The goal of this study is to compare the changes that occur in sensation and chemical properties of the brain following SCI between individuals that experience chronic pain and those that do not, and between those with SCI and the able-bodied.

This study investigates the differences in certain neurochemicals present in areas of the brain linked to pain processing in people with SCI and neuropathic pain, in people with SCI but no pain, and in able-bodied persons. We will also investigate the relationship between these concentrations of neurochemicals and different aspects of chronic neuropathic pain, including the intensity of pain, quality of life issues, sensitivity changes in areas of the body that are both painful and non-painful, and neurological status.

Inclusion Criteria:

1. SCI and neuropathic pain:

   • fluent in English
   • incomplete or complete traumatic SCI
   • the injury must have occurred at least 2 years prior to entering the study
   • the injury level must be above L1 and the subjects must have evidence of preserved distal cord functions (lower extremity reflexes and bulbocavernosus or anal wink reflexes)
   • must have experienced chronic neuropathic pain at or below the level of injury for a minimum of six months
   • must have moderately severe or greater neuropathic pain
   • must be able to attend three sessions ranging from 2 to 6 hours over a period of 4 to 5 weeks

2. SCI and no neuropathic pain:

   - same as a., but participants in this group must NOT have unremitting moderate-severe pain and there will only be two sessions ranging from 2 to 6 hours over a period of 1 to 2 weeks

3. Able-bodied control subjects:

   • fluent in English
   • no history of chronic pain conditions
   • no substantial brain or body injury
   • must be able to attend two sessions ranging from 2 to 6 hours over a period of 1 to 2 weeks

Exclusion Criteria:

• current pregnancy or women who are contemplating pregnancy
• recent (one-year) history of alcohol or drug abuse
• known intra-cerebral pathology or epilepsy
• MRI findings indicative of intra-cerebral pathology
• significant post-traumatic encephalopathy from head trauma sustained at SCI or cognitive impairment indicative of traumatic brain injury
• current diagnosis of DSM-IV Axis I disorder
• inability to meet the MRI screening requirements (including, but not limited to, the presence of a pacemaker or other electronic devices, prosthesis, artificial limb or joint, shunt, some metal rods, some tattoos, or moderate to severe claustrophobia or anxiety)

Both spinal cord injured (85) and able-bodied (25) subjects will be studied. Of those with spinal cord injury, 60 will be those who experience central neuropathic pain and 25 will not. An additional 25 people who screen positive for mild to moderate TBI symptoms and pain attributable to TBI will be studied.