Vaporized Cannabis and Spinal Cord Injury Pain

This study will demonstrate that vaporized cannabis can produce antinociceptive effects compared to placebo in human subjects with spinal cord injury (SCI). A within-subject crossover study of the effects of cannabis versus placebo on spontaneous and evoked pain will be performed. A synopsis of antinociception with mood, cognitive impairment, psychomotor performance, and side effects will be obtained to help evaluate the utility of vaporized marijuana in SCI neuropathic pain.

This study will compare the analgesic and side effect profile of low (3.5%) to high dose (7.0%) delta 9-tetrahydrocannabinol in subjects with spinal cord injury pain. It is hypothesized that a low dose will produce a lesser degree of neuropsychological impairment while maintaining a similar degree of pain relief to the higher dose. The use of two different strengths will help determine tolerable dosing for the treatment of SCI neuropathic pain.

Inclusion criteria

• Age greater than 18 and less than 70
• Pain intensity ≥ 4/10
• Neuropathic pain defined as chronic pain in an area of sensory abnormality corresponding to the spinal cord or nerve root lesion, and the pain should have no primary relation to movement, inflammation or other local tissue damage
• Leeds Assessment of Neuropathic Symptoms and Signs score greater than or equal to 12
• Spinal cord injury of 3 or more months duration (to avoid spontaneous recovery obfuscating generalizability)

Exclusion criteria

• Known concomitant cerebral damage/cognitive impairment (TBI, Alzheimer's Disease Vascular dementia, Parkinson's disease, dementia with Lewy Bodies and Front temporal dementia
• Clinically significant or unstable medical condition (i.e., cardiac, respiratory, hepatic or renal disease) that, in the opinion of the investigator, would compromise participation in the study
• Neurologic disorders unrelated to spinal cord injury that may confound the assessment of the central neuropathic pain due to spinal cord injury (hereditary neuropathies; diabetic peripheral neuropathy; traumatic neuropathy; and immune-mediated neuropathies)
• Active substance abuse within past year using "The Substance Abuse Module of Diagnostic Interview Schedule for DSM-IV
• Pregnancy as ascertained by a self-report and a mandatory commercial pregnancy test
• Currently on probation or parole.
• Hx of Schizophrenia, Bipolar Depression with Mania, current suicidal ideation or past history of suicide attempt 8. Severe depression (Patient Health Questionnaire-9 ≥ 15) 9. Current suicidal ideation