Intra-articular botulinum toxin A as an adjunctive therapy for refractory joint pain in patients with rheumatoid arthritis receiving biologics: a report of two cases.

We report the use of intra-articular Botulinum toxin A in two RA patients with persistently painful monoarthritis in ankle/feet joints. Both patients had monarticular pain despite a good response of all other joints to a combination therapy that included anti-tumor necrosis factor therapy. Both patients had failed intra-articular corticosteroid injections and declined surgical options. After a single, "off-label", intra-articular injection of Botulinum toxin A into the right ankle (100 unit) and left first metatarsophalangeal joint (25 unit), respectively, pain and function improved significantly (> or =40%) in both patients. Durable response with improvement of pain and function lasting 15-18 months was noted (follow-up continuing). Ankle joint swelling resolved by 15 months and MTP joint swelling by one month. Intra-articular BoNT/A may be an additional therapeutic option in RA patients with persistent monoarthritis. A randomized study is underway to confirm these findings.