Efficacy of transcranial direct current stimulation (tDCS) on pain and shoulder range of motion in post-mastectomy pain syndrome patients: a randomized-control trial

Abstract

Background Post-mastectomy pain syndrome (PMPS) is a highly prevalent complication after surgical treatment for breast cancer, and it affects the patient’s quality of life in aspects of losing shoulder full range of motion, pain, and depression. Transcranial direct current stimulation (tDCS) is non-invasive brain stimulation technique that was used in numerous clinical applications and in pain reduction in cancer patients. However, the effectiveness of tDCS on PMPS has never been evaluated in an experimental study. Aim To investigate the effect of bilateral anodal tDCS of motor cortex (M1) on pain, depression, and shoulder range of motion (ROM) in post-mastectomy pain syndrome. Study design Randomized controlled trial. Methods A total of 30 female patients with post-mastectomy neuropathic pain were randomized into two groups; the intervention group which received bilateral tDCS on motor cortex (M1) and the control group that received sham bilateral tDCS on M1. As pain affects shoulder range of motion (ROM), shoulder ROM was measured by electronic goniometer pre- and post-tDCS application. In addition, the levels of pain and depression have been measured pre and post treatment. Pain has been measured with visual analogue scale (VAS) and depression with Beck-Depression-Inventory-BDI questionnaire (BDI). Results A significant difference was noted in group A regarding pain, depression and shoulder ROM (p= 0.001, p= 0.003, and p= 0.003, respectively). Between group comparison revealed a significant difference of VAS scores and shoulder flexion ROM between groups, the study group and the control group (p=0.041 and 0.048, respectively). Pain decreased by 32% and Shoulder flexion increased by 4.8% post-treatment while there were no significant difference in group B (p=0.567 and p=0.866, respectively). Conclusions The application of tDCS decreases the severity of pain and improves shoulder range of motion suffered by breast cancer patients after total mastectomy surgery.

Cancer Pain and Non-Invasive Brain Stimulation—A Narrative Review

“…Details, as well as the IMMPACT recommendation score, can be found in Table 2. Two of the trials [28,29] have a score of four, while Hanna's article [30] received three points.…”

“…The types of pain analyzed in the three randomized trials were diverse, ranging from chronic visceral pain in hepatocellular carcinoma [28] and acute post thoracotomy thoracic pain [29] to neuropathic post mastectomy pain syndrome [30]. The first two trials [28,29] included mostly men, whereas the last trial included only female patients [30]. Chronic pain was defined as pain resistant to medical treatment for at least two months or associated with significant adverse effects, ref.…”

“…Chronic pain was defined as pain resistant to medical treatment for at least two months or associated with significant adverse effects, ref. [28], or six months of neuropathic pain in the post mastectomy region, with a DN score of >4 [30]. In the Serbian trial [29], only acute pain was considered, and patients with chronic pain conditions were excluded.…”

“…The size of the study population was limited, even though the Serbian trial [29] had the largest number of patients (55). Ibrahim [28] and Hanna [30] included 40 and 30 patients, respectively. As an endpoint, the VAS was maintained as the principal measurement of pain relief.…”

“…As an endpoint, the VAS was maintained as the principal measurement of pain relief. Furthermore, the studies reported results based on the VDS, HAM-D, Beck Depression Inventory, morphine dose [29], and measurements of shoulder range of motion using a digital goniometer [30].…”