What is the most likely diagnosis and recommended management for a patient with a severe (9/10) left‑sided headache accompanied by aura and daily rhinorrhea for two weeks?

Likely Diagnosis: Trigeminal Autonomic Cephalalgia (Cluster Headache) or Chronic Migraine with Autonomic Features

This presentation most strongly suggests a trigeminal autonomic cephalalgia—specifically cluster headache—rather than typical migraine, based on the daily occurrence, strictly unilateral location, severe intensity (9/10), and prominent autonomic symptom (rhinorrhea). 1

Key Diagnostic Features Supporting Cluster Headache

• Daily attacks for 2 weeks indicate an active cluster period, which typically lasts weeks to months with daily or multiple-daily attacks. 1
• Strictly left-sided headache is characteristic of trigeminal autonomic cephalalgias; migraine can be unilateral but often alternates sides or becomes bilateral. 1
• Ipsilateral rhinorrhea is a cranial autonomic symptom that defines trigeminal autonomic cephalalgias and is uncommon in typical migraine without aura. 1
• Severity of 9/10 is consistent with cluster headache, which produces excruciating pain described as the most severe pain humans experience. 2
• Presence of aura is atypical for cluster headache but does not exclude it; approximately 15–30% of migraine patients experience aura, and this patient may have both conditions or migraine with prominent autonomic features. 1, 2

Alternative Consideration: Chronic Migraine with Autonomic Features

• If headaches occur ≥15 days per month for >3 months with migraine features on ≥8 days, chronic migraine should be diagnosed. 1
• The 2-week duration described does not yet meet the 3-month threshold for chronic migraine, but daily headaches for 2 weeks warrant immediate evaluation for medication-overuse headache and consideration of preventive therapy. 1, 3
• Cranial autonomic symptoms occur in up to 50% of migraine attacks and do not exclude migraine; however, the strictly unilateral, daily pattern with rhinorrhea favors cluster headache. 1

Red-Flag Exclusion Required Before Diagnosis

• Rule out secondary causes with a focused history for thunderclap onset, recent head trauma, fever, progressive worsening, new neurological deficits, age >50 years with new-onset headache, or immunosuppression. 2, 4
• Neuroimaging (MRI preferred) is indicated if any red-flag features are present; in their absence, imaging is not required for typical primary headache patterns. 1, 4

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Acute Treatment Algorithm

First-Line Acute Therapy for Suspected Cluster Headache

• High-flow oxygen 12–15 L/min via non-rebreather mask for 15–20 minutes is the most effective abortive treatment for cluster headache, providing relief in 70–80% of patients within 15 minutes. 3
• Subcutaneous sumatriptan 6 mg is the most effective pharmacologic option, achieving complete pain relief in approximately 59% of patients within 2 hours and onset within 15 minutes. 3, 2
• Intranasal sumatriptan 5–20 mg or intranasal zolmitriptan 5–10 mg are alternatives when subcutaneous administration is not feasible. 3

First-Line Acute Therapy if Migraine is More Likely

• Combination therapy: sumatriptan 50–100 mg PLUS naproxen sodium 500 mg is the strongest-rated intervention for moderate-to-severe migraine, achieving sustained pain relief at 48 hours in 130 additional patients per 1,000 compared with either agent alone. 3
• Add metoclopramide 10 mg IV or PO 20–30 minutes before or with the NSAID to provide synergistic analgesia and treat nausea. 3

Critical Medication-Overuse Prevention

• Limit all acute medications to ≤2 days per week (≤10 days per month) to prevent medication-overuse headache, which paradoxically increases headache frequency and can lead to daily headaches. 1, 3
• Daily headaches for 2 weeks already suggest possible medication overuse if the patient has been using acute medications frequently; immediate withdrawal of overused agents is required. 3

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Preventive Therapy: Immediate Initiation Required

Indications for Preventive Therapy

• Daily headaches for 2 weeks meet the threshold for preventive therapy, which is indicated for patients with ≥2 migraine attacks per month causing disability ≥3 days or requiring acute medication use >2 days per week. 1, 5
• Preventive therapy should be initiated immediately to break the cycle of daily attacks and restore responsiveness to acute treatments. 3, 5

First-Line Preventive for Cluster Headache

• Verapamil 240–960 mg/day (divided doses) is the first-line preventive for cluster headache, with most patients requiring 360–480 mg/day; baseline ECG and follow-up ECG monitoring are required due to risk of heart block. 5
• Prednisone 60–80 mg/day for 5–7 days, then rapid taper can be used as a bridge therapy while verapamil is titrated to therapeutic dose. 5

First-Line Preventive for Chronic Migraine

• Topiramate 50–100 mg/day is the only oral preventive with strong RCT evidence for chronic migraine and should be initiated if migraine is the primary diagnosis. 3, 5
• OnabotulinumtoxinA (Botox) 155–195 U injected across 31–39 sites every 12 weeks is the only FDA-approved preventive specifically for chronic migraine and should be used when three oral preventives have failed. 3, 5
• Propranolol 80–240 mg/day or candesartan 16–32 mg/day are alternative first-line oral preventives for episodic migraine but have weaker evidence for chronic migraine. 5

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Diagnostic Workup and Follow-Up

Headache Diary

• Instruct the patient to keep a headache diary (paper or smartphone app) recording attack frequency, duration, severity, associated symptoms (rhinorrhea, lacrimation, conjunctival injection, ptosis, miosis), triggers, and medication use. 1, 5
• Diary data will clarify whether the pattern meets criteria for cluster headache (attacks lasting 15–180 minutes, occurring 1–8 times per day during cluster periods) or chronic migraine (≥15 headache days per month for >3 months). 1

Neuroimaging Indications

• MRI brain with and without contrast is indicated if red-flag features are present (thunderclap onset, progressive worsening, new neurological deficits, age >50 with new-onset headache, fever, immunosuppression). 1, 4
• In the absence of red flags, neuroimaging is not required for typical primary headache patterns. 1, 4

Referral to Headache Specialist

• Immediate referral to a neurologist or headache specialist is required for suspected cluster headache, refractory chronic migraine, or when the diagnosis is uncertain. 3, 5
• Specialist evaluation is essential for onabotulinumtoxinA administration, verapamil titration with ECG monitoring, and comprehensive management of refractory headache disorders. 3, 5

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Critical Pitfalls to Avoid

• Do not prescribe opioids or butalbital-containing compounds for cluster headache or migraine; they have limited efficacy, high risk of medication-overuse headache, potential for dependence, and poorer long-term outcomes. 3, 5
• Do not delay preventive therapy while trialing multiple acute strategies; daily headaches for 2 weeks mandate immediate preventive intervention. 3, 5
• Do not allow continued daily use of acute medications "because they work"; this perpetuates medication-overuse headache and guarantees treatment failure. 3
• Do not assume migraine based solely on aura; the daily pattern, strictly unilateral location, and prominent rhinorrhea strongly suggest cluster headache, which requires different acute and preventive management. 1, 2