Current perception thresholds of patients with long-term administration of maprotiline

The purpose of this study was to evaluate sensory nerve function using current perception thresholds (CPTs) in patients who were administrated maprotiline. Twelve patients with post-herpetic neuralgia and 20 control subjects were studied. The patients with post-herpetic neuralgia were given a daily dose of 60 mg of maprotiline and were maintained at the same dose for 6 months. Twenty control subjects were randomly selected from healthy volunteers. ACPT test was used for quantitative assessment of A beta, A sigma, and C fiber transmission, which are associated with pain, by three (2000, 250, and 5 Hz) different frequencies of electric stimulation. CPTs of 5, 250, and 2000 Hz in patients with post-herpetic neuralgia 2 months after administration of maprotiline were 141.7 +/- 17.3 for 5 Hz, 120.8 +/- 12.9 for 250 Hz, and 256.4 +/- 18.0 for 2000 Hz, which were significantly (P < 0.01) higher than those (67.0 +/- 9.1 for 5 Hz, 73.4 +/- 7.0 for 250 Hz, and 191.3 +/- 20.2 for 2000 Hz) before treatment and than those (35.3 +/- 15.8, 62.0 +/- 18.9, and 198.9 +/- 15.8) of control subjects. An increase in CPT for 5 Hz at 2 months after administration of maprotiline correlated (r = 0.71, p = 0.01) with a decrease in pain score. There were no correlations between an increase in CPT and changes in Hamilton Depression Scale (HAMD) values until 3 months after maprotiline treatment. However, we found that an increase in CPT for 5 Hz at 6 months after maprotiline treatment correlated (r = 0.68, p = 0.015) with a decrease in HAMD values. In conclusion, administration of 60 mg maprotiline significantly increased current perception thresholds at 2 months after the administration.