Trigeminal Neuralgia

Background

• Trigeminal neuralgia is characterized by recurrent brief episodes of severe, sharp, unilateral pain in the distribution of 1 or more branches of the trigeminal nerve.
• Trigeminal neuralgia is usually caused by neurovascular compression, often involving the superior cerebellar artery.
• It is sometimes secondary to other conditions such as multiple sclerosis, compression by a tumor, connective tissue disease, or arteriovenous malformation.

Evaluation

• Diagnosis is made clinically:
  • Classic history is a brief (a few seconds up to 2 minutes), strong, sharp, unilateral shooting pain in 1 or more branches of cranial nerve V (trigeminal nerve).
  • The quality of pain is sharp, stabbing, shooting, electric-like, and the pain can be severe enough to cause the patient to wince resulting in a "tic"-like appearance.
  • Pain can be triggered by mechanical stimuli over the trigeminal nerve distribution, often with a specific trigger point.
  • There is often a refractory period after an episode, during which pain cannot be triggered.
  • The pain does not go beyond the distribution of cranial nerve V and there are no other neurologic deficits (unless it is due to a secondary cause affecting the trigeminal nerve).
• Perform magnetic resonance imaging (MRI) to assess for secondary causes of trigeminal neuralgia (Strong recommendation). Combining several imaging modalities, such as 3D time-of-flight angiography, T1-weighted gadolinium imaging, and T2-weighted imaging appears to improve performance for detecting neurovascular contact.
• If MRI is contraindicated or unavailable, consider electrophysiologic measurement of trigeminal reflexes (includes measurement of blink reflex) to help distinguish primary (idiopathic or classical) trigeminal neuralgia from secondary trigeminal neuralgia (Weak recommendation).

Management

• Treat with carbamazepine or oxcarbazepine to reduce the number of episodes (Strong recommendation).
  • carbamazepine 200-1,200 mg/day
  • oxcarbazepine 600-1,800 mg/day
• If carbamazepine and oxcarbazepine are ineffective or not tolerated, consider additional medications as monotherapy or add-on therapies such as:
  • baclofen 40-80 mg/day
  • gabapentin up to 3,600 mg/day
  • lamotrigine 400 mg/day
  • pregabalin up to 600 mg/day
• Consider alternative options for add-on medical management, but note that evidence supporting efficacy is weak. Options include:
  • botulinum toxin type A injected into painful area (Weak recommendation)
  • pimozide 4-12 mg/day
  • topical or local anesthetics such as ropivacaine or lidocaine
• Consider lidocaine IV, fosphenytoin IV, or phenytoin IV for management of acute exacerbations.
• Do not use topical ophthalmic anesthesia (Strong recommendation).
• Consider early surgery for patients with trigeminal neuralgia refractory to medical therapy (Weak recommendation).
• Use microvascular decompression instead of Gamma Knife radiosurgery, and consider over other neuroablative percutaneous procedures, if a neurovascular compression is identified.