Noninvasive somatosensory monitoring of the injured inferior alveolar nerve using magnetic source imaging.

Purpose: This study evaluates magnetoencephalography (MEG) as an objective monitor for the evaluation of post-traumatic inferior alveolar nerve injuries.

Materials And 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.

Conclusion: This technology may differentiate between intact but damaged nerves and transected nerves.