Anticonvulsant drugs have been used in the management of pain since the 1960s. The clinical impression is that they are useful for chronic neuropathic pain, especially when the pain is stabbing or burning.
Anticonvulsants work by calming hyperactivity in the brain in various ways. For this reason, some of these drugs are used to treat epilepsy, prevent migraines, and treat other brain disorders. They are often prescribed for people who have rapid cycling -- four or more episodes of mania and depression in a year.