DISTINCTIVE ABNORMALITIES OF FACIAL REFLEXES IN PATIENTS WITH PROGRESSIVE SUPRANUCLEAR PALSY

Spontaneous and voluntary eyelid motility is often abnormal in patient s with progressive supranuclear palsy. In contrast, their eyelid refle x responses are relatively preserved, and only those generated by an a coustic startle have been found absent or severely reduced. We hypothe sized that, because of their relevant brainstem pathology, patients wi th progressive supranuclear palsy might have other brainstem reflex ab normalities which, on detection, could help with their neurophysiologi cal characterization. In this study, we examined facial reflex respons es in 14 patients with progressive supranuclear palsy, 12 patients wit h multisystem atrophy, 10 patients with Parkinson's disease, six patie nts with corticobasal ganglionic degeneration, II patients with variou s non-parkinsonian neurological illnesses and 10 normal subjects. EMG activity was simultaneously recorded from the orbicularis oculi and me ntalis muscles following electrical stimulation of the median nerve at the wrist. Mentalis responses were obtained in two normal subjects an d in all patients except one with Parkinson's disease, one with progre ssive supranuclear palsy and one with corticobasal ganglionic degenera tion; there were no differences between groups of subjects regarding l atency or peak amplitude, Orbicularis oculi responses were always pres ent in control subjects and patients who exhibited mentalis responses, with the significant exception of patients with progressive supranucl ear palsy, in whom only the response of mentalis was obtained. Blink-r eflex responses to supraorbital nerve electrical stimuli were present at a normal latency and amplitude in all patients. An abnormally enhan ced blink-reflex excitability recovery curve to paired stimuli was fou nd in a similar percentage of patients with progressive supranuclear p alsy, multisystem atrophy and Parkinson's disease, but in only two pat ients with corticobasal ganglionic degeneration. Patients with progres sive supranuclear palsy have a functional involvement of circuits medi ating orbicularis oculi responses to median nerve electrical stimuli, that is a distinctive feature with respect to other parkinsonian syndr omes.