Effects of nonprescription therapies on vestibular migraine: a questionnaire-based observational study.

BACKGROUND: Vestibular migraine (VM) is a common cause of recurrent vertigo. Migraine headache preventative therapies are currently prescribed to control vertigo symptoms in VM. Clinical trials of nutraceuticals for migraine headache prevention have shown positive outcomes, but, to date, there have been no studies to assess their effectiveness in the management of VM. AIMS: To report the effects of nonprescription therapy management on VM symptoms. METHODS: We undertook a prospective, questionnaire-based assessment of patients diagnosed with VM between November 2019 and August 2021 at two Sydney tertiary referral clinics. Patients were advised on optimising sleep, hydration, exercise and nutrition and instructed to use an over-the-counter combination product containing riboflavin 200 mg, magnesium 150 mg, coenzyme Q10 75 mg and feverfew 200 mcg. Symptom severity and frequency were assessed using the Dizziness Handicap Inventory (DHI), the Vertigo Symptom Score short-form (VSS-sf) and two visual analogue scales for severity (VAS-s) and frequency (VAS-f) before and 3 months after commencing treatment. RESULT: In 82 participants (78% female; mean age, 44 ± 14 years) we recorded a decrease in DHI (mean, 16.8 [95% confidence interval (CI), 12.8-20.9], VSS-sf (9.3, 7.1-11.5), VAS-s (3.0, 2.2-3.8) and VAS-f (2.8, 2.1-3.4), equating to an improvement of 44.1%, 44.9%, 44.1% and 38.9% for each measure respectively. On the DHI and VSS-sf, 41 (50%) and 44 (53.7%) patients showed improvement in their symptoms; 39 (47.6%) and 36 (43.9%) patients noted no change and two patients reported worsening. The supplement was well-tolerated. CONCLUSIONS: The results provide preliminary evidence that VM symptom frequency and severity can be reduced by using nonprescription therapies.

A Portrait of Menière's Disease Using Contemporary Hearing and Balance Tests.

OBJECTIVE: Menière's disease (MD) is characterized by recurrent vertigo and fluctuating aural symptoms. Diagnosis is straightforward in typical presentations, but a proportion of patients present with atypical symptoms. Our aim is to profile the array of symptoms patients may initially present with and to analyze the vestibular and audiological test results of patients with a diagnosis of MD. DESIGN: A retrospective study of patient files. SETTING: A tertiary, neuro-otology clinic Royal Prince Alfred Hospital, Sydney, Australia. METHOD: We identified 375 patients. Their history, examination, vestibular-evoked myogenic potentials (VEMP), video head-impulse test, canal-paresis on caloric testing, subjective visual horizontal (SVH), electrocochleography, ictal nystagmus, and audiometry were assessed. RESULTS: Atypical presenting symptoms were disequilibrium (n = 49), imbalance (n = 13), drop-attacks (n = 12), rocking vertigo (n = 2), and unexplained vomiting (n = 3), nonspontaneous vestibular symptoms in 21.6%, fluctuation of aural symptoms only (46%), and headaches (31.2%). Low velocity, interictal spontaneous-nystagmus in 13.3% and persistent positional-nystagmus in 12.5%. Nystagmus recorded ictally in 90 patients was mostly horizontal (93%) and of high velocity (48 ±â€Š34°/s). Testing yielded abnormal caloric responses in 69.6% and abnormal video head impulse test 12.7%. Air-conducted cervical VEMPs were abnormal in 32.2% (mean asymmetry ratio [AR] 30.2 ±â€Š46.5%) and bone-conducted ocular VEMPs abnormal in 8.8% (AR 11.2 ±â€Š26.8%). Abnormal interictal SVH was in 30.6%, (ipsiversive n = 46 and contraversive n = 19). Mean pure-tone averages 50 dB ±â€Š23.5 and 20 dB ±â€Š13 for affected and unaffected ears. CONCLUSION: Menière's disease has a distinctive history, but atypical presentations with normal vestibular function and hearing are a diagnostic challenge delaying treatment initiation.

