Injecting Botulinum Toxin A Underneath the Skin to Treat Spinal Cord Pain in Patients With Spinal Cord Injury

Subcutaneous Injection of Botulinum Toxin A for At--Level Back Pain in Patients With Spinal Cord Injury

Back pain is a common secondary condition of both acute and chronic spinal cord injury (SCI). Current existing treatment including both pharmacologic and non-pharmacologic are limited by marginal efficacy or intolerable side effects. The purpose of this study is to evaluate the potential of subcutaneous injections of botulinum toxin A to provide pain relief in spinal cord injury patients with back pain near the level of injury in the spine. Botulinum toxin A has been shown in both pre-clinical and clinical studies to help with nerve pain. The researchers propose a double blinded placebo controlled crossover study to study the effects of subcutaneous botulinum injections to at--level SCI back pain in patients with spinal cord injury.

In this study, there will be 2 procedure performed. The first procedure will be named P1 and consists of subcutaneous injection of either placebo or Botulinum Toxin A. The second procedure will be the cross-over procedure named P2. For the cross-over procedure, the subjects who had initially received Botulinum Toxin A will receive placebo and the subjects who had initially received placebo will receive Botulinum Toxin A. This is a Randomized Double-Blinded Placebo Controlled Trial. Recruited subjects will be consented, enrolled and evaluated immediately prior to P1 (or during a visit prior to the visit for P1). After the initial pre-treatment evaluation, subjects will randomly receive either placebo or Botulinum Toxin A subcutaneously (P1). A telephone follow-up (or e-mail follow up) will be performed at 2 weeks and 8 weeks post- P1. An onsite follow up will be performed 4 weeks post P1 and 12 weeks post P1.

Cross-over Study: After the 3rd month on-site evaluation (12 weeks post P1), during the same visit, the subject will proceed to the cross-over study. At this time, the patient will have the option to receive a repeat subcutaneous injection of the cross-over agent. If they desire one, a subcutaneous injection of the cross-over agent will be performed at that same visit. If they wish to defer the repeat injection, they will be contacted and asked every 4 weeks - between 12 weeks and 24 weeks post P1 (no subject will receive P2 after week 24) if they would like to have the subcutaneous injection of the cross-over agent. If they desire one, a repeat injection will be scheduled for the following week.

The rationale for a variable length of time after the initial Botulinum Toxin A/Placebo injection (P1) is to document the variability of individuals' pain response after Botulinum Toxin A. It has been reported in literature, of the subjects that respond to subcutaneous Botulinum Toxin A injections for pain, most will return to their base-line pain score in 12--24 weeks.

Inclusion Criteria:

• Between the ages of 18 and 80 years old
• Diagnosed with traumatic spinal cord injury
• Target pain is considered by the physician as at-level SCI in nature to a high degree of certainty (4 or 5 using a Likert confidence scale ranging from 0-5 where 0 is "purely a guess" and 5 is "absolutely certain")
• Able to give written informed consent
• Target pain that has been continuously present for at least one month
• Target pain is of at least moderate average intensity over the past week, e.g., greater than or equal to 4/10 on a numeric rating scale, the cutoff point for moderate pain in an SCI population.
• Target pain is localized within the dermatome which identifies the NLI or within 3 levels below the NLI
• Subject has been on a stable dose of analgesic mediation (or not on analgesic medication) for at least 3 weeks and is agreeable to remaining on current regimen for the duration of the study (previous prescribed breakthrough analgesics will be allowed)

Exclusion Criteria:

• Pregnancy
• History of intolerance, hypersensitivity or known allergy to botulinum toxin or its preservatives
• History of intolerance, hypersensitivity or known allergy to EMLA cream (lignocaine/prilocaine eutectic mixture) which is used as an analgesic during BoNT injection
• Recent history of administration of botulinum toxin (within previous 6 months)
• Contraindications to botulinum toxin (myasthenia gravis or other disease of the neuromuscular junction)
• Coagulation disorder
• Current infection
• Insufficient command of English to complete self-report instruments.