Effect of Local Anesthesia on Trigeminal Somatosensory-evoked Magnetic Fields

• Published in: Journal of dental research 2012-12, Vol.91 (12), p.1196-1201
• Main Authors: Otsuka, T., Dan, H., Dan, I., Sase, M., Sano, T., Tsuzuki, D., Fujita, A., Sasaguri, K., Okada, N., Kusama, M., Jinbu, Y., Watanabe, E.
• Format: Article
• Language: English
• Subjects: Adult; Anesthesia; Anesthesia, Dental - methods; Anesthesia, Local - methods; Anesthetics, Local - pharmacology; Brain Mapping - methods; Cortex (somatosensory); Cortex (temporal); Dentistry; Electric Stimulation; Electrical stimuli; Electroencephalography; Evoked Potentials, Somatosensory - drug effects; Evoked Potentials, Somatosensory - physiology; Female; Humans; Latency; Lidocaine; Lidocaine - pharmacology; Lip; Lip - innervation; Local anesthesia; Localization; Magnetic fields; Magnetic resonance imaging; Magnetoencephalography; Male; Mandibular Nerve - drug effects; Mandibular Nerve - physiology; Nerve Block; NMR; Nuclear magnetic resonance; Reaction Time - drug effects; Reference Values; Somatosensory Cortex - physiology; Studies; Trigeminal nerve
• ISSN: 0022-0345; 1544-0591
• DOI: 10.1177/0022034512462398

For objective neurophysiological evaluation of the function of the trigeminal system, magnetoencephalography- based TSEF (trigeminal somatosensory-evoked field) assessment would be valuable in providing spatial and temporal profiles of cortical responses. However, this necessitates knowledge of how TSEF varies with trigeminal nerve dysfunctions. We introduced a conduction block of the trigeminal nerve using local anesthesia (lidocaine) to temporally mimic nerve dysfunctions, and monitored TSEF changes. Following an electrical stimulation of the lower lip, a magnetic response with peak latency of approximately 20 ms was identified in all participants. Dipole for the peak was estimated on the post-central gyrus in the participant’s own magnetic resonance image. After normalization to Montreal Neurological Institute (MNI) space and inter-participant data integration, the summary equivalent current dipole localization among participants remained in the post-central gyrus, suggesting validity of the use of MNI space. Partial anesthesia of the lower lip led to a loss of the waveform characteristics of TSEF for electrical stimulation to the trigeminal nerve. We verified that the 20-ms latency cortical response of TSEF components localized at the primary sensory cortex can serve as a robust neurofunctional marker of experimental trigeminal nerve dysfunction.