Facial nerve and branch dysfunction in leprosy - a study from India

Objective

Involvement of the facial nerve in leprosy can result in debilitating features, including blindness. Electrophysiological studies addressing abnormalities in the facial nerve along with its branches are limited. This study was designed to assess the prevalence and pattern of clinical and subclinical involvement of the facial nerve and its branches in patients with active disease.

Methods

A hospital-based cross-sectional study was done in 75 patients who had leprosy. The facial nerve and branches were examined clinically and assessed electro-physiologically with nerve conduction studies (NCS), F wave, blink reflex and synkinesis.

Results

64/75 (85%) patients had facial nerve involvement, of whom 58 had subclinical involvement. detected by electrophysiology and 6 had facial nerve palsy. 83% of patients had subclinical involvement and belonged to the borderline spectrum (27-BL, 21-BT), and 23 (48%) were in reactional states (T2R-12, T1R-11). Patients with facial lesions and reactional states showed significant association (p = 0.035) with clinical or subclinical facial nerve involvement.

The marginal mandibular branch was the most commonly affected (50%) in those with subclinical involvement while in those with facial nerve palsy, the facial nerve trunk was most affected (50%). 12/58 (21%) with subclinical involvement and 5/6 patients with facial nerve palsy had an abnormal blink reflex. Abnormal F wave was observed in 7/42 (17%), (4 subclinical/3 facial nerve palsy).

Conclusion

Electrophysiological changes in the facial nerve, without clinical signs are common among patients in the borderline spectrum with about half being in reactional states. We know that many institutions may not have the equipment to conduct nerve studies, but the higher incidence of subclinical facial nerve involvement underscores the need to monitor facial and autonomic functions closely.