Lm. Odkvist et al., THE SUBJECTIVE HORIZONTAL IN ECCENTRIC ROTATION INFLUENCED BY PERIPHERAL VESTIBULAR LESION, Acta oto-laryngologica, 116(2), 1996, pp. 181-184
Peripheral vestibular equilibrium disorders may originate in various p
arts of the labyrinth or the vestibular nerve. Traditionally, the func
tion of the lateral semicircular canals has been assessed with caloric
irrigation, and sometimes falsely been interpreted as a vestibular ne
rve lesion. The vertical semicircular canals are not easily assessed.
Caloric testing with the head in different positions is not very helpf
ul, but the canals may pairwise be tested using specific rotational te
chniques. Often the otolithic organs, capable of detecting linear acce
leration forces, are forgotten as a source of vertigo and dizziness. W
e have implemented horizontal rotatory testing with the subject seated
eccentrically facing the direction of rotation as a means of assessin
g otolithic function. The subject experiences a lateral tilt and is in
structed in darkness to put a short light bar in the position he think
s a water surface would have, which is identical to his perceived tilt
. In 39 normal subjects, a theoretical tilt of 24 degrees was estimate
d as approximately 19.5 degrees, and the standard deviation was 6 degr
ees. A side difference index was proposed to be normal if below 25%. T
he preliminary findings in a few patients with known labyrinthine lesi
ons are presented. We propose that otolithic as well as lateral semici
rcular canal functions are useful to monitor in patients with suspecte
d peripheral equilibrium disorders.