Otolith Function Research Articles

The importance of vestibular evoked myogenic potentials for the assessment of the otolith function in the patients presenting with benign paroxysmal positional vertigo

The objective of the present study was to evaluate the otolith function in the patients presenting with idiopathic benign paroxysmal positional vertigo (pBPPV) attributable to the occlusion of the posterior semicircular canal (PSCC) of the inner ear with the use of vestibular evoked myogenic potentials (VEMP). Cervical (cVEMP) and ocular VEMP (oVEMP) were measured in 34 patients with idiopathic pBPPV before and 7 days after the treatment by means of reposition maneuvers. The results of the repeated Dix-Hallpike test performed 7 days after the repositioning maneuver were negative in 27 patients and positive in 7 patients. There was no statistically significant difference in the amplitude of cervical VEMP between the healthy and affected ears either before or after the repositioning treatment. The measurement of oVEMP revealed a reduction of the response amplitude on the affected side. The average values of the plnl on the healthy side were 12.84±1.09 and those on the affected side 4.62±0.69 (p<0,05). The successful repositioning treatment resulted in a significant increase of the oVEMP amplitude on the affected side (p<0,05). In the patients presenting with the persistent symptoms of pBPPV, the repositioning maneuvers did not cause an appreciable increase in the amplitude of oVEMP on the affected side (p<0.05). The results of the present study give evidence that pBPPV of the posterior semicircular canal is associated with the impairment of the function of the receptor structures of the utriculus and the preserved function of the succulus as suggested by the reduction of the oVEMP amplitude and clinically significant asymmetry of ocular VEMP on the affected side with intact cervical VEMP on both sides. The successful treatment of pBPPV of PSCC with the use of the liberatory maneuver results in the increase of the oVEMP amplitude on the affected side increases while the response asymmetry between both sides significantly decreases which indicates the repair of the utriculus otolith function.

Assessment of endolymphatic hydrops and otolith function in patients with Ménière's disease.

Ménière's disease is associated with hydrops of the inner ear endolymphatic space, and histopathologically, the cochlea and vestibule are usually involved. We used gadolinium-enhanced magnetic resonance imaging and measured cervical and ocular vestibular evoked myogenic potentials and the gain in the utricular induced linear vestibulo-ocular reflex to test the hypothesis that vestibular hydrops in Ménière's disease patients is associated with otolith organ dysfunction. We evaluated 21 patients diagnosed with unilateral definitive Ménière's disease using gadolinium magnetic resonance imaging to detect endolymphatic hydrops in the cochlea and vestibule. Cervical and ocular vestibular evoked myogenic potentials and the gain in utricular induced linear vestibulo-ocular reflex during eccentric rotation were measured to assess otolith organ function. For eccentric rotation, patients were rotated while displaced from the axis of rotation, while linear acceleration stimulated the utricle and induced the vestibulo-ocular reflex. Magnetic resonance imaging revealed vestibular hydrops in 14 of 20 patients (70%). Among the 14 patients, ten (71%) had abnormal cervical and three (21%) had abnormal ocular vestibular evoked myogenic potentials. Four patients (4/21, 19%) had abnormal linear vestibulo-ocular reflexes, three of whom also had abnormal ocular vestibular evoked myogenic potentials. Overall, 16 of 17 patients had normal linear vestibulo-ocular reflexes and normal ocular vestibular evoked myogenic potentials. Vestibular endolymphatic hydrops in Ménière's disease patients caused otolith organ dysfunction, mainly in the saccule. The number of Ménière's disease patients with abnormal ocular vestibular evoked myogenic potentials was low (19%), and they also had abnormal utricular induced linear vestibulo-ocular reflexes.

Visual verticality perception after stroke: A systematic review of methodological approaches and suggestions for standardization

