Clinical trial NCT00725322: Subcutaneous Botulinum Toxin for Cutaneous Allodynia
Official title: Subcutaneous Botulinum Toxin for Cutaneous Allodynia
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Pain
Lead sponsor: Stanford University
Sponsor class: OTHER
First posted: 2008-07-30
Enrollment: 84
Sex: ALL
Minimum age (years): 18
Standard ages: ADULT
OLDER_ADULT
Accepts healthy volunteers: no
Allocation: RANDOMIZED
Intervention model: CROSSOVER
Primary purpose: TREATMENT

Brief summary: 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).

Detailed description: 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.

Eligibility criteria: Inclusion Criteria:- Moderate to severe pain (greater than 4/10) of duration more than 6 months despite previous therapy.

* The patient exhibits at least 80% pain relief following injection of local anesthetic subcutaneously into scar as assessed by change in NRS
* The patient reports the presence of hyperalgesia, allodynia, dysesthesia, or hypoesthesia surrounding the scar
* Age 18-100
* Ability to read, write, and converse in English, provide informed consent, and follow study procedures

Exclusion Criteria:

1. Any neuromuscular disorder such as myasthenia gravis, eaton lambert, muscular dystrophy
2. Any ongoing legal action related to their pain
3. Allergy to local anesthetics
4. A current or history of any severe psychiatric disorder
5. History of any adverse reaction to botulinum toxin
6. History of botulism
7. Untreated infection
8. Coagulopathy
9. Females - positive pregnancy test
10. Surgery within the past 6 months at the site of the painful scar

Primary outcomes:
measure: Time Until Analgesic Failure
timeFrame: Each participant was assessed for up to 224 days per intervention (injection) or until they returned to NRS baseline
Secondary outcomes:
measure: NRS Score Three Weeks After Injection
timeFrame: Three weeks after injection
Other outcomes:
Locations:
city: Stanford
country: United States
facility: Stanford University School of Medicine
state: California
Study officials:
affiliation: Stanford University
name: Ian R Carroll
role: PRINCIPAL_INVESTIGATOR
affiliation: Stanford University
name: Sean Mackey
role: PRINCIPAL_INVESTIGATOR
References: