Blink reflex: review of methodology and its application to patients with stroke syndromes.

The blink reflex may be elicited in the orbicularis oculi following electrical stimulus to the periorbital regions. It consists of a direct early component (R1) and a late component (R2) which is both direct and consensual. The amplitudes of R1 and R2 are reduced and the latencies normal in patients with lesions affecting the parietal lobe of the cerebral hemisphere. The blink reflex may well include tactile contributions from the parietal lobe. The latency of R1 may be prolonged by injuries of the pons and that of R2 by lateral medullary lesions. Blink reflexes may help to distinguish bulbar from pseudobulbar lesions and to estimate the response to therapy in patients with communication disorders.