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New insights into positional alcohol nystagmus using three‐dimensional eye‐movement analysis
Author(s) -
Fetter Michael,
Haslwanter Thomas,
Bork Martin,
Dichgans Johannes
Publication year - 1999
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/1531-8249(199902)45:2<216::aid-ana12>3.0.co;2-f
Subject(s) - nystagmus , vestibular system , vestibule , buoyancy , hypergravity , linear acceleration , eye movement , semicircular canal , audiology , anatomy , optokinetic reflex , horizontal plane , geodesy , physics , medicine , geology , acceleration , ophthalmology , mechanics , classical mechanics
The semicircular canals selectively transduce angular velocity and are normally insensitive to gravity and linear acceleration. In acute alcohol intoxication, however, the cupula becomes lighter than the endolymph, rendering it sensitive to gravity (buoyancy hypothesis). This results in positional alcohol nystagmus (PAN) and rotatory vertigo. We evaluated PAN in 8 normal subjects by means of three‐dimensional eye‐movement analysis in an attempt to clarify if the buoyancy mechanism is sufficient to explain PAN. Forty minutes after intake of 0.8 g of alcohol/kg of body weight, the subjects were positioned such that the lateral canals were earth vertical. They were then rotated in the plane of the lateral canals about an earth‐horizontal axis to either 45° or 90°, right or left ear down, and eye movements were recorded for 40 seconds in each position. The spatial analysis of the responses showed that in addition to the nystagmus induced by the buoyancy of all six cupulae, alcohol intoxication also causes a vertical velocity offset (in all subjects, slow phase down) that is independent of the orientation of the subject in space. The offset may represent a toxic effect on central vestibular pathways, producing a tone imbalance of the vertical vestibulo‐ocular reflex. Ann Neurol 1999;45:216–223