What is the treatment for trigeminal neuralgia (TN)?

Treatment of Trigeminal Neuralgia

Carbamazepine is the first-line treatment for trigeminal neuralgia, with strong evidence supporting its efficacy (NNT of 1.7) and approximately 70% of patients showing partial or complete pain relief at therapeutic doses. 1

Medical Management Algorithm

First-Line Treatment

• Carbamazepine:

  • Target dose: 400-800 mg daily divided in 2-3 doses
  • Maximum dose: 1200 mg daily 1
  • Mechanism: Blocks post-tetanic potentiation and reduces polysynaptic responses 2
  • Monitor for side effects: drowsiness, dizziness, ataxia, hyponatremia, liver function abnormalities, blood count changes, and skin reactions 1

• Oxcarbazepine (alternative first-line):

  • Similar efficacy to carbamazepine with fewer side effects (30.3% vs 43.6%) 1
  • Particularly useful when carbamazepine is not tolerated

Second-Line and Adjunctive Treatments

• Gabapentin: 300-3600 mg/day (start at 100-200 mg/day in older adults) 1
• Pregabalin: 150-600 mg/day (start at 25-50 mg/day in older adults) 1
• Baclofen: Can be combined with carbamazepine for synergistic effects (NNT of 1.4) 1, 3
• Lamotrigine: Particularly effective as adjunctive therapy with carbamazepine (NNT of 2.1) 1, 3

Important Monitoring

• Regular blood counts, sodium levels, and liver function tests, especially during dose adjustments 1
• Screening electrocardiogram for patients older than 40 years, especially with cardiac history 1
• HLA-B*15:02 testing in at-risk populations before starting carbamazepine (to prevent severe skin reactions) 1, 4

Diagnostic Evaluation

• Contrast-enhanced MRI: Essential to rule out secondary causes (tumors, multiple sclerosis) and identify neurovascular compression 1
• MR angiography: To evaluate vascular compression 1

Surgical Management (when medical therapy fails)

1. Microvascular Decompression (MVD):

   • Preferred for younger patients with identifiable neurovascular compression
   • 70% of patients remain pain-free at 10 years
   • Preserves trigeminal nerve function
   • Risks: 0.2-0.4% mortality and 1-4% hearing loss 1

2. Stereotactic Radiosurgery (Gamma Knife):

   • More appropriate for elderly patients
   • 75% initial complete pain relief, 50% maintaining relief at 3 years
   • Pain relief typically occurs within three months
   • Most common complication: sensory disturbance 1

3. Radiofrequency Lesioning:

   • Appropriate when pain persists despite adequate medication trials
   • Consider when quality of life is significantly impacted 1

Clinical Pearls and Pitfalls

• Low-dose titration is crucial to avoid severe adverse effects, particularly rashes and Stevens-Johnson syndrome 4
• Combination therapy (e.g., carbamazepine with lamotrigine or baclofen) may allow for lower doses of individual medications while maintaining efficacy 1, 3
• Don't delay surgical consultation if medical management is inadequate or side effects are intolerable 1
• Absence seizures do not appear to be controlled by carbamazepine, so differentiate from trigeminal neuralgia 2
• Therapeutic blood levels of carbamazepine are between 4 and 12 mcg/mL 2
• Autoinduction of carbamazepine metabolism occurs after 3-5 weeks of fixed dosing, which may necessitate dose adjustments 2

Trigeminal neuralgia treatment should be initiated promptly with carbamazepine or oxcarbazepine, with careful monitoring for side effects. If medical management fails, surgical options should be considered based on patient age, comorbidities, and the presence of neurovascular compression.