Introduction Visual vertical (VV) measurements are being increasingly used for routine clinical assessment of spatial cognition, to investigate otolithic vestibular function and identify altered verticality perception as a possible cause of postural disorders after stroke. The objective of this paper was to synthesize knowledge of assessment methods for testing VV after stroke. Material and methods This systematic review, following the PRISMA statement, involved a search for articles in MEDLINE via PubMED published up to November 2015 by using the search terms “visual vertical”, “verticality perception” and “stroke”. We included only case or group studies on VV perception after hemispheric, brainstem or cerebellar strokes. Two authors independently assessed data on patients’ and VV assessment characteristics, outcome measures, ranges of normality and psychometric properties. Results We assessed reports for 61 studies (1982 patients) of VV for hemispheric (n = 43), brainstem (n = 18) or cerebellar (n = 8) stroke. VV assessment procedures varied widely in paradigm, type of stimulus, patient posture, number of trials and outcome measures. However, some emerging guidelines recommend assessing VV in absolute darkness, with an even number of trials, from 6 to 10, with the body maintained upright (at least the trunk). Under these conditions, normal VV orientation (mean of VV estimates) can be considered from −2.5° to 2.5° and is highly reliable for use in clinical practice and research. A difference ≥ 2° between repeated measures for a given patient can be interpreted as a real change in VV perception. Myriad of protocols have been proposed, for which psychometric properties must be better analyzed. Discussion–conclusion This first review of VV assessment methods after stroke shows a great heterogeneity of procedures, settings and parameters, among which only some are eligible for standardization to limit measurement errors and better interpret the results.

An Attempt of Early Detection of Poor Outcome after Whiplash.

The main concern with whiplash is that a large proportion of whiplash patients experience disabling symptoms or whiplash-associated disorders (WAD) for months if not years following the accident. Therefore, identifying early prognostic factors of WAD development is important as WAD have widespread clinical and economic consequences. In order to tackle that question, our study was specifically aimed at combining several methods of investigation in the same WAD patients at the acute stage and 6 months later. Our longitudinal, open, prospective, multi-center study included 38 whiplash patients, and 13 healthy volunteers matched for age, gender, and socio-economic status with the whiplash group. Whiplash patients were evaluated 15–21 days after road accident, and 6 months later. At each appointment, patients underwent a neuropsychological evaluation, a full clinical neurological examination, neurophysiological and postural tests, oto-neurological tests, cervical spine cord magnetic resonance imaging (MRI) with tractography (DTI). At 6 months, whiplash patients were categorized into two subgroups based on the results of the Diagnostic and Statistical Manual of Mental Disorders as having either favorable or unfavorable progression [an unfavorable classification corresponding to the presence of post-concussion symptom (PCS)] and we searched retrospectively for early prognostic factors of WAD predicting the passage to chronicity. We found that patients displaying high level of catastrophizing at the acute stage and/or post-traumatic stress disorder associated with either abnormalities in head or trunk kinematics, abnormal test of the otolithic function and at the Equitest or a combination of these syndromes, turned to chronicity. This study suggests that low-grade whiplash patients should be submitted as early as possible after the trauma to neuropsychological and motor control tests in a specialized consultation. In addition, they should be evaluated by a neuro-otologist for a detailed examination of vestibular functions, which should include cervical vestibular evoked myogenic potential. Then, if diagnosed at risk of WAD, these patients should be subjected to an intensive preventive rehabilitation program, including vestibular rehabilitation if required.

Normal values of otolith function tests and age-related changes

Objective:To explore the normal values of otolith function tests and agerelated changes in health volunteers.Method: One hundred and seventyone health volunteers were distributed to seven age groups, all subjects accepted otolith function tests, including fundus photography, static subjective visual vertical(SSVV), cervical vestibular evoked myogenic potential(cVEMP)and ocular vestibular evoked myogenic potential(oVEMP), the fundus photographs was used to measure the discfovea angle(DFA). DFA, SSVV and VEMPs were analyzed and compared among groups. Result: For DFA and SSVV,there were no significant differences either between different ages or between the two eyes in one individual（P>0.05）. For cVEMP, the detection rate declined with age over 60 years old（P<0.01）; the cVEMP threshold increased with every 20 years old(P<0.05); and the cVEMP amplitude decreased with every 10 years old(P<0.05),however, there was an exception that no significant difference was found between 41-50 years old and 51-60 years old groups（P=0.93）;the cVEMP P1 latency prolonged with age over 70 years old（P<0.01）.For oVEMP, the detection rate also declined with age over 60 years old（P<0.01）; the oVEMP threshold was lowest at the age less than 30 years old and the largest threshold was found at the age over 70 years old（P<0.01）; consistently, the oVEMP amplitude was found largest at the age less than 20 years old and lowest at the age over 60 years old(P<0.05).The P1 and N1 latencies were found significantly longer in the group of over 70 years old than other groups（P<0.01）.No significant difference was found between both sides in one individual for oVEMP threshold,amplitude or latency (P>0.05). Conclusion: In health volunteers,there were no obvious aged related changes in DFA and SSVV. However,the detection rate, threshold, amplitude and latency of cVEMP and oVEMP greatly changed with age.

