The use of anticonvulsants in orofacial pain

Anticonvulsants are medications used primarily for prevention and treatment of seizures as well as for migraine headache prophylaxis. In more recent years, however, various anticonvulsants have seen extended use in the treatment of affective disorders and in the control of a variety of chronic pain conditions (Table I). Clinically, they have been shown to be beneficial in treating bursts of spontaneous pain often described as lightning or shooting in nature. Diabetic neuropathy, poststroke pain, postherpetic neuralgia, and phantom limb pain have all demonstrated a response to these agents.(1-8) Trigeminal neuralgia, atypical facial pain, complex regional pain syndrome, and atypical odontalgia are often encountered by the practitioner attempting to manage orofacial pain. These syndromes might also improve with anticonvulsant medications.(2-4, 9-13) Between 1978 and 1992, no new anticonvulsants were approved in the United States, limiting the choice of available drugs. In 1993, felbamate was marketed as a result of a federal program to develop new agents, but was plagued by serious bone marrow and hepatic toxicity. Since then, additional new anticonvulsants, such as gabapentin, lamotrigine, oxcarbazepine, tiagabine, and topiramate, have been added to the practitioner's armamentarium, whereas others are under development. The two newest drugs, zonisamide and levetiracetam, were approved in the spring of 2000, but clinical data regarding their effects on pain have yet to be published. Investigational medications include remacemide and vigabatrin.