Early assessment of nerve degeneration using the antidromic facial nerve response.

CONCLUSION

The antidromic facial nerve response (AFNR) is recommended as a monitoring method to detect cases resulting in facial nerve degeneration within 1 week after onset in patients with Bell's palsy and Hunt syndrome.

OBJECTIVES

The purpose of this study was to establish criteria for the AFNR to predict the prognosis of Bell's palsy and Hunt syndrome in the early stages, not exceeding 1 week after onset.

MATERIALS AND METHODS

54 patients, including 40 with Bell's palsy and 14 with Hunt syndrome, were examined in this study. All patients were tested for the AFNR within 1 week after onset of paralysis and AFNR waveforms were analyzed. Four AFNR parameters, the total (peak-to-peak) amplitude (T-amp), the amplitudes of the positive wave (P-amp) and the negative wave (N-amp), and the N-amp/T-amp (N/T) ratio, were compared with the outcomes of facial paralysis.

RESULTS

In most patients with poor outcomes, T-amp was <4 microV and N-amp was <2 microV. The mean value of the N/T ratio in patients with a poor outcome fell to <0.4 after the 3rd day from onset, while that in patients with a good outcome was stable between 0.4 and 0.6 during the first week.