Physiological Abnormalities in Experimental Allergic Encephalomyelitis (EAE):I. Vestibular Hyperreactiuity (VH) in Rats with EAE

Abstract

Twelve Lewis rats were inoculated with a guinea pig spinal cord tissue preparation. They developed experimental allergic encephalomyelitis (EAE) after 12-14 days, manifested by weight loss, tail flaccidity, ataxia, hind limb paresis and incontinence. The CNS lesions are produced in this animal model on the basis of inflammatory demyelination, which provides a useful model for multiple sclerosis. Concomitantly with EAE, all animals developed vestibular hyperreactivity (VH) of otolith and canal reflexes. In surviving animals these reflexes renormalized after full clinical recovery. The major effect on the canal response was an increased duration of postrotatory nystagmus caused by an increase in time constant. These findings are similar in part to those previously reported in patients with multiple sclerosis. Acta Otolaryngol Downloaded from informahealthcare.com by McMaster University on 01/05/15For personal use only.

Diagnostic Value of Velocity-Step Responses

“…The finding of a signifi cantly increased time constant(s) may be of some differential diagnostic meaning. It has been also demonstrated in an experimental animal model of demyelinative disease [19], A novelty in vestibular diagnosis is the finding that patients with a hyperventilation (HV) syndrome display a significant increase in gain, especially those patients complaining of daily 'attacks' of dizziness. The initial ve locity showed a significant negative correla tion with the PCCh of the hyperventilators.…”

Flunarizine Treatment in Dizzy Patients with Vestibular Hyperreactivity and Hyperventilation

“…These authors reported that diaze pam decreases the gain and increases the time constant of the VOR. The vestibular commissure can be invoked for explaining effects on the VOR in a variety of conditions, such as demyelination, clinical [11] and ex perimental [12], unilateral canal paresis [7] and, most relevant for the moment, flunari zine treatment [4], The effect of this drug may differ from that of dimenhydrinate and scopolamine, since the latter two cause a de crease in VOR gain and the gain of optoki netic nystagmus. This could be explained by a postsynaptic effect in the vestibular nuclei [1].…”