Curriculum · Neurology
Thunderclap headache
What it is
A thunderclap headache is a headache that is very severe with abrupt onset, reaching maximum intensity in less than a minute. It is a medical emergency and calls for urgent evaluation for the underlying cause. The same feature sits among the red flags for a secondary headache, in the SNOOP mnemonic, as an onset that occurs with maximal intensity within minutes.
Causes and risk
The causes are listed by how often they occur.
- Most common: subarachnoid haemorrhage and reversible cerebral vasoconstriction syndrome.
- Less common: cerebral infection, cerebral venous sinus thrombosis, cervical artery dissection, complicated sinusitis, hypertensive crisis, ICH, ischemic stroke, spontaneous intracranial hypotension, and SDH.
- Possible: idiopathic thunderclap headache and unruptured intracranial aneurysm.
- Uncommon: aqueductal stenosis, brain tumor, giant cell arteritis, pituitary apoplexy, pheochromocytoma, spontaneous spinal epidural hematoma, and third ventricle colloid cyst.
For the subarachnoid bleed itself, the PCoA is the most common aneurysmal site; it may be spontaneous, due to an aneurysm as in PCKD, an AVM or dissections, or traumatic, and its headache goes with meningism. The wider red flags for a secondary headache, alongside thunderclap onset, are systemic symptoms, illness or condition such as cancer, chills, fever, immunocompromise, infection, myalgias, night sweats, pregnancy or postpartum and weight loss; neurologic symptoms or abnormal signs such as confusion, diplopia, focal neurologic signs, impaired consciousness, meningismus, pulsatile tinnitus and seizures; age 50 years or older at onset; progression in features, pattern or severity; headache precipitated by Valsalva; postural aggravation; papilledema; and exertional provocation.