Subcutaneous Botulinum Toxin for Cutaneous Allodynia
Superficial injection of Botulinum toxin has been advocated for cosmetic purposes but has also been reported to be helpful for some pain conditions. The investigators have observed prolonged profound analgesia following subcutaneous superficial injection of Botulinum Toxin Type A (BTA) in patients with certain types of neuropathic pain. The investigators propose to study if addition of BTA extends pain relief compared to placebo when injected subcutaneously into areas of cutaneous allodynia (the property that a normally non-noxious stimulus is perceived as painful).
|Study Design:||Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
|Official Title:||Subcutaneous Botulinum Toxin for Cutaneous Allodynia|
- Time until analgesic failure [ Time Frame: duration of trial ] [ Designated as safety issue: No ]
- Reduction in area of allodynia and hyperalgesia [ Time Frame: duration of trial ] [ Designated as safety issue: No ]
- Improvement in psychosocial function as assessed by outcomes as dictated by the IMMPACT guidelines [ Time Frame: duration of trial ] [ Designated as safety issue: No ]
- Proportion of patients experiencing a reduction of 2 points or more on NRS, three weeks after injection compared to baseline NRS [ Time Frame: duration of trial ] [ Designated as safety issue: No ]
|Study Start Date:||December 2007|
|Estimated Study Completion Date:||January 2013|
|Estimated Primary Completion Date:||October 2012 (Final data collection date for primary outcome measure)|
|Placebo Comparator: Placebo - Saline||
Drug: Placebo - Saline
Subcutaneous Saline injection given at site of scar neuroma
|Experimental: Botulinum Toxin Type A||
Drug: Botulinum Toxin A
Subcutaneous injection of Botulinum Toxin Type A into the patient's scar tissue
Post-surgical neuromatous pain patients have marked cutaneous allodynia. Touching their skin with normally non-painful stimuli results in pain. Injected local anesthetics are often effective in providing temporary relief. In the course of clinical practice the investigators have observed that a number of patients with cutaneous allodynia have had marked persistent benefit from subcutaneous injection of Botulinum toxin Type A.
Rather than killing targeted neurons, Botulinum toxin type A inhibits release of acetylcholine from cholinergic nerve terminals in a prolonged but ultimately reversible manner. Neuropathic pain and its hallmark allodynia are classically difficult to treat. Standard treatment with tricyclic antidepressants, anti-epileptic drugs, opiates and spinal cord stimulation is frequently disappointing leaving patients with refractory pain. Surgical or percutaneous ablation of involved nerves has fallen out of favor among many due to disappointing results.
A pilot study is needed to assess the efficacy of superficially injected Botulinum Toxin type A for treatment of cutaneous allodynia and spontaneous pain among patients with neuropathic pain.
|United States, California|
|Stanford University School of Medicine|
|Stanford, California, United States, 94305|
|Principal Investigator:||Ian R Carroll||Stanford University|
|Principal Investigator:||Sean Mackey||Stanford University|