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Objective: To examine the properties and potential clinical uses of myogenic potentials to bone conducted sound. Methods: Myagenic potentials were recorded from normal volunteers, using bone conducted tone bursts of [...]

Edited by R.W. Baloh and V. Honrubia (Pp 408, US$98.50). Published by Oxford University Press, New York, 2001. ISBN 0-19-513982-8. The first edition of Clinical neurophysiology of the vestibular system, [...]

Abstract: Malignant leptomeningitis can present as the clinical syndrome of pseudotumor cerebri due to infiltration of arachnoid villi in the superior sagittal sinus. We show that malignant pachymeningitis can also present with pseudotumor cerebri, likely due to cerebral venous hypertension from transverse sinus compression. We present 3 cases of pseudotumor cerebri due to pachymeningeal or leptomeningeal metastases and discuss the mechanism of intracranial hypertension in such cases, its diagnosis and treatment. [Copyright &y& Elsevier]

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. Copyright © 2012 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Research into vestibular responses to sound has evolved in four stages. The first, largely the work of Tullio in the 1920s, involved inspection of the eye, head, and postural responses to sound of alert animals with surgical fenestrae into various parts of the bony labyrinth. The second, begun in 1964 by Bickford and his group and continued by our group and then by others in the last 10 years, involves the measurement of evoked myogenic potentials to air-conducted and bone-conducted clicks and tones in normal humans. The third, begun by Mikaelian at about the same time as Bickford and continued by McCue, our group, and others, involves electrophysiological recordings of primary vestibular afferent neuron responses to sound in anesthetized animals. The fourth involves measurements of vestibulo-ocular responses to sound in humans with the Tullio phenomenon. It was begun by Minor and his group in 1998 with the observation that sound-induced nystagmus in humans, the Tullio phenomenon, aligned with the rotation axis of the superior semicircular canal. They then showed a defect in the temporal bone between the apex of the superior semicircular canal and the middle cranial fossa, which was the cause of most, if not all, cases of sound-induced nystagmus. Here some of the key observations made in each of these four stages are reviewed. [ABSTRACT FROM AUTHOR]

Bone-conducted vibration of the forehead, in the midline at the hairline (Fz) causes linear acceleration stimulation of both mastoids and results in an ocular vestibular-evoked myogenic potential (oVEMP), recorded by surface electromyogram (EMG) electrodes just beneath the eyes. The early n10 component of the oVEMP is symmetrical in healthy subjects, absent in patients with bilateral vestibular loss, and in patients after unilateral vestibular loss (uVL) n10 is small or absent on the side contralateral to the uVL, but of normal amplitude on the side contralateral to the healthy ear. The n10 component probably reflects mainly otolithic function, since in the guinea pig, primary otolith irregular neurons are selectively activated by bone-conducted vibration (BCV) at low intensities (0.1 g), whereas semicircular canal primary afferents are not activated even at high intensities (10 g). [ABSTRACT FROM AUTHOR]

Abstract: Isolated hypoglossal nerve lesions often reflect sinister neoplastic or vascular pathology. Rarely, reversible lesions occur, perhaps via mechanisms similar to Bell’s palsy. We report a patient with reversible isolated hypoglossal nerve palsy as the first and predominant early manifestation of pre-eclampsia and speculate on the pathogenesis behind this abnormality. [Copyright &y& Elsevier]

Abstract: The mitochondrial 12S rRNA is considered a hotspot for mutations associated with nonsyndromic (NSHL) and aminoglycoside-induced hearing loss (AIHL). Although aminoglycoside ototoxicity is the most common cause of bilateral vestibular dysfunction, the conceivable role of 12S rRNA mutations has never been systematically investigated. We sequenced the 12S rRNA of 66 patients with bilateral vestibulopathy (BV) with (n =15) or without (n =51) prior exposure to aminoglycosides, as well as 155 healthy controls with intact vestibular function (sport pilots), and compared these to 2704 published sequences (Human Mitochondrial Genome Database). No mutations with a confirmed pathogenicity were found (A1555G, C1494T), but four mutations with a hitherto tentative status were detected (T669C, C960del, C960ins, T961G). Due to their predominant occurrence in patients without aminoglycoside exposure, their detection in controls and a weak evolutionary conservation, their pathogenic role in vestibulocochlear dysfunction remains provisional. [Copyright &y& Elsevier]