gms | German Medical Science

Recently developed tests of otolith function have led to significant improvements in the differential diagnosis of peripheral vestibular disorder. In the present study attention is focussed on those cases presenting with normal caloric and rotatory responses, but with symptoms of dizziness.

In the period from January 2002 to June 2004 otolith function was tested in 230 patients by measuring subjective visual vertical (SVV). The patients estimated their SVV 1) while seated stationary and upright and 2) during constant velocity yaw-axis rotation (240º/s). As demonstrated during previous unilateral centrifugation studies, in contrast to the stationary condition, any existing otolith asymmetry will be enhanced during such on-axis rotation, i.e. without eccentric displacement. In 203 patients additional bilateral caloric irrigation (44°C and 30°C) was documented by electrooculography.

Normal caloric and SVV responses during rotatory testing were found in 29,9% of the examined patients. In 23,9% normal caloric but pathological SVV responses were found; whereas pathological caloric but normal SVV were observed in 20,9%. Finally, pathological responses in both caloric and SVV tests were observed in. 25,3% of the cases.

Of those patients with normal caloric responses, only 55% made normal SVV estimates; of those with unilateral caloric weakness 46% showed normal SVV estimates; of those with complete unilateral loss 43% showed normal estimates.

17% of the all subjects demonstrated normal SVV estimation during on-axis rotation but pathological results under stationary condition.

The findings indicate that a combined lesion of lateral SCC and utricle occurs in only about 50% of patients presenting with peripheral dysfunction. It appears that isolated utricular dysfunction must be considered as a separate entity.