[Electromyography studies for objective assessment of loss of function of the lateral pterygoid muscles after dislocation fractures of the mandibular processes].

The aim of treatment for luxation fractures of the mandibular articular processes is not only complete anatomical restitution but also restoration of the mobility. In a retrospective study on 242 patients after operative and conservative treatment, it was possible to demonstrate that there are no correlations between fragment position and functional result. Functional restitution was observed after conservative treatment in 65% of cases and after operative treatment in 57%. In order to establish the causes for dysfunction of the lateral pterygoid muscle an electromyographical technique was developed to dissipate the action potentials of the muscle. Another retrospective study, performed in 23 patients with dysfunction of the mandible revealed loss of activity of the lateral pterygoid muscle after fracture treatment, independent of the treatment method, in 11.5% of cases (two patients). Without any connection to the treatment method, the remaining results permit to conclude that there are preoperative neurological defects. Therefore the pre- and posttherapeutic functions of muscles and nerves were investigated in a prospective study on 18 patients. Before the treatment 16.6% of the patients (n = 3) showed defects of the lateral pterygoid nerve with a resulting loss of muscle function. According to the findings, residual dysfunction of the lateral pterygoid muscle is determined by the extend of the traumatic nerve injury, independent of the treatment method. In the case of axonal defects of the pterygoid nerve, there can be no expectation of a restitutio ad integrum after the operative fragment position.