[Neurosensory disorders and functional impairment after bilateral sagittal split osteotomy: role of the anatomical situation of the alveolar pedicle in 76 patients].

INTRODUCTION

Bilateral sagittal split osteotomy (BSSO) of the mandibular ramus is the most frequent orthognatic surgery. The risk of neurosensory disorders remains high even their incidence varies according to numerous publications. The anatomical location of the alveolar pedicle seems to be one of the most important factors in these disorders. The aim of this study was to determine its exact role.

MATERIAL AND METHOD

We performed a retrospective study on 76 patients and 152 osteotomy sides, all of them operated according to the Epker technique by the same surgeon between 2000 and 2004. For each operative side we noted the position of the inferior alveolar nerve during the split: Type I entirely in the internal cortical bone, Type II partially in the external cortical bone, Type III mostly or completely in the external cortical bone. The neurosensory disorders were recorded during clinical examination and simply classified into two categories: "absent" or "present". The outcome was noted during the postoperative follow-up at D1; D15; M1,5, M6, and M12. After that, it was documented through a written questionnaire or telephone conversation.

RESULTS

Since there was no difference between the right and the left sides, the study enclosed all of the operative sides together (152). The anatomical distribution was: 97 Type I (63.8%), 28 Type II (18.4%), and 27 Type III (17.8%). Immediate postoperative neurosensory disorders (D1) occurred on 74.3% of sides, with important significant differences between Type I (64.9%) on one hand, Type II (89.2%) and Type III (92.6%) on the other hand. At one year of follow-up, the rate of neurosensory disorders was 20.4% with also a difference between Type I (13.4%) and Types II and III (35.7% and 29.6%).

DISCUSSION

The anatomical location of the alveolar pedicle seems to be important. This study confirms previously published studies and raises the question of CT scan assessment before performing BSSO.