Facial nerve injury following surgery for temporomandibular joint ankylosis: a prospective clinical study.

OBJECTIVE The purpose of this prospective study was to evaluate the incidence and degree of facial nerve damage and time taken for its recovery following surgery for temporomandibular joint (TMJ) ankylosis. MATERIALS AND METHODS A total of 30 subjects with the TMJ ankylosis with or without history of previous surgery were included in this prospective study. House-Brackmann grading system was used to assess the function of the facial nerve post-operatively. RESULTS Most of the subjects were in the age range of 13-15 years. Eight subjects had bilateral ankylosis and remaining 22 had unilateral ankylosis. Out of 32 joints in which gap arthroplasty was performed, 4 had Grade 1 injury, 14 had Grade 2 injury, 12 had Grade 3, and 2 with the Grade 4 injury 24 h post-operatively. Whereas, out of 6 cases of interpositional arthroplasty 4 had Grade 1 injury and 2 had Grade 4 injury. According to House-Brackmann grading system, at 24 h, 78.9% patients had different grades of facial nerve injury, which gradually improved and came to normal limits within 1-3 months post-operatively. Comparison of change in the Grade of injury at 3 months follow-up as compared to baseline (24 h) showed full recovery in all the cases (100%) showing a statistically significant difference from baseline (P < 0.001). CONCLUSION When proper care is taken during surgery for TMJ ankylosis, permanent facial nerve injury is rare. However, the incidence and degree of temporary nerve injury could be either due to the heavy retraction causing compression and or stretching of nerve fiber resulting in neuropraxia.