computerized DVA testing including static visual acuity, minimum perception time, and DVA using the NeuroCom inVision System. Testing was performed by two examiners in the same session and then repeated at a follow-up session 3 to 14 days later. Intraclass correlation coefficients (ICCs) were used to determine inter-rater and test-retest reliability. ICCs for inter-rater reliability ranged from 0.323 to 0.937 and from 0.434 to 0.909 for horizontal and vertical head movements, respectively. ICCs for test-retest reliability ranged from 0.154 to 0.856 and from 0.377 to 0.9062 for horizontal and vertical head movements, respectively. Overall, raw scores (left/right DVA and up/down DVA) were more reliable than DVA loss scores. Reliability of a commercially available DVA system has poor-to-fair reliability for DVA loss scores. The use of a convergence paradigm and not incorporating the forced choice paradigm may contribute to poor reliability.

Preserved Vestibular Function in Mice with Loss of α-9 Subunit of the α-9/10 Nicotinic Acetylcholine Receptor (α-9/10 nAChR)

Background: The α-9/10 nicotinic acetylcholine receptor is known to be the primary channel through which both vestibular and auditory efferents mediate the inhibition of their respective peripheral hair cells and afferents. With respect to the auditory system, the deletion of the α-9 subunit results in abnormalities in the development of properly functioning cochlear hair cells. Given the high degree of similarity between the au- ditory and the vestibular systems, we hypothesize that α-9 knockout mice should have impaired vestibular hair cell development and consequently compromised vestibular-mediated functions.&#x0D; Methods: In order to characterize vestibular function in α-9 knockout alert mice, we quantified the vestibu- lo-ocular reflex (VOR) through both gain and phase. Additionally, the optokinetic nystagmus (OKN) was sim- ilarly assessed as a control. VOR in light (VORl) was also quantified to further evaluate VOR and OKN efficacy. Furthermore, as information from the vestibular system mediates postural regulation and head stabilization, we assessed these properties through rotor rod and balance beam paradigms.&#x0D; Results: Surprisingly, the loss of the α-9 subunit in knockout mice did not result in any attenuation in VOR gain nor deviations in phase compared to wild type. OKN and VORl’s gain and phase values remain similarly unchanged, confirming preserved function within the vestibular nucleus. Descending vestibulospinal infor- mation seems to be unaltered as well, as no significant difference was observed in postural testing.&#x0D; Limitations: The α-9 knockout mice used specifically had exon 1 and exon 2 of the α-9 gene targeted, which could potentially limit generalizability. Also, frequencies greater than 3Hz were not tested.&#x0D; Conclusions: Our findings demonstrate that α-9 knockout mice still maintain normal vestibular function.

Monothermal Caloric Screening Test Accuracy: A Systematic Review.

To minimize discomfort, time, and costs, vestibular laboratories may perform monothermal caloric irrigations and discontinue testing if responses are symmetric. This systematic review aimed to determine the diagnostic accuracy of the monothermal caloric screening test (MCST) for unilateral vestibular dysfunction compared with bithermal caloric testing (BCT). Ovid-MEDLINE, EMBASE, Scopus, Cochrane CENTRAL, and manual bibliographic searches. Inclusion criteria specified concurrent MCST and BCT performance and reporting of test measures (monothermal caloric asymmetry, unilateral weakness). The primary outcomes were between-measure correlation, sensitivity, and specificity. Meta-analysis was performed with hierarchical bivariate and univariate random-effects models. Heterogeneity was assessed with the I(2) statistic. Fifteen studies (n = 5572 participants) met inclusion criteria. Thresholds varied between studies. Asymmetries calculated by MCST and BCT were strongly correlated, but a subgroup analysis showed no correlation for those with mild unilateral weakness. The sensitivity and specificity of the MCST ranged from 0.54 to 1.00 and 0.25 to 0.96, respectively. Predictably, higher sensitivity resulted from lower cutoff points for the MCST, higher thresholds for the BCT, and additional test positivity criteria. Warm irrigations yielded higher sensitivity than cool. Studies excluding participants with severe unilateral weakness yielded lower sensitivity estimates. After pooling by threshold, temperature, and risk of bias, most performance estimates remained substantially heterogeneous (I(2) > 60%). Accuracy of the MCST is lacking precisely where it is needed most-at the border of normal and abnormal vestibular function. To guide clinical practice, research should include analysis of subgroups with varying levels of function and employ standardized testing parameters.

