Symptom Management in Adults With Knee Osteoarthritis Using Transcranial Direct Current Stimulation: A Pilot Study

Thursday, 27 July 2017: 4:30 PM

School of Nursing, University of Texas Health Science Center at Houston, Houston, TX, USA
Roger Fillingim, PhD
College of Dentistry, University of Florida Pain Research and Intervention Center of Excellence, Gainesville, FL, USA

Purpose: Osteoarthritis is a leading cause of pain and functional impairments in people 45 years and older (Lakkireddy, Bedarakota, Vidyasagar, Rapur, & Karra, 2015). Noninvasive brain stimulation, such as Transcranial Direct Current Stimulation (tDCS), has received significant attention for the treatment of pain in chronic conditions owing to its neuromodulatory effect (Ayache et al., 2016; Woods et al., 2016). tDCS involves the application of weak direct electric current to the head in a noninvasive and painless manner, leading to the modulation of the brain activity involved in pain processing (DaSilva et al., 2016; O'Connell & Wand, 2015). Therefore, we assessed the preliminary efficacy and safety of tDCS on pain symptoms in adults with knee osteoarthritis.

Methods: We conducted a double-blind, randomized, sham-controlled pilot clinical study in 40 community-dwelling participants with knee OA who were 50−70 years old. The participants were randomly assigned to receive either five daily sessions of 2mA tDCS for 20 minutes or sham tDCS (1:1 for two groups). Randomization was performed by a statistician with no clinical involvement in this trial. The anode electrode was placed over the primary motor cortex of the hemisphere contralateral to the affected knee, and the cathode electrode was placed over the supraorbital region ipsilateral to the affected knee. Osteoarthritis-related pain symptoms were measured at baseline and after tDCS via the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The WOMAC consisted of 3 subscales relating to pain during activities (5 items), stiffness during the day (2 items), and impairments of physical function (17 items), with higher scores indicating worse pain, stiffness, and impairments of physical function. Also, we monitored possible side effects of tDCS by asking whether participants experienced the symptoms of tingling, itching sensation, burning sensation, pain, fatigue, nervousness, headache, difficulty concentrating, mood changes, or changes in vision or visual perception (Bikson et al., 2016). All the side effects were recorded, and their severity was graded from 0 (not at all) to 10 (highest degree). The safety questionnaire was administered after each stimulation session.

Results: The mean age was 59 years (Standard deviation = 8 years), and 53% were female. After five daily sessions, the tDCS group had a greater reduction than the sham group in pain during activities (active tDCS: 1.25 ± 3.13, sham: 0.60 ± 2.11), stiffness during the day (active tDCS: 0.55 ± 1.36, sham: 0.20 ± 0.83), and impairments of physical function (active tDCS: 2.40 ± 10.44, sham: 0.10 ± 7.33). Effect sizes (Cohen’s d) ranged from d=0.24 for reducing pain during activities (t=0.77, df=38, p=0.44), d=0.31 for reducing stiffness during the day (t=0.98, df=38, p=0.33), and d = 0.27 for reducing impairments of physical function (t=0.88, df=38, p=0.39). Also, all participants tolerated tDCS well without experiencing any significant adverse effects. No participants complained about fatigue, nervousness, headache, difficulty concentrating, mood changes, or vision changes during tDCS sessions. A few adverse events occurred during tDCS session, such as tingling, itching sensation, burning sensation, pain, and change in visual perception. However, these symptoms were mild (less than or equal to 2 out of 10) and transient, and the symptoms had resolved at the completion of the stimulation session.

Conclusion: Although our primary results were nonsignificant, there is a preliminary suggestion that tDCS targeting primary motor cortex may reduce osteoarthritis-related pain symptoms in adults with knee OA without any significant adverse effects. Future studies are needed to refine this novel approach for pain neuromodulation.