SCI pain is typically a mixture of nociceptive pain, which is caused by activation of primary afferents' receptors, and neuropathic pain, which is caused by damage to the nervous system. Neuropathic pain of SCI is most frequently treated by anticonvulsant agents. There is good evidence from randomized control trials for some degree of effectiveness of gabapentin and pregabalin, with weaker evidence for valproic acid. Tricyclic antidepressants are also used to control SCI pain, but the supporting evidence is not as strong. Thus amitriptyline has proved somewhat effective when the patient is depressed, but trazodone was reported not to reduce post-SCI neuropathic pain more than placebo. Traditional analgesics are also useful. Morphine can provide effective relief of neuropathic pain due to SCI, and can be combined with the alpha-2 agonist clonidine for this purpose. Subarachnoid or epidural lidocaine has been used to obtain short-term relief. For the musculoskeletal pain in SCI, which nociceptive, antispasticity agents are frequently used; intrathecal baclofen, for example, can be fairly effective. Despite this considerable range of choices, pharmacological treatment for the pain of SCI remains inadequate. Low effectiveness, tolerance, side effects or difficulties with prolonged local administration (e.g., subdural) are among problems encountered.