Objective: To investigate clinical differences in warm and cold complex regional pain syndrome (CRPS) phenotypes.
Background: CRPS represents inhomogeneous chronic pain conditions; approximately 70% patients with CRPS have "warm" affected limbs and 30% have "cold" affected limbs.
Methods: We examined 50 patients with "cold" and "warm" CRPS (n = 25 in each group). Both groups were matched regarding age, sex, affected limb, duration of CRPS, and CRPS I and II to assure comparability. Detailed medical history and neurologic status were assessed. Moreover, quantitative sensory testing (QST) was performed on the affected ipsilateral and clinically unaffected contralateral limbs.
Results: Compared with patients who had warm CRPS, patients who had cold CRPS more often reported a history of serious life events (p < 0.05) and chronic pain disorders (p < 0.05). In cold CRPS, the incidence of CRPS-related dystonia was increased (p < 0.05), and cold-induced pain had a higher prevalence (p < 0.01). Furthermore, QST revealed a predominant sensory loss in patients with cold CRPS (p < 0.05). In contrast, patients with warm CRPS were characterized by mechanical hyperalgesia (p < 0.05) in the QST of affected limbs.
Conclusion: Our results indicate that warm and cold complex regional pain syndromes (CRPS) are associated with different clinical findings, beyond skin temperature changes. This might have implications for the understanding of CRPS pathophysiology.