Vestibular neuritis affects both superior and inferior vestibular nerves.

To characterize the profiles of afferent dysfunction in a cross section of patients with acute vestibular neuritis using tests of otolith and semicircular canal function sensitive to each of the 5 vestibular end organs. Forty-three patients fulfilling clinical criteria for acute vestibular neuritis were recruited between 2010 and 2016 and studied within 10 days of symptom onset. Otolith function was evaluated with air-conducted cervical and bone-conducted ocular/vestibular evoked myogenic potentials and the subjective visual horizontal test. Canal-plane video head impulse tests (vHITs) assessed the function of each semicircular canal. Patterns of recovery were investigated in 16 patients retested after a 6- to 12-month follow-up period. Rates of horizontal canal (97.7%), anterior canal (90.7%), and utricular (72.1%) dysfunction were significantly higher than rates of posterior canal (39.5%) and saccular (39.0%) dysfunction (p < 0.008). Twenty-four patients (55.8%) had abnormalities localizing to both vestibular nerve divisions; 18 patients (41.9%) had superior neuritis; and 1 patient (2.3%) had inferior neuritis. A test battery that included horizontal and posterior canal vHIT and the cervical/vestibular evoked myogenic potentials identified superior or inferior neuritis in all patients tested acutely. Eight of 16 patients who were retested at follow-up had recovered a normal vestibular evoked myogenic potential and vHIT profile. Acute vestibular neuritis most often affects both vestibular nerve divisions. The horizontal vHIT alone identifies superior nerve dysfunction in all patients with vestibular neuritis tested acutely, whereas both cervical/vestibular evoked myogenic potentials and posterior vHIT are necessary for diagnosing inferior vestibular nerve involvement.

Stimulation from Cochlear Implant Electrodes Assists with Recovery from Asymmetric Perceptual Tilt: Evidence from the Subjective Visual Vertical Test.

Vestibular end organ impairment is highly prevalent in children who have sensorineural hearing loss (SNHL) rehabilitated with cochlear implants (CIs). As a result, spatial perception is likely to be impacted in this population. Of particular interest is the perception of visual vertical because it reflects a perceptual tilt in the roll axis and is sensitive to an imbalance in otolith function. The objectives of the present study were thus to identify abnormalities in perception of the vertical plane in children with SNHL and determine whether such abnormalities could be resolved with stimulation from the CI. Participants included 53 children (15.2 ± 4.0 years of age) with SNHL and vestibular loss, confirmed with vestibular evoked myogenic potential (VEMP) testing. Testing protocol was validated in a sample of nine young adults with normal hearing (28.8 ± 7.7 years). Perception of visual vertical was assessed using the static Subjective Visual Vertical (SVV) test performed with and without stimulation in the participants with cochleovestibular loss. Trains of electrical pulses were delivered by an electrode in the left and/or right ear. Asymmetric spatial orientation deficits were found in nearly half of the participants with CIs (24/53 [45%]). The abnormal perception in this cohort was exacerbated by visual tilts in the direction of their deficit. Electric pulse trains delivered using the CI shifted this abnormal perception towards center (i.e., normal; p = 0.007). Importantly, this benefit was realized regardless of which ear was stimulated. These results suggest a role for CI stimulation beyond the auditory system, in particular, for improving vestibular/balance function.

Visual verticality perception after stroke: A systematic review of methodological approaches and suggestions for standardization

Visual vertical (VV) measurements are being increasingly used for routine clinical assessment of spatial cognition, to investigate otolithic vestibular function and identify altered verticality perception as a possible cause of postural disorders after stroke. The objective of this paper was to synthesize knowledge of assessment methods for testing VV after stroke. This systematic review, following the PRISMA statement, involved a search for articles in Medline via PubMed published up to November 2015 by using the search terms “visual vertical”, “verticality perception” and “stroke”. We included only case or group studies on VV perception after hemispheric, brainstem or cerebellar strokes. Two authors independently assessed data on patients’ and VV assessment characteristics, outcome measures, ranges of normality and psychometric properties. We assessed reports for 61 studies (1982 patients) of VV for hemispheric ( n = 43), brainstem ( n = 18) or cerebellar ( n = 8) stroke. VV assessment procedures varied widely in paradigm, type of stimulus, patient posture, number of trials and outcome measures. However, some emerging guidelines recommend assessing VV in absolute darkness, with an even number of trials, from 6 to 10, with the body maintained upright (at least the trunk). Under these conditions, normal VV orientation (mean of VV estimates) can be considered from -2.5° to 2.5° and is highly reliable for use in clinical practice and research. A difference ≥ 2° between repeated measures for a given patient can be interpreted as a real change in VV perception. Myriad of protocols have been proposed, for which psychometric properties must be better analyzed. This first review of VV assessment methods after stroke shows a great heterogeneity of procedures, settings and parameters, among which only some are eligible for standardization to limit measurement errors and better interpret the results.

