Blink recovery in patients with Bell's palsy: A neurophysiological and behavioral longitudinal study

PURPOSE. To examine the recovery process of blinking in a longitudinal study of nine patients severely affected by Bell's palsy. METHODS. Kinematics of bilateral eyelid and eye movements and concomitant orbicularis oculi activity during voluntary blinking and air-puff- and acoustic-click-induced reflex blinking were determined by using the magnetic search coil technique and electromyographic recording of the orbicularis oculi muscle (OO-EMG). RESULTS. In the first 3 months of absence of OO-EMG activity, reduced eyelid and eye movement of the palsied eyelid were observed during all types of blinking. First OO-EMG activity was determined 3 months after onset of the affliction. After 1 year, OO-EMG activity was normalized and showed values similar to those on the nonpalsied side. Clinically, eyelid movements were normal after 1 year, although corresponding maximum amplitudes and corresponding velocities were two times smaller, expressed in reduced eyelid motility. Directions of eye movement during reflex blinking were normal after 1 year, although maximum amplitudes were smaller on the palsied side. Eye movements during voluntary blinking remained impaired. A simultaneous horizontal upward shift of both eyes in the same direction was recorded throughout the study. CONCLUSIONS. Although OO-EMG activity on the palsied side was normalized 1 year after onset of the affliction, the accompanying eyelid movements and their maximum amplitudes and velocities remained smaller throughout the study. The consistent impairment of eye movements in voluntary blinking during the study and reduced motility of eyelid movements indicates that higher brain structures, which modify eyelid and eye movement control during blinking, may be altered by the affliction.