Positional Nystagmus in Patients Evaluated for Dizziness and Imbalance

There is variability in the literature regarding the presence of positional nystagmus in healthy participants with reportedly normal vestibular and central nervous system function. This ranges from 7.5% to 88% and raises an important clinical question. If 88% of healthy participants have positional nystagmus then how is the clinician to interpret the presence of positional nystagmus in a patient presenting with dizziness and/or disequilibrium? The primary purpose of this investigation was to examine the prevalence and characteristics of positional nystagmus in patients evaluated specifically for dizziness and imbalance. Data was collected using retrospective chart review. 200 charts were randomly selected from all patients seen for evaluation of dizziness and imbalance over a period of eight months. Clinicians independently reviewed the data from positional testing for each chart. Nystagmus was present if there was a clear slow and fast phase component and there were three beats in a 10 s time window. Nystagmus direction and intensity data were collected. Results indicate positional nystagmus is present in 10.5% to 21% of patients evaluated for dizziness and imbalance. Use of liberal criteria for determining presence of positional nystagmus (i.e., 3 beats in 20 sec) may account for higher prevalence rates across other studies.

Facial and vestibular neuropathy of unknown origin in 16 dogs.

The aim of this study was to describe the signalment, clinical presentation, diagnostic findings and long-term follow-up in dogs with concomitant facial and vestibular neuropathy of unknown origin. Appropriate cases were located through medical record searches. Inclusion criteria comprised dogs that had: clinical signs of facial paralysis with concomitant peripheral vestibular syndrome, thyroid function tests, no abnormalities on magnetic resonance imaging of the brain and tympanic bullae, and cerebrospinal fluid analysis. Sixteen dogs met the inclusion criteria. Facial paralysis had acute onset (<24 hours) in all dogs, thyroid function was within normal limits. There was albuminocytologic dissociation in cerebrospinal fluid of 69% of the dogs. There was complete resolution of clinical signs in 31% of the dogs but 38% showed long-term vestibular deficits, 46% developed hemifacial contracture, 15% had permanent facial paralysis and 15% relapsed. Facial and vestibular neuropathy of unknown origin shares similarities with idiopathic facial paralysis. The prognosis for return of normal facial and vestibular function is guarded and there may be relapse after recovery.

Vestibular Implant: Are We Ready for It?

ABSTRACTThe present article aims to provide an overview of the research and development in the field of vestibular implants for patients suffering from bilateral vestibulopathy. There is a strong justification for surgical intervention in such patients because of a negative impact and disability of disease on the life of the patients. A few animal and human studies have been undertaken, and the available data from both animal and human studies are encouraging. It is evident that there is a technical feasibility for the use of vestibular implants. Although normal vestibular function is not expected, significant, physical improvement is expected in these patients.How to cite this articleMohan C, Srivastava A. Vestibular Implant: Are We Ready for It? Int J Adv Integ Med Sci 2016; 1(4):183-185.

Cinical and genetic characteristics of familial Meniere's disease: three families report

To investigate the clinical and genetic characteristics of three Chinese Meniere's disease (MD) families and decipher the mechanism of MD further. Personal and family medical evidence of hearing loss, vestibular symptoms, and other clinical abnormalities of the participants were identified, clinical and genetic features were analyzed. Targeted 307 genes capture and high-throughput sequencing were performed on the two ascertained members of family 1007184. Eight patients from these three families showed post-lingual sensorineural hearing loss, six women and two men were involved. Age of onset in these affected members concentrated in the middle age, with the average age of 39.3 years old. Among them, patients from 1407278 were accompanied by migraine. All of the three probands presented as recurrent vertigo firstly, and then fluctuated hearing loss showed up, accompanying by tinnitus and ear fullness feeling. The hearing loss manifested as late-onset, low frequency-involved pattern, with subsequent gradual progression from moderate to severe level. Some of the patients progressed to severe level involving all frequencies at higher ages. In addition, most of the cases showed revitalization. Four cases received vestibular function tests, three of which had varying dysfunction of vestibular function, while the other one had normal vestibular function. Patients who had abnormal vestibular function showed much more severe hearing impairment. The three-generation family 1007193 had an autosomal recessive genetic characteristics, family 1007184 showed autosomal dominant inheritance of characteristics, family 1407278 were either autosomal dominant or X-linked dominant pattern. Through target genes capture high-throughput sequencing technology, we identified two candidate variants in the two members of family 1007184, named c. 2057G>A in EGFLAM and c. 1961C>T in ITGA8. Meniere's disease has some genetic and familial aggregation in Chinese population, but its complex genetic pathogenic mechanisms need further study.

