Prognostic value of blink test in patients with facial paralysis

In order to gain an early estimate of a prognosis for facial paralysis, the vertical eye movements associated with eyeblinks (Bell's phenomenon) in 39 patients with acute unilateral Bell's paralysis and Hunt's syndrome and of 21 normal subjects were recorded by electronystagmography. These data were then analysed with a small digital computer (PDP 11/34). The results were compared with electroneurography (ENoG) and nerve excitability test (NET) results and can be summarized as follows: 1. Difference in velocity and amplitude between left and right eye movement during eyeblink (called blink index), diminished in inverse proportion to any improvement of lagophthalmos. 2. All the 5 patients showing more than 80% in maximum blink index (MBI) proved to have a poor prognosis, whereas 18 of 19 patients having a MBI of 40% or less proved to have a good prognosis. The blink test was deemed to be of equal clinical significance to ENoG and NET for predicting facial paralysis. 3. The blink test does not require needle electrodes for electrical stimulus, nor any special equipment other than electronystagmography, and yet this test can provide a quantitative analysis of a degeneration profile in facial paralysis.