To investigate the efficacy of lithium carbonate in the treatment of neuropathic pain of patients with spinal cord injury.

This is a randomized, placebo-controlled, double-blinded trial. Sixty spinal cord injured subjects with neuropathic pain will be randomized into two groups. The subject in the Treatment Group will receive lithium carbonate tablet, while the Control Group will receive placebo tablet. Neither the subjects nor the physicians know which group the subjects are allocated.

Each subject will receive 6 weeks of oral lithium carbonate or placebo. In the Treatment Group, the dose will be adjusted according to the serum lithium level. While in the Control Group, the dose will be adjusted based on the dummy serum level report.

The outcome will be assessed during visits at 1 week, 2 weeks, 6 weeks and 12 weeks, and a phone call follow-up at 24 weeks from the start of the medication. The primary outcome measure is the severity level of pain. The efficacy and safety will be analyzed by comparing the results of the Treatment Group with those of the Control Group

Inclusion Criteria:

• Age 18 - 65;
• Diagnosis of traumatic spinal cord injury;
• Clinically diagnosed neuropathic pain;
• Pain severity is at least 4 on a 11-point numeric rating scale at screening;
• Pain present regularly for at least 6 weeks before enrollment;
• Able to understand instructions and provide reliable pain assessments;
• Subjects who are voluntarily signed and dated an Ethics Committee approved informed consent form;

Exclusion Criteria:

• Significant renal, cardiovascular, hepatic, infectious or psychiatric disease;
• Significant brain injury with neurological deficits;
• Debilitation or dehydration;
• Addison's disease;
• Recent (within 1 week) or current use of anti-diuretics or other drugs that interacts with lithium, such as tricyclic antidepressants, nonsteroidal antiinflammatory drug and tetracyclines;
• A history of substance or alcohol abuse within past 1 year;
• A need for elective surgery involving preoperative or postoperative analgesics or anesthetics during the study period;
• Current pregnant or breast feeding, or female who has childbearing potential but is not willing to use an approved method of birth control;
• Participation in any drug study in the last three months;
• History of oral lithium intake for any reason; or
• any criteria, which in the opinion of the investigator, suggests that the subject would not be compliant with the study protocol.