The Role of Saposins in Auditory and Vestibular Systems

AbstractProsaposin, and its cleaved byproducts saposin A-D, are crucial proteins necessary for glycoshpingolipid degradation and metabolism. Mutations in these proteins can lead to devastating lysosomal storage diseases, including Gaucher’s disease, symptoms of which often include hearing loss. Until recently, little was known about the role that prosaposin and saposins A-D played in auditory and vestibular system function. Early studies in knockout mouse models showed prosaposin to be important for normal cochlear innervation and maintenance of normal hearing (Akil et al., 2006). Severe vestibular dysfunction paired with inclusion body accumulation in the vestibular end-organs of prosaposin KO mice suggests its role in the maintenance of normal hearing and the maturation of normal vestibular system function (Akil et al., 2012). To determine if these phenotypes were attributable to the loss of prosaposin as a whole or one of its constituent proteins, saposin A-D, KO mice of individual saposins were subsequently studied. Given the nature of the hearing loss, as well as efferent and afferent neuronal sprouting in the prosaposin KO mouse, it was hypothesized that saposin C, a protein known for its neurotigenic properties, was responsible for these changes. However, a null-mutant mouse lacking both saposin C and D showed no effect on hearing (Lustig et al., 2015). In contrast, a loss of functional saposin B led to a progressive sulfatide accumulation in satellite cells around cochlear spiral ganglion (SG) neurons resulting in satellite cell degeneration, SG degeneration, and ultimately, loss of hearing (Akil et al., 2015). While saposin B KO mice did not show any vestibular dysfunction phenotype, vestibular evoked potentials demonstrated profound vestibular dysfunction likely attributable to the large-scale neuronal degeneration (Akil et al., 2015). Furthermore, the data suggests that saposin B appears to have a much greater role in auditory neuronal maintenance and balance than saposin C and/or D.

Study of clinical characteristics and curative effects of sudden hearing loss patients with vertigo

To analyze the clinical characteristics, prognosis and therapeutic effects of sudden sensorineural hearing loss (SSHL) patients associated with vertigo, and to investigate the strategy of diagnosis and treatment. We retrospectively analyzed the clinical characteristics of 240 patients diagnosed as SSHL with vertigo, who were treated in the Chinese PLA General Hospital from July 2008 to August 2012. Various factors affecting the therapeutic effects were analyzed, such as audiological features, vestibular function tests, genders, audiograms, lasting before seeing a doctor, courses of vertigo and vascular factors. Among the contemporaneous SSHL patients (873 cases), the cases with vertigo accounted for 27.49% (240/873). Among the 240 patients with vertigo, the cases with different hearing impaired degree of mild, moderate, severe and profound were 30, 13, 28 and 34, respectively, primarily by the profound cases. Detailed vestibular function tests were performed in 97 patients, with 54 cases having unilateral vestibular disfunction and 43 patients having normal vestibular function, among which 23 cases were diagnosed as benign paroxymal positional vertigo (BBPV). The relationship between vestibular function and different hearing impaired degrees or various audiogram types had no statistically significant difference. 219 cases had detailed records of the onset time of cochlear and vestibular symptoms, including 122 patients with cochlear symptoms and dizziness occurring simultaneously. After standardized drug treatment, the total effective rate was 46.67%, with recovery in 17 cases, excellent in 34 cases, better in 61 cases and poor in 128 cases, respectively. Statistical analysis showed that different genders, audiogram types, vertigo courses of time, the results of vestibular function and neck vascular ultrasounds were not related to the curative effects, while, the treatment time after onset was significantly associated with treatment effects. SSHL with vertigo has a high incidence, primarily single side affected, with relatively severe hearing impairment, and total deafness and downslope hearing curve mainly. Vestibular function can be normal or low in SSHL patients with vertigo, with a higher incidence of BPPV. Vestibular and cochlear symptoms occur simultaneously in more than half of the patients. The detection rate of vestibular dysfunction gradually increased, as the degree of hearing loss increased, without statistical significance although. The therapeutic effects of sudden hearing loss with vertigo cases have no relationship with dizziness duration or vestibular function, while the disease course plays an important role in treatment.

