Thunderclap headache

see Benign Thunderclap headache.

A thunderclap headache (TCH) is a severe headache that reaches peak intensity within seconds to one minute of onset. It is often described as the worst headache of a person's life and can be a symptom of a serious underlying condition, such as subarachnoid hemorrhage (SAH), or a benign primary headache disorder.

- Sudden onset, reaching maximum intensity within seconds to 1 minute.

- Severe intensity, often described as explosive, crushing, or unbearable.

- May be associated with nausea, vomiting, photophobia, neck stiffness, or neurological deficits.

- Can occur spontaneously or be triggered by exertion, sexual activity, coughing, or Valsalva maneuvers.

Serious Causes (Need Urgent Evaluation)

1. Subarachnoid hemorrhage (SAH) from a ruptured aneurysm

1. The most dangerous cause.

1. Often presents with a sudden, severe headache, loss of consciousness, vomiting, or neck stiffness.

1. Requires urgent CT scan ± lumbar puncture.

2. Reversible cerebral vasoconstriction syndrome (RCVS)

1. Characterized by sudden, recurrent headaches over days/weeks.
2. May be triggered by sexual activity, exertion, stress, or vasoactive drugs.

3. Cervical or intracranial artery dissection

1. Can cause headache with neck pain and neurological symptoms (e.g., Horner syndrome, stroke).

4. Intracranial hemorrhage (other than SAH)

1. Hypertensive crisis or vascular malformations can cause sudden bleeding.

5. Cerebral venous sinus thrombosis (CVST)

1. May present with headache, seizures, or focal neurological deficits.

6. Meningitis or encephalitis

1. Accompanied by fever, altered mental status, and photophobia.

7. Pheochromocytoma or hypertensive emergency

1. Sudden blood pressure surges can trigger severe headaches.

#### Benign Causes (Diagnosis of Exclusion) - Primary thunderclap headache (idiopathic, but must rule out secondary causes first). - Primary sexual headache (orgasmic headache). - Primary exertional headache. - Primary cough headache.

### Evaluation & Diagnosis - CT brain (non-contrast) → First-line test for ruling out SAH. - Lumbar puncture (if CT is negative but SAH is suspected). - MRI/MRA or CTA head and neck → Evaluate for RCVS, dissection, or vascular pathology.

### Management - Emergency evaluation required for any first-time TCH. - Treat underlying cause if identified. - If benign (primary headache disorder), preventive medications like indomethacin, propranolol, or calcium channel blockers may be used.