Rachael L. Taylor

The vestibular evoked-potential profile of Ménière’s disease

OBJECTIVE To define the ocular and cervical vestibular evoked myogenic potential (oVEMP and cVEMP) profile in Ménières Disease (MD), we studied air-conducted (AC) sound and bone-conducted vibration (BCV)-evoked responses in 77 patients and 35 controls. METHODS oVEMPs were recorded from unrectified infra-orbital surface electromyography (EMG) during upward gaze. cVEMPs were recorded from rectified and unrectified sternocleidomastoid EMG during head elevation against gravity. Responses to AC clicks delivered via headphones and BC forehead taps delivered with a mini-shaker (bone-conduction vibrator) and a triggered tendon-hammer were recorded. RESULTS In clinically definite unilateral MD (n=60), the prevalence of unilateral VEMP abnormalities was 50.0%, 10.2% and 11.9% for click, minitap and tendon-hammer evoked oVEMPs, 40.0%, 22.8% and 10.7% for click, minitap and tendon-hammer evoked cVEMPs. The most commonly observed profile was abnormality to AC stimulation alone (33.3%), followed by abnormalities to both AC and BCV stimuli (26.7%). Isolated abnormalities to BCV stimuli were rare (5%) and limited to the minitap cVEMP. The prevalence of abnormalities for each of the AC VEMPs was significantly higher than for any one BCV VEMP. For click cVEMP, click oVEMP and minitap cVEMP, average Reflex Asymmetry Ratios (AR) were significantly higher in MD compared with controls. Test results for AC cVEMP, AC oVEMP, minitap cVEMP and caloric asymmetry were significantly correlated with hearing loss. CONCLUSIONS Predominance of abnormalities in oVEMP and cVEMP responses to AC sound is characteristic of MD and indicative of saccular involvement. SIGNIFICANCE This pattern of VEMP abnormalities may enable separation of Ménières disease from other peripheral vestibulopathies.

Vestibular evoked myogenic potentials to sound and vibration: characteristics in vestibular migraine that enable separation from Menière’s disease

Objectives: It can be difficult to distinguish vestibular migraine (VM) from Menière’s disease (MD) in its early stages. Using vestibular-evoked myogenic potentials (VEMPs), we sought to identify test parameters that would help discriminate between these two vestibular disorders. Methods: We first recorded ocular and cervical VEMPs (oVEMP/cVEMP) to air-conducted clicks and bone-conducted vibration in 30 control participants, 30 participants with clinically definite VM and 30 participants with clinically probable VM. Results were compared with a group of 60 MD patients from a previous study. oVEMPs and cVEMPs were then recorded at octave frequencies of 250 Hz to 2000 Hz in 20 controls and 20 participants each with clinically definite VM and MD. Inter-aural amplitude asymmetry ratios and amplitude frequency ratios were compared between groups. Results: For click, tendon-hammer-tap and minishaker-tap VEMPs, there were no significant differences in reflex amplitudes or symmetry between controls, definite VM and probable VM. Compared with MD patients, participants with VM had significantly fewer reflex abnormalities for click-cVEMP, click-oVEMPs and minitap-cVEMPs. The ratio of cVEMP amplitude generated by tone bursts at a frequency of 0.5 kHz to that generated by 1 kHz was significantly lower for MD affected ears than for VM or controls ears. cVEMP asymmetry ratios for 0.5 kHz tone bursts were significantly higher for MD than VM. Conclusions: The 0.5/1 kHz frequency ratio, 0.5 kHz asymmetry ratio and caloric test combined, separated MD from VM with a sensitivity of 90.0% and specificity of 70.0%.

Tuning Characteristics of Ocular and Cervical Vestibular Evoked Myogenic Potentials in Intact and Dehiscent Ears

Cervical and ocular vestibular evoked myogenic potentials (cVEMPs and oVEMPs) to air-conducted tone bursts (250–2000 Hz) were recorded in 14 patients with superior canal dehiscence (SCD) and 32 healthy controls. For cVEMPs, the most common ‘optimal frequency’ in control ears (48.2%) was 500 Hz; for oVEMPs, it was 1000 Hz (51.8%). We found a significant interaction between age and frequency, with a shift towards higher-frequency tuning in older subjects. cVEMP and oVEMP tuning in SCD was characterised by a broadening of amplitude and threshold tuning curves. The tendency of cVEMPs to tune to lower frequencies compared to oVEMP was enhanced in SCD. Differences in cVEMP and oVEMP ‘optimal frequencies’, demonstrated in 57.1% intact ears and 81.3% dehiscent ears, imply differences in the recruitment of hair cells generating these two reflexes. Age-matched oVEMP amplitudes provided excellent separation between SCD and control ears. Although cVEMP amplitudes overlapped between SCD and control ears, better separation was achieved by using a 2-kHz stimulus.

