A 38-year-old woman presents to your office because of sudden episodes of severe, right-sided facial pain. She describes the pain as "a knife stabbing my face." The pain lasts several seconds and is usually instigated by a meal or teeth brushing. There is no nausea or vomiting. She denies any visual changes. Her past medical history is significant for hyperlipidemia. She drinks alcohol socially and does not use tobacco. She has no family history of facial pain. Her vital signs are within normal limits, and physical examination shows no rash. Which of the following is the best initial treatment for this patient?
This case presents a classic picture of trigeminal neuralgia (tic douloureux). This condition presents with episodes of sudden and severe pain in the distribution of CN V (particularly V2 and V3). The pain is described as "stabbing" or like an "electrical shock"; it is usually unilateral, and does not last more than few seconds; but occurs repeatedly. Pain is triggered by any stimulus to CN V, for example chewing, teeth brushing, shaving or washing an affected area of the face, swallowing, or exposure to hot or cold temperatures. These painful episodes may occur for several months. In the majority of cases, trigeminal neuralgia is not caused by any structural abnormality and its pathogenesis remains unclear.
Carbamazepine is the drug of choice for the treatment of trigeminal neuralgia. It is effective in pain reduction in up to 80% of patients. Like phenytoin, it inhibits neuronal high-frequency firing by reducing the ability of sodium channels to recover from inactivation. Carbamazepine can cause aplastic anemia, so CBC should be monitored regularly. Carbamazepine is a P450 inducer that increases the metabolism of many other medications, thereby decreasing their effectiveness.
(Choices A and G) Baclofen and valproic acid can be used for trigeminal neuralgia, but are not first-line choices.
(Choice B) Haloperidol is a neuroleptic medication used for the treatment of schizophrenia, acute psychoses, acute mania, and Tourette syndrome. It is not indicated in trigeminal neuralgia.
(Choice E) Propranolol has various uses, including migraine prophylaxis and the reduction of portal venous pressure to prevent variceal bleed. It is not used for trigeminal neuralgia.
(Choice F) Phenobarbital is effective for the management of generalized tonic-clonic seizures. It is not used for trigeminal neuralgia.
Educational objective:
Trigeminal neuralgia presents with brief episodes of sudden and severe "electric shock-like" or "stabbing" pain in the distribution of CN V (particularly V2 and V3). Carbamazepine is the drug of choice.