Comparison of optokinetic nystagmus elicited by full versus partial visualfield stimulation: Diagnostic implications

Optokinetic nystagmus (OKN) testing is one method to determine central vest ibular dysfunction, OKN may be elicited by partial visual field stimulation with a light bar (OKN-ENG) or by full visual field stimulation with rotati ng stripes in a rotational chair test booth (OKN-RVT). OKN-ENG and OKN-RVT were elicited in 36 healthy subjects and 48 patients with known peripheral or central vestibular disorders. Abnormal test results suggested central pa thology in 29 of 36 healthy subjects with OKN-ENG versus 1 of 36 with OKN-R VT. Twenty-eight of 33 patients with peripheral pathology demonstrated abno rmal OKN-ENG findings, whereas 4 of 33 had abnormal OKN-RVT results. Thirte en of 15 patients with central vestibular disorders had abnormal OKN-ENG, w hereas 7 of 15 had abnormal OKN-RVT. Sensitivity and specificity of OKN-ENG were 86.7% and 17.4% versus 46.7% and 92.7%, respectively, for OKN-RVT, Th ese findings were statistically significant (P < 0.00001). OKN elicited by full visual field stimulation (OKN-RVT) is a more accurate indicator of cen tral disease than OKN elicited by partial visual field stimulation (OKN-ENG ). The use of OKN-ENG to identify central vestibular dysfunction is questio nable.