What is the recommended physical exam and initial management for a patient presenting with symptoms of trigeminal neuralgia?

Physical Examination for Trigeminal Neuralgia

The physical examination in trigeminal neuralgia is typically normal between painful episodes, and the diagnosis is made primarily on clinical history alone. 1, 2, 3

Key Physical Examination Components

Sensory Testing

• Light touch testing is the most critical examination maneuver—gently touch the affected trigeminal distribution(s) to identify trigger zones and potentially provoke characteristic pain 1
• Look for allodynia (pain from normally non-painful stimuli) or other sensory changes, though these are rare in classic trigeminal neuralgia 1
• Absence of sensory deficits is typical; if present, this suggests secondary causes like tumors or multiple sclerosis 1, 3

Motor Function Assessment

• Test muscles of mastication (masseter, temporalis) for weakness—motor abnormalities suggest structural pathology affecting the trigeminal nerve 1
• Observe for facial spasms during intense pain episodes (tic douloureux) 3

Trigger Zone Identification

• Systematically test for trigger zones by light touch to face, particularly around nose, lips, and cheeks 3
• Document specific activities that provoke pain: talking, chewing, brushing teeth, cold wind exposure 1, 3

Critical Red Flags Requiring Further Investigation

• Any sensory loss or numbness—suggests secondary trigeminal neuralgia from tumor, multiple sclerosis, or other structural lesion 1, 4
• Bilateral symptoms—classic trigeminal neuralgia is unilateral 1, 3
• Continuous pain rather than paroxysmal attacks—consider alternative diagnoses 1
• Autonomic features (tearing, rhinorrhea, conjunctival injection)—suggests trigeminal autonomic cephalalgias like SUNCT/SUNA rather than trigeminal neuralgia 1, 5

Initial Management Algorithm

Immediate Diagnostic Workup

MRI with contrast is mandatory for all patients with suspected trigeminal neuralgia to rule out secondary causes and assess for neurovascular compression 1, 5, 3

• Order high-resolution MRI with gadolinium contrast including 3-D heavily T2-weighted sequences and MR angiography 5, 6
• Ensure imaging covers the entire trigeminal nerve course from brainstem to peripheral branches 6
• CT is useful only for evaluating skull base bony anatomy and foramina, not for primary diagnosis 1

First-Line Pharmacotherapy

Carbamazepine is the drug of choice and should be initiated immediately while awaiting imaging results 2, 3, 7, 8

• 75% of patients achieve initial symptom control with carbamazepine 3
• Oxcarbazepine is an alternative first-line option with potentially better tolerability 2, 8
• Start treatment before imaging is complete—do not delay pain relief 2

When to Refer for Neurosurgical Evaluation

• Refractory pain despite adequate medication trials 3, 8
• Intolerable medication side effects 3
• Patient preference for definitive treatment, particularly in younger patients 8
• Seek neurosurgical opinion early rather than waiting for complete medication failure 2

Common Pitfalls to Avoid

• Do not diagnose trigeminal neuralgia based on examination alone—history is paramount, and exam is typically normal 2, 3
• Do not order MRI head alone—this misses extracranial nerve pathology; order dedicated trigeminal nerve protocol 6
• Do not omit contrast—noncontrast MRI is inadequate for excluding secondary causes 6
• Do not confuse with dental pain—trigeminal neuralgia has characteristic brief, electric shock-like quality with trigger zones 1, 2
• Do not miss trigeminal autonomic cephalalgias—presence of autonomic features distinguishes SUNCT/SUNA from trigeminal neuralgia 1, 5