Introduction and background

Complex regional pain syndrome (CRPS) is a chronic pain disorder characterized by pain disproportionate to the inciting event and accompanied by variable combinations of sensory, vasomotor, sudomotor, motor, and trophic abnormalities. The syndrome most commonly develops following fractures, soft-tissue trauma, surgery, or peripheral nerve injury and frequently affects the distal upper extremity. Despite decades of investigation, CRPS remains one of the most challenging postoperative and post-traumatic complications encountered by hand surgeons because no individual clinical feature, imaging study, or laboratory investigation is sufficiently sensitive or specific to establish the diagnosis independently. Instead, diagnosis relies on careful clinical evaluation while systematically excluding competing explanations for the patient's symptoms [1-3].

Historically referred to as reflex sympathetic dystrophy and causalgia, CRPS is now recognized as a complex interaction among peripheral inflammation, autonomic dysfunction, central sensitization, immune activation, and maladaptive cortical plasticity. These overlapping mechanisms help explain the remarkable heterogeneity observed among patients and likely account for the inconsistent response to individual therapies reported throughout the literature. Rather than representing a single disease process, CRPS should be viewed as a syndrome involving multiple biological pathways that evolve over time and differ among patients [1-4].

Incidence figures should be interpreted with caution. Reported rates vary widely across studies because they depend heavily on which diagnostic criteria were applied, how intensively patients were surveilled, and how the study was designed. Distal radius fracture is the most frequently reported antecedent injury in the upper extremity [1,3]. CRPS following carpal tunnel release is uncommon but clinically meaningful, and most affected patients improve within one year. What matters clinically is less the population incidence than the recognition that any hand surgeon with a reasonable trauma and elective volume will encounter this condition.

For the practicing hand surgeon, CRPS presents unique diagnostic and therapeutic challenges. Patients recovering from distal radius fractures, tendon repairs, nerve reconstruction, crush injuries, or elective procedures such as carpal tunnel release frequently experience pain, edema, and stiffness during normal healing. Distinguishing expected postoperative recovery from evolving CRPS requires thoughtful clinical judgment and serial examination. Conversely, assigning a diagnosis of CRPS without excluding infection, persistent nerve compression, tendon pathology, hardware failure, vascular compromise, or fracture-related complications risks delaying appropriate surgical management. Maintaining a broad differential diagnosis is therefore essential throughout evaluation [1,3].

Although numerous pharmacologic, rehabilitative, and interventional therapies have been investigated, contemporary evidence demonstrates that few individual treatments consistently produce large or durable improvements when used in isolation. International guidelines, Cochrane reviews, systematic reviews, and randomized trials increasingly converge on a common principle: successful management depends upon coordinated multidisciplinary care centered on restoration of function rather than elimination of pain alone. Occupational and physical therapy, patient education, desensitization, and graded return to limb use remain the foundation of treatment, while medications, sympathetic blockade, infusion therapies, and neuromodulation should be considered adjunctive interventions designed to facilitate rehabilitation when pain prevents meaningful functional progress [1-5].

Unlike previous reviews that primarily catalog available interventions, the objective of this article is to provide a practical, evidence-based framework for the diagnosis and management of CRPS relevant to hand surgeons and upper-extremity specialists. Drawing upon contemporary international guidelines, systematic reviews, randomized controlled trials, and hand surgery-specific literature, we summarize current evidence while emphasizing clinical decision-making, multidisciplinary care, and realistic interpretation of therapeutic efficacy. Rather than identifying a single best treatment, this review advocates a staged approach in which treatment intensity is individualized according to disease severity, chronicity, functional impairment, and patient response.