Differences in Pain Perception Between Men and Women of Reproductive Age: A Laser-Evoked Potentials Study

Objective

We investigated differences in pain perception between men and women of reproductive age by using Laser-Evoked Potentials (LEPs).

Design, Setting, Subjects

Forty-four right-handed healthy volunteers (19 males/25 females), aged 30–40 years were studied. A CO2 laser generated three series of 10 thermal pulses (4.5 W) on the radial aspect of the dorsum of the left hand. A recording montage for late LEPs was used, and the potentials of each series of stimuli were averaged to calculate mean latency and amplitude for each subject. Volunteers scored verbally pain intensity (Numerical rating scale [NRS]; 0–10). Three series of 10 numbers were averaged for calculation of mean NRS score.

Methods

LEP peak-to-peak amplitude, latency, and NRS scoring were compared between genders, and correlations between LEP amplitude/latency and NRS scores were assessed.

Results

Data from 44 subjects were analyzed. LEP amplitudes differed significantly (P < 0.001) between men (24.2 ± 6.0 µV) and women (38.9 ± 15.28 µV), while no difference was found for latency (156.5 ± 8.6 versus 160.4 ± 19.8 ms, P = 0.42) or NRS score (2.6 ± 1.5 versus 2.4 ± 1.4, P = 0.63), respectively. Menstrual cycle phase did not influence LEP parameters (P = 0.59 for amplitude and P = 0.69 for latency) or NRS score (P = 0.95). No significant correlation was found between latency or amplitude and NRS score (P = 0.43 and P = 0.90, respectively).

Conclusions

Our results demonstrate a significant gender-related difference in LEP amplitudes with lower mean values in men, while no difference was found in LEP latencies or in subjective pain ratings. Further research is required to clarify the clinical significance of the above experimental findings.