Smooth-pursuit eye movement--a convenient bedside indicator for evaluating frontal lobe and intellectual function.

We hypothesized that smooth-pursuit eye movement is related to higher brain functions and that its impairment (iSPEM) could be useful in diagnosing neurological dysfunctions. We prospectively examined 305 patients and studied the relations between iSPEM and five items that reflect intellectual and/or frontal lobe function (dementia, sucking, snouting, hand grasping, elbow flexion response). We divided these patients into four subgroups: group A, patients with cerebellar ataxia as the presenting manifestation and with main lesions in the cerebellum; group B, patients with main lesions in brain regions other than the cerebellum; group C, patients with main lesions in the spinal cord, peripheral nerves, and muscles; and group D, patients with non-organic functional disorders, such as paroxysmal attacks and physical pain. Consequently, iSPEM was significantly (p<0.01) related to impairment in intellectual and frontal lobe functions in patients with cerebral lesions, and it also can be regarded as being equivalent to primitive reflexes.