Dissociation of caloric and head impulse tests: a marker of Meniere's disease.

A retrospective analysis of the horizontal video head impulse test (vHIT) results and caloric testing results was undertaken on 644 patients who attended a neuro-otology outpatient facility. Presenting symptoms included spontaneous vertigo, positional vertigo, imbalance or chronic subjective dizziness. For 570 patients, the results of vHIT and caloric testing were concordant. Both tests were normal in 500 subjects with an average vHIT gain = 0.92 ± 0.09 (L); 0.98 ± 0.10 (R) and canal paresis (CP) = 7.88 ± 6.12; (range 0-28%). 54 had concordant asymmetries, average ipsilesional vHIT gain = 0.56 ± 0.15, average contralesional vHIT gain = 0.88 ± 0.12. CP = 68.02 ± 24.38 (range 31-100%). 16 subjects had bilateral vestibular hypofunction with average vHIT gains of 0.42 ± 0.20 (L); 0.41 ± 0.19 (R), peak slow phase velocity (SPV) on warm caloric testing = 2.68 ± 2.08, range 0-6°/s (L) and 3.75 ± 3.43 range, 0-10°/s (R). 36 patients showed a dissociation of results between the two tests. In these subjects, the vHIT gain was normal (0.93 ± 0.06 left and 0.98 ± 0.07 right) and the caloric test showed a CP > 30% (48 ± 13.8%). Their final diagnoses included clinically definite Meniere's disease (MD) (n = 27), vestibular schwannoma (VS) (n = 2) vestibular migraine (VM) (n = 1), vestibular neuritis (VN) (n = 5) and unknown (n = 1). No patient with abnormal HSCC gain on vHIT had a normal caloric result. The caloric test complements the vHIT in the assessment of vestibular disorders and is most useful in suspected endolymphatic hydrops. Asymmetric caloric function in the presence of normal horizontal head impulse tests is most commonly associated with Meniere's disease and may function as a diagnostic marker.

Bioinformatics-Based Identification of Expanded Repeats: A Non-reference Intronic Pentamer Expansion in RFC1 Causes CANVAS.

Genomic technologies such as next-generation sequencing (NGS) are revolutionizing molecular diagnostics and clinical medicine. However, these approaches have proven inefficient at identifying pathogenic repeat expansions. Here, we apply a collection of bioinformatics tools that can be utilized to identify either known or novel expanded repeat sequences in NGS data. We performed genetic studies of a cohort of 35 individuals from 22 families with a clinical diagnosis of cerebellar ataxia with neuropathy and bilateral vestibular areflexia syndrome (CANVAS). Analysis of whole-genome sequence (WGS) data with five independent algorithms identified a recessively inherited intronic repeat expansion [(AAGGG)exp] in the gene encoding Replication Factor C1 (RFC1). This motif, not reported in the reference sequence, localized to an Alu element and replaced the reference (AAAAG)11 short tandem repeat. Genetic analyses confirmed the pathogenic expansion in 18 of 22 CANVAS-affected families and identified a core ancestral haplotype, estimated to have arisen in Europe more than twenty-five thousand years ago. WGS of the four RFC1-negative CANVAS-affected families identified plausible variants in three, with genomic re-diagnosis of SCA3, spastic ataxia of the Charlevoix-Saguenay type, and SCA45. This study identified the genetic basis of CANVAS and demonstrated that these improved bioinformatics tools increase the diagnostic utility of WGS to determine the genetic basis of a heterogeneous group of clinically overlapping neurogenetic disorders.

Passive motion reduces vestibular balance and perceptual responses.