Feature of semicircular canal function in obstructive sleep apnea-hypopnea syndrome

The aim of this study was to evaluate the effects of obstructive sleep apnea-hypopnea syndrome (OSAHS) on semicircular canal function. By means of a series prospective study at Department of Otolaryngology Head and Neck Surgery of our hospital, the study was performed on 77 patients suffering from OSAHS in a period from 2012 to 2014, who underwent polysomnography (PSG) and caloric test. The maximal slow-phase velocity (SPV) and unilateral weakness (UW) were used to measure the vestibular function. Severity of OSAHS was evaluated by the lowest oxygen saturation (LSaO₂) and apnea hypopnea index (AHI). The SPV after cool was signed, warm test was performed for each ear, and the sum of left ear SPV were calculated, and then, the SPV of right ear was counted as the same way. Finally, the relationships between LSaO₂, AHI, age, BMI, and SPV of caloric test were analyzed. Caloric vestibular tests in the 77 OSAHS patients demonstrated abnormal findings in 52 patients (67.5%) and normal vestibular functions in the remaining 25 patients (32.5%). Of the 52 patients with an abnormal test result, 16 (20.8%) patients had unilateral vestibular hyporeflexia and 36 (46.7%) patients revealed a bilateral vestibular hyporeflexia. There was no linear relationship between AHI, age, BMI with SPV of caloric test (P > 0.05). The SPV had significant difference between Lower LSaO₂group (LSaO₂< 50%) and higher LSaO₂group (LSaO₂≥ 80%) (P < 0.05). LSaO₂was lower in patients undertaken bilateral vestibular hyporeflexia. OSAHS patients with long-term intermittent hypoxia can disturb the vestibular organs and reduce semicircular canal function. The heavier hypoxemia will lead to the lower reflex of semicircular canal, with the heavier degree of hypoxemia, and the bilateral horizontal semicircular canal involvement may also be higher at the same time. Due to the effect of vestibule centre compensatory, OSAHS patients lack of dizziness and symptoms from balance disturbances such as typically acute vestibular damage.

195 The effect of aminoglycoside antibiotics therapy on audiovestibular function in cystic fibrosis patients at the All Wales Adult Cystic Fibrosis Centre (AWACFC)

Aims 1.To determine the prevalence and severity of audiovestibular (AV) disease in adult CF patients attending the AWACFC. 2.To examine any potential link between AV disease and number of days of IV aminoglycosides (AG) received and duration of nebulised AG. Method The annual reviews of patients attending the AWACFC between 2009 and 2014 were reviewed retrospectively. Patients who had reported AV symptoms and received an assessment at an AV clinic were included and their cumulative number of days of IV AG and the length of time receiving nebulised AG was collected. Results 30 (12 male) of the 254 (12%), with a mean (SD) age of 34.2 (8.9) years, had described AV symptoms and been seen in AV clinic. 19 of the 30 patients were found to have some sensorineural (SN) hearing loss. Patients with SN hearing loss had a greater mean number of days on IV AG (340 days) than those with measured normal hearing (247 days) but the least days nebulised AG. 7 patients had vestibular dysfunction (VD). Patients with VD had a greater mean number of days on IV AG than those with normal vestibular function (386 vs 152 days). Conclusion The prevalence of SN hearing loss in AWACFC is less than previous reports (CF Trust 2009) perhaps due to underreporting of symptoms. SN hearing loss and VD were associated with greater number of days on IV AG which concurs with previous studies (Mulheran 2001). The greater the number of days on nebulised AG conferred less hearing damage. This may be explained by nebulised AG being withheld during course of IV AG or by greater long term nebulised AG usage resulting in reduced need for more toxic IV courses of AG. However, patient adherence was not assessed.

Clinical vestibular testing assessed with machine-learning algorithms.

