Discriminant analysis in predicting prognosis of Bell's palsy.

A prospective study was carried out to objectively quantificate the most important predictive factors in idiopathic facial paralysis (Bell's palsy). Stepwise discriminant analysis was applied to data prospectively obtained from 570 patients with Bell's palsy treated at the ENT Department of La Paz Hospital between January 1983 and January 1986. Due to statistical requirements the final number of patients included for discriminant analysis was 140. In all, 37 variables were studied in each patient. With data obtained from these variables a linear discriminant function was obtained, with an overall accuracy of 95%. The rate of correct prediction is 95.8% for patients with an expected complete facial recovery, and 90.9% for the group of patients with an expected recovery of less than 100%. The 8 predictor variables selected are: ENoG amplitude, stapedius reflex, familial incidence, Hilger test, maximum degree of the palsy, recurrent facial paralysis, facial pain, and hyperacusis. The discriminant function obtained is an easily adaptable method for routine practice in order to objectively assess the prognosis of patients with Bell's palsy.