With the hypothesis that vestibular sensitivity is regulated to deal with a range of environmental motion conditions, we explored the effects of passive whole-body motion on vestibular perceptual and balance responses. In 10 subjects, vestibular responses were measured before and after a period of imposed passive motion. Vestibulospinal balance reflexes during standing evoked by galvanic vestibular stimulation (GVS) were measured as shear reaction forces. Perceptual tests measured thresholds for detecting angular motion, perceptions of suprathreshold rotation and perceptions of GVS-evoked illusory rotation. The imposed conditioning motion was 10 min of stochastic yaw rotation (0.5-2.5 Hz ≤ 300 deg s(-2) ) with subjects seated. This conditioning markedly reduced reflexive and perceptual responses. The medium latency galvanic reflex (300-350 ms) was halved in amplitude (48%; P = 0.011) but the short latency response was unaffected. Thresholds for detecting imposed rotation more than doubled (248%; P < 0.001) and remained elevated after 30 min. Over-estimation of whole-body rotation (30-180 deg every 5 s) before conditioning was significantly reduced (41.1 to 21.5%; P = 0.033). Conditioning reduced illusory vestibular sensations of rotation evoked by GVS (mean 113 deg for 10 s at 1 mA) by 44% (P < 0.01) and the effect persisted for at least 1 h (24% reduction; P < 0.05). We conclude that a system of vestibular sensory autoregulation exists and that this probably involves central and peripheral mechanisms, possibly through vestibular efferent regulation. We propose that failure of these regulatory mechanisms at different levels could lead to disorders of movement perception and balance control during standing.

Galvanic and acoustic vestibular stimulation activate different populations of vestibular afferents.

OBJECTIVE: To deduce whether similar or distinct populations of vestibular afferents are activated by acoustic and galvanic vestibular stimulation by comparing the effectiveness of 'matched' stimuli in eliciting vestibulospinal reflexes. METHODS: Twelve subjects (5 men, 7 women) underwent individual 'matching' of 2 ms tone burst and galvanic stimuli, using vestibulocollic reflexes so that corrected reflex amplitudes to tone burst and galvanic stimuli were within 10% of each other. These same intensities were then administered using 20 ms durations to determine whether they were equally effective in evoking vestibulospinal responses. RESULTS: Corrected reflex amplitudes for vestibulocollic responses to tone burst and galvanic stimulation were not significantly different for the right (P=0.45) or left (P=0.68) sides. All subjects had vestibulospinal responses to galvanic stimulation (average intensity 4.0 mA for both sides). The short latency (SL) and medium latency (ML) components of the vestibulospinal reflexes were larger after galvanic compared to tone burst stimulation in 11 of 12 subjects (P<0.01). CONCLUSIONS: Despite evoking equal-sized vestibulocollic reflexes, there was a clear dissociation between the magnitude of tone burst and galvanic-induced vestibulospinal reflexes. Galvanic stimulation evoked SL and ML reflexes in all subjects. Tone burst stimuli evoked only small SL reflexes and, in most cases, no ML reflexes. Acoustically-evoked vestibulocollic reflexes are likely to be due to saccular excitation. The limited effectiveness of longer tone burst stimuli to evoke ML vestibulospinal reflexes suggests that saccular afferents have, at most, only a minor role in the production of these reflexes. We conclude that galvanic stimulation is more effective in eliciting vestibulospinal reflexes than tone burst stimulation, and that the two methods activate different populations of vestibular afferents.

Focal pathological startle following pontine infarction.

A 36-year-old male developed an acute right-sided weakness due to left-sided pontine infarction. Two months later, he first noticed sudden right elbow flexion in response to a loud unexpected noise. Detailed electrophysiological assessment was performed. A large, short-latency (median 39 msec), synchronous electromyographic discharge occurred in the right biceps brachii electrodes following a 50-msec, 120-dB 1-kHz tone burst, with habituation only with very short (30-second) interstimulus intervals. Less synchronous activity at longer latencies was present both in a number of right-sided arm muscles at rest and on the clinically unaffected side during a tonic voluntary contraction. We discuss possible underlying mechanisms and our reasons for considering this a focally enhanced startle response. Our report broadens the range of expression of acquired startle disorders.