Botulinum toxin A (Botox) for treatment of proximal myofascial pain in complex regional pain syndrome: two cases.

Objectives: To describe development of myofascial pain syndrome (MFPS) with trigger points in the proximal muscles of the patients with complex regional pain syndrome (CRPS1) and improvement of distal symptoms of CRPS 1 after successful treatment of proximal MFPS.

Setting And Design: In our practice, we frequently encounter patients in whom a proximal myofascial pain syndrome develops ipsilateral to the distal limb of CRPS1 patients. We describe two such patients in detail with their treatment. PATIENT 1: A 48-year-old woman experienced severe allodynia, swelling and autonomic changes in the right hand after surgery for carpal tunnel syndrome. Over the succeeding months, she developed painful trigger points in the right trapezius and upper back muscles which was treated with administration of botulinum toxin A (BoNT-A) into the trigger points (20 unit/point). PATIENT 2: A 41-year-old woman following a traumatic forearm injury suffered from CRPS1 affecting the left hand and forearm. Proximal MFPS gradually developed on the same side over 12 months and was treated with administration of BoNT-A into the trapezius, splenius capitis, and rhomboid muscle trigger points.

Results: In both patients treatment with BoNT-A improved the proximal pain of MFPS and the distal symptoms of CRPS1.

Conclusion: proximal MFPS develops ipsilateral to the distal painful limb in patients with CRPS1. Administration of BoNT-A into the affected proximal muscles may alleviate both MFPS and the distal allodynia, discoloration and, tissue swelling of CRPS.