Dizziness and imbalance are common clinical problems, and accurate diagnosis depends on determining whether damage is localized to the peripheral vestibular system. Vestibular testing guides this determination, but the accuracy of the different tests is not known. To determine how well each element of the vestibular test battery segregates patients with normal peripheral vestibular function from those with unilateral reductions in vestibular function. Retrospective analysis of vestibular test batteries in 8080 patients. Clinical medical records were reviewed for a subset of individuals with the reviewers blinded to the vestibular test data. A group of machine-learning classifiers were trained using vestibular test data from persons who were "manually" labeled as having normal vestibular function or unilateral vestibular damage based on a review of their medical records. The optimal trained classifier was then used to categorize patients whose diagnoses were unknown, allowing us to determine the information content of each element of the vestibular test battery. The information provided by each element of the vestibular test battery to segregate individuals with normal vestibular function from those with unilateral vestibular damage. The time constant calculated from the rotational test ranked first in information content, and measures that were related physiologically to the rotational time constant were 10 of the top 12 highest-ranked variables. The caloric canal paresis ranked eighth, and the other elements of the test battery provided minimal additional information. The sensitivity of the rotational time constant was 77.2%, and the sensitivity of the caloric canal paresis was 59.6%; the specificity of the rotational time constant was 89.0%, and the specificity of the caloric canal paresis was 64.9%. The diagnostic accuracy of the vestibular test battery increased from 72.4% to 93.4% when the data were analyzed with the optimal machine-learning classifier. Rotational testing should be considered the primary test to diagnose unilateral peripheral vestibular damage in patients with dizziness or imbalance. Most physicians, however, continue to rely on caloric tests to guide their diagnoses. Our results support a significant shift in the approach used to determine diagnoses in patients with vestibular symptoms.

Anxiety and depression among patients with different types of vestibular peripheral vertigo.

Numerous studies have been published on comorbid anxiety and depression in patients with vertigo. However, very few studies have separately described and analyzed anxiety or depression in patients with different types of vestibular peripheral vertigo. The present study investigated anxiety and depression among patients with 4 different types of peripheral vertigo.A total of 129 patients with 4 types of peripheral vertigo, namely, benign paroxysmal positional vertigo (BPPV, n = 49), migrainous vertigo (MV, n = 37), Menière disease (MD, n = 28), and vestibular neuritis (VN, n = 15), were included in the present study. Otological and neurootological examinations were carefully performed, and self-rating anxiety scale and self-rating depression scale were used to evaluate anxiety and depression.Patients were divided into 2 groups, according to the vestibular function: normal and abnormal vestibular function. There was no significant difference in the risk of anxiety/depression between these 2 groups. However, for patients with the 4 different vertigo types, the prevalence of anxiety (MV = 45.9%, MD = 50%) and depression (MV = 27%, MD = 28.6%) was significantly higher in the patients with MV or MD than those with BPPV or VN (P < 0.05).Vestibular function is not significantly associated with the risk of anxiety/depression. Anxiety/depression is more common in patients with MV or MD than those with BPPV or VN. This may be due to the different mechanisms involved in these 4 types of vertigo, as well as differences in the prevention and self-control of the patients against the vertigo.

A Non-canonical Pathway from Cochlea to Brain Signals Tissue-Damaging Noise

Intense noise damages the cochlear organ of Corti, particularly the outer hair cells (OHCs) [1]; however, this epithelium is not innervated by nociceptors of somatosensory ganglia, which detect damage elsewhere in the body. The only sensory neurons innervating the organ of Corti originate from the spiral ganglion, roughly 95% of which innervate exclusively inner hair cells (IHCs) [2-4]. Upon sound stimulation, IHCs release glutamate to activate AMPA-type receptors on these myelinated type-I neurons, which carry the neuronal signals to the cochlear nucleus. The remaining spiral ganglion cells (type IIs) are unmyelinated and contact OHCs [2-4]. Their function is unknown. Using immunoreactivity to cFos, we documented neuronal activation in the brainstem of Vglut3(-/-) mice, in which the canonical auditory pathway (activation of type-I afferents by glutamate released from inner hair cells) is silenced [5, 6]. In these deaf mice, we found responses to noxious noise, which damages hair cells, but not to innocuous noise, in neurons of the cochlear nucleus, but not in the vestibular or trigeminal nuclei. This response originates in the cochlea and not in other areas also stimulated by intense noise (middle ear and vestibule) as it was absent in CD1 mice with selective cochlear degeneration but normal vestibular and somatosensory function. These data imply the existence of an alternative neuronal pathway from cochlea to brainstem that is activated by tissue-damaging noise and does not require glutamate release from IHCs. This detection of noise-induced tissue damage, possibly by type-II cochlear afferents, represents a novel form of sensation that we term auditory nociception.

