Evaluation of the somatosensory evoked blink response in patients with neurological disorders.

BACKGROUND The somatosensory evoked blink response (SBR) is a characteristic reflex blink elicited by electrical stimulation of peripheral nerves or other anatomical sites. METHODS 139 patients with neurological disorders were examined for presence of the SBR. Although the SBR was not usually elicitable, it was present in a subset of patients with Parkinson's disease and with hemifacial spasm. It was also present in a patient with Guillain-Barré syndrome before the recovery phase. The latency of the EMG activities responsible for the SBR was significantly shorter than that of the startle blink. CONCLUSIONS The SBR is not a variant of the startle blink, but is a release phenomenon transmitted via the brainstem reticular formation. This response may be clinically relevant in disorders associated with brainstem lesions and abnormal blinking.