Bilateral Long-Lasting Changes in Multimodal Sensitivity After Cutaneous High-Frequency Electrical Stimulation: A New Comprehensive Dermatomal Examination

Background/Objectives: Little is known about long-term changes in sensitivity and pain following cutaneous 100 Hz high-frequency stimulation (HFS) in humans. Thus, the aim of this study was to investigate long-lasting changes in multimodal sensitivity after HFS using a comprehensive systematic dermatomal examination, including two innovative protocols, and to identify common factors associated with these changes. Methods: Long-lasting changes were assessed with thermal and mechanical bedside and quantitative sensory testing at the homotopic (ipsilateral C6 or L4 dermatomes), adjacent heterotopic (ipsilateral C5 or L3 dermatomes) and contralateral dermatomal sites (C6 or L4 dermatomes) in two sessions (session A: upper limb dermatomal examination protocol; session B: lower limb dermatomal examination protocol). Before and after 100 Hz HFS, test stimuli (TS) were administered to the ipsilateral C6 dermatome for session A or ipsilateral L4 dermatome for session B. Individuals reported pain intensity or sensation related to TS, and fulfilled questionnaires associated with psychological health, pain descriptors, or perceived quality of life. Results: Long-lasting changes in both cold and mechanical sensitivity were observed up to 30 min following HFS at all sites in both sessions (p < 0.05). No significant differences between sessions were found for significant HFS-induced changes in sensitivity (p > 0.05). Common changes in cold sensitivity were dependent on age (p < 0.05). Fatigue was associated with common changes in mechanical or cold sensitivity (p < 0.05). Conclusions: Bilateral long-lasting changes in multimodal sensitivity after HFS have been revealed in a novel comprehensive systematic dermatomal examination. These findings provide new insight into persistent pain mechanisms and an innovative approach for its management.