Central sensitization of nociceptive pathways demonstrated by robot-controlled pinprick-evoked brain potentials

The aim of this study was to assess the effect of central sensitization, induced by high frequency electrical stimulation of the skin (HFS), on pinprick-evoked brain potentials (PEPs) using robot-controlled mechanical pinprick stimulation and a stimulus evaluation task.

In 16 healthy volunteers HFS was applied to the right volar forearm. Robot- controlled pinprick stimuli (64 mN) were applied before and 20 minutes after HFS to the skin surrounding the area onto which HFS was applied. During pinprick stimulation, the EEG was recorded and the quality of perception and perceived intensity of the pinprick stimuli was collected.

After HFS, the skin surrounding the site at which HFS was delivered showed increased mechanical pinprick sensitivity. Both the early-latency negative peak of PEPs and the later-latency peak were significantly increased after HFS.

This study shows increased PEPs after HFS when they are elicited by a robot-controlled mechanical pinprick stimulator and participants are engaged in a stimulus evaluation task during pinprick stimulation.

This is the first study that shows a significant increase of both PEP peaks, and therefore, it provides a preferred setup for assessing the function of mechanical nociceptive pathways in the context of central sensitization.