Botulinum toxin helps sufferers of complex regional pain syndrome

MONTREAL — There is no cure for complex regional pain syndrome (CRPS), previously known as reflex sympathetic dystrophy syndrome (RSD), and most experts would agree that effective therapies are few and far between. Recent research, however, has shown that the extreme pain often experienced by CRPS patients can be effectively treated and controlled with administration of botulinum toxin injections.

In a recent single-center trial, eight patients with refractory upper-extremity CRPS received an average of nine injections of Botox (onabotulinumtoxinA, Allergan) administered subcutaneously in the affected area. The regimen consisted of a successive repetition of treatments once every three to four weeks over a nine-month period. Clinical improvement was followed using a pain scale of 0 to 10, and patients were followed up for a total of 17 months.

STUDY RESULTS Results showed that all of the study patients responded to and improved as a result of the therapy. Results did not show a complete reversal of symptoms, but they did indicate a better quality of life and better sleep for most study participants. Patients demonstrated an average reduction of 31.25 percent in their subjective pain scores, with maximum pain relief occurring at the ninth dose. What's more, daily pain perceived by the patient was significantly improved and controlled throughout the follow-up period, in some cases for up to 17 months.

"As current treatment approaches are typically less than optimal in quelling this sometimes-extreme level of pain, the positive result we achieved with this therapy is very much welcomed for these patients dealing with such an enormous challenge," she says.

Study participants did not report any permanent numbness or discomfort as a result of the injections, Dr. Lessard says.

OTHER CRPS THERAPIES Current treatment modalities used to alleviate pain in CRPS patients include massage, physiotherapy, stretching and strengthening exercises, and heat/cold therapy, coupled with a battery of medications such as analgesics, nonsteroidal anti-inflammatory drugs, corticosteroids, antidepressants, anticonvulsants, antispasmodics and nerve blocks/pain clinic consultations. However, many patients are unresponsive to these approaches and continue to experience recurring disruptive pain.

According to Dr. Lessard, traditional therapeutic approaches in combination with a series of Botox injections may be the first steps in finding a treatment protocol that works in patients.

"Botulinum toxin has now been shown to have a long-term, well-maintained effect in reducing pain in patients with chronic neuropathic pain conditions. It is possible that combination therapies consisting of botulinum toxin injections, oral medications as well as traditional physical therapies may be a potentially effective approach in addressing pain in CRPS patients. However, it is still early, and trials investigating various treatment protocols need to be performed," Dr. Lessard says.

CRPS I, CRPS II There are two forms of CRPS — CRPS I and CRPS II — and both are believed to be the result of dysfunction in the central or peripheral nervous systems. Both forms present as allodynia, hyperalgesia, hyperesthesia and autonomic instability, and both forms of the disease are characterized by dramatic changes in the color and temperature of the skin (waxy, shiny, atrophic appearance) over the affected limb or body part, accompanied by intense burning pain, skin sensitivity, erratic sweating, swelling and severe cold intolerance.

The patients involved in the study described in this article suffer from CRPS I, the form that is commonly triggered by tissue injury but no underlying nerve injury. Patients with CRPS II experience the same symptoms, but their cases are associated with nerve injury. The neuropathic pain seen in both forms is often refractory to traditional treatment approaches.

"It is possible that botulinum toxin injections may be a useful adjunct therapy in the treatment of CRPS. Though our study results are encouraging, larger patient trials with a longer follow-up and an investigation into the effects of botulinum toxin in combination with other treatment modalities would need to be conducted. The next series of studies will involve more complex outcome/quality of life assessment tools to document the positive effect seen in this first report," Dr. Lessard says. "This novel therapy is a light of hope at the end of the tunnel for these patients dealing with a big challenge affecting their life, their sleep, their family and their capacity to earn an income."

DISCLOSURES:
Dr. Lessard reports no relevant financial interests. For this study, patients purchased their own Botox through the provincial pharmacy infrastructure.