A prospective electromyographic and computer-aided thermal sensitivity assessment of nerve lesions after sagittal split osteotomy and Le Fort I osteotomy

Purpose: The purpose of this study was to determine the incidence of tempor ary and permanent sensory disturbance of the inferior alveolar nerve (IAN) after bilateral sagittal split osteotomy (BSSO) of the mandible and of the infraorbital nerve (ION) after Le Fort I osteotomy, as well as the rate of recovery of sensory function using subjective and objective measures. Patients and Methods: Preoperatively and after 1 week, and 1, 3, 6, and 12 months postoperatively, sensibility in the distribution of 36 IONs after Le Fort I osteotomy and 24 IANs after BSSO in 19 patients were investigated b y using sharp-blunt testing, 2-point discrimination, electromyographic reco rding, and thermal sensitivity (Pain and Thermal Sensitivity Test Device [P ATH]) tests of the A delta and C nerve fibers. Results: With conventional clinical sharp-blunt and 2-point discrimination tests, the incidence of temporary impairment was 81% for the ION (29 of 36) and 83% for the IAN (20 of 24). The rate of permanent sensibility disturba nce with conventional clinical testing was 6% for the ION and 15% fur the I AN. Obvious recovery was found after 1 to 3 months fur the ION, but it took 6 to 12 months for the IAN. In contrast, electromyography (EMG) testing sh owed lower rates of temporary sensory disturbance, namely, 54% (13 of 24) f or die ION and 68% (15 of 22) for the LAN. Permanent sensory losses mere no t found. The results of the EMG test was confirmed by the PATH test. Conclusions: Objective tests for sensory disturbances show lower rates than the conventional tests. For quality control, preoperative and postoperativ e measurement and documentation of postoperative recovery of sensation is r ecommended. (C) 2001 American Association of Oral and Maxillofacial Surgeon s.