Sk. Jaaskelainen et al., Intraoperative monitoring of the inferior alveolar nerve during mandibularsagittal-split osteotomy, MUSCLE NERV, 23(3), 2000, pp. 368-375
In order to evaluate the risk of nerve injury and to prevent iatrogenic dam
age at different stages of bilateral sagittal-split osteotomy (BSSO) of the
mandible, we monitored the function of the inferior alveolar nerve (IAN) c
ontinuously on both sides in 13 orthognathic patients undergoing BSSO, The
IAN was stimulated at the mental foramen with two monopolar needle electrod
es fixed to the dental splint, and the orthodromic sensory nerve action pot
entials (SNAP) of the IAN were recorded with a silver-wire electrode insert
ed near the oval foramen on each side. The latencies, amplitudes, and senso
ry nerve conduction velocities at baseline, after medial opening, sawing, s
plitting, eventual manipulation, and fixation of the mandible were analyzed
. The monitoring method functioned technically well in 25 of 26 nerves. Bot
h the surgical technique and the duration of medial opening had conspicuous
effects on the function of the IAN, which led us to modify the medial appr
oach. When finer instruments were used for retraction and the duration of m
edial opening was shortened to less than 10 min, the SNAP of the IAN was al
ways preserved at this stage, Monitoring of the IAN also prevented nerve in
jury during splitting and fixation. This technique for intraoperative monit
oring of the IAN seems to be a feasible and promising tool for objective ev
aluation of intraoperative events and for prevention of nerve injury during
BSSO. (C) 2000 John Wiley & Sons, Inc. Muscle Nerve 23: 368-375, 2000.