Noninvasive somatosensory monitoring of the injured inferior alveolar nerve using magnetic source imaging.
OBJECTIVE
This study evaluates magnetoencephalography (MEG) as an objective monitor for the evaluation of post-traumatic inferior alveolar nerve injuries.


METHODS
Six patients with unilateral inferior alveolar nerve injuries were assessed using conventional sensory examination techniques. All damaged nerves, and their contralateral controls, were then reexamined using MEG technology. Regions of somatosensory-induced magnetic activity were superimposed on three-dimensional magnetic resonance imaging (MRI) scans to give cortical magnetic source images (MSI). All patients subsequently underwent surgical exploration of the damaged nerves.


RESULTS
All six patients had no sensitivity to conventional testing on the damaged side. On evaluation with MEG, all six control nerves had an appropriate cortical signal in response to repetitive lip stimulation. Somatosensory stimulation of two of the six damaged nerves resulted in cortical magnetic field changes. Surgical exploration showed that the four nerves with negative MEG tests had discontinuity defects. In contrast, the two patients with positive MEG signals had intact nerves.


CONCLUSIONS
This technology may differentiate between intact but damaged nerves and transected nerves.
McDonald
A R
AR
Department of Oral and Maxillofacial Surgery, University of California, San Francisco 94143-0440, USA.
Roberts
T P
TP
Rowley
H A
HA
Pogrel
M A
MA
D000328:Adult; D003729:Dental Care / Q000009:adverse effects; D005073:Evoked Potentials, Somatosensory; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D012678:Sensation Disorders / Q000175:diagnosis / Q000209:etiology; D013003:Somatosensory Cortex / Q000503:physiopathology; D014276:Trigeminal Nerve / Q000503:physiopathology*; D061221:Trigeminal Nerve Injuries