Efficacy Study of Botox to Treat Neuropathic Pain

Randomized Placebo-controlled Study of the Efficacy of Botulinum Toxin Type A (Botox) in Spontaneous Pain and Allodynia Related to Traumatic Nerve Injury or Postherpetic Neuralgia

Objectives : to investigate the analgesic effects and safety of intradermal botulinum toxin A injection in the treatment of focal painful neuropathies (eg, postherpetic neuralgia, nerve trauma)

The study will be randomized, performed in parallel group and double blind versus saline and will include 30 patients. Botulinum toxin injection will be injected intradermally in the painful area (one single injection) following a method adapted from that used in hyperhidrosis. The patients will be followed for 6 months after the injection. Primary outcome will be self-reported pain from the patients diaries. Secondary outcomes will be neuropathic symptoms, quality of life, allodynia to brush and pressure, detection and pain thresholds, proportion of responders, pain relief and clinical global impression. Clinical assessment will take place before injection then at 1 month, 3 months and 6 months.

active treatment arm using botulinum toxin A max 200 U injected into the painful area using SC injections 2 cm apart

mean pain (VAS) at each visit Quality of life Proportion of responders % pain relief Clinical global impression Assessment of blindedness

Inclusion Criteria: daily pain for at least 6 months of at least moderate intensity clearly attributed to the nerve lesion limited area of pain mechanical allodynia in the painful area Exclusion Criteria: contraindication to BTXA formulation coagulation disorders another painful condition current major depression history of drug or alcohol abuse compensation claim or litigation facial neuropathic pain