[THE VIDEO HEAD IMPULSE TEST (VHIT): CAN WE RELY ON THE GAIN PARAMETER ALONE?]

INTRODUCTION: While the bedside head impulse test evaluates the presence of refixation saccades (RS) as a measure of failing vestibulo-ocular reflex (VOR) the VOR gain calculated by the video head-impulse test (vHIT) is considered the primary measure for semicircular canal function while the role RS is still under evaluation. AIMS: To evaluate the benefit of various RS characteristics towards the diagnosis of the left horizontal semicircular function by vHIT. METHODS: The vHIT recordings of 40 patients with left sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. RESULTS: Gain values > 0.72 were found in all patients with no vestibular disease, and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain < 0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72-0.79 the presence of RS with frequency > 80% improved vHIT sensitivity. CONCLUSIONS: Although VOR gain<0.8 is considered to reflect dysfunction, a significant false positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72-0.79. The presence of RS with frequency >80% could improve vHIT diagnostic accuracy in these patients.

[THE VIDEO HEAD IMPULSE TEST (VHIT)].

INTRODUCTION: The video head impulse test (vHIT) is a new tool in the vestibular tests' arsenal. It is based on the clinical Head Impulse Test, where the integrity of the vestibulo-ocular reflex is tested by high frequency excitation of the semi-circular canals. The vHIT system is composed of an accelerometer measuring the head movements, and a high frequency infra-red camera for eye tracking mounted on a light-weighted goggles. The main measures obtained are the vestibulo-ocular reflex gain - the ratio between the head and eye velocities, and the recording of corrective saccades taking place during the head movement (covered saccades) or following it (overt saccades).

Refining the Video Head Impulse Test Diagnostic Accuracy: A Case-Control Study.

INTRODUCTION: Current clinical practice considers the vestibulo-ocular reflex (VOR) gain as registered by the video head impulse test (vHIT) as the primary measure for semicircular canal function, while the role of the re-fixation saccades (RSs) is still under evaluation. The goal of the study was to appraise the added benefit of RS towards the improvement of vHIT diagnostic accuracy in cases of suspected left horizontal semicircular canal dysfunction. METHODS: The vHIT recordings of 40 patients with left-sided horizontal VOR gains <0.8 were retrospectively evaluated for the presence of RS. The study groups included 20 patients with a final diagnosis of left horizontal semicircular canal dysfunction and 20 patients for whom vestibular dysfunction was ruled out. RESULTS: Gain values >0.72 were found in all patients with no vestibular disease and in 4 (20%) patients having vestibulopathy. Significantly higher average left-sided RS velocity and frequency were found among the vestibular patients. VOR gain <0.72 was found to be highly specific for the diagnosis of vestibular dysfunction. However, for gain values in the range of 0.72-0.79, the presence of RS with frequency >80% largely improved vHIT diagnostic accuracy. CONCLUSIONS: Although VOR gain <0.8 is considered to reflect dysfunction, a significant false-positive rate for left-sided horizontal vHIT was found for gains in the range of 0.72-0.79. The presence of RS with frequency >80% could improve vHIT diagnostic ability in these patients.

Bone Mineral Density in Patients Suffering from Ménière's Disease.

INTRODUCTION: Previous studies have reported an association between reduced bone mineral density and the occurrence of benign paroxysmal positional vertigo, balance impairment, and saccular dysfunction. Furthermore, the results of recent animal studies have raised the possibility that vestibular dysfunction could affect bone remodeling and bone mass. The goal of the study was to compare bone mineral density of patients suffering from definite Ménière's disease to that of a matched control group. METHODS: We conducted a case-control cross-sectional study in a tertiary referral center. The study group included 23 patients suffering from definite Ménière's disease, and the control group was comprised of 23 patients matched in their race, gender, and age parameters in whom no vestibular pathology could be found. Dual energy X-ray absorptiometry of the femoral head was used for the assessment of bone mineral density. The T and Z scores of the femoral heads' bone mineral density were compared. RESULTS: The average T scores were -1.53 ± 1.08 in the study and -0.39 ± 0.72 (p = 0.016) in the control groups, and the Z scores were -0.4 ± 0.63 and 0.33 ± 0.31 (p = 0.018), respectively. Seventeen patients (74%) of the study group and 9 (39%) of the control group had T scores less than -1.0, indicating osteopenia/osteoporosis (p = 0.036). CONCLUSIONS: The results showed a significant association between Ménière's disease and reduced bone mineral density of the femoral head. Bone mineral density studies of the weight-bearing bones are warranted in Ménière's disease for the early diagnosis and treatment of osteopenia/osteoporosis on the one hand and possible benefit of this treatment for the evolution of Ménière's disease on the other hand.

