Usefulness of botulinum toxin in local rebel pain after spine arthrodesis

Abstract

Botulinum toxin (BT) is widely used to treat spasticity, as well as blepharospasm, torticollis, hyperhidrosis. Simultaneously, a specific effect on pain has been observed, whom physiopathological rational is being more and more understood. Among the new BT indications, neuropathic pain and chronic back pain take a big place. After arthrodesis correcting important spine static trouble, despite efficient multimodal treatment, focal rebel pain is frequently observed. This is a monocentric, open, current care, retrospective and prospective study. Its purpose was to evaluate the interest of using BT to treat resistant focal pain after spine arthrodesis. All included patients had spine arthrodesis for scoliosis or spondylolisthesis and rebel focal pain, after 6 months postsurgery, without infectious or orthopaedic complication. The main judgment criteria were the pain improvement evaluated with the VAS (Visual analogic scale) and the subjective improvement. We used type A BT in cervical, and/or thoracic and/or lumbar paraspinal muscles, trapezius, rhomboids, splenium capitis, uni or bilaterally. Fourteen patients had BT injection, sometimes repeated, with a mean benefit of 3.4 points on the VAS and a subjective improvement estimated at 40%, without adverse event. Four patients had an excellent outcome and 9 had a good improvement. The mean delay between surgery and the first injection was nearly 5 years. Only 6 patients needed to be reinjected. The observed pain improvement is probably linked to a mixed effect, at least for some patients, on muscle contracture and on neuropathic pain. The long lasting analgesic effect suggests an important neuropathic part according to nowadays knowledge. In view of BT efficiency on this refractory pain and of its safety, it would be justified to propose sooner this additive treatment and to precise if pain has a mixed origin, muscular and neuropathic, to improve the injection schema (subcutaneous injection for the neuropathic part). Lastly, it would be useful to conduct more reliable essays to confirm BT effect in this indication and so widen its marketing authorization.