Vestibular function in patients with Niemann-Pick type C disease.

We investigated whether vestibular dysfunction may cause or contribute to postural imbalance and falls in patients with Niemann-Pick type C disease (NP-C). Eight patients with NP-C disease and 20 healthy controls were examined using the video-based head impulse test (vHIT) and caloric irrigation to investigate horizontal canal function as well as ocular- and cervical vestibular evoked myogenic potentials (o- and cVEMP), and binocular subjective visual vertical estimation (SVV) for otolith function, and static posturography. There were no significant differences in vestibulo-ocular gain, caloric excitability, o-/cVEMP measures or SVV between the two groups. Posturographic total sway path (tSP) and root mean square (RMS) were significantly higher in NP-C than in controls in 3 out of 4 conditions. The Romberg quotient (RQ) to assess the amount of visual stabilization was significantly lower in the NP-C than in the HC group. In contrast to other inherited metabolic disorders, such as Morbus Gaucher type 3, we did not find any evidence for an impairment of canal or otolith function in patients with NP-C as their cause of postural imbalance. Since RQ was low in NP-C patients, indicating proper sensory input, the observed increased postural sway is most likely due to a cerebellar dysfunction in NP-C, which may therefore, explain postural imbalance.

EP 140. Vestibular evoked myogenic potentials: A retrospective analysis

Diagnostic testing of the vestibular system is an integral part of assessment of patients with balance dysfunction. Rediscovery of Vestibular Evoked Myogenic Potentials (VEMP) has introduced a new dimension to vestibular assessment, especially otolith function. We present a retrospective analysis of both C-VEMP and O-VEMP in neurologic & otologic conditions. Data collated retrospectively from records of 98 patients referred for diagnostic VEMP testing to the Electrophysiology laboratory. Presenting symptoms were imbalance and giddiness. 45 male and 53 female patients in the age range of 17–79 years. 38 had Benign Paroxysmal Positional Vertigo (BPPV), 12 Acute Vestibular Neuronitis, 11 Meniere’s Disease, 7 Chronic Otitis Media ( 3 right, 2 left and 2 bilateral ). 1 was referred to confirm left Superior Canalicular Dehiscence, 9 Parkinson Disease, 1 ProgressiveSupranuclearPalsy and 4 Multiple Sclerosis. 15 remained unclassifiable and were categorised as Vertigo Not Otherwise Specified (NOS). Cervical and Ocular VEMP were performed on both ears on all the patients with Medicaid EP machine. Testing done in one session lasting about 30 minutes for each patient. Rest periods given between sets to prevent muscle fatigue. Cervical VEMP: active recording electrodes on Sternocleidomastoid belly ipsilateral to auditory stimuli. Reference on the manubrium sterni. Patients instructed to raise the head about 30 degrees above the bed and hold it actively at that level . Ocular VEMP: recording electrodes were placed contralaterally, active 1 cm inferior to lower eyelid and reference, 2 cm below that. Maximum upgaze was encouraged during testing. Ground electrode: forehead for both tests. Stimulation Parameters: Rarefaction clicks: 100 microsec duration, 5 Hz frequency , intensity 120–125 dB nHL, headphones. Recording Parameters: Filters: Low frequency filter- 20 Hz, High frequency filter- 3 KHz. Sweep: 10 msec/divn. Total sweep of 100 msec. Gain: 100 microvolts /divn. Notch: None. Averages: 100/set, 2 sets for each test. Parameters analysed : Latencies of P13, N23 and amplitude of cervical VEMP on both sides. Latencies of N10, P16 and amplitude of ocular VEMP on both sides. Comparison against normative values and two tailed t test with unequal variance were performed to look for statistically significant deviation in each subgroup of diseases. There was no statistically significant difference in latencies and amplitudes of cervical (p = 0.39 and 0.28 for left and right respectively ) and ocular VEMP (p = 0.4 and 0.64 for left and right respectively) in BPPV. In some patients with Acute Vestibular Neuronitis cervical and ocular responses were absent. Very significant difference in latencies and amplitudes (p < 0.01 on left, p < 0.001 bilaterally) were noted. In Meniere’s disease, p values < 0.01 were obtained uniformly for both cervical and ocular VEMP. p < 0.001 for cervical and ocular VEMP in Otitis Media except the left ocular VEMP which trended the disease. PD and PSP group showed statistically significant differences in cervical and ocular VEMP latencies and amplitudes (p < 0.01). Number of patients with Multiple Sclerosis is small and the results are inconclusive. In the sole patient with left Superior canal dehiscence, the cervical and ocular VEMP were larger than normal ( more than twice in amplitude as against average for the age) on the left thus underscoring its use in this condition. 15 patients had imbalance and giddiness, but not diagnosed with a CNS, PNS or vestibular disorder. Interestingly the Cervical VEMP was significantly abnormal (p < 0.001) but the Ocular VEMP did not show statistically significant deviation in latency or amplitude. This suggests a dichotomy between saccular & utricular pathology, the former being responsible for the patients symptoms. This is, to the best of our knowledge the first report of abnormalities of both Cervical and Ocular VEMP in patients with neurologic and neurootologic disorders from India. The role of VEMPs in studying degenerative neurological disorders (PD and PSP) with imbalance and falls has been explored and since abnormalities in both cervical and ocular VEMPs are noted,suggesting a role for the vestibular system and central connections in imbalance & loss of posture in these conditions. Role of VEMP in MS is routinely mentioned, but it is at best an adjunct diagnostic procedure. The lack of usefulness of VEMP in BPPV has been underscored by this study. But it may be useful in acute attacks of Meniere’s disease and Acute Vestibular Neuronitis to guage the extent and laterality of damage, especially since these disorders are bilateral.Our findings suggest that Ocular VEMP is more sensitive than Cervical VEMP in Vestibular Neuronitis. In chronic otitis media VEMPs are abnormal and can be useful to evaluate integrity of labyrinthine function. The main drawback is the paucity of numbers in different categories. Based on these findings we propose to enrol more patients, especially in the neurological subsets prospectively to elucidate the role of VEMP.

