The Safety and Feasibility of tDCS Combined With Conservative Treatment for Cervicogenic Headaches

Annually, up to 150,000 people in Canada and experience cervicogenic headaches (CGH) with many of these patients suffering from chronic CGH. CGH is a pain disorder where pain is perceived in the head but caused by dysfunction of the cervical spine and its anatomical structure. More specifically, the pathogenesis of CGH is due to the convergence of nociceptive afferents from the upper three cervical nerves and trigeminal nerves onto second-order neurons in the trigeminocervical nucleus. The pain signaling resulting from this is also modulated through sensorineural pathways involving the thalamus and the sensorimotor cortex. As such symptoms of CGH include restricted movement, local tenderness of the upper cervical spine joints, musculoskeletal impairments, headache, local pressure hyperalgesia and bilateral thermal hypoesthesia. To date, there is no "cure" for chronic CGH and current treatment entails trial and error with behavior management, environmental modifications and medications. Consequently, there is a significant need for new approaches to symptom management in order to help improve functional impairment and disease burden associated with treating CGH. Transcranial direct current stimulation (tDCS) and physiotherapy have a high degree of safety and have been studied as an intervention for many other chronic pain conditions and headache disorders, including arthritis and migraines, demonstrating considerable potential. The investigators propose to study the safety and feasibility of tDCS alongside physiotherapy as a treatment for CGH in a randomized sham controlled trial.

RESEARCH QUESTIONS AND OBJECTIVES

The overall objective is to study the feasibility and safety of tDCS applied to the primary motor cortex in patients with CGH and to explore whether active tDCS augments the effect of rehabilitation therapy.

Specifically the objectives are:

Primary Objective: To determine whether active tDCS is feasible and safe compared to sham when administered with rehabilitation therapy for patients with CGH when administered 3 times per week over the course of 6 weeks. Safety will be measured through serious adverse events (defined as events requiring medical attention). Feasibility will be measured by recruitment (greater than 30%), retention (greater than 80%), and adherence (greater than 70%). These outcomes will be measured throughout the treatment process up to immediately post-treatment.

Secondary Objective: To determine what secondary outcomes such as quality of life, headaches, pain sensitivity, neck mobility, anxiety, and depression improve with active tDCS treatment in individuals suffering with CGH. Quality of life will be measured via the European Quality of Life Five Dimension (EQ-5D), headache intensity, frequency, duration, and impacts on life will be measured via headache diaries and the Headache Intensity Test - 6 (HIT-6), headache effects on participant function will be measured via the Headache Disability Index (HDI), neck pain intensity will be measured through the numeric pain rating scale (NPRS), pain sensitivity will be measured via the Pain Sensitivity Questionnaire (PSQ), pain impacts on quality of life will be measured through the patient reported outcomes measurement information system - pain interference scale (PROMIS-PI), neck mobility will be measured through various motor control, strength, and endurance tests, feelings of depression will be measured via the PHQ-9 and anxiety via the GADS-7 before treatment after treatment and at 6- and 12- weeks post treatment.

Third objective: To explore whether the effects of active tDCS will augment the effects of rehabilitation therapy in treating individuals with CGH.

METHODS

This study will be a double-blind, sham-controlled, concealed allocation, randomized, clinical trial.

Clinical Assessments: Demographic information will be collected two weeks prior to starting the study including age, sex, education, headache history, concussion history, past medical history, medication use, and family medical history. Baseline questionnaires will be completed including 2-weeks of Headache Diaries Headache Impact Test - 6 (HIT-6), Rivermead PPCS questionnaire (RPQ), Headache Disability Index (HDI), European Quality of Life Five Dimension (EQ-5D), patient health questionnaire-9 (PHQ-9), generalized anxiety disorder scale-7 (GADS-7), Patient Reported Outcomes Measurement Information System Pain Interference Sub-scale (PROMIS-PI), the Pain Catastrophizing Scale (PCS), and the Numeric Pain Rating Scale (NPRS). Furthermore the following baseline neck mobility assessments will be used: the Craniocervical Flexion Test (CCFT), the Cervical Extensor Endurance Test (CEET), the Dynamometry Neck-Strength Assessment (DNSA), a range of cervical motion assessment (ROM), and a manual examination of the cervical joints (MECJ). Patients will keep a two-week baseline headache diary before treatment, 2 weeks during treatment, 2 weeks following tDCS, and for 2 weeks before the 6 and 12 week follow up assessments (total of 8 weeks). Patients will be reassessed at the completion of their tDCS treatment, and at 6- and 12-weeks post-treatment. The assessments administered at each follow up are: 2-week Headache Diaries, RPQ, HIT-6, HDI, EQ-5D, PHQ-9, GAD-7, NPRS, PCS, PROMIS-PI, CCFT, CEET, DNSA, ROM, and MECJ.

tDCS Protocol: Patients will engage in a six-week treatment protocol with 3 sessions per week (18 treatments). This was chosen to give participants at least a day between each session in order to minimize discomfort and because the number of sessions is consistent with previous migraine literature. The primary motor cortex (M1) will be the treatment target given previous literature highlighting reduced pain sensitivity and improved motor learning outcomes following tDCS stimulation of this region. M1 will be found through measurements of the head; more specifically the point halfway between the nasion and inion as well as halfway between the left and right tragus will be found, from here we will move down 20% of the distance between the left and right tragus while staying on the line between tragi. The anode will be placed over the M1 while the cathode will be placed over the super orbital region; each electrode will be held in place with a strap and will make as much contact with the skin as possible. tDCS will be delivered via two 35cm2 surface sponge electrodes at an intensity of 2mA in the active group and 0mA in the sham group. There will be a 30 second fade in and fade out period before and after stimulation with 20 minutes of active stimulation. In the sham condition, participants will only experience the 30 second fade in period and then the stimulator will be turned off. Previous sham studies have demonstrated the efficacy of this blinding method.

Physiotherapy Protocol: Participants will engage in a six-week physiotherapy program which will occur immediately following each tDCS session. The exercises to be used focus on head and back strength and motor control and were assembled by a licensed physiotherapist based on previous physiotherapy protocols for treating CGH. The exercises are performed at a level that is pain-free and are progressed when goals are reached (approximately every 2 weeks). Participants will also be expected to increase daily physical activity levels to 30 minutes per day for at least 5 days a week as a part of the physiotherapy program. This will be tracked using an exercise diary to be completed by participants each day.

Statistical Analysis: Summary statistics will be done and reported so that feasibility and safety can be assessed and future studies can use the results presented for power calculations.