Meniere's disease and the summating potential. II. Vestibular test results.

Results of electronystagmographic (ENG) position and bithermal caloric tests from patients with abnormally enlarged summating potentials (SPs) were compared with results from a unilateral weakness (UW)-matched ENG-comparison group and with a group of patients with unilateral cochlear deficits and dizziness but without enlarged SPs. The patients with enlarged SPs had significantly higher incidence of caloric UW on the involved side than did the patients with cochlear deficits but without enlarged SPs. Also, the patients with SP enlargement had a significantly higher incidence of directional preponderance toward the involved side than did either of the comparison groups. Across-group differences in position test results were predictable from the caloric test results, but these differences were not statistically significant.