Interest of vestibular evaluation in sequentially implanted children: Preliminary results

IntroductionAn early acquired or congenital absence of sensory input of the vestibule will lead to severe delayed posturomotor milestones. Previous studies have proven modifications and even complete ipsilateral loss of vestibular function after unilateral cochlear implantation. The objective of this study was to evaluate whether sequential cochlear implantation has an impact on vestibular function. MethodsRetrospective study from January 2012 to January 2015 including 26 patients. The first stage consisted of determining the vestibular status of 26 hearing impaired children who were candidates for a second cochlear implant. Three months after contralateral implantation, we reevaluated the vestibular function of the same patients. The vestibular evaluation consisted of multiple tests for canal and otolith function. A complete clinical vestibular evaluation was performed, including the head thrust test. This was followed by an instrumental assessment composed of the classic bicaloric test and vestibular evoked myogenic potentials testing with tone bursts. ResultsA high prevalence of vestibular dysfunction (69%) was found in our group of unilaterally implanted children. Three patients had a unique functional vestibule at the not yet implanted ear. Vestibular evoked myogenic potentials responses stayed present in 15 of the 19 patients with a VEMP-response before contralateral implantation. Results of the caloric test changed for 6 patients after contralateral implantation. ConclusionsAfter contralateral implantation, 37% of our patients manifested modifications of their vestibular status. Intrasubject comparison of bicaloric and vestibular evoked myogenic potentials testing before and after contralateral cochlear implantation showed that canal function was better preserved than saccular function. Seeing the high prevalence of vestibular dysfunction in our test group of unilateral implanted children, sequential implantation must be preceded by a vestibular assessment to prevent complete bilateral vestibular areflexia and its potential consequences. Presence of hyporeflexia at the yet-to-be implanted ear seems to be a situation particularly at risk.

