The effect of acute stress on high-frequency electrical stimulation–induced pain and pinprick hypersensitivity in healthy women

Transcutaneous high-frequency electrical stimulation (HFS) elicits pain and produces prolonged mechanical pinprick hypersensitivity. This study investigated whether acute stress, induced by the Mannheim Multicomponent Stress Test (MMST), elevates HFS-related pain and pinprick hypersensitivity in healthy women. Two between-subject experiments were conducted. In experiment 1 (N = 66), the MMST or a control task was applied before HFS to assess whether stress enhances pain during HFS and contributes to subsequent pinprick hypersensitivity. In experiment 2 (N = 60), stress was induced 20 minutes after HFS to evaluate its effect on already established pinprick hypersensitivity. Unlike the control task, the MMST significantly increased subjective stress in both experiments. In experiment 1, the average pain ratings across all 5 HFS trains did not differ significantly between groups. However, exploratory analysis showed that pain ratings for the first HFS train were 10 points higher (on a 0-100 scale) in the MMST group, although this effect diminished over subsequent trains. Pinprick hypersensitivity developed similarly in both groups, suggesting that stress before HFS may elevate HFS pain but does not influence the development of hypersensitivity. In experiment 2, pinprick hypersensitivity significantly increased after the MMST compared to the control task, although the absolute effect size was relatively small (5 points on a 0-100 scale). Collectively, these findings indicate that acute stress before HFS may elevate HFS pain without influencing the development of subsequent pinprick hypersensitivity. Conversely, when acute stress is induced after HFS, when pinprick hypersensitivity has already been established, it increases hypersensitivity.