The current study is a phase I open-label clinical trial to examine plasma levels after oral lithium treatments in 20 subjects with chronic spinal cord injury. The subjects will receive standard doses of oral lithium used in treatment of manic depression. The goal of the trial is to show feasibility and safety of maintaining plasma levels of 0.6 mmol/L to 1.2 mmol/L for six weeks in subjects with chronic spinal cord injury.