What is the recommended workup and treatment approach for an older adult patient, possibly over 50, with symptoms of trigeminal neuralgia, considering potential underlying conditions such as multiple sclerosis, stroke, or facial trauma?

Trigeminal Neuralgia Workup

Diagnostic Approach

Diagnose trigeminal neuralgia by clinical history alone: sudden, unilateral, severe, brief stabbing paroxysmal pain in trigeminal nerve distribution, triggered by innocuous stimuli (touching face, chewing, talking), with mandatory pain-free refractory periods between attacks lasting seconds to minutes. 1

Key Clinical Features to Elicit

• Pain character: Electric shock-like, lancinating attacks lasting seconds to minutes—not continuous pain 2, 1
• Distribution: Most commonly affects V2 (maxillary) and V3 (mandibular) branches 1
• Trigger zones: Gentle palpation of perioral and nasal regions may reproduce pain 1
• Refractory periods: Mandatory pain-free intervals between attacks distinguish this from other facial pain syndromes 2, 1

Critical Red Flags Requiring Urgent Evaluation

• Age over 50 with temporal region pain: Consider giant cell arteritis—check ESR and C-reactive protein urgently to prevent blindness 3, 1
• Sensory deficits in trigeminal distribution: Requires urgent imaging to rule out secondary causes 2
• Motor weakness in muscles of mastication: Rare finding suggesting secondary cause 1
• Continuous pain without refractory periods: Prompts MRI evaluation for multiple sclerosis, tumors, or structural lesions 2, 1

Imaging Protocol

Obtain MRI with high-resolution thin-cut sequences through the trigeminal nerve in all suspected cases. 1

• Sequences required: 3D heavily T2-weighted sequences combined with MRA to characterize neurovascular compression (83-100% congruence with surgical findings) 1
• Include pre- and post-contrast imaging: Best opportunity to identify secondary causes such as tumors or multiple sclerosis plaques 1
• Pituitary fossa views: Add if trigeminal autonomic cephalgias (SUNCT/SUNA) suspected 2

Secondary Causes to Exclude

• Multiple sclerosis: Look for demyelinating plaques in brainstem or trigeminal pathway 2, 1
• Tumors: Contrast enhancement identifies mass lesions 1
• Post-traumatic injury: History of dental procedures, facial trauma, or surgery within 3-6 months 2
• Post-herpetic neuralgia: Previous herpes zoster eruption in trigeminal distribution 2

Differential Diagnoses to Exclude

Trigeminal Autonomic Cephalgias (SUNCT/SUNA)

• Distinguishing features: Prominent autonomic symptoms (tearing, conjunctival injection, rhinorrhea, nasal blockage, facial redness, ear fullness) with up to 200 attacks daily and no refractory period 3, 2, 1
• Pain distribution: Mainly first and second trigeminal divisions 2

Glossopharyngeal Neuralgia

• Pain location: Deep ear and/or back of tongue, tonsils, neck—not V2/V3 distribution 3, 2
• Triggers: Swallowing, coughing, or touching the ear 2
• Associated feature: May cause syncope due to vagus nerve proximity 3, 2

Post-Stroke Pain

• Pain character: Continuous ipsilateral aching or burning pain with dysesthesia—not lancinating quality 2

Persistent Idiopathic Facial Pain

• Presentation: Continuous, non-anatomical pain without paroxysmal attacks or characteristic triggers 2

Treatment Algorithm

First-Line Medical Management

Start carbamazepine as the gold standard first-line treatment. 1, 4

• Initial dose: 100 mg twice daily (200 mg/day) 4
• Titration: Increase by up to 200 mg/day in increments of 100 mg every 12 hours as needed to achieve freedom from pain 4
• Maximum dose: 1200 mg/24 hours 4
• Maintenance: Control of pain maintained in most patients with 400-800 mg daily 4

Alternative first-line: Oxcarbazepine is equally effective with fewer side effects 1, 5

Second-Line Options

If carbamazepine/oxcarbazepine ineffective or not tolerated 1:

• Lamotrigine 1, 5
• Baclofen 1, 5
• Gabapentin combined with ropivacaine 1
• Pregabalin 1, 5

Surgical Intervention

Obtain neurosurgical consultation early when medications become ineffective or intolerable. 1

Microvascular Decompression (MVD)

• Indication: Preferred surgical option for patients with documented neurovascular compression on MRI without significant comorbidities 1
• Efficacy: 70% pain-free at 10 years 3, 1
• Risks: 2-4% hearing loss, 0.4% mortality 3, 1
• Mechanism: Identifies and removes vascular compression while preserving nerve integrity 3

Alternative Surgical Options

For patients with multiple sclerosis or poor MVD candidates 6:

• Percutaneous trigeminal rhizotomy (radiofrequency thermocoagulation, glycerol rhizotomy, balloon compression) 3
• Stereotactic radiosurgery (Gamma Knife) 3
• Note: All ablative procedures destroy sensory fibers to varying degrees, resulting in sensory loss 3

Common Pitfalls

• Continuous pain: If patient describes continuous pain or ability to trigger attacks repeatedly without pain-free intervals, consider alternative diagnoses and obtain MRI to rule out secondary causes 2
• Type 2 trigeminal neuralgia: Presents with prolonged continuous pain between sharp shooting attacks, may originate from more central mechanisms rather than peripheral neurovascular compression 2
• Reassessment: At least once every 3 months throughout treatment, attempt to reduce medication dose to minimum effective level or discontinue 4