Sensory Action Potentials of the Maxillary Nerve: A Methodologic Study With Clinical Implications

Purpose

Recently, recording of sensory nerve action potentials (SNAPs) of the inferior alveolar nerve (IAN) was described and is used as a diagnostic test of traumatic neuropathic trigeminal disorders. The technique is limited to IAN damage; therefore, we adapted the technique to the maxillary nerve, which is also frequently injured by either trauma or orthognathic surgery.

Patients and Methods

Fourteen healthy volunteers participated in this methodologic study in which the infraorbital nerve (ION) was stimulated with 2 needle electrodes. The SNAPs were recorded from the maxillary nerve with a unipolar needle electrode close to the foramen rotundum.

Results

The mean latency of the SNAPs was 0.73 ms (95% CI, 0.55 to 0.85 ms) with a 0.08 ± 0.09 ms interside difference. The mean baseline to peak amplitude was 31.3 ± 7.0 μV (95% CI, 24.2 to 38.3 μV) with a 6.5 ± 32.4 μV interside difference. Repeated tests within a session test demonstrated no significant differences in the latency data (ANOVA: P = .225) or amplitude data (ANOVA: P = .44). Stimulus-response curves indicated that the SNAPs saturated at 5.1 ± 4.4 mA stimulus intensity. In 1 subject, stimulation of the mental nerve elicited SNAPs (latency: 1.6 ms; amplitude 38 μV) in accordance with published values. A local anesthetic block of the ION was associated with a distinct decay of the SNAP in 1 subject.

Conclusion

We suggest that SNAPs of the maxillary nerve can be a valuable technique for a comprehensive examination of the trigeminal system.