Test your medicine knowledge with the MKSAP challenge, in partnership with the American College of Physicians.

A 36-year-old woman is evaluated for a 1-week history of recurrent episodes of facial pain that are 1 to 3 seconds in duration and occur spontaneously dozens of times throughout the day. The pain is sharp, severe, and located in the right infraorbital area. During this same period, she has developed worsening bilateral lower extremity weakness and urinary incontinence. The patient has an 18-year history of relapsing-remitting multiple sclerosis treated with interferon beta-1a; she also takes baclofen to control spasticity. She has had no nausea, photophobia, phonophobia, nasal congestion, nasal drainage, or ocular/visual changes.

On physical examination, blood pressure is 100/64 mm Hg and pulse rate is 80/min. Moderate bilateral lower extremity weakness and hyperreflexia are noted. Sensory spinal cord level for pain and temperature is T6. Plantar responses are extensor bilaterally. Internuclear ophthalmoplegia is noted, but other findings from an examination of the cranial nerves are unremarkable.

Results of laboratory studies, including a comprehensive metabolic profile, a complete blood count, and urinalysis, are normal.

Which of the following is the most likely cause of the facial pain?

A. Chronic paroxysmal hemicrania
B. Herpes zoster
C. Primary stabbing headache
D. Trigeminal neuralgia

MKSAP Answer and Critique

The correct answer is D: Trigeminal neuralgia.

This patient has developed trigeminal neuralgia. Although more common among older patients, trigeminal neuralgia can be seen in young adults, particularly those with multiple sclerosis. Affected patients describe brief episodes of lancinating pain affecting either the second or third distribution of the trigeminal nerve (cranial nerve V₂ or V₃). The pain may occur spontaneously or be triggered by sensory stimulation of the face or mouth. The diagnosis is made clinically. Brain MRI may be indicated in patients with atypical presentations, including those developing symptoms in young adulthood. As many as 15% of patients with trigeminal neuralgia may have a structural explanation for their disease, such as cerebellopontine angle tumors in older patients or demyelinating disease in younger patients. Brain MRI is also indicated in the course of surgical evaluation, if appropriate. Glucocorticoids are typically ineffective. Carbamazepine is the drug of choice for initial management, with a greater than 50% response rate. Oxcarbazepine, a structural derivative of carbamazepine, is also effective and has fewer adverse effects and drug interactions but is a more expensive medication.

Chronic paroxysmal hemicrania is typically expressed along the first branch of the trigeminal nerve (cranial nerve V₁). Pain attacks are brief but generally last a mean of 15 minutes rather than seconds and may recur between 8 to 40 times daily. The diagnosis also requires concomitant ipsilateral autonomic findings, such as tearing, nasal congestion, or rhinorrhea, none of which this patient has.

The eruption of herpes zoster is preceded by a prodrome of constant pain or burning, commonly for up to several days. The patient’s intermittent sharp facial pain is most consistent with trigeminal neuralgia.

Primary stabbing headaches are brief paroxysms of pain lasting seconds, without associated autonomic features. The face is typically spared. This patient’s pain does not fit this description.

Key Point

• Trigeminal neuralgia typically results in brief episodes of lancinating pain affecting either the second or third distribution of the trigeminal nerve (cranial nerve V₂ or V₃); the pain can occur spontaneously or be triggered by sensory stimulation of the face or mouth.

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