What is the initial approach and treatment for a patient presenting with Trigeminal Autonomic Cephalgia (TAC)?

Trigeminal Autonomic Cephalgia: Initial Approach and Treatment

For a patient presenting with suspected trigeminal autonomic cephalgia, immediately establish the specific TAC subtype by documenting attack duration and frequency, then initiate subtype-specific acute and preventive therapy while ordering brain MRI to exclude secondary causes.

Diagnostic Differentiation: Critical First Step

The TACs must be distinguished from trigeminal neuralgia based on the presence of ipsilateral cranial autonomic features (conjunctival injection, tearing, rhinorrhea, nasal congestion, eyelid edema, facial sweating) accompanying the pain 1, 2. Classical trigeminal neuralgia lacks these autonomic features and presents with paroxysmal attacks lasting only seconds to minutes with mandatory refractory periods 1.

Key Clinical Features to Document

• Pain location: Strictly unilateral, in the distribution of the first trigeminal branch (periorbital/temporal region) 3, 4
• Pain quality: Moderate to severe intensity 4
• Autonomic symptoms: Must be present and ipsilateral to pain 2, 3
• Attack duration and frequency: This determines the specific TAC subtype 3, 4

Subtype Classification by Attack Pattern

Cluster Headache

• Attack duration: 15-180 minutes 2
• Attack frequency: 1-8 attacks per day 2
• Most common TAC subtype 5

Paroxysmal Hemicrania

• Attack duration: 2-30 minutes 2
• Attack frequency: More than 5 attacks per day (often >10) 2
• Pathognomonic feature: Absolute response to indomethacin 2, 6

SUNCT/SUNA

• Attack duration: Seconds to several minutes 1, 2
• Attack frequency: Up to 200 attacks daily with no refractory period 1
• Distinguishing feature: Extremely brief attacks with prominent tearing and conjunctival injection 1, 2

Immediate Diagnostic Workup

Obtain brain MRI with contrast in all TAC patients to exclude secondary causes including tumors, vascular malformations, pituitary lesions, and inflammatory conditions 3, 4. The ACR recommends MRI as the preferred modality for investigating trigeminal nerve pathology, with 3D heavily T2-weighted sequences and MR angiography to evaluate vascular anatomy 7.

Acute Treatment by Subtype

Cluster Headache: First-Line Acute Therapy

• 100% oxygen inhalation: 12-15 L/min via non-rebreather mask for 15-20 minutes 2, 6
• Sumatriptan 6 mg subcutaneous: Most effective acute treatment 2, 6
• Alternative: Sumatriptan 20 mg nasal spray or zolmitriptan 5 mg nasal spray as second choice 2

Paroxysmal Hemicrania: Diagnostic and Therapeutic

• Indomethacin 75-150 mg/day: Absolute response confirms diagnosis 2, 6
• Start with 25 mg three times daily and titrate up 2

SUNCT/SUNA: Acute Management

• Intravenous lidocaine 1-4 mg/kg/hour: Short course during severe exacerbations 2, 6
• Acute abortive therapy is generally ineffective due to attack brevity 2

Preventive Treatment Strategies

Cluster Headache Prevention

First-line preventive: Verapamil at minimum 240 mg/day, often requiring 360-480 mg/day for efficacy 2, 6. Monitor ECG for PR interval prolongation and heart block 6.

Bridge therapy (while waiting for preventive to take effect):

• Prednisone 60-100 mg/day for 5 days, then taper over 7-21 days 2, 6
• Alternative: Methylprednisolone 250-500 mg/day IV for 5 days 2

Second-line preventives:

• Lithium carbonate 800-1600 mg/day (monitor levels, aim 0.6-1.2 mEq/L) 2, 6
• Topiramate 100-200 mg/day 2, 6
• Methylergonovine 0.4-1.2 mg/day 2
• Melatonin 10 mg at bedtime 6

SUNCT/SUNA Prevention

• Lamotrigine 100-300 mg/day: Drug of choice 2, 6
• Alternatives: Gabapentin 800-2700 mg/day, topiramate 50-300 mg/day, carbamazepine 200-1600 mg/day 2

Paroxysmal Hemicrania Prevention

• Indomethacin 75-150 mg/day: Only effective preventive, serves as diagnostic criterion 2

Chronic Refractory Cases

For chronic cluster headache unresponsive to all medical therapies 6:

• Occipital nerve stimulation: Consider after medication failure 6
• Deep brain stimulation of posterior hypothalamus: Highly successful in specialized centers 6
• Surgical options: Ganglyogliolysis of trigeminal nerve branches at root entry zone 6

For chronic cluster specifically, galcanezumab (CGRP monoclonal antibody) showed efficacy at 12 months in large case series despite negative 3-month randomized trial results 5.

Critical Safety Considerations

Sumatriptan contraindications 8:

• Uncontrolled hypertension
• Coronary artery disease or risk factors
• Cerebrovascular disease
• Peripheral vascular disease
• Concurrent MAO-A inhibitor use

Monitor for rare but serious complications including coronary vasospasm, myocardial infarction, and cerebrovascular events, particularly within 1 hour of administration 8.

Common Pitfalls to Avoid

• Misdiagnosing as trigeminal neuralgia: TACs have autonomic features and longer attack duration than classical trigeminal neuralgia 1, 9
• Failing to obtain MRI: Secondary causes must be excluded in all TAC patients 3, 4
• Inadequate verapamil dosing: Most patients require >240 mg/day for cluster prevention 2, 6
• Not using bridge therapy: Patients suffer unnecessarily while waiting weeks for preventives to work 6
• Treating paroxysmal hemicrania without indomethacin trial: Absolute response to indomethacin is pathognomonic 2