Conditions: Complex Regional Pain Syndrome Type I Complex Regional Pain Syndrome Type II
Keywords: Analgesia Causalgia CRPS Neuropathic Pain Oral Surgery Reflex Sympathetic Dystrophy Sympathetic Nervous System Chronic Regional Pain Syndrome
Allocation: RANDOMIZED | Intervention model: CROSSOVER
Enrollment: 21
Healthy volunteers: no

Brief summary:
This study will examine the effectiveness of the drug neurotropin in treating chronic pain after injury to a limb or a large nerve.

Two groups of patients will participate in this study: patients with complex regional pain syndrome type 1, or CRPS-I (also called reflex sympathetic dystrophy) and patients with complex regional pain syndrome type 2, or CRPS-II. CRPS-I is pain that develops after relatively minor injury to an arm or leg, but lasts much longer and is much more severe than would normally be expected. CRPS-II is pain resulting from injury to a large nerve. Candidates will have a history and physical examination, blood tests, and electrocardiogram. Participants will undergo the following tests and procedures:

Patients with CRPS I and II will receive an individualized regimen of physical therapy and standard treatment to control their pain. In addition, they will receive neurotropin or placebo tablets for 5 weeks, then no trial medicine for at least 1 week, and then the other trial drug for the next 5 weeks. That is, patients who took placebo the first 5 weeks will take neurotropin the second 5 weeks and vice versa. Neither the patients nor the doctors will know who received which drug during the two intervals until the study is over. Patients will complete questionnaires about their pain, quality of life, and ability to perform daily living activities. They will have various tests to measure pain (such as sensitivity to heat and cold, to an electric current, to a mild pin prick, etc.); to provide information about changes in their condition (such as tests of range of motion of joints and limb size); to measure blood circulation and sweating in the arm or leg (such as measurements of blood flow to the limb, skin temperature, and sweat production), and other procedures.

Detailed description:
Patients with Reflex Sympathetic Dystrophy (RSD), re-named Complex Regional Pain Syndrome, type I (CRPS-I), have chronic, post-traumatic pain that spreads beyond the distribution of any single peripheral nerve without evidence of major peripheral nerve damage. A similar disorder, Causalgia, re-named CRPS-II, presents with clear evidence of nerve injury. No successful drug treatment exists for these disorders. Neurotropin is a non-protein extract of cutaneous tissue from rabbits inoculated with vaccinia virus. Neurotropin has been used extensively in Japan to treat RSD and other painful conditions; however, the drug has not undergone clinical therapeutic testing in the United States. This protocol is to carry out double-blind, placebo-controlled, crossover studies about clinical efficacy of Neurotropin for acute pain in dental outpatients and for chronic pain in outpatients with CRPS-I or II.

Arms:
arm 1: Double blind cross-over study: receive placebo for 5 weeks and then Neurotropin for 5 weeks (after at least 1 week washout period). Assignment to each group was in random order, selected by the pharmacy with all others blind. arm 2: Double blind cross-over study: receive Neurotropin for 5 weeks and then placebo for 5 weeks (after at least 1 week washout period). Assignment to each group was in random order, selected by the pharmacy with all others blind.

Interventions: intervention 1: Placebo intervention 2: Neurotropin
Intervention descriptions: intervention 1: 4 tabs b.i.d. intervention 2: 4 tabs b.i.d.

Protocol document: