Clinical and electrophysiologic studies of facial nerve function after hypoglossal-facial nerve anastomosis

Abstract

The functional and cosmetic results after hypoglossal-facial nerve anastomosis (HFA) have primarily been described using a subjective grading system of good, fair, or poor. To obtain more objective results, the postoperative mimic function was investigated using a combination of clinical and electrophysiological methods. A total of 29 patients with hypoglossal-facial anastomosis were evaluated using a standardized questionnaire and the Stennert's paralysis index as clinical scoring system and electroneurography (NMG/ENoG) and electromyography (EMG) as electrophysiological assessments. Twenty-six of 29 patients (89%) judged their own facial function as very good or good, and three as poor. Under resting tone conditions, no patient showed a difference between palpebral fissures (> 3 mm), an ectropium, a substantial loss of nasolabial fold, or a drop of angulus oris (> 3 mm). With attempted movement, the lid closure was complete in 76% of patients, and the cornea was lid-covered in 100%. Sixty-seven percent of the patients were able to whistle. The second upper incisor was visible (full width) in 19%. No patient could frown sufficiently or expose the upper and lower canine teeth. The mean Stennert's score decreased from 9 to 4 after surgery. The relative amplitudes of the NMGs were increased in patients with low clinical indices. Patients with a complete eye closure showed a higher density of EMG patterns in their orbicularis oculi muscles. No significant differences for clinical or electrophysiological parameters could be observed based on age, sex, or time point of operation. Combining the Stennert's paralysis index with NMG and EMG allows a more objective assessment of functional and cosmetic results after HFA.