New Guideline on Diagnosis and Treatment of Trigeminal Neuralgia

Susan Jeffrey

August 21, 2008

August 21, 2008 — The American Academy of Neurology has published a new practice parameter on the treatment of trigeminal neuralgia (TN). The guideline, developed as a joint venture with the European Federation of Neurological Societies, recommends carbamazepine as first-line treatment, with oxcarbazepine as a possible alternative, but suggests surgery be considered for refractory cases.

"There are very few drugs with strong evidence of effectiveness in treating trigeminal neuralgia," said lead author Gary Gronseth, MD, from the University of Kansas, in Kansas City, in a statement from the American Academy of Neurology. "If people fail to respond to these drugs, physicians should not be reluctant to consider referring the patient for surgery. Often surgery is considered a last resort, and patients suffer while the well-intentioned physician tries other medications with limited effectiveness."

The guideline also recommends that physicians consider sending all patients with trigeminal neuralgia for magnetic resonance imaging (MRI) or trigeminal reflex testing, since up to 15% of patients have an underlying structural cause such as a tumor.

The guidelines are published online August 20 before publication in the October 7 issue of Neurology.

Common Cause of Facial Pain

TN is a common cause of facial pain, the authors write, with an annual incidence of 4 to 5 in 100,000. The International Association for the Study of Pain defines TN as sudden, usually unilateral, severe, brief, stabbing, recurrent episodes of pain in the distribution of the trigeminal nerve.

For this practice parameter, a panel of experts reviewed the literature to make recommendations on the diagnosis and treatment of this condition. Their recommendations include:

  • For patients with TN, routine imaging should be done to identify those patients with symptomatic TN (STN) — that is, TN arising from some other structural abnormality (level C).

  • The presence of trigeminal sensory deficits should be considered useful to identify those with STN, they note, but because of poor specificity, the absence of these features cannot rule out STN (level B).

  • Measuring trigeminal reflexes in a qualified electrophysiologic laboratory should be considered useful for distinguishing STN from classic TN (CTN), a designation that includes all cases without an established etiology (level B).

  • Younger age at onset, involvement of the first division of the trigeminal nerve, unresponsiveness to treatment, and abnormal trigeminal-evoked potentials should be disregarded in identifying those with STN (level B).

  • To control pain in TN, carbamazepine should be offered (level A), and oxcarbazepine should be considered (level B). Although the evidence for carbamazepine is stronger, they note, oxcarbazepine may pose fewer safety concerns. Baclofen or lamotrigine may be considered (level C). Topical ophthalmic anesthesia should not be considered (level B).

  • For patients refractory to medical therapy, early surgical therapy may be considered (level C), they note. "Some TN experts believe patients with TN failing to respond to first-line therapy are unlikely to respond to alternative medications and suggest early surgical referral," the authors write. Percutaneous procedures on the Gasserian ganglion, gamma knife, and microvascular decompression may be considered (level C).

Future Research

Finally, the authors outline several areas where more information is needed as a focus for future research. Among these are the need for efficacy of new drugs and in particular surgical interventions, to be tested in well-designed randomized controlled trials, they note. "Although double-blinded studies are impractical for surgical trials, randomized treatment allocation and independent outcome assessment would go a long way to establish the efficacy of the surgical techniques."

Other questions, including the "crucial" question of the optimal timing of surgical referral, the authors conclude, "could be answered by a large prospective cohort survey of patients with TN treated in a standardized, stepwise fashion."

Dr. Gronseth reports that he has received speaker honoraria from Boehringer Ingelheim, Pfizer, and GlaxoSmithKline and has been compensated by Ortho-McNeil for serving on a safety monitoring committee. Disclosures for coauthors appear in the paper.

Neurology. Published online August 20, 2008.

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