The Course of the Inferior Alveolar Nerve in Craniofacial Microsomia: Virtual Dissection Using Three-Dimensional Computed Tomography Image Analysis

Abstract

Computer-assisted medical imaging was used to locate the mandibular foramen and the portion of the inferior alveolar nerve canal at the level of the angle of the mandible in 19 hemimandibles of patients with craniofacial microsomia. The distance from each of these two points to the borders of the mandible was measured. The ratios of these distances to the height, anteroposterior, and buccolingual extents of the mandibular ramus were calculated. These ratios were compared among affected hemimandibles (Pruzansky classification I, n = 4; and Pruzansky classification II, n = 10), unaffected hemimandibles (n = 9), and the hemimandibles of patients with nonsyndromic, sutural synostosis (n = 7). Comparison of mean distance ratios showed that the mandibular foramen was located significantly more proximally in the affected cohort than in either the unaffected or synostosis control groups. The mandibular foramen was also located significantly closer to the buccal cortex of the mandible in the affected cohort when compared with unaffected patients. The distance from the mandibular foramen to the anterior or posterior tables of the mandible divided by the total anteroposterior distance did not vary among the three groups studied. The distance ratios between the inferior alveolar nerve canal at the level of the angle of the mandible and the mandibular borders also did not vary significantly among the groups studied. An inferior alveolar nerve canal could not be identified in any patient with Pruzansky grade III mandibular deficiency. This quantitative, three-dimensional description of points along the proximal path of the inferior alveolar nerve canal in patients with craniofacial microsomia provides useful information to assist the surgeon during osteotomy planning and may help in avoiding injury to the nerve at the time of surgery.