Three-dimensional analysis of otolith-ocular reflex during eccentric rotation in humans

When a participant is rotated while displaced from the axis of rotation (eccentric rotation, ER), both rotational stimulation and linear acceleration are applied to the participant. As linear acceleration stimulates the otolith, the vestibulo-ocular reflex (VOR) caused by the otolith (linear VOR; lVOR) would be induced during ER. Ten participants were rotated sinusoidally at a maximum angular velocity of 50°/s and at frequencies of 0.1, 0.3, 0.5, and 0.7Hz. The radius of rotation during ER was 90cm. The participants sat on a chair at three different positions: on the axis (center rotation, CR), at 90cm backward from the axis (nose-in ER, NI-ER) and at 90cm forward from the axis (nose-out ER, NO-ER). Their eye movements during rotation were recorded and analyzed three-dimensionally. The VOR gain during NI-ER was lower at 0.5 and 0.7Hz, and that during NO-ER was higher at 0.3, 0.5, and 0.7Hz than during CR. These results indicate that lVOR actually worked at 0.5 and 0.7Hz during ER and that the enhancement and decline of the VOR gain relative to the VOR gain during CR was seen in humans. Thus, we suggest that otolith function can be assessed via rotational testing of NI-ER and NO-ER.

Residual dizziness after the first BPPV episode: role of otolithic function and of a delayed diagnosis.

Residual dizziness (RD) following the resolution of a benign paroxysmal positional vertigo (BBPV) episode is frequently reported by patients. Possible causes are still under debate in the literature. This study discusses the possible role of otolithic function and of elapsed time from onset of symptoms to diagnosis in the genesis of RD. In total, 116 patients younger than 65years with their first episode of BPPV and without any other comorbidities were enrolled in the study. Before a bedside examination, subjective visual vertical (SVV) was determined in the case of a history suggestive of BPPV. SVV was tested 1week later in those patients with BPPV of the posterior semicircular canal, and in whom positioning maneuvers showed resolution of BPPV. At 1week control, reported RD and Dizziness Handicap Inventory (DHI) were recorded. Diagnosis and treatment of BPPV occurred within 4days in 43 patients (group A), between 5 and 8days in 38 patients (group B) and in more than 9days in 35 patients (group C). Higher values of reported RD and DHI were recorded in group C, while higher values of SVV deviation were recorded in group A with an inverse relationship between SVV and DHI. Initial peripheral vestibular function asymmetry due to BPPV can induce a new central adaptation. This adaptation becomes better established the longer otoconia remain floating in the endolymph. Because of these changes, the brain is unable to quickly readapt to the old pattern after resolution resulting in more persistent RD.

Normal pressure hydrocephalus: Increase of utricular input in responders to spinal tap test.

To investigate whether there is a change in ocular (oVEMP) and cervical (cVEMP) vestibular evoked myogenic potentials in patients with normal pressure hydrocephalus (NPH) before and after spinal tap test (STT). In 25 patients (6 females, age 62-83years) c/oVEMP were measured before and after STT. Patients with an increase of >20% of walking velocity were classified as responders (n=10). VEMP were also measured in a control group of 13 non-NPH patients. All patients had reproducible oVEMP; 68% had cVEMP. There was a significant increase of the peak-to-peak (pp) oVEMP amplitude after STT in responders (8.5±2.7 to 18.9±7.5μV (p=0.010)). No significant changes were found in non-responders (13.4±7.6 to 15.3±8.6μV) or controls (12.4±7.6 to 12.5±6.8μV). There were no significant differences in cVEMP before and after spinal tap test (STT). One third of patients with suspected NPH had impaired otolith function. Responders to STT only had a significant increase of oVEMP and thereby utricular input, probably due to a decrease of pressure. Both findings indicate that otolith dysfunction may contribute to imbalance in NPH and that increased utricular function after STT may be relevant for gait improvement.

Up-Down Chair: A novel mechatronic device to assess otolith function in patients with vestibular disorders

This paper describes a novel mechatronic platform, named “Up-Down Chair” (UDC), aimed at investigating otolith function in patients with vestibular disorders. The UDC was designed to provide a wide range of repeatable and controllable vertical oscillations of the head whose kinematic features match those encountered during daily activities.The following parameters were assessed to characterize the performance of the UDC: accordance between expected and measured kinematics in both loaded and unloaded conditions; Dynamic Visual Acuity (DVA) of a group of 15 healthy subjects who were asked to identify a set of Snellen optotypes while being repeatedly moved at different perturbation intensities.Results revealed a good agreement between expected and measured kinematic patterns, and excellent reliability of DVA assessed across enrolled participants. In addition, we observed that the proposed paradigm was effective in inducing oscillopsia in enrolled subjects and that the frequency of the oscillation significantly induced blurred vision during the experimental tests.The UDC appears to be usable as a complementary vestibular clinical test to investigate the effects of therapeutic treatments while applying a wide range of physiological stimuli compatible with those encountered during daily activities.

