Capsaicin 8% Patch for Spinal Cord Injury Neuropathic Pain (Capsaicin)

A prospective case control study to determine the effectiveness and longevity of 8% capsaicin patch(es) in treating neuropathic pain in persons with spinal cord injury. The investigators will study spinal cord injury patients at South Texas Veterans Health Care Systems Spinal Cord Injury inpatient unit and outpatient clinics.

The investigators will recruit ~ 20 patients with chronic spinal cord injury (SCI) and chronic neuropathic pain (>6months) below level of injury who have failed multiple pharmacological agents. Pre-study data collection will include subjective description of pain, baseline visual analog scale (VAS), numeric pain rating scale (NPRS), a numerical scale such as short form (SF) 36 form that measures quality of life parameters, subjective functional independence (FIM) scores, and pain diagrams will be obtained on each participant. Written informed consent will be obtained. After randomization patients will be assigned to a different sequence of treatment. All patients will receive either the treatment and control patches in a randomized order for a total of three treatment periods (control, treatment, treatment for example). When assigned to received treatment arm of study patients will receive Qutenza Capsaicin 8% patch(es) applied for 1 hour after pre- treatment with topical lidocaine. The control group will receive a low dose (0.04%) amount of capsaicin in patch form using an identical application procedure. Investigators will give each patient a diary to self record daily VAS/NPRS scores. Investigators will then schedule routine f/u via telephone call at 2, 4, 8, and 12 weeks post application to accurately report onset of relief and obtain NPRS scores at 2, 4, 8, 12 week points. Patients will follow up in clinic at the end of the 12 week study to repeat data collection using our quality of life scale (SF 36) and FIM scores. Investigators will then use data analysis to record percentage of reduction in NPRS/ VAS, and changes in SF 36 and FIM scores at any given time point vs baseline. For those that continue to have pain relief at 12 week mark we will periodically call every 4 months after study completion to assess for total duration of pain relief for up to 1 year post application.

Study participants are assigned to both strengths of the intervention, so all study participants receive both strengths, thus acting as their own control. Data will be compared according to intervention, rather than following each subject from beginning of study through both interventions.

Active control with low dose capsaicin 0.025% Well Patch used for 12 weeks followed by Qutenza 8% Patch

The Visual Analog Scale (VAS) was used as the primary outcome measure to quantify pain on a scale of 0-10, with 0 being no pain and 10 being the worst pain. VAS was measured at weeks 2,4,6,8,10 and12 during each 12- week block.

The World Health Organization Quality of Life (WHOQOL-BREF) questionnaire is a scale used to assess an individual's perception of their quality of life. Its domains include physical health, psychological health, social relationships, and patient environment. It is scored from 0-100, where lower scores indicate poorer perception of quality of life and higher scores indicate better perception. This scale was used to investigate if there was any pattern of change in QOL due to improved pain control. WHO-QOL-BREF was also measured every 4 weeks of each period.

The Spinal Cord Independence Measure (SCIM) is a reliable scale that measures proficiency of activities of daily living (ADL's) of patients with spinal cord injuries. (28) It is broken up into four subscales including self-care, respiration and sphincter control, and mobility with a total score combining all 3 outcomes. It is scored from 0-100, where lower numbers indicate more dependence on others and higher numbers indicate less dependence. This tool can be applied practically to the study to investigate everyday function before and after patch application. SCIM was administered every 4 weeks of each period.

Inclusion Criteria: Diagnosis of SCI Neuropathic pain below level of injury Surface area of pain no larger than 2 patches Failed or did not tolerate gabapentin 3600mg/day, pregabalin 600mg/day, capsaicin cream and/or lidocaine cream Skin over painful area intact Exclusion Criteria: Pain over open wound Previously documented allergy to capsaicin Superficial burn over area of pain Premorbid (before SCI) neuropathic pain HIV/AIDS neuropathy