Botulinum toxin type A for failed back syndrome

Abstract

Chronic low back pain (LBP) is usually a debilitating syndrome with musculoskeletal and neuropathic pain features. Prior studies have shown that botulinum toxin type A (BTX-A) is efficacious for LBP. We retrospectively reviewed charts of 17 consecutive patients who were referred for chronic LBP, who had prior lumbar surgery and who were treated with BTX-A injections given bilaterally in the lumbar paravertebral muscles. Pain ratings included the Visual Analogue Scale (VAS), the Short Form McGill Pain Questionnaire (SFMPQ)and Present Pain Intensity (PPI) before injection and at a mean of 6 weeks post-injection. Adverse events were assessed. Nine patients received 100 to 200 units of BTX-A (only one patient received 100) and 8 patients received between 300 and 400 units BTX-A (only one patient received 400). The mean dose of BTX-A was 250 units. Most patients received BTX-A via a 26-gauge, 50 mm or 37 mm EMG guided injection to ensure intramuscular injection in these post-operative patients. Results of BTX-A treatment were pretreatment VAS mean of 79 and post-treatment mean of 62 (p 0.008). Pre-treatment SFMPQ mean was 24; post-treatment SFMPQ mean was 16 (p 0.007). Pre-treatment PPI mean was 3.4; post-treatment PPI mean was 2.5 (p 0.01). Side effects were limited to transient injection site discomfort. No patients developed weakness. A sub-analysis of patients receiving 300 units BTX-A compared to patients receiving 200 units BTX showed greater efficacy at 300 units. BTX-A appears to be effective in a high percentage of patients with significant, long-term LBP who have failed surgery and multiple other modalities of treatment. No significant side effects occured in any of our patients.