Purpose: Chronic neuropathic pain is believed to result from post-injury alterations to the human nervous system. This aberrant reorganization can be of either peripheral or central origins and result in clinical symptoms of allodynia, hyperalgesia, hyperesthesia, and autonomic instability that are often refractory to current treatment standards.

Complex regional pain syndrome Type I (CRPS I) is a sympathetically maintained chronic neuropathic pain condition accompanied by sudomotor and vasomotor disturbances; incidence estimates vary between 5 to 26 cases per 100,000. Previously referred to as Reflex Sympathetic Dystrophy (RSD) traditional treatments have included massage, physiotherapy, stretching and strengthening exercises, TENS, ultrasound, heat and cold therapy, local, regional, and sympathetic direct analgesia. Despite these options, patients often continue to experience pain and discomfort that significantly affects their quality of life.

Botox has been shown in the literature to have a long-term well-maintained effect in reducing pain in patients with chronic neuropathic pain conditions that are refractory to other treatments. Benefits in pain and symptom relief allow greater effectiveness of more conservative therapies and are maintained with minimal to no side effects. Our study aims to investigate the efficacy of Botox for pain reduction in refractory upper extremity patients diagnosed with CRPS.

Methods: We have followed 8 CSST-WCC patients who have presented with refractory upper extremity CRPS at our institution over the past two years and have treated them with interval doses of Botulism Toxin Type A; all patients had previously failed at least two forms of traditional treatments, including guanethidine and stellate ganglion blocks, intensive physical therapy regimens and prolonged analgesic medication trials. Our treatment protocol consisted of subcutaneous injections of Botox every four weeks directly into areas of maximum tenderness. At the beginning of each visit, patients reported their pain on a scale of 0-10. Occupational therapy and range of motion protocols were maintained for all patients throughout the duration of our study.

Results: The mean number of treatments per patient was 9.5 (range 5-13). Patients reported an average reduction in subjective pain scores of 31.25% with maximum pain relief occurring most often at dose #9. Improvements in pain scores were significant (p= 0.0128) and were maintained throughout the follow-up period (mean 6 months).

Conclusion: Our initial investigations at the MUHC indicate that Botox may be considered a useful adjunct in the treatment of CRPS. Our patients all presented initially with severe symptoms refractory to traditional treatment modalities and reported significant improvement in their daily pain control that were maintained for up to 17 months. Larger patient samples, continued follow-up, and investigation into the effects of Botox in combination with other treatment modalities may set the ground for a breakthrough in the symptomatic relief of this often debilitating condition.