How is trigeminal neuralgia diagnosed and treated?

Diagnosis and Treatment of Trigeminal Neuralgia

Trigeminal neuralgia is diagnosed primarily through clinical history of characteristic sudden, unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the trigeminal nerve, with MRI serving as a supportive rather than diagnostic tool to identify potential causes and guide treatment decisions. 1

Diagnostic Approach

Clinical Diagnosis

• Based on characteristic pain pattern:
  • Sudden, unilateral, severe, brief, stabbing pain
  • Occurs within distribution of trigeminal nerve branches (ophthalmic, maxillary, or mandibular)
  • Paroxysmal attacks lasting seconds to minutes
  • Up to 200 attacks daily with no refractory period between attacks
  • Pain triggered by innocuous stimuli (light touch, talking, eating)
  • Pain-free intervals between attacks

Imaging Studies

• MRI with high-resolution sequences is essential but supportive rather than diagnostic 1
  • 3D heavily T2-weighted sequences and MRA to visualize potential neurovascular compression
  • Congruence rates between imaging and intraoperative findings range from 83-100%
  • Both false-positive and false-negative results occur
  • Pre- and post-contrast imaging recommended to identify and characterize lesions
  • Thin-cut high-resolution techniques through the course of trigeminal nerve

Differential Diagnosis

• Must distinguish from:
  • Dental pain (toothache)
  • Trigeminal autonomic cephalalgias
  • Glossopharyngeal neuralgia (pain behind ear, tonsils, neck) 2
  • Post-traumatic or postherpetic pain
  • Other facial pain syndromes

Treatment Algorithm

First-Line Pharmacological Treatment

• Carbamazepine is the first-line medication with strongest evidence 1, 3

  • Initial dose: 100 mg twice daily
  • Gradually increase by up to 200 mg/day using increments of 100 mg every 12 hours
  • Maintenance: 400-800 mg daily (range 200-1200 mg)
  • Maximum dose: 1200 mg daily
  • Attempt dose reduction every 3 months

• Oxcarbazepine is equally effective with fewer side effects 1, 2

Second-Line Pharmacological Options

• Lamotrigine (when first-line fails or is not tolerated) 1, 4
• Baclofen (limited evidence but may be effective) 1
• Gabapentin or pregabalin (as adjunctive therapy) 4

Surgical Management

• Early neurosurgical consultation recommended when medications fail or cause intolerable side effects 1, 2

• Non-ablative procedure:

  • Microvascular decompression (MVD)
    • 70% chance of being pain-free at 10 years
    • 0.4% mortality risk
    • 2-4% risk of hearing loss

• Ablative procedures (when MVD contraindicated):

  • Radiofrequency thermocoagulation
  • Glycerol rhizotomy
  • Balloon compression
  • Gamma Knife radiosurgery
  • All result in varying degrees of sensory loss with 50% chance of being pain-free for 4 years

Clinical Pearls and Pitfalls

• Pitfall: Relying solely on imaging for diagnosis - MRI is supportive rather than diagnostic and should be interpreted in context of symptoms 1

• Pitfall: Delaying neurosurgical consultation - obtain early when medications fail 1

• Pitfall: Missing secondary causes - always perform MRI to rule out tumors, multiple sclerosis, or other structural lesions 5, 6

• Pearl: Trigeminal nerve measurements on MRI may have prognostic value - nerve is typically smaller on the symptomatic side 1

• Pearl: Attempt medication reduction every 3 months to find minimum effective dose or potentially discontinue 3

• Pearl: Quality of life is significantly improved with successful surgical intervention 5