THE ASSESSMENT OF TRIGEMINAL SENSORY NERVE PARESTHESIA AFTER BILATERAL SAGITTAL SPLIT OSTEOTOMY - MODIFIED SOMATOSENSORY-EVOKED POTENTIALS RECORDING METHOD

Trigeminal neurosensory impairment is frequently observed following or thognathic surgery. The purpose of the present study is to visualize t he degree of trigeminal nerve impairment following bilateral sagittal split osteotomy (BSSO). Twenty patients who underwent BSSO were in the present study. To record the modified somatosensory evoked potentials (SEP), two electrostimulation clips were applied. One clip was placed on the mucous surface of the lower lip and the other was placed on th e skin surface. Each contact surface contained a separate 2 mm diamete r silver anode and cathode attached to a 5 x 15 mm basement plate. The results obtained using this method revealed that complete recovery fr om neural impairment was observed in 7 cases (36.8%) on the right oper ative side and 4 (20.0%) on the left side at 6 months postoperatively. A definite delay in latency was observed on the left operative side a t all the examination periods. The recovery period evaluated by the SE P method was longer than that of the objective two-point discriminatio n thresholds. Clinical records obtained showed considerable implicatio ns for trigeminal nerve function after BSSO.