Resident Editor: Monica Parks, M.D.

Faculty Editor: Vanja Douglas, M.D.

Background

• Classic Trigeminal Neuralgia (TN): no apparent cause other than secondary to vascular compression (80-90% of cases).
• Secondary TN: Caused by structural lesions other than vascular compression (schwannoma, cysts, meningioma or demyelination from multiple sclerosis (MS))
• Idiopathic TN: TN symptoms without MRI or electrophysiological testing abnormalities
• Estimated lifetime prevalence of 0.3%
• Annual incidence approximately 4.5/100,000; highest incidence occurs between the ages of 40-60 years
• Slight female to male predominance (1.5-1.7:1)
• Some rare familial forms do exist
• The incidence of TN in patients with MS is 1-2%

Signs and Symptoms

• Intense “lancinating,” sharp or stabbing pain, located in a territory of the trigeminal nerve
• Unilateral; symptoms may occur on either side, but not usually at the same time
• Pain lasts seconds to minutes; events may occur in clusters or be isolated
• Common triggers of TN pain: light touch, wind, drinking, chewing, brushing teeth, shaving, or applying makeup anywhere in the trigeminal nerve territory
• V2/V3 >>> V1
  • If pain is in V1 territory, have a higher suspicion for Zoster rather than TN
• Consider secondary TN if:
  • abnormal neuro/oral/ dental/ear exam
  • age <40
  • bilateral symptoms
  • dizziness/vertigo, hearing loss
  • numbness, pain lasting >2 min
  • pain outside of the trigeminal distribution
  • visual changes
• Variable course, with episodes lasting weeks to months with pain-free intervals lasting months to years. Recurrence is common (~70% have more than one cluster).

Evaluation

• The International Classification of Headache Disorders (ICHD-3) criteria:
  • At least 3 attacks of pain meeting the below criteria:
  • Occurring in the trigeminal distribution
  • At least 3 of the following characteristics:
    • Recurring paroxysmal attacks lasting seconds-2 minutes
    • Severe intensity
    • Shock-like, shooting, stabbing, sharp
    • At least three attacks precipitated by stimuli to the affected side (some may be spontaneous)
  • No clinically evident neurologic deficit
  • No alternative diagnosis

Testing

• Routine neuroimaging may identify a cause of TN in up to 15% of patients (but concern for selection bias in supporting studies)
• The American Academy of Neurology (AAN) rates routine neuroimaging as a Level C recommendation for TN (possibly effective)
• Consider imaging if any of the following: trigeminal nerve sensory loss, bilateral symptoms or is <40 years, optic neuritis, family h/o MS, poor treatment response
• Measuring trigeminal reflexes (e.g. blink reflex) in an electrophysiology lab could be considered to distinguish idiopathic from classic TN (Level B recommendation; probably effective); trigeminal evoked potentials are not recommended by the AAN.
• Routine labs are not recommended, though often required before starting meds as below.

Treatment

• Carbamazepine (CBZ): 4 clinical trials comparing CBZ to placebo (total n=147) found a clinical response rate of between 58-100%, compared to 0-40% with placebo
  • CBZ decreased both the frequency and intensity of TN pain; NNT= 2
  • Starting dose of CBZ is usually 100-200mg BID. This may be up-titrated by 200mg daily to achieve pain control, with a max daily dose of 1200mg. (split BID).
  • Some authors suggest that treatment with CBZ is useful as a diagnostic test for classical TN.
• Oxcarbazepine (OXC) was compared to CBZ in 2 RTCs (total n=178) and found that both decreased symptoms. Given the larger clinical familiarity, CBZ is still usually tried before OXC.
  • OXC is usually started at 300mg BID and increased by 300mg increments q3 days to a total dose of 1200-1800 mg daily
• Test HLA-B*1502 genotype in patients of Asian or South Asian ancestry before starting CBZ/OXC (high risk of Stephens-Johnson Syndrome)
• Other drugs have been studied, but insufficient evidence exists to recommend their use. These include baclofen (10-80mg daily), lamotrigine (400mg daily), pimodizine (4-12mg daily), gabapentin (300-1800mg daily), and tocainide (12mg daily).
• Botulinum toxin injections may have a role in medically refractory TN. The largest RCT to date (total n= 47) compared injections to placebo with a 68 vs 15% response rate.
• No evidence for combination therapy compared to monotherapy
• Symptomatic treatment for secondary TN is generally the same as for classic/idiopathic.

When to Refer

• Referral to surgery can be considered when symptoms are refractory to medical therapy.
  • Surgical options include: microvascular decompression, radiotherapy, thermocoagulation, and rhizotomy

References

Headache Classification Committee of the International Headache Society (IHS), “The International Classification of Headache Disorders, 3^rd edition.” Cephalalgia. 2013;33(9):629-808.  

Zakrzewska JM, Linskey ME. “Clinical Review: Trigeminal neuralgia.” BMJ. 2014;348:474. 

Gronseth, G. Cruccu, J. Alksne, et al, “Practice Parameter: The diagnostic evaluation and treatment of trigeminal neuralgia (an evidence-based review): Report of the Quality Standards Subcommittee of the American Academy of Neurology and the European Federation of Neurological Societies.” Neurology. 2008; 71;1183

Krafft RM, “Trigeminal Neuralgia.” Am Fam Physician. 2008 May 1;77(9):1291-1296. http://www.aafp.org/afp/2008/0501/p1291.html#afp20080501p1291-t2

Lambert M, “AAN and EFNS Guideline on Diagnosing and Treating Trigeminal Neuralgia.”Am Fam Physician. 2009 Jun 1;79(11):1001-1002. http://www.aafp.org/afp/2009/0601/p1001.html

Love, S., Coakham, B., “Trigeminal Neuralgia: Pathology and Pathogenesis.” Oxford University Press 2001.

Mueller, D., Obermann, M., Franziska Poitz, M., Hansen, N., Slomke, M., Dommes, P., Gizewski, E., Diener, H., Katsarava, Z., “Prevalence of trigeminal neuralgia and persistent idiopathic facial pain: A population-based study.” Cephalalgia. 2011; 31(15);1542–1548.

 Wu CJ, Lian YJ, Zheng YK, Zhang HF, Chen Y, Xie NC, Wang LJ. “Botulinum toxin type A for the treatment of trigeminal neuralgia: results from a randomized, double-blind, placebo-controlled trial.” Cephalalgia. 2012;32(6): 443-50.