Blink reflex and discomplete facial nerve palsy

Electrophysiologic findings of the blink reflex in patients with Bell's palsy are usually said to be either prolonged latencies and/or absent early and middle responses of it.

Facial nerve conduction and blink reflex studies were performed on a 42-year-old male patient with right-side Bell's palsy. Studies were done using protocols previously validated and published elsewhere.

The right compound muscle action potential was not found after stimulation of the right facial nerve as expected. Absence of the short (R1) and middle (R2) responses of the blink reflex were also noted after right and left supraorbital nerve stimulation. Further, the late (R3) response of the blink reflex was displayed on the abnormal side when electrical stimuli were applied to the right supraorbital nerve while the patient attempted to perform voluntary movement of the paralyzed facial muscles including eye closing.

The recording of R3-a late response following fibers and using motoneurons other than those employed by R1 and R2-on the paralyzed side after performing some reinforcement maneuvers allows us to suggest that, in some facial nerve palsies, there are some structures remaining alive that may be useful for carrying out a more timely and accurate diagnosis and follow-up.