Electronystagmographic analysis of optokinetic and smooth pursuit eye movement disorders in vestibular lesions

The electronystagmographical analysis of the eye movements is an important method in the evaluation and topical diagnostic procedure of several vestibular lesions. The aim of the study was to compare the electronystagmographical results of the optokinetic and the smooth pursuit eye-movement, and their sensitivity in several vestibular disorders. The patients were divided into five groups: right and left unilateral and bilateral peripheral lesions, central vestibular dysfunction, and normal vestibular function. In patients with normal vestibular system the optokinetic eye movement was pathological in 9.53% of patients, while the smooth pursuit eye movements were pathological in 8.3% of patients with normal vestibular function. In unilateral lesions, 17.42% of the OKNs were pathological, compared with the smooth pursuit test's 20.3% pathological ratio. In the bilateral peripheral vestibular dysfunction the ratio of the pathological eye-movements was 28% equally with to two methods. In central vestibular lesions 22.72% of the patients had abnormal optokinetic eye movements, and the smooth pursuit eye movement was abnormal in 41.6%. Our results show that in the unilateral peripheral vestibular lesions the smooth pursuit eye movement examination seems to be more sensitive than the OKN test, while in central dysfunctions the smooth pursuit eye movement examination is more sensitive than OKN examination.