Middle-Aged Man With Recurring Facial Pain

A 49-year-old man presents with recurring facial pain of 6 months' duration. The pain initially occurred several times per week; it now occurs as often as several times per day. The paroxysmal pain is intense and incapacitating but abates within several minutes. It occurs in the right maxillary region and lower jaw and is sharp and lancinating. Hard chewing and teeth cleaning are the usual precipitating events. Between episodes, the patient is asymptomatic, without numbness or deficit in the affected region.

A thorough review of systems reveals no aura, transient neurologic deficit, or other neurologic symptoms. There is no history of trauma to the region or of any kind of head injury. He has seen a dentist, but the dentist could find no pathology to explain his symptoms.

HISTORY

The patient's health is excellent. He smokes 1 pack of cigarettes every 2 days and drinks alcohol on social occasions. He has no drug allergies. He takes NSAIDs as needed for minor arthritic symptoms.

PHYSICAL EXAMINATION

Vital signs are normal. There is no tenderness to percussion in the temporal or maxillary region or in the lower jaw. Examination of the head, eyes, ears, nose, and throat reveals no abnormalities. There are no carotid bruits. Chest is clear and heart is normal. A neurologic examination, including evaluation of all cranial nerves, shows no deficits.

LABORATORY AND IMAGING RESULTS

Results of a screening laboratory battery, including a biochemistry profile and hemogram, are all normal. Radiographs of the sinuses and teeth show no abscess, mass, or infection.

Which of the following is the most appropriate next step?
A. Order an MRI scan with gadolinium.
B. Initiate therapy with valacyclovir.
C. Obtain an erythrocyte sedimentation rate (ESR) and initiate therapy with prednisone, 60 mg/d.
D. Start a propranolol regimen.

CORRECT ANSWER: A

Severe chronic facial pain has a broad differential that includes a variety of dental disorders (fractured tooth, caries, root abscess); trauma and fracture; vascular disorders, such as migraine and temporal arteritis; and neurologic disorders. Those neurologic disorders capable of causing chronic facial area pain include facial postherpetic neuralgia, acoustic neuroma, multiple sclerosis (MS), and primary trigeminal neuralgia (still frequently referred to as tic douloureux).

Diagnosis of primary trigeminal neuralgia. This disorder is the most commonly seen cause of chronic facial pain in men in the fifth and sixth decades of life and has typical clinical characteristics. The pain involves one or more branches of the trigeminal nerve (maxillary, mandibular, ophthalmic) and usually has the following characteristics:

• Is frequently neuropathic in nature--sudden, intense, stabbing, lancinating, or burning.
• Occurs in paroxysms.
• Has triggering events and trigger zones, such as hard chewing and tooth brushing.
• Has no associated neurologic deficits.
• Leaves the patient totally symptom-free between paroxysms.¹

   

The last 2 characteristics are particularly important.

In most patients, primary trigeminal neuralgia is diagnosed on the basis of the history and physical examination. When there is any doubt, radiologic studies, such as jaw/sinus films and an MRI scan are ordered. An MRI scan with gadolinium is usually performed because this can rule out MS and acoustic neuroma, the most common causes of secondary trigeminal neuralgia. In fact, MS is the most common cause of secondary trigeminal neuralgia, and exclusion of that entity is the most pertinent reason for ordering an MRI scan.^1,2

This patient meets essentially all of the clinical criteria for trigeminal neuralgia. His symptoms are paroxysmal and neuropathic, involve distributions of the trigeminal nerve, and leave him symptom-free between attacks. He has no neurologic deficits either during or after an attack. However, MRI with gadolinium to exclude secondary causes (choice A) would help confirm the diagnosis and is the best option for this patient.

Advances in the treatment of primary trigeminal neuralgia. In addition to aiding in diagnosis, MRI technology has elucidated the likely pathogenesis of primary trigeminal neuralgia. Increasing evidence indicates that demyelination of the nerve root as a result of its compression by overlying blood vessels is the cause in most instances. This discovery has therapeutic implications for patients in whom medical treatment fails.

The medication of choice is carbamazepine, which is effective in 70% of patients.^1,3 Other agents, such as gabapentin and phenytoin, are also effective. However, breakthrough of symptoms is very common after initial control.

Most patients eventually require surgery. The procedures range from microvascular decompression to percutaneous rhizotomy. Specific neurosurgical factors, the difficulty of the proposed surgery, patient age, and radiologic findings determine which procedure is used. Surgery relieves symptoms in 70% to 80% of patients.³

Other causes of neuropathic facial pain. Herpes zoster, or shingles, is an extremely common cause of facial pain, and the course of this infection may be shortened by prompt antiviral therapy (choice B). Shingles begins as neuropathic pain in the infected dermatome but almost always manifests the typical maculopapular then vesicular eruption along that dermatome within 1 to 5 days of pain onset. In the subacute course of this patient's pain, more than enough time has elapsed for the rash to develop; its absence essentially excludes herpes zoster.⁴

Giant cell arteritis is a common cause of headache and facial pain in elderly patients. Measurement of the ESR can help with diagnosis, and corticosteroids are the standard treatment (choice C). However, this patient is younger than 50 years and lacks the associated pain and stiffness in the neck, shoulders, and torso that are the keystones of the clinical diagnosis of giant cell arteritis. Thus, this condition is very unlikely here.⁵

Migraine, for which propranolol (choice D) is a commonly used first-line prophylactic therapy, can produce facial pain. However, nothing in this patient's history suggests aura, and his symptoms are localized to the trigeminal nerve. In addition, migraine has a female:male prevalence ratio of 3:1, which makes another diagnosis far more likely.⁶

Outcome of this case. A thorough neurologic examination revealed no neurologic deficit. The patient's ESR was 18 mm/h (which is within normal limits). MRI with gadolinium showed no white matter lesions characteristic of MS but did show linear enhancement crossing the fifth cranial nerve, a finding consistent with a crossing blood vessel. Trigeminal neuralgia was diagnosed, and therapy with carbamazepine was started. At 3 months, pain control remains good.