Evaluation of the otolith function using c/oVEMPs in patients with Ménière's disease.

BackgroundCervical and ocular vestibular evoked myogenic potentials (c/oVEMPs) reflect otolith function. Up-to-date, there are no published reports on the systemic evaluation of otolith function in Ménière’s Disease (MD) nor are there any reports on the differences in VEMPs between patients with early and late stage MD. The aim of this study was to evaluate the difference in c/oVEMPs between patients with MD and normal controls, as well as between patients with early and late stage MD.MethodsThirty patients with unilateral MD and thirty healthy subjects (as normal controls) were prospectively enrolled. c/oVEMPs using 500 Hz tone-burst stimuli were performed. VEMP tests were repeated 3 times on each subject to ensure reliability and reproducibility of responses. VEMPs were defined as present or absent. Abnormal VEMP was defined by lack of VEMP response.ResultsIn the control group, abnormal cVEMPs and oVEMPs responses were detected in 6.67 and 3.34 % respectively. In MD patients (20 with early stage MD [ES-MD], 10 with late stage MD [LS-MD]), abnormal cVEMPs and oVEMPs responses were detected in 40 and 16.7 % respectively. More patients with MD showed abnormal responses in c/oVEMPs as compared to the control group (p < 0.05). cVEMPs was more often abnormal as compared to oVEMPs in MD patients (p < 0.05). There was a significant difference in abnormal cVEMP responses between ES-MD patients (25 %) and LS-MD patients (70 %) (p < 0.05). Difference in abnormal oVEMP responses (ES-MD, 5 %; LS-MD, 40 %) was significant (p < 0.05).ConclusionAn increased occurrence of abnormal c/oVEMP recordings appeared in MD patients, possibly as a result of hydrops of the otolith. cVEMPs were more often abnormal in MD patients as compared to oVEMPs, suggesting that saccular dysfunction may be more common than utricular dysfunction. Furthermore, o/cVEMP abnormalities in the LS-MD group were significantly higher than those in the ES-MD group, suggesting the trend that otolith damage is gradually increasing with the aggravation of cochlear injury in MD.

Chapter 17 - Bilateral vestibulopathy

The leading symptoms of bilateral vestibulopathy (BVP) are postural imbalance and unsteadiness of gait that worsens in darkness and on uneven ground. There are typically no symptoms while sitting or lying under static conditions. A minority of patients also have movement-induced oscillopsia, in particular while walking. The diagnosis of BVP is based on a bilaterally reduced or absent function of the vestibulo-ocular reflex (VOR). This deficit is diagnosed for the high-frequency range of the angular VOR by a bilaterally pathologic bedside head impulse test (HIT) and for the low-frequency range by a bilaterally reduced or absent caloric response. If the results of the bedside HIT are unclear, angular VOR function should be quantified by a video-oculography system (vHIT). An additional test supporting the diagnosis is dynamic visual acuity. Cervical and ocular vestibular-evoked myogenic potentials (c/oVEMP) may also be reduced or absent, indicating impaired otolith function. There are different subtypes of BVP depending on the affected anatomic structure and frequency range of the VOR deficit: impaired canal function in the low- and/or high-frequency VOR range only and/or otolith function only; the latter is very rare. The etiology of BVP remains unclear in more than 50% of patients: in these cases neurodegeneration is assumed. Frequent known causes are ototoxicity mainly due to gentamicin, bilateral Menière's disease, autoimmune diseases, meningitis and bilateral vestibular schwannoma, as well as an association with cerebellar degeneration (cerebellar ataxia, neuropathy, vestibular areflexia syndrome=CANVAS). In general, in the long term there is no improvement of vestibular function. There are four treatment options: first, detailed patient counseling to explain the cause, etiology, and consequences, as well as the course of the disease; second, daily vestibular exercises and balance training; third, if possible, treatment of the underlying cause, as in bilateral Menière's disease, meningitis, or autoimmune diseases; fourth, if possible, prevention, i.e., being very restrictive with the use of ototoxic substances, such as aminoglycosides. In the future vestibular implants may also be an option.

