What are the diagnosis and treatment options for trigeminal neuralgia?

Trigeminal Neuralgia: Diagnosis and Treatment

Diagnosis

Trigeminal neuralgia is diagnosed by history alone: sudden, unilateral, severe, brief (seconds to minutes) stabbing paroxysmal pain in one or more trigeminal nerve branches, triggered by innocuous stimuli like chewing or touching the face, with mandatory pain-free refractory periods between attacks. 1

Key Diagnostic Features

• Pain character: Electric shock-like, lancinating attacks lasting seconds to minutes—not continuous pain 1
• Triggers: Touch, chewing, speaking, brushing teeth, or cold air exposure 2
• Refractory periods: Mandatory pain-free intervals between attacks distinguish this from other facial pain syndromes 1
• Distribution: V2 (maxillary) and V3 (mandibular) branches most commonly affected 3

Critical Differential Diagnoses to Exclude

• Trigeminal autonomic cephalgias (SUNCT/SUNA): Present with autonomic features (tearing, conjunctival injection, rhinorrhea) and up to 200 attacks daily without refractory periods 1
• Postherpetic neuralgia: Continuous burning pain following herpes zoster eruption, not paroxysmal attacks 4
• Glossopharyngeal neuralgia: Pain in deep ear, back of tongue, or throat triggered by swallowing; may cause syncope 3
• Giant cell arteritis: Must be considered in patients over 50 with temporal region pain to prevent blindness 3
• Persistent idiopathic facial pain: Continuous, non-anatomical pain without paroxysmal attacks or characteristic triggers 3

Mandatory Imaging

• Obtain MRI with high-resolution thin-cut sequences through the trigeminal nerve in all suspected cases 1
• Use 3D heavily T2-weighted sequences combined with MRA to identify neurovascular compression (83-100% congruence with surgical findings) 1
• Pre- and post-contrast imaging excludes secondary causes: multiple sclerosis, tumors, or structural lesions 1
• Any sensory deficits in trigeminal distribution require urgent imaging 1

Treatment

First-Line Pharmacological Treatment

Carbamazepine is the gold standard first-line treatment for trigeminal neuralgia. 3, 5

• Starting dose: 100 mg twice daily (200 mg/day total) 5
• Titration: Increase by up to 200 mg/day in increments of 100 mg every 12 hours as needed for pain control 5
• Maintenance dose: 400-800 mg daily in most patients 5
• Maximum dose: 1200 mg/day 5
• Goal: Achieve freedom from pain, then attempt dose reduction every 3 months to minimum effective level 5

Oxcarbazepine is equally effective with fewer side effects and serves as an alternative first-line agent. 3, 4

Second-Line Pharmacological Options

When first-line agents fail or cause intolerable side effects:

• Lamotrigine: Supported by guideline evidence 3, 6
• Baclofen: Supported by guideline evidence 3, 6
• Gabapentin combined with ropivacaine: Demonstrated efficacy in randomized controlled trials 3, 4
• Pregabalin: Long-term cohort studies show efficacy 3, 4

Surgical Intervention

Obtain neurosurgical consultation early when medications become ineffective or intolerable. 3

Microvascular Decompression (MVD)

• Preferred surgical option: Only non-ablative procedure that preserves nerve integrity 3
• Indication: Patients with documented neurovascular compression on MRI without significant comorbidities 4
• Efficacy: 70% pain-free at 10 years 3
• Risks: 2-4% hearing loss, 0.4% mortality 3

Ablative Procedures

When MVD is contraindicated or fails:

• Peripheral level: Neurectomy, cryotherapy 3
• Gasserian ganglion level: Radiofrequency thermocoagulation, glycerol rhizotomy, balloon compression 3
• Posterior fossa level: Rhizotomy, Gamma Knife radiosurgery 3, 6
• Efficacy: 50% pain-free at 4 years 7
• Consequence: All ablative procedures cause varying degrees of sensory loss in the trigeminal distribution 3

Common Pitfalls to Avoid

• Do not use carbamazepine for trivial aches or pains—it is not a simple analgesic 5
• Do not diagnose trigeminal neuralgia if pain is continuous without paroxysmal attacks—this suggests alternative diagnoses like persistent idiopathic facial pain or postherpetic neuralgia 1, 4
• Do not miss giant cell arteritis in patients over 50—check ESR and C-reactive protein urgently 3
• Do not delay neurosurgical referral—early consultation improves outcomes when medical management fails 3, 7
• Recognize Type 2 trigeminal neuralgia (continuous pain between sharp attacks) may originate from central mechanisms and respond differently to treatment 1