Is botulinum toxin type A effective in the treatment of spastic shoulder pain in patients after stroke? A double-blind randomized clinical trial

OBJECTIVE: To determine the efficacy of botulinum toxin type A for the treatment of spastic shoulder pain in patients after stroke. DESIGN: Double-blind randomized clinical trial. PATIENTS: Of 31 patients enrolled from an acute-care hospital in Spain, 2 cases dropped out (drop-out rate 6.5%). Fourteen subjects were treated with infiltration of 500 units of botulinum toxin type A in the pectoralis major muscle of the paretic side, and 15 with a placebo. METHODS: After infiltration, both groups received transcutaneous electrical nerve stimulation for 6 weeks. Patients were assessed by the use of the Visual Analogue Scale for pain. A good result concerning pain was considered when the Visual Analogue Scale score was below 33.3 mm or less than half the initial score. The patients were followed-up for 6 months. RESULTS: The patients treated with botulinum toxin type A showed a significantly greater pain improvement from the first week post-infiltration. Persistent shoulder pain was observed more frequently in the placebo group, with relative risks in the range 0.32-0.41 during the follow-up period. CONCLUSION: Patients with spastic shoulder pain treated with a botulinum toxin type A infiltration in the pectoralis major muscle of the paretic side have a higher likelihood of pain relief (between 2.43- and 3.11-fold).