What is a Primary Thunderclap Headache?

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. 

In fact, a thunderclap headache is actually more likely to be from a serious blood vessel problem in the brain (like a subarachnoid hemorrhage) or another organic brain problem, than this rare primary headache disorder.

What is a Primary Thunderclap Headache?

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.

In other words, primary thunderclap headache is a diagnosis of exclusion—everything else must be ruled out first.

Symptoms of a Primary Thunderclap Headache

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.

Diagnosis of a Primary Thunderclap Headache

A thunderclap headache is an unusual cause of 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). Usually, a magnetic resonance angiography (MRA), and/or venography (MRV) is done to further rule out any blood vessel problem in the brain. Sometimes a cerebral angiogram is performed.

Examples of headaches that may mimic primary thunderclap headache are:

• Subarachnoid hemorrhage
• Intracerebral hemorrhage
• Cerebral Venous Thrombosis
• Pituitary Apoplexy
• Arterial Dissection
• Infections like Acute Sinusitis or Meningitis
• Ischemic Stroke
• Acute Hypertensive Crisis
• Reversible cerebrovasoconstriction syndrome
• Spontaneous intracranial hypotension
• Colloid cyst of the third ventricle

Cause of a Primary Thunderclap Headache

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 Primary Thunderclap Headache

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 older 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.

Sources:

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 headacheNeurology. 2004 Apr 27;62(8):1414-6.

Schwedt TJ & Dodick DW. (2014). Thunderclap headache. In: UpToDate, Swanson JW (Ed), UpToDate, Waltham, MA.