THE MAXIMAL STIMULATION AND FACIAL-NERVE CONDUCTION LATENCY TESTS - PREDICTING THE OUTCOME OF BELLS-PALSY

To test the hypothesis that the facial nerve conduction latency test i s a better and earlier indicator of prognosis than other electrodiagno stic tests, 86 patients with Bell's palsy were followed for a minimum of 4 months. To select control subjects for our own research clinic an d for comparison with the patient population, latency values in 25 nor mal volunteers (50 sides) were determined. Serial maximal stimulation tests (MST) and latency tests were conducted to determine disease seve rity and prognosis in Bell's palsy patients. Outcome was graded using the Facial Paralysis Recovery Profile (FPRP) and Facial Paralysis Reco very Index (EPRI) as well as the House grading system. The capability of the two tests to accurately predict outcome was evaluated. The MST accurately predicted outcome in 94% of patients studied. In the contro l group, normal latency values were a mean 3.8 msec with a standard de viation of 0.49. In the patient population, latency values were either within normal limits or absent. When done within 4 days of onset of B ell's palsy, neither test was capable of predicting axonal degeneratio n. Statistical analyses included Fisher's Exact Test, the paired Stude nt's t test, and correlation coefficient calculations.