Case Report: Histoplasmosis: First Autochthonous Case from Israel.

We present an autochthonous Histoplasma infection in Israel. The patient presented with hoarseness and weight loss. Pathology findings and molecular tests confirmed the diagnosis, and the patient responded to antifungal therapy. Because the patient had an atypical presentation of histoplasmosis, it is likely that other more typical cases have gone unreported. To our knowledge, no other cases have been previously reported from Israel or the Middle East region.

Hearing and Otoacoustic Emissions Outcome of Stapedotomy: Does the Prosthesis Diameter Matter?

OBJECTIVE: To compare the hearing and otoacoustic emissions (OAE) outcome of stapedotomy employing 0.4 and 0.6 mm diameter prostheses. MATERIALS AND METHODS: In total, 18 patients with otosclerosis participated in a prospective, double-armed, randomized cohort study. All the patients underwent small fenestra drill stapedotomy employing the Causse fluroplastic large loop piston prostheses. The patients were randomly assigned to groups of 0.4 mm (n=9) and 0.6 mm (n=9) diameter prostheses. The results of pure tone air and bone audiometries, speech audiometry, and OAE conducted 12 months post operatively were compared within and between the groups. RESULTS: The within-group analysis showed significant post-stapedotomy improvements in the average air conduction pure tone thresholds in both groups (52.9±9.6 vs. 25.6±5.2 dB HL; p<0.0001 and 54.6±10.4 vs. 22.2±8.2 dB HL; p<0.0001 for the 0.4 and 0.6 mm groups, respectively) and average air-bone gap (ABG; 37.1±8.5 vs. 8.1±3.9 dB HL; p<0.0001 and 38.3±7.5 vs. 9.9±4.5 dB HL; p<0.0001 in the 0.4 and 0.6 mm groups, respectively). No significant differences were found between the groups in these outcome measures, as well as in the rate of ABG closure within 10 dB HL and the word recognition scores. Favorable outcome in the post-stapedotomy bone conduction (BC) was found for the 0.6 mm prosthesis group, reflecting superior cancellation of the Carhart phenomenon for the 500-3000 Hz pure tone thresholds average (-1.7±3.7 vs. 3.9±6.2 dB HL for the 0.4 and 0.6 mm groups, respectively; p<0.04) and 1000, 2000, and 4000 Hz average (-2.6±4.33 vs. 3.9±7.8 dB HL for the 0.4 and 0.6 mm groups, respectively; p<0.05). Small signal-to-noise ratio (SNR) values of the transient-evoked OAE (TEOAE) and distortion product OAE (DPOAE) were found at baseline and follow-up evaluation with no consistent changes post stapedotomy. CONCLUSION: Similar post-stapedotomy hearing results were found for the 0.4 and 0.6 mm prostheses with small but statistically significant advantage in BC gain and the overclosure parameter for the 0.6 mm prosthesis. OAE testing was not found to be of clinical value in the evaluation of stapedotomy hearing outcome.

Suppression of neuroinflammation and immunomodulation by the acetylcholinesterase inhibitor rivastigmine.

In this study we determined the influence of cholinergic up-regulation by rivastigmine, an acetylcholinesterase inhibitor, on central nervous system inflammation. Neuroinflammation was induced in experimental autoimmune encephalomyelitis (EAE). Rivastigmine markedly ameliorated clinical symptoms of EAE and the spatial memory deficits induced by EAE. It also reduced demyelination, microglia activation and axonal damage. Rivastigmine decreased the reactivity of encephalitogenic T-cells and the production of pro-inflammatory cytokines (TNF-alpha, IFN-gamma and IL-17) without affecting IL-10 production. These effects were abolished by alpha7 nicotinic acetylcholine receptor antagonists. Antigen presentation was also affected by this treatment. Thus, rivastigmine treatment had immunomodulatory activity in EAE.