Prospective study on post-traumatic and postoperative sensory disturbancesof the inferior alveolar nerve and infraorbital nerve in mandibular and midfacial fractures

In a prospective study (January 1999 to December 1997), 34 patients with 26 mandibular and 20 midfacial fractures mere investigated. All the fractures were managed by osteosynthesis, To evaluate the incidence and duration of recovery of post-traumatic and postoperative sensory disturbances, the foll owing tests were carried out: sharp/blunt testing, and the two-point discri mination test as conventional clinical examination methods, and electromyog raphic recording of the masseter reflex to calibrate the clinical findings. To establish the sensory status of the inferior alveolar and the infraorbi tal nerves in the region of the fracture, and on the intact and control sid es, the tests were performed pre-operatively and postoperatively on the sev enth day after 4 weeks and after 3, 6 and 12 months. The incidence of post- traumatic sensory disturbance was 46% for mandibular fractures and 65% for fractures to the midface (sharp/blunt test, two-point discrimination test). The rate of postoperative sensory disturbance in surgical treatment of man dibular fracture involving the region of the intra bony course of the infer ior alveolar nerve, including the post-traumatic sensory disturbance, was 7 6.9%, and 55%, following surgical treatment of midfacial fractures. The inc idence of persistent sensory disturbances following surgical treatment was 7.7% in the case of mandibular fractures, and 15% in the case of midfacial fractures (sharp/blunt test, two-point discrimination test, masseter reflex ). Recovery of neurological function is delayed in the presence of a displa ced fracture (>1 mm) as compared with non-displaced fractures. For the post operative calibration of sensory disturbances, electromyographic recording of the masseter reflex from the fourth postoperative week onwards has prove d useful.