Electro-nystagmographic Findings in Localized Inner Ear Disease and Localized Central Nervous System Disorders

Abstract

In order to determine the incidence of abnormal ENG findings, the findings of neurotological examinations were statistically analyzed with special reference to localized lesions. During 1978 and 1979, 1, 200 patients with vertigo and/or dizziness were examined by ENG. Of 289 patients with definitely diagnosed lesions 218 had localized inner ear disease (75 had Meniere's disease) and 71 had brain-stem or cerebellar lesions (19 operated acoustic tumors).The following ENG examinations were carried out: 1) spontaneous nystagmus, 2) gaze nystagmus, 3) positional nystagmus, 4) caloric test, 5) horizontal (H) and vertical (V) optokinetic test (OKN), and 6) H and V eye-tracking test (ETT). The examinees were divided into two groups. Group 1 received spontaneous, gaze and positional nystagmus tests, caloric test and H-ETT, all performed by routine instrument examination. Group 2 examinees were given such advanced special examinations for eye movements as V-ETT and H-V OKN.1. Abnormal ENG findings were observed in 95% of the 289 patients with definite lesions in group 1.2. Abnormal ENG findings (by H-ETT and gaze nystagmus test) were also observed in 60% of brain-stem and cerebellar lesion patients, and in 84% of acoustic tumor patients.An analysis of these abnormal ENG findings indicate that the OKN tests are necessary for the differential diagnosis of inner ear disease and CNS disorders.