What is the recommended workup and treatment for a patient presenting with symptoms of trigeminal neuralgia?

Trigeminal Neuralgia Workup

Diagnostic Approach

Diagnose trigeminal neuralgia based on clinical history alone: sudden, unilateral, severe, brief stabbing paroxysmal pain in one or more trigeminal nerve branches (typically V2/V3), triggered by innocuous stimuli like talking or light touch, with mandatory pain-free refractory periods between attacks lasting seconds to minutes. 1, 2

Key Clinical Features to Elicit

• Pain character: Electric shock-like, lancinating attacks lasting seconds to minutes—not continuous pain 1, 3
• Refractory periods: Mandatory pain-free intervals between attacks that distinguish this from other facial pain syndromes 3, 2
• Trigger zones: Small perioral or nasal areas where minimal stimulation precipitates attacks 2, 4
• Distribution: Most commonly affects maxillary (V2) and mandibular (V3) branches 2
• Unilateral presentation: Pain is strictly one-sided 1, 4

Physical Examination

• Neurological exam is typically normal between attacks in classical trigeminal neuralgia 4, 5
• Assess for motor weakness in muscles of mastication—rare finding that suggests secondary cause 2
• Identify trigger points by gentle palpation of perioral and nasal regions 2
• Look for sensory deficits in trigeminal distribution—their presence requires urgent imaging to rule out secondary causes 3

Mandatory Imaging

Obtain brain MRI with contrast using high-resolution thin-cut sequences through the trigeminal nerve in all suspected cases. 2, 6

• Use 3D heavily T2-weighted sequences combined with MRA to identify neurovascular compression (83-100% congruence with surgical findings) 2
• Pre- and post-contrast imaging identifies secondary causes: multiple sclerosis plaques, tumors, or other structural lesions 3, 2
• MRI distinguishes classical TN (neurovascular compression), secondary TN (MS, tumor), and idiopathic TN 4, 6

Critical Differential Diagnoses to Exclude

• Trigeminal autonomic cephalgias (SUNCT/SUNA): Up to 200 attacks daily with no refractory period, plus autonomic features (tearing, conjunctival injection, rhinorrhea) 1, 3, 2
• Giant cell arteritis: Consider urgently in patients over 50 with temporal region pain to prevent blindness 1, 2
• Post-herpetic neuralgia: Continuous burning pain at site of previous herpes zoster eruption, not paroxysmal attacks 1, 3
• Glossopharyngeal neuralgia: Deep ear/back of tongue pain triggered by swallowing, may cause syncope 3, 2
• Persistent idiopathic facial pain: Continuous non-anatomical pain without paroxysmal attacks or characteristic triggers 1, 3

Red Flags Requiring Alternative Diagnosis

• Continuous pain or ability to trigger attacks repeatedly without pain-free intervals warrants MRI to rule out secondary causes 3
• Presence of autonomic features indicates trigeminal autonomic cephalgias, not true trigeminal neuralgia 3
• Sensory deficits mandate urgent imaging 3

Treatment Algorithm

First-Line Pharmacotherapy

Start carbamazepine as the gold standard first-line treatment. 1, 2, 7

• Initial dose: 100 mg twice daily (200 mg/day) 7
• Titration: Increase by up to 200 mg/day in increments of 100 mg every 12 hours as needed 7
• Target dose: 400-800 mg daily for maintenance 7
• Maximum dose: Do not exceed 1200 mg/24 hours 7
• Expected response: 75% of patients achieve initial symptom control 4

Alternative first-line: Oxcarbazepine is equally effective with fewer side effects. 1, 2, 8

Second-Line Options

When carbamazepine/oxcarbazepine are ineffective or poorly tolerated 1, 2:

• Lamotrigine 1, 8, 6
• Baclofen 1, 8, 6
• Gabapentin (combined with ropivacaine shows efficacy) 1, 2
• Pregabalin 1, 8, 6

Surgical Referral Indications

Obtain neurosurgical consultation when pain control becomes suboptimal despite medication optimization or medication side effects become intolerable. 1, 2

Surgical Options Based on Patient Profile

For patients with documented neurovascular compression on MRI without significant comorbidities: Microvascular decompression (MVD) is the preferred procedure. 1, 2, 5

• 70% pain-free at 10 years 1, 2
• Risks: 2-4% hearing loss, 0.4% mortality 1, 2
• Preserves nerve integrity (non-ablative) 2, 5

For elderly patients or those with major comorbidities, consider ablative procedures: 1, 5

• Radiofrequency thermocoagulation 1, 5
• Glycerol rhizotomy 1
• Balloon compression 1
• Gamma Knife radiosurgery (pain relief typically within 3 months, complete relief initially in 75% but only 50% maintain at 3 years) 9, 1

Common Pitfalls to Avoid

• Do not diagnose trigeminal neuralgia if patient describes continuous pain—this suggests Type 2 TN, post-herpetic neuralgia, or atypical facial pain 3
• Do not skip MRI imaging—it is mandatory to exclude secondary causes and determine surgical candidacy 2, 4, 6
• Do not use carbamazepine as a simple analgesic for trivial aches or pains 7
• Attempt dose reduction every 3 months to find minimum effective level 7