What might cervical vestibular-evoked myogenic potential abnormalities mean in essential tremor?

AIM/BACKGROUND: Essential tremor (ET) is one of the most common movement disorders. However, its pathogenesis is unclear. Human vestibular reflexes are essential not only for gait and posture but also for goal-directed voluntary movements. In this study, cervical vestibular-evoked myogenic potentials (cVEMPs), the electrophysiological equivalent of the vestibulo-collic reflex was studied in ET patients to understand the interaction between the tremor network and the vestibular neural pathways. METHODS: cVEMPs were recorded in 40 ET patients and 40 age and sex-matched healthy controls (HCs). The latencies of peaks p13 and n23 and peak-to-peak amplitude of p13-n23 were measured. RESULTS: There was no statistically significant difference between the p13 latencies of the HC and ET groups (p 0.79 and p 0.23 for the right and left sides respectively). n23 latency was shortened bilaterally in the ET group (p 0.009 and p 0.02 for the right and left sides respectively). p13-n23 amplitudes of the ET patients were bilaterally reduced when compared with the HC (p <0.001 and p 0.001 for the right and left sides respectively). CONCLUSION: Information provided by vestibular afferents is crucial in the control of voluntary movements in humans. Despite this silent but significant effect, the role of the vestibular system in movement disorders is often overlooked. In this study, it was found that cVEMP responses reflecting the activity of the vestibulo-collic pathway were affected in ET which can be either caused by dysfunctional structures or pathways responsible from ET or an additional disorder of vestibular information processing in these patients.

Cervical Vestibular Evoked Myogenic Potentials in Idiopathic Intracranial Hypertension.

PURPOSE: Idiopathic intracranial hypertension (IIH) is raised intracranial pressure without any identifiable etiology. The inner ear structures are susceptible to cerebrospinal fluid (CSF) pressure changes because of connections between the CSF space and the labyrinth to explain the audiovestibular symptoms, such as pulsatile tinnitus or dizziness, reported in 50% to 60% of these patients. The aim of this study was to investigate the vestibular functions using cervical vestibular evoked myogenic potentials (cVEMPs) in IIH. METHODS: cVEMPs were recorded in 30 patients with IIH before lumbar puncture. Thirty healthy volunteers constituted the control group. The latencies of peaks p13 and n23 and peak-to-peak amplitude of p13-n23 were measured. RESULTS: Responses were gathered bilaterally from all healthy controls. In 30 patients with IIH, 49 responses could be gathered from 60 tests (81.7%). The potential was absent bilaterally in five and unilaterally in one patient. When recorded, the latency and amplitude values of the responses of the patients were not significantly different from the healthy controls (P > 0.005). A correlation between CSF pressure and response persistence could not be determined. CONCLUSIONS: cVEMPs are affected in patients with IIH and the main finding is the absence of the responses. Increased intracranial pressure causing sound transmission changes within the inner ear can affect the saccular afferents and may end up with absent responses on air-conducted cVEMP recordings. To comment on the correlation between the CSF pressure and cVEMP changes, successive cVEMP recordings with longitudinal CSF pressure monitoring seem necessary.

Transient Contrast Neurotoxicity After Percutaneous Coronary Intervention Mimicking Subarachnoid Hemorrhage in a Patient With Chronic Kidney Disease.

Transient contrast neurotoxicity is a rare but well-recognized complication of angiography that is due to neurotoxicity of the contrast agent. Patients with renal dysfunction may be inclined to develop contrast medium neurotoxicity due to delayed elimination of the contrast medium in renal metabolism. In this report, we present an unusual case of transient neurotoxicity in a patient with severe chronic kidney disease following percutaneous coronary intervention mimicking clinically and radiologically subarachnoid hemorrhage. The patient's clinical symptoms improved rapidly and fully recovered after hemodialysis and conservative treatment. We believe that performing early hemodialysis is an effective treatment to improve symptoms in end-stage renal disease patients with contrast-induced encephalopathy.