Complex Regional Pain Syndrome: Analgesic Outcome

About This Study

This retrospective observational study aims to describe the use and analyze the effectiveness of various analgesic interventions in patients diagnosed with Complex Regional Pain Syndrome (CRPS) at the Pain Management Center of Hôpital Maisonneuve-Rosemont (HMR) between January 2020 and October 2025. Background: Complex Regional Pain Syndrome is a chronic pain condition characterized by severe, persistent pain accompanied by sensory, vasomotor, sudomotor, and motor/trophic changes, often following trauma or surgery. Despite established diagnostic criteria (Budapest criteria), its pathophysiology remains poorly understood, and evidence-based treatments are limited. While multidisciplinary functional rehabilitation remains the cornerstone of management, various analgesic interventions are used to facilitate recovery when medications fail to adequately control pain. Common interventions include: * Plexus or peripheral nerve blocks (brachial or sciatic, with or without adjuvants such as dexamethasone or dexmedetomidine) * Intravenous ketamine infusions * Sympathetic blocks (stellate or lumbar) * Intravenous pamidronate infusions Although all these techniques are used in clinical practice, their relative efficacy and predictive factors for success remain unknown. Clinicians rely on experience rather than data-driven guidance to select an initial intervention. Identifying factors such as CRPS subtype or symptom duration that predict analgesic response could improve treatment efficiency and functional recovery. Objectives: Primary objective: To determine the frequency distribution of first-line analgesic interventions used in patients with CRPS treated at HMR's Pain Management Center. Secondary objectives: * To evaluate the success rate ("significant analgesia") of each intervention when used first-line. * To assess the incidence of significant adverse effects. * To analyze success rates according to CRPS clinical subtype (vasomotor, sensory, florid, or indeterminate) and symptom duration (\<12 months, 12-18 months, \>18 months). * To determine the number of unsuccessful interventions required before achieving pain relief. Methods: This is a retrospective chart review including all adult patients with a CRPS diagnosis established using the Budapest criteria who received at least one eligible analgesic intervention during the study period. Data will be extracted from electronic medical records by the research team. Exclusion criteria include incomplete clinical documentation or missing information regarding the first consultation, intervention type, or analgesic outcome. Collected variables include demographics, medications, CNESST (workers' compensation) status, PTSD diagnosis, trauma type, CRPS characteristics (affected limb, type, subtype, symptom duration), details of the first intervention (technique, dose, use of adjuvants), analgesic response, and adverse effects.

Conditions Studied

Eligibility

Inclusion Criteria:

* Patients with a diagnosis of complexe regional pain syndrome
* Patients who received at least one of the following intervention: peripheral nerve block (infraclavicular, intrerscalene, axillary, popliteal sciatic), sympathetic block (stellate, lumbar), intravenous ketamine infusion, or intravenous pamidronate infusion)

Exclusion Criteria:

* First consultation is not digitalized
* Information on signs and symptoms at the first consultation is missing

Study Locations (2)