Experiencing sudden, severe head pain

Similar to primary thunderclap headaches, secondary thunderclap headaches are defined as sudden onset headaches that achieve maximal intensity within one minute. They are severe, occur suddenly, and persist for hours. Thunderclap headaches may be associated with photosensitivity, phonosensitivity, neck stiffness, and nausea with vomiting.

Usually, these are recognised by a patient’s declaring, “this is the worst headache of my life.”

Features and characteristics of a secondary thunderclap headache
Features and characteristics of a secondary thunderclap headache

Sinister causes of secondary thunderclap headaches

Serious causes of secondary thunderclap headaches include subarachnoid haemorrhage (SAH), cervical artery dissection, stroke, and a hypertensive crisis.

Since severe, abrupt onset headaches are often ominous, imaging in the form of magnetic resonance (MRI), computed tomography (CT), or MR angiography is usually performed to exclude secondary causes. Lumbar puncture may also be required.

Subarachnoid haemorrhage

Severe and sudden onset headache may indicate subarachnoid haemorrhage due to aneurysmal rupture or a sentinel bleed from a leaking aneurysm. Intraparenchymal bleeds into the brain tissue also often present with headache.

The thunderclap headache syndrome can also be a primary headache type. The primary headache is indistinguishable clinically from thunderclap headache secondary to a subarachnoid haemorrhage.

Note: SAH is the most common secondary cause of thunderclap headache and should be the focus of evaluation when thunderclap headache occurs.

Rupture of a berry aneurysm

The most common cause of subarachnoid hemorrhage is rupture of a berry aneurysm producing a severe headache which can be associated with loss of consciousness.

Brain CT without contrast is diagnostic if done in the first 6 hours but the sensitivity decreases after that. A lumbar puncture must be done if the patient presents more than 12 hours after onset.


Subdural haematoma is often preceded by trauma, but the haematoma may develop slowly, such that sometimes the inciting event is not recalled. Epidural haematoma is also caused by trauma, but is rapid in development and the incident is very evident.

Cervical artery dissection

Cervical artery dissection most commonly presents with headache and neck pain. The headache usually develops over a 24-hour period. However, in one out of five patients, it presents as a thunderclap headache. The headache often precedes the later, focal, stroke-like neurological symptoms. It occurs ipsilateral to the vessel which is dissecting.

Cerebrovascular accident (CVA/Stroke)

Both ischaemic and hemorrhagic stroke may produce a thunderclap headache which can precede other stroke symptoms. The severity and location depends on the location and severity of the ischemia or haemorrhage.

For these reasons, in most cases of thunderclap headache, a formal study of the cervical vasculature is indicated, with CT or MR angiography.

Those patients who suffer from migraine may be more prone to headache as an accompaniment to stroke.

Hypertensive crisis

A hypertensive crisis can precipitate a thunderclap headache. Most often the headaches are posterior in location.

Posterior reversible encephalopathy syndrome (PRES) is a consequence of uncontrolled hypertension. It is associated with thunderclap headache, vision loss, altered mental state, and, possibly, seizures. Focal neurological signs and nausea and vomiting also occur.

Benign causes of secondary thunderclap headache

It is important to rule out the more serious causes of a thunderclap headache first, but there are also benign causes such as low cerebrospinal fluid (CSF) pressure, rapid onset migraine, post-coital headache, and exertional headaches.

Benign causes of secondary thunderclap headache.
Low cerebrospinal fluid pressure

Physicians are usually familiar with post lumbar puncture headaches caused by low CSF pressure. This can happen if there is CSF leakage at the puncture site.

Cerebrospinal fluid leaks can also occur spontaneously. The hallmark is a positional headache which occurs and worsens when a patient is upright. Half of all patients who have CSF low pressure headaches will present with a thunderclap headache elicited by assuming an upright posture. This can be steady or throbbing and may be associated with nausea and vomiting, dizziness, visual changes, and neck pain.

Perhaps ironically, a lumbar puncture should be done in the setting of a thunderclap headache to rule out a subarachnoid haemorrhage.

The opening pressure is measured during a lumbar puncture and a low opening pressure is diagnostic of a cerebrospinal fluid leak.

MRI with enhancement often will show diffuse meningeal enhancement.

Rapid onset migraine

Rapid onset migraine is often referred to a crash migraine and the primary feature is the rapidity with which the headache reaches maximal intensity. This diagnosis should not be considered unless the patient has a clear history of migraine headache and other causes of thunderclap headache have been excluded.

Post-coital headache

Post-coital headache, a thunderclap-like primary headache disorder, which can occur before or with orgasm. These headaches are usually bilateral. Be aware that subarachnoid haemorrhage can also occur with orgasm, so the patient should be evaluated for an aneurysmal bleed upon initial presentation with this type of headache.

Exertional headaches

Exertional headaches are a primary headache disorder, with a thunderclap-type presentation, precipitated by any type of exercise or high-level physical activity. The headache is pulsating or throbbing and may last anywhere from a few minutes up to 48 hours.

This is an edited excerpt from the Medmastery course Headache Masterclass by Robert Coni, DO, EdS, FAAN. Acknowledgement and attribution to Medmastery for providing course transcripts.


Neurology Library: Secondary headaches

Neurology Library

LITFL author Robert Coni DO EdS

Robert Coni, DO, EdS, FAAN. Vascular neurologist and neurohospitalist and Neurology Subspecialty Coordinator at the Grand Strand Medical Center in South Carolina. Former neuroscience curriculum coordinator at St. Luke’s / Temple Medical School and fellow of the American Academy of Neurology. In my spare time, I like to play guitar and go fly fishing. | Medmastery | Linkedin |

Dr Hannah Bone LITFL Author

BMBS (The University of Nottingham) BMedSci (The University of Nottingham). Emergency Medicine RMO at Sir Charles Gairdner Hospital Perth, WA. Interested in Medical Education and Emergency Medicine. Swimmer and frequent concert attendee.

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