A 52-year-old man complains of episodes of severe unilateral, stabbing facial pain that is intermittent for several hours, and then disappears for several days. The pain is described as "electric shock-like" and only lasts a few seconds. Physical examination of the face and mouth is entirely normal. Which of the following treatments is most effective for this condition?

This patient has trigeminal neuralgia. Carbamazepine (an anticonvulsant drug) is given in doses varying from 600 to 1200 mg/day. Phenytoin has also been used. The two drugs can also be used in combination. Operative procedures include alcohol injection of the nerve or ganglion, partial section of the nerve in the middle or posterior fossa, decompression of the root, and medullary tractotomy. Radiofrequency surgery can destroy pain fibers but spare motor fibers.