Genetic Factors in Vestibular Function and Motion Sickness

Genetic Factors in Vestibular Function and Motion Sickness Objectives: To determine if motion sickness has a genetic basis, and, if so, to determine if there is a correlation between motion sickness genetic factors and genetic factors governing vestibular function. Data sources: The scope of review in this paper includes studies involving collection of primary data on susceptibility to motion sickness, correlated with any genetic factor; and, review articles concerning vestibular function and genetic factors. Study selection: A literature review was conducted to obtain articles that pertained to genetic factors governing vestibular function. To locate articles, sources including PubMed were utilized to locate review articles with the key words genetic,vestibular and motion sickness. Data extraction: Requirement that articles are written in English and published in the past 25 years. Data synthesis: Direct correlation. Conclusions: The selected articles revealed that: (1) Genetic polymorphism of the alpha-2a adrenergic receptor is correlated with motion sickness susceptibility in that the 6.3 Kb gene is correlated with increased susceptibility to motion sickness as compared to the 6.7 Kb polymorph; and (2) There is a lack of significant genetic correlation between the gene for the alpha-2a adrenergic receptor and genetic factors governing vestibular function. This data is in agreement with the observation that individuals who are highly susceptible to motion sickness tend to have normal vestibular function. In other words, subjects with a lack of peripheral vestibular function are generally resistant to motion sickness.

PS-348 Children’s Clinical Profile: Tertiary Paediatric Balance Clinic

Main purpose The main aim was to analyse the clinical profile of children with and without hearing impairment referred with various vestibular related symptoms attending a tertiary balance clinic over six months. Children undergoing pre-cochlear implant assessment were also included. Design of study A thorough clinical history and evaluation of auditory and vestibular assessment was undertaken. Diagnosis of the medical condition was made on the basis of all the above. Results One hundred and twenty four consecutive patients (55 female and 69 male) were included. The age range was 9 months to 18.5 years (mean age 9.41 years). Multiple professionals referred these patients. Associated conditions: Ten patients had a history of migraine, 8 had cyclical vomiting, 8 had CHARGE syndrome, 7 referred post-meningitis had labyrinthitis ossificans. Three patients sustained head injury. Signs:- Two patients had positional nystagmus: one with history of head injury, the other sustained vibration injury to the labyrinth caused during fairground rides. Head impulse test was positive bilaterally in seventeen patients, indicated by the presence of catch-up saccade, a clinical feature of vestibular failure. Objective Vestibular assessment:- Electronystagmography showed central vestibular abnormalities in 18 (14.5%), 66 had normal vestibular function and 41 had vestibular hypofunction. Seventeen had bilateral vestibular failure. Implications and relevance of results In children, numerous aetiologies of dizziness and balance problems may have a similar clinical picture. The symptoms of non-vestibular disorders can masquerade those of vestibular disorders and vice-versa. Close multispecialty working is vital for positive clinical outcome.

Long-Term Vestibulaorcochlear Function and Vestibular Compensation after Microsurgical Resection of Vestibular Schwannoma via the Retrosigmid Approach

Objective: To evaluate long-term vestibulocochlear function of patients (P) who were operated on vestibular schwannoma via retrosigmoid approach. Methods: A total of 64 P were enrolled in this study. A questionnaire was applied to evaluate current vestibulocochlear complaints comparing with the preoperative status. Cochlear function was assessed by audiometry, vestibular function (VF) by video-oculography (VOG), and central compensation (CC) by rotational chair testing. Results: Mean follow-up was 77 months, mean tumor size was 22.4 mm. As compared to preoperative status, rate of tinnitus (61%) did not change at follow-up. Vertigo improved significantly (pre. vs. post: 40-28%). Balance disturbances (BD) increased slightly (50-58%). In the audiometry, postoperative useful hearing (UH) rate of 52% could be estimated. VOG showed that 80% had lost VF, 16% had hypofunction, and 4% normal VF. Overall 84% showed CC. P without CC at follow-up complained significantly more frequently of BD than those with CC, p = 0.035. Risk of developing postoperative non-UH increased with initial tumor size by a factor of 2.2 every 10 mm, p = 0.020. P age raised risk of developing postoperative non-UH by a factor of 1.7 every 10 years, p = 0.039. A better preoperative hearing function increased the chance of keeping postoperative UH significantly p = 0.002. Conclusions: Young P with small tumors and good preoperative hearing seem to have better chances of preserving UH. Developing CC is not obligatory but a process, which might fail leading more frequently to BD.