Electrophysiological measures in facial paresis and paralysis

Facial nerve injuries are debilitating events for patients. In many cases recovery is spontaneous and complete; in others prompt medical and/or surgical intervention will be necessary to improve the patient’s outcome. Objective measurements are valuable tools that can help identify candidates for intervention. Electroneuronography and electromyography are the most commonly used objective measures of facial function. Basic examination techniques and recording parameters are discussed. A literature review indicated that, depending on the criteria used, Electroneuronography was 50-91% accurate (Positive Predictive Value or PPV) in identifying individuals requiring intervention and 80-100% accurate in predicting those who recover spontaneously (Negative Predictive Value or NPV). Electromyography can be used to assess both volitional movements (PPV 75-91% and NPV 62-89%) and for spontaneous activity (PPV 80-100% and NPV 92-96%). Attention is paid to how grading criteria and the timing of the examinations impacts the accuracy of both Electroneuronography and Electromyography. Specific protocols are suggested for patients with facial nerve injury.