The use of sensory action potential to evaluate inferior alveolar nerve damage after orthognathic surgery.

To assess and monitor the common event of neurosensory disturbance to the inferior alveolar nerve (IAN) after bilateral sagittal split osteotomy, we used clinical sensory tests and neurophysiologic test sensory action potentials. The diagnostic value of these tests was evaluated by comparing them with the degree of nerve damage reported by patients. Fourteen patients undergoing bilateral sagittal split osteotomy were analyzed preoperatively and 2 years postoperatively. Patients were evaluated bilaterally for positive and negative symptoms: light touch sensation, paraesthesia, hyperesthesia, and dysaesthesia; a "sensation score" was then calculated for each patient. Patients were also asked if they would be willing to repeat the procedure knowing the sensation loss they had now. Next, the right and left IAN were evaluated using sensory action potential and correlated with the other results. Before surgery, the medium latency difference between left and right was lower compared with postsurgery, with all patients having some deficit. The reduction in medium amplitude of 67% after the intervention was statistically significant. The frequency of abnormal findings in the electrophysiologic tests indicating IAN injury correlated with subjective sensory alteration. All patients said that they would repeat the surgery. Electrophysiologic testing is recommended for the evaluation of nerve dysfunction and seems a sensitive method for accurately assessing postsurgical nerve conduction.

Complications of orthognathic surgery: the inferior alveolar nerve.

This study analyzes permanent paresthetic disorders regarding the inferior alveolar nerve (IAN) after mandibular ramus sagittal osteotomy procedures. Fifty patients (ie, 100 nerves) who underwent mandibular bilateral sagittal split osteotomy between 2003 and 2007 were evaluated to detect sensorial disorders of the IAN. The evaluation was performed for each patient at least 1 year after surgical intervention. The sagittal osteotomy of the mandible ramus was performed according to Epker-Hunsuk technique. The method of fixing through titanium plates and monocortical screws and the displacement width of the osteotomized stumps were also considered. The evaluation of the IAN functionality was performed both subjectively, by means of a questionnaire, and clinically, by using 4 types of tests: light-touch sensation, pinprick sensation, Weber test, and Dellon test.The clinical test analysis revealed that no nervous lesion was detected in 52% of the tested sites, whereas 24% reported significant nervous lesions. In the subjective evaluations, 74% of the patients described the discomfort related to the neurologic alteration as "absent to mild" or "mild to moderate," 10% as "moderate to serious," and 4% as "serious."We observe that the percentage of significant nervous lesions is relatively low and that it matches the mean described in literature. The central nervous system capacity to hide or compensate for functional deficits due to peripheral nervous lesions was confirmed by the comparison between the results of the clinical tests and the patients' subjective evaluations.