Quantitative sensory nerve conduction threshold (sNCT) evaluation of the trigeminal nerve at the mental foramen area

Statement of problem. There is a need for a quick, objective, quantitative sensory test of the mandibular inferior alveolar nerve to assess sensory dysfunction due to trauma, infection, or disease. Purpose. This study evaluated the reliability and reproducibility of a commercially available electrodiagnostic quantitative sensory nerve conduction threshold (sNCT) evaluation testing method and established normative values for future evaluation of nerve dysfunction. Material and methods. Rapid current perception threshold (R-CPT) values were obtained with Neurometer CPT/ C, an electrodiagnostic sNCT device that administers an alternating constant-current sinusoid waveform stimulus at either 2000 Hz (H) (Hertz [cycles/ second]), 250 Hz (M), or 5 Hz (L) at intensity levels ranging from 0.001 to 10 mA. Thirty-four healthy subjects were tested then retested by the same operator from 7 days to 153 days. R-CPT evaluation was performed over the mental foramen bilaterally with dual disposable gold-plated electrodes and a hypoallergenic electrode gel held in place using nonconductive adhesive tape. Two consecutive identical R-CPT measures were obtained for each stimulation frequency for determination of the final R-CPT value. Results. On the left side, there was no difference between the first and second test (P>.05). On the right side, there was a statistical difference between the first and second test for L, M, and H, but the confidence interval is very narrow and the differences are not clinically significant. Conclusion. From the values obtained, R-CPT testing was reliable for the quantification of sensory function in healthy individuals.