Management and Determining the Cause

Chief Complaint: Headache

Clinical algorithm organized to help you rapidly separate dangerous secondary causes from benign primary headaches.

Red Flags Present << >> No Red Flags Present

Systemic symptoms (fever, weight loss)
Neurologic deficits (focal signs, altered mental status)
Onset sudden (“thunderclap”)
Older age (> 50 years)
Pattern change or new type of headache

Additional high‑risk clues:

Immunosuppression
Cancer history
Pregnancy/postpartum
Trauma
Papilledema
Positional headache
Precipitated by Valsalva
Progressive worsening

If ANY red flag → go to STEP 2A.
If NO red flags → go to STEP 2B.

STEP 2A — Red Flags Present → Evaluate for Secondary Causes

Immediate tests based on presentation

Thunderclap headache → CT head (non‑contrast) → if negative, lumbar puncture
Fever, neck stiffness → Lumbar puncture (after CT if focal deficits)
Focal neurologic deficits → MRI brain ± MRA/CTA
Papilledema → MRI brain + MRV (rule out venous sinus thrombosis)
New headache > age 50 → ESR/CRP (rule out temporal arteritis)
Trauma → CT head
Cancer or HIV → MRI brain

Common secondary diagnoses

Subarachnoid hemorrhage
Meningitis/encephalitis
Brain tumor
Temporal arteritis
Cerebral venous thrombosis
Intracranial hypertension or hypotension
Carbon monoxide poisoning
Acute glaucoma

If secondary cause found → treat accordingly.
If no secondary cause found → proceed to STEP 3.

STEP 2B — No Red Flags → Consider Primary Headaches

Primary headaches are diagnosed clinically:

Migraine
Tension-type headache
Cluster headache
Other trigeminal autonomic cephalalgias

Proceed to STEP 3 to differentiate.

STEP 3 — Classify the Headache by Key Features

A. Migraine

Unilateral
Pulsating
Moderate–severe
Worsened by activity
Nausea/vomiting
Photophobia/phonophobia
± Aura

B. Tension-Type

Bilateral
Band-like pressure
Mild–moderate
Not worsened by activity
No nausea/vomiting
± Mild photophobia or phonophobia

C. Cluster Headache

Severe unilateral orbital/temporal pain
Autonomic signs: tearing, rhinorrhea, ptosis, miosis
Occurs in clusters (daily for weeks)
Restlessness

D. Other Primary Headaches

Trigeminal neuralgia
Primary stabbing headache
Primary cough/exertional headache

STEP 4 — Consider Special Situations

Headache with medication overuse

Occurs ≥15 days/month
Regular use of analgesics or triptans
Improves after withdrawal

Headache triggered by exertion, sex, or cough

Rule out secondary causes first (aneurysm, Chiari malformation)
If negative → primary exertional/sexual headache

STEP 5 — If Diagnosis Still Unclear

Keep a headache diary
Consider MRI brain
Evaluate for sleep apnea, TMJ disorder, bruxism, hypertension
Review medications (nitrates, SSRIs, OCPs, caffeine withdrawal)

Summary Table

Step	Purpose
1	Screen for red flags (SNOOP10)
2A	If red flags → evaluate for secondary causes
2B	If no red flags → primary headache likely
3	Classify migraine vs tension vs cluster
4	Consider special categories (med overuse, exertional)
5	Further evaluation if unclear