CRPS (Complex Regional Pain Syndromes)

Complex Regional Pain Syndrome (CRPS) is a chronic pain condition characterized by severe regional pain, sensory disturbances, and functional impairment. Current treatment options are limited, and many patients experience substantial pain-related disability and symptom fluctuations, including flare-ups triggered by invasive procedures. Perineural administration of botulinum toxin A has shown analgesic effects in other neuropathic pain conditions and may represent a less painful alternative to subcutaneous injection techniques. However, the feasibility, tolerability, and safety of perineural botulinum toxin administration in patients with CRPS have not been systematically evaluated. The PINCom study is a single-center, open-label feasibility study designed to assess the safety, tolerability, and practical feasibility of ultrasound-guided perineural injection of incobotulinumtoxin-A in patients with unilateral chronic CRPS affecting an upper or lower limb. Participants receive a single perineural injection targeting major sensory nerves supplying the affected limb and are followed for 12 weeks. Primary outcomes focus on feasibility metrics, including recruitment, retention, adherence, and data completeness, as well as safety outcomes, including serious adverse events and procedure-related complications. Tolerability is assessed through monitoring of CRPS flare-ups and a dedicated qualitative interview exploring participant experience. Exploratory outcomes include pain intensity, CRPS severity, and patient-reported measures collected to inform the design of a future randomized controlled trial.

This study seeks to evaluate the use of intermittent dosing as an alternative paradigm for patients with DRG stimulation in place for at least 1 year and minimum 50% pain relief in the targeted area. Patients will be prospectively randomized to one of two stimulation paradigms both of which involve intermittent dosing at 30 seconds ON and 90 seconds OFF. Group 1 will have their frequency set at 20 Hz with amplitude levels adjusted in order to remain in the therapeutic window (subthreshold stimulation). Group 2 will have their frequency set at 5 Hz with amplitude levels adjusted in order to remain in the therapeutic window (subthreshold stimulation) This study will be performed in a crossover fashion, meaning patients will be changed to the alternate dosing regimen at the 13-week time period. Patients will be seen and evaluated prior to randomization and reprogramming, and thereafter evaluated at 4, 8, and 12-weeks. At the 12-week time period, patients will begin a 1-week washout period of continuous stimulation. At the 13-week time period, patients will be evaluated, crossed over to the other study arm and thereafter evaluated at 17, 21, and 25-weeks.

The aim of the study is to investigate and improve non-pharmacological rehabilitation methods for patients with Complex Regional Pain Syndrome (CRPS) to reduce pain and restore work and functional capacity to lower overall treatment costs. Current treatment methods offer limited rehabilitation potential for this challenging pain condition, so efforts should be made to raise the level of care and rehabilitation for a disease that often causes long-term and severe reductions in patients' functional and occupational abilities. CRPS patients almost always have to substantially reduce their work hours or withdrawn from the workforce for extended periods, and often permanently, increasing the urgency of strengthening rehabilitation approaches; a CRPS symptoms can end a patient's productivity for society. In addition, commonly used medications are a significant expense for both individuals and the healthcare system. CRPS rarely resolves fully, and even with extensive rehabilitation only a small proportion of patients regain sufficient improvement to return to work at a level of at least 60% capacity. Participants will be recruited from the Department of Physical Medicine and Rehabilitation at Oulu University Hospital, where CRPS diagnostics for the Northern Ostrobothnia area are primarily conducted. The study will be carried out at OYS rehabilitation outpatient clinics. A total of 39 participants will be recruited into each of four study groups, for an overall sample size of 156 individuals. Each study group will receive repetitive transcranial magnetic stimulation (rTMS) at some point, and functional neurological rehabilitation will be combined with rTMS in varying ways (content and timing will differ between groups). All participants will receive basic CRPS rehabilitation (physiotherapy and occupational therapy) that is provided for all RPS patients, and the timing of this relative to rTMS will also be varied. Recruitment is planned to begin in a autumn 2025.