Intra-articular botulinum toxin injection in complex regional pain syndrome: Case report and review of the literature.

Complex regional pain syndrome (CRPS) is characterized by hyperalgesia, autonomic and trophic alterations of bones, muscles and skin. It is supported by neurogenic inflammation and impairment of sympathetic nervous system. Botulinum Toxin (BTX) is an option for the management of pain, with level B evidence of efficacy in neuropathic, joint and myofascial pain syndrome. We report a case of CRPS treated with intra articular injection of BTX-A (IaBI). BTX-A 100 U in 2 cc Na Cl 0,9% was injected into the gleno-humeral joint. Visual analogue scale (VAS) pain score and McGill Pain Questionnaire (MPQ) were administered at T0 (baseline), T1 (one month after IaBI) and T2 (four months after IaBI). Autonomic and trophic skin disorders were clinically monitored. Pain decreased at T1, with a lasting effect at T2, associated with improvement of range of motion (ROM). No improvement in terms of autonomic and trophic skin disorders were reported neither at T1 nor T2. These findings support a possible antinociceptive role of BTX-A in the management of CRPS pain related to inhibition of pain neurotransmitters release. A literature revision of IaBI is provided.