Clinical and electromyographic assessment of facial nerve function after temporomandibular joint surgery

The aim of this study was to evaluate the factors that may cause alterations in facial nerve function during temporomandibular joint (TMJ) surgeries. Forty-six patients were included (66 joints) between the years 2000 and 2007. Study patients were those undergoing various surgical procedures for the treatment of TMJ disorders. Patients who had made an incomplete recovery from a facial nerve injury resulting from a previous operation and patients who presented with facial palsy after a previous TMJ surgery were excluded. The facial nerve function of all patients was evaluated at different time intervals using a facial nerve grading system, motor unit action potentials of the frontalis and orbicularis oculi muscles, and a facial nerve latency test. Various degrees of facial nerve affliction were initially noticed in 71% of the study cases (47 of 66 joints). Statistical analyses (x(2) goodness-of-fit) revealed that several factors could lead to facial nerve injury following TMJ surgery, including the design of the skin incision, prior surgeries, type of surgery, and duration of surgery. Facial nerve injury during TMJ surgery is multifactorial. Electromyographic studies are non-invasive and valuable diagnostic and prognostic tools for assessing facial nerve function.