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Otol Neurotol. 2013 Jun;34(4):743-7. doi: 10.1097/MAO.0b013e318287f343.

Spontaneous plugging of the horizontal semicircular canal with reversible canal dysfunction and recovery of vestibular evoked myogenic potentials.

Author information

1
Health Sciences Institute, Portuguese Catholic University, Lisbon, Portugal. leonelluis@me.com

Abstract

OBJECTIVE:

To evaluate the clinical pathophysiology of oculomotor changes in a patient presenting with a spontaneous semicircular horizontal canal plug.

PATIENT:

A 42-year-old man with acute spontaneous vertigo with spinning and persistent left-horizontal nystagmus, intensity but not direction dependent on head orientation with respect to gravity, indicating a benign paroxysmal positional vertigo due to otoconia causing a plug in the horizontal semicircular canal.

INTERVENTION:

Electrophysiological and video-oculographic testing; vestibular rehabilitation.

MAIN OUTCOME MEASURES:

Cervical and ocular vestibular evoked myogenic potentials (VEMPs); video head impulse testing.

RESULTS:

The video head-impulse test revealed an eye velocity cutoff at 80°/s in the time interval from 40 to 90 ms after initiation of head impulses to the right. This normalized within 2 days after liberatory maneuvers, documenting for the first time a reversible deficiency of the cupular-endolymph high-frequency system dynamics. Cervical and ocular vestibular myogenic potentials were absent during stimulation of the affected side before the liberatory maneuvers but normalized within 30 to 80 days.

CONCLUSION:

This case is special in 4 respects: 1) nystagmus intensity, but not direction, was dependent on head orientation with respect to gravity, indicating a horizontal canal plug; 2) VEMPs were asymmetrical before liberatory maneuvers; 3) VEMPs recovered after Day 30; and 4) video head-impulse test asymmetry recovered. These observations challenge the common belief that VEMPs are evoked by otolith stimulation only. Instead, the assumption of a reversible canal dysfunction by a plug offers a more plausible explanation for all effects.

PMID:
23632787
DOI:
10.1097/MAO.0b013e318287f343
[Indexed for MEDLINE]

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