Electronystagmographic assessment of cerebellar lesions.

Remarkable progress has been achieved in the neurophysiological study of the cerebellum. Based on these neurophysiological data, electronystagmographic (ENG) assessment of cerebellar lesions was made to ascertain to what extent cerebellar lesions could be diagnosed. In 13 patients out of 17 whose lesions were mainly localized on one side through CT, cerebellar lesions could be diagnosed by electronystagmographic findings. In the 1 patient with amyotrophic lateral sclerosis of the remaining 4, asymptomatic cerebellar infarction was detected unexpectedly through CT. In the remaining 3 patients, differential diagnosis from brainstem lesions was difficult to evaluate on the basis of ENG findings. In 13 patients showing cerebellar signs and symptoms, pursuit eye movements, optokinetic nystagmus (OKN), and fixation-suppression of caloric nystagmus were impaired on both sides, suggesting large mass effects upon the bilateral brainstem. However, either rebound nystagmus or opposing positioning nystagmus characteristic of cerebellar lesions was detected in 13 patients (81%). The same was true in patients with bilateral cerebellar lesions. ENG test, however, could not detect any patients who showed neither cerebellar signs nor symptoms. Further investigations are needed to supplement the gap between basic and clinical research.