Quantitative method to evaluate the functionality of the trigeminal nerve.

Purpose: The primary objective of this study was to yield normal range values, with a current perception threshold technique, that could be used to assess the functionality of the third division of the trigeminal nerve on a healthy population. Moreover, we wanted to evaluate the impact of gender and training on these values.

Patients And Methods: Standardized current perception threshold (CPT) measures using constant alternating current sinusoid waveform stimulus at 5, 250, and 2,000 HZ were obtained from 50 healthy patients at the mental foramen area bilaterally using a Neurometer current perception threshold device (Neurotron Inc, Baltimore, MD) (2,000 Hz specifically stimulates Abeta fibers, 250 Hz Adelta fibers, and 5 Hz stimulates C fibers).

Results: The mean CPT values for the 2,000, 250, and 5 Hz groups were respectively, 157.6 +/- 54.67, 53.10 +/- 27.64, and 33.44 +/- 23.17 mAmp. These values were used to construct a CPT scale to classify patients in the hyperesthetic, normative, or hypoesthetic range. There were no significant differences when comparing CPT values in men and women except in the 2,000 Hz group (P < .02; n = 23). In addition, the test was carried out a first time on the right side and a second time on the left. This training procedure showed a significant decrease in the CPT values in men at 2,000 Hz (P < .01; n = 23) for the second measure.

Conclusion: The Neurometer can be beneficial for the evaluation and intraneural localization of sensory dysfunctions associated with the third division of the trigeminal nerve. It also could be used for initial diagnosis and subsequent evaluation of the patient's neurologic status through the course of their condition.