Prognostic Value of Electroneurography and Electromyography in Facial Palsy

Objectives: To compare the prognostic value of electroneurography (ENG) and needle electromyography (EMG) to estimate facial function outcome after acute facial palsy. Study Design: Retrospective study using electrodiagnostic data and medical chart review. Methods: Two hundred one patients treated 1995 to 2004 were included. Initial and final facial function was established clinically by the House-Brackmann (HB) scale. ENG results were classified into amplitude loss less than 75% and amplitude loss 75% or greater to predict complete recovery and defective healing, respectively. Initial and follow-up EMG results were classified into neurapraxia and predicted complete recovery. In contrast, axonotmesis/neurotmesis and mixed lesions predicted, by definition, defective healing. Results: Initial HB was II to IV in 154 patients and V to VI in 47 patients. The etiology was idiopathic palsy in 139, iatrogenic lesion in 29, traumatic in 18, and herpes zoster in 15 patients. Finally, 134 (67%) patients showed a full recovery. Sixty-seven (33%) patients showed signs of defective healing. ENG presented a sensitivity, specificity, accuracy, positive predictive value (to predict defective healing), and negative predictive value of 60%, 79%, 73%, 59%, and 80%, respectively. The values for the initial EMG were 66%, 98%, 89%, 91%, and 89%. The best results showed the follow-up EMG with 85%, 100%, 97%, 100%, and 96%. EMG results were not classifiable in 32 (16%) patients. Conclusions: EMG showed higher prognostic values than ENG, especially when repeated during the time course of the facial palsy. ENG might be helpful if the EMG result is not classifiable.