Bell's phenomenon was used to evaluate orbicularis oculis muscle function in patients with facial paralysis. Vertical eye movements associated with blinking were recorded by electronystagmography in 39 patients with acute unilateral Bell's paralysis and Hunt's syndrome and 21 normal subjects and analysed by PDP 11/34 computer. Simultaneously the eyelid motion of 2 patients and one normal subject were photographed by high-speed motion picture camera to investigate the reliability of our “blink test”.
1. The difference in velocity and amplitude between left and right eye movements during blinking, called the "blink index", decreased as lagophthalmos improved.
2. All 5 patients with more than 80% maximum blink index (MBI) had a poor prognosis. Eighteen of 19 patients with 40% or less MBI had a good prognosis.
3. Nine patients showed a 20% or lower response to ENoG, 10 showed 3.5mA or more in the NED and 12 showed a 60% or higher response to the MBI, indicating a poor prognosis in 66.7%, 80% and 75%, respectively.
4. The blink test does not require any needle electrodes, any electrical stimuli or any special equipment except an electronystagmography, and it can provide a quantitative analysis of a degeneration in patients with facial paralysis.
