Vestibular decruitment: an indicator of central pathology?

Torok studied the ratio obtained between the responses to two different heat stimulation intensities of the same temperature. A decrease in response to the strong stimulus (i.e., a diminished ratio) was called "vestibular decruitment," and was regarded as a topodiagnostic indicator of central vestibular lesion, reflecting "adaptation" or "fatigue." The authors studied the reliability of vestibular decruitment obtained by Torok's technique in the indication of central vestibular pathology. Twenty-eight normal individuals and 30 patients previously diagnosed by other methods with diffuse pathology of the central nervous system were evaluated. The results obtained show that the two stimuli used are both supraliminal and of different intensity regarding the labyrinth. In no case was vestibular recruitment obtained. In view of the high percentage of normal individuals (57.14%) who presented vestibular decruitment, we consider the latter to lack topodiagnostic value as an indicator of either central or vestibular pathology; the smaller response to the mass stimulus might be explained by the vestibular habituation phenomenon that occurs on applying Torok's technique in both normal individuals and in patients with central vestibular pathology.