Abstract
The neuromuscular manifestations of beriberi (vitamin B1 deficiency), the so-called “convulsions, spasticity and paralysis”, simulate in some respects the disturbances of equilibrium and coordination which follow injury to the labyrinths. It has been suggested that these manifestations are the consequence of a lesion of the vestibular apparatus, but histological examination has failed to substanstiate this hypothesis. 1 The investigation here reported was therefore devoted to a functional examination of the vestibular system to gain further information regarding the existence of such a lesion.
Vestibular function was tested by a modification of the well known Barany test. The character and duration of nystagmus following a standardized rotational stimulus served as the index. More than 2,000 tests have been made on 84 rats under various experimental conditions. The basal diet used throughout these experiments, when supplemented with codliver oil and brewer's yeast, permitted normal growth and health. When the whole yeast in the supplement was replaced by autoclaved yeast, however, the neuromuscular manifestations of beriberi appeared in 5 to 7 weeks.
The standard rotational stimulus was given by means of an electric phonograph motor and turntable upon which the animal was placed with its head held in the normal resting position at the center of the rotating disk. A speed of 2 revolutions per second was employed and this speed was attained in approximately 8 seconds. At the end of 20 seconds' rotation the electromagnetic brake was applied, bringing the turntable to a stop in 3 to 4 seconds. With the aid of a metronome the seconds were counted off from the moment the brake was applied until the pendular movements of the eyes induced by rotation had ceased. The animal was completely covered during rotation. A definite relation between speed of rotation and duration of nystagmus has been worked out.
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