Ocular vestibular evoked myogenic potentials: The effect of head and body tilt in the roll plane

OBJECTIVE To explore effects of whole-head/body tilt in the roll plane on ocular-vestibular evoked myogenic potentials (oVEMP). METHODS Twenty healthy subjects were randomly tilted in an Eply Omniax rotator across a series of eight angles from 0° to 360° (at 45° separations) in the roll plane. At each position, oVEMPs to air-conducted (AC) and bone-conducted (BC) stimulation were recorded from unrectified infra-orbital surface electromyography during upward gaze. oVEMP amplitudes, latencies and amplitude asymmetry were compared across each angle of orientation. RESULTS Head orientation had a significant effect on oVEMP reflex amplitudes for both AC and BC stimulation (p<0.001). For both stimuli there was a trend for lower amplitudes with increasing angular departure from the upright position. Mean amplitudes decreased by 42.6-56.8% (AC) and 23.2-25.5% (BC) when tilted 180°. Roll-plane tilt had a significant effect on amplitude asymmetry ratios recorded in response to AC stimuli (p<0.001), indicating a trend for lower amplitudes from the dependent (down) ear. Amplitude asymmetry ratios for BC stimuli were unaffected by head and body orientation. CONCLUSIONS The results confirm an effect of head and body orientation on oVEMP reflexes recorded in response to air- and bone-conducted stimuli. SIGNIFICANCE The upright position yields an optimal oVEMP response.

Vestibular neuritis affects both superior and inferior vestibular nerves

Objective: 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. Methods: 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. Results: 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. Conclusions: 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.

Augmented ocular vestibular evoked myogenic potentials to air-conducted sound in large vestibular aqueduct syndrome.

Objective: To demonstrate the value of recording air-conducted ocular Vestibular Evoked Myogenic Potentials (oVEMP) in a patient with bilaterally enlarged vestibular aqueducts. Design: Cervical VEMP and oVEMP were recorded from a patient presenting with bilateral hearing loss and imbalance, attributable to large vestibular aqueduct syndrome. The stimuli were air-conducted tone bursts at octave frequencies from 250 to 2000 Hz. Amplitudes and thresholds were measured and compared with the normal response range of 32 healthy control subjects. Results: oVEMP reflexes demonstrated pathologically increased amplitudes and reduced thresholds for low-frequency tone bursts. Cervical VEMP amplitudes and thresholds were within normal limits for both ears across all frequencies of stimulation. Conclusions: This study is the first to describe the augmentation of AC oVEMPs in an adult with large vestibular aqueduct syndrome.

Vestibular schwannoma mimicking horizontal cupulolithiasis

Positional vertigo and nystagmus can be due to canalithiasis, cupulolithiasis and less commonly, an underlying peripheral or central vestibular disorder. We present a patient with vestibular schwannoma who initially sought treatment for positioning vertigo. Video-oculography on the roll-test revealed direction-changing horizontal apogeotropic nystagmus, consistent with horizontal cupulolithiasis. However, further audio-vestibular investigations and imaging confirmed a right vestibulopathy attributable to a schwannoma of the right vestibular nerve. This case report suggests that vestibular schwannoma should be considered as another potential mimicker of horizontal cupulolithiasis.

Bilateral sequential peripheral vestibulopathy.

A 61-year-old man presented to the emergency room with a 48-hour history of acute spontaneous vertigo without aural symptoms. Two years previously, he had 6 spells of spontaneous vertigo and tilt illusion lasting seconds within a 24-hour period. At that time, his examination, brain MRI, and CT angiography were normal. As a teenager, he had experienced posttraumatic migraine headaches for 4 years. His emergency room assessment revealed third-degree right-beating spontaneous nystagmus, a positive left horizontal head impulse, no skew deviation, and no cerebellar or long tract signs.

Lhermitte–Duclos disease presenting with atypical positional nystagmus

We describe a patient with dysplastic cerebellar gangliocytoma (Lhermitte-Duclos disease) who presented with an acute onset of positional disequilibrium. Video-oculography in the right Hallpike position revealed rightward torsional down-beat nystagmus, initially thought to be right anterior canal benign positional vertigo. However, the presence of spontaneous nystagmus, the persistent character of the positional nystagmus and the absence of fatigability indicated central positional nystagmus, attributable to his right-sided Lhermitte-Duclos disease. These findings emphasise the need for clinicians to reconsider a central cause before diagnosing the rare anterior canal benign positioning vertigo variant.

Behçet’s disease presenting as a peripheral vestibulopathy

Prolonged acute spontaneous vertigo can be secondary to acute vestibular neuritis or posterior circulation ischaemia. We present a 66-year-old man who first developed an acute vestibular syndrome with profound unilateral hearing loss 34 years ago. First treated as vestibular neuritis, he subsequently developed manifestations of Behçets disease, including mouth ulcers, genital ulcers and erythema nodosum over a period of 10 years. Subsequently, sudden sensorineural hearing loss affecting his only hearing ear responded to immunomodulation, confirming an autoimmune cause for the audiovestibular symptoms. This report serves as a reminder that vestibular neuritis seldom causes hearing loss; ischaemic, infective and autoimmune causes should be sought when an acute vestibular syndrome is accompanied by hearing impairment.