Vestibular, Visual Acuity, and Balance Outcomes in Children With Cochlear Implants

There is a high incidence of vestibular loss in children with cochlear implants (CCI). However, the relationship between vestibular loss and various outcomes is unknown in children. The objectives of this study are to (1) determine whether age-related changes in peripheral vestibular tests occur; (2) quantify peripheral vestibular function in children with normal hearing and CCI; and (3) determine whether amount of vestibular loss predicts visual acuity and balance performance. Eleven CCI and 12 children with normal hearing completed the following tests of vestibular function: ocular and cervical vestibular-evoked myogenic potential to assess utricle and saccule function and the video head impulse test to assess semicircular canal function. The relationship between amount of vestibular loss and the following balance and visual acuity outcomes was assessed: dynamic gait index, single-leg stance, the sensory organization test, and tests of visual acuity, including dynamic visual acuity and the gaze stabilization test. (1) There were no significant age-related changes in peripheral vestibular testing with the exception of the n23 cervical vestibular-evoked myogenic potential latency, which was moderately correlated with age. (2) CCI had significantly higher rates of vestibular loss for each test of canal and otolith function. (3) Amount of vestibular loss predicted performance on single-leg stance, the dynamic gait index, some conditions of the sensory organization test, and the dynamic visual acuity test. Age was also a contributing factor for predicting the performance of almost all outcomes. Preliminarily, children with vestibular loss do not recover naturally to levels of their healthy peers, particularly with activities that utilize vestibular input; they have poorer visual acuity and balance function.

Cortical aspects of balance and spatial orientation

Spatial orientation (“am I upright?”) and postural control (“I must stand upright”) are closely linked. Human disease often disturbs both processes simultaneously, either by interfering with one of the critical sensory inputs (vestibular, visual, proprioceptive) or the CNS integrative processes. Part of this central integration is responsible for the process of “sensory re-weighting” which, among other functions, allows clinical recovery following peripheral sensory deficits. The more common of these is an acute peripheral vestibular lesion, in which case we say that recovery is mediated by “central vestibular compensation”. In this lecture, rather than discussing eye movements recovery in vestibular lesions, we will focus on compensation of perceptual and orientation functions. We will see how vestibular perception undergoes a shut-down process which may be viewed as a central anti-vertiginous mechanism [1] and how long term symptomatic recovery can be predicted on the basis of a simple perceptual assessment of “visual dependence” [2] , that is, how much “weight” a person places on visual input (as opposed to vestibular) for spatial orientation. We will touch on a clinical and research tool, the subjective visual vertical (SVV), to illustrate via patients’ examples the critical role played by tactile cues in setting the SVV [3] and dispel the myth that the SVV is a selective test of otolith function [4] . Finally, we will touch upon the central integrative processes and show how visuo-spatial and vestibular functions are lateralised to the right hemisphere, accounting for the interesting “pusher” syndrome in right parietal strokes [5] and for co-lateralisation of handedness and vestibular function [6] .

The hidden dysfunction of otolithic organs in patients with profound sensorineural hearing loss

ObjectiveTo define the profiles of ocular and cervical vestibular-evoked myogenic potentials (oVEMP and cVEMP, respectively) in patients with profound sensorineural hearing loss (PSHL). MethodsTwenty-nine patients with PSHL and 20 healthy volunteers were investigated. The patients' medical records were collected and analyzed. The ACS-evoked oVEMPs and cVEMPs and caloric test were tested and analyzed. ResultsThe oVEMP and cVEMP response rates in the patients with PSHL were 38.9% and 44.4%, respectively, and these values were significantly less than those in the healthy volunteers (both were 100%). Regarding the oVEMPs, significantly higher threshold (p < 0.001) and smaller amplitude (p = 0.022) were observed in the patients. Regarding the cVEMPs, a significant elevation in the threshold (p < 0.001) and a decrease in the amplitude (p = 0.024) were observed, and marked reductions in the P1 (p = 0.002) and N1 latencies (p = 0.001) were observed in the patients. Regarding the caloric test, the ratio of semicircular canal dysfunction in patients with PSHL was significantly higher than that in healthy volunteers (p < 0.001). However, neither the patients nor the doctors noticed balance problems or the loss of otolithic function in the summaries of the medical records of all 29 of the patients. ConclusionThe utricular and saccular dysfunction that can be concealed in patients with PSHL can be observed in oVEMPs and cVEMPs. Otolithic function should receive attention in the diagnosis and treatment of PSHL. VEMPs have special value for the observation of hidden dysfunctions of the otolithic organs of patients with PSHL.