Transcranial Direct Current Stimulation Reduces Pressure Pain Sensitivity in Patients with Non-Malignant Chronic Pain.

Objectives: Non-malignant chronic pain is a clinical challenge because pharmacological treatment often fails to relieve pain. Transcranial direct current stimulation (tDCS) is a treatment that could have the potential for pain relief and improvement in quality of life. However, there is a lack of clinical trials evaluating the effects of tDCS on the pain system. The aim of the present study was to evaluate the effect of 5 days of anodal tDCS treatment on the pain system in chronic non-malignant pain patients using quantitative sensory testing (QST) and quality of life questionnaires: (1) Brief Pain Inventory-short form (BPI-sf), (2) European Organization for Research and Treatment of Life Questionnaire (EORTC-C30), and (3) Hospital Anxiety Depression Scale (HADS).

Methods: Eleven non-malignant chronic pain patients (51±13.6 years old, 5M) participated in the study. Anodal tDCS was applied for five consecutive days, followed by sham stimulation after a washout period of at least two weeks. Pressure pain thresholds (PPT) and pain tolerance thresholds (PTT) were assessed in different body regions on days 1 and 5.

Results: Anodal tDCS appeared to maintain PTT at C5 (clavicle) on day 5, but sham stimulation decreased PTT (P=0.007). Additionally, anodal tDCS increased PTT compared to sham at day 5 at Th10 ventral dermatomes (P=0.014). Both anodal and sham tDCS decreased the BPI-sf total and interference scores, and the EORTC-C30 fatigue score, but no interaction effect was observed.

Discussion: This study adds to the evidence in the literature that tDCS may be a potential therapeutic tool for the management of non-malignant chronic pain.