Prognostic value of electroneurography and electromyography in facial palsy

To compare the prognostic value of electroneurography (ENG) and needle electromyography (EMG) to estimate facial function outcome after acute facial palsy.

Retrospective study using electrodiagnostic data and medical chart review.

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.

: 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.

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.