What is a Primary Thunderclap Headache?

How Primary Thunderclap Headache Mimics Life-Threatening Brain Disorders
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Imagine you witness the sudden, loud bang of a significant car crash. Now imagine this car explosion is occurring in your brain. This may be analogous to a primary thunderclap headache — a headache disorder that causes a sudden, extraordinarily severe and explosive onset of head pain.

It's important to note that this headache can mimic the same type of pain that accompanies life-threatening brain disorders — so, if a person has a thunderclap headache, he needs to seek emergent medical attention.

Let's take a closer look at this rare type of primary headache disorder.


The International Headache Society defines a primary thunderclap headache as a “high-intensity headache of abrupt onset mimicking that of a ruptured cerebral aneurysm, in the absence of any intracranial pathology."

Also, according to the IHS "evidence that thunderclap headache exists as a primary disorder is rare." This means that an extremely thorough workup needs to be done on a person with a thunderclap headache to make sure nothing more serious is going on.


According to the classification criteria of the third edition of the International Classification of Headache Disorder, symptoms of a primary thunderclap headache include:

Intensity: Severe, "worst headache of my life."

Onset: Sudden, reaching maximum intensity in < 1 minute

Duration : Lasts 5 or more minutes.

In addition to the above features, a primary thunderclap headache cannot be explained by another medical condition.


A thunderclap headache is an unusual cause for a primary headache and every means should be taken to rule out other more serious medical conditions.  For instance, vascular or blood vessel disorders of the brain, like a subarachnoid hemorrhage, often cause a thunderclap headache — so it's imperative these life-threatening conditions are ruled out first.

A person with a thunderclap headache must have a lumbar puncture showing normal cerebrospinal fluid or CSF, as well as normal brain imaging, usually with a brain CT scan and/or brain magnetic resonance imaging (MRI). Sometimes,  a cerebral angiogram, a magnetic resonance angiography (MRA),  and/or venography (MRV) is done to further rule out any blood vessel problem in the brain.

Examples of headaches that may mimic primary thunderclap headache are:


The cause of a primary thunderclap headache is largely unknown. It may be related to spasm of the blood vessels in the brain.


Treatment of a thunderclap headache depends on the origin. For instance, treatment of a subarachnoid hemorrhage would involve emergent medical and/or neurosurgical interventions.

If medical emergencies have been ruled out, treatment for a primary thunderclap headache can be challenging. Individuals generally do not respond well to typical headache pain relievers. One small 2004 study in Neurology showed that nimodipine, a calcium channel blocker may provide headache resolution in people with primary thunderclap headache. But, the study was quite small — only 11 patients — and there was no control group, which suggests a possible placebo effect. More research on this rare primary headache disorder would be useful.

Take-Home Points

  • Primary thunderclap headache is a rare headache disorder of unknown cause that leads to an explosive, severe and sudden headache, similar to a "clap of thunder." If you do experience this type of headache, seek emergent medical attention.
  • Before being diagnosed with a primary thunderclap headache, you need an exhaustive workup  to ensure there is no life-threatening medical emergency causing the thunderclap headache, especially a subarachnoid hemorrhage.
  • Treatment of this rare headache disorder involves first ruling out worrisome brain etiologies. If deemed a primary or benign thunderclap headache, nimodipine is a potential therapy, although treatment is still largely unknown.


Headache Classification Committee of the International Headache Society. "The International Classification of Headache Disorders: 3rd Edition (beta version)". Cephalalgia 2013;33(9):629-808.

Lu SR, Liao YC, Fuh JL, Lirng JF, Wang SJ. Nimodipine for treatment of primary thunderclap headache. Neurology. 2004 Apr 27;62(8):1414-6.

Schwedt TJ & Dodick DW. Thunderclap headache. In: UpToDate, Basow DS (Ed), UpToDate, Waltham, MA, 2013.

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