Headache is one of the most common medical complaints throughout human history. Although headache reduces quality of life, it mostly does not pose a life threat. However, there is such a type in the headache family that, with its manner of emergence and potential dangers, separates from all other types and is considered a red flag requiring urgent medical intervention. This is Thunderclap Headache, which takes its name from its sudden and explosive nature. This article will address this most urgent and potentially most dangerous condition among headache diseases in all aspects and explain why it is described as “the worst headache of your life.”

What is Thunderclap Headache?

Thunderclap Headache is an explosive quality headache that starts suddenly, without any prior warning, and within seconds, generally in less than 60 seconds, reaches the most severe level imaginable (severity 10 out of 10). The naming comes from comparing this sudden and severe onset to a thunderclap suddenly exploding in a quiet environment.

The most basic feature distinguishing this headache from others is that it does not develop slowly. While in migraine or tension-type headaches pain generally reaches peak by increasing slowly over minutes or hours, in Thunderclap Headache the time to reach peak is under one minute. Patients often describe this situation with dramatic expressions such as “something exploded inside my head,” “I was suddenly hit on the head with a sledgehammer,” or “pain of a severity I’ve never experienced before and couldn’t even imagine.”

It must be emphasized that Thunderclap Headache is not a disease in itself, but a symptom, a precursor symptom of a serious and potentially life-threatening underlying condition. Therefore, every individual experiencing such a headache should apply to the nearest emergency room without delay.

What Causes Thunderclap Headache?

Thunderclap headache itself is not a disease; rather, it is an alarm that needs to be urgently investigated. In a significant portion of cases, a serious life-threatening cause underlies this explosive headache. The most common and most dangerous causes are:

• Subarachnoid Hemorrhage (SAH): It is the most common and most feared cause. It is the rupture of an aneurysm (balloon) formed in an artery on the brain surface and bleeding between the brain and the membranes surrounding it. In approximately 10-25% of patients describing thunderclap headache, the cause is SAH and this situation requires urgent medical intervention.
• Reversible Cerebral Vasoconstriction Syndrome (RCVS): A condition characterized by temporary sudden narrowing (vasospasm) of brain arteries. Generally occurs in the postpartum period, after use of some medications (especially decongestants, SSRI group antidepressants) or drug use. Progresses with recurrent attacks of thunderclap headaches.
• Cerebral Venous Sinus Thrombosis (CVST): Clot formation in the main veins (venous sinuses) carrying dirty blood from the brain. Generally seen in pregnancy, puerperium, or genetic predisposition to clotting.
• Cervical Artery Dissection: A tear occurring in the wall of the carotid artery or vertebral artery carrying blood from the neck to the brain. This tear can lead to stroke. Headache is generally also accompanied by neck pain.
• Pituitary Apoplexy: A sudden-onset neuroendocrine emergency characterized by sudden hemorrhage or infarction (tissue death due to vascular occlusion) in the pituitary gland.
  Generally occurs in a pre-existing pituitary adenoma; can more rarely be seen in normal pituitary gland as well.
• Acute Hypertensive Crisis: Sudden and dangerous elevation of blood pressure.

More rarely, brain infections (meningitis), sudden changes in intracranial pressure (both high and low), or brain tumors can also cause thunderclap headache. Thunderclap Headache is often a warning symptom of an underlying urgent medical condition.

Rarely, despite all investigations, no underlying cause may be found. This condition is called “Primary Thunderclap Headache,” but this diagnosis can only be made after all other dangerous causes have been definitively excluded.

What Are the Symptoms of Thunderclap Headache?

The most basic symptom of Thunderclap Headache is the explosive onset from which it takes its name. However, depending on the underlying cause, other symptoms may also accompany this main symptom:

• Explosive Onset: Pain reaches its most severe level within 60 seconds.
• Extremely Severe Headache: Pain is severe enough for the patient to describe as “the worst headache of my life” (10 out of 10 on the pain scale).
• Accompanying Neurological Symptoms: These symptoms are red flags showing the seriousness of the underlying cause:
  • Nausea and Vomiting: Can be a sign of increased intracranial pressure.
  • Neck Stiffness: A typical finding that develops due to irritation of the meninges (brain membranes) by blood in subarachnoid hemorrhage.
  • Consciousness Changes: Sleepiness, confusion, fainting, or coma.
  • Having an Epileptic Seizure.
  • Weakness or Numbness on One Side of the Body (Paralysis Symptoms).
  • Vision Disorders: Double vision, blurred vision, or vision loss.
  • High Fever.

The presence of any of these additional symptoms further increases the seriousness of the situation. Emergency medical help should be sought.

International Classification of Headache Disorders (ICHD-3) Diagnostic Criteria – 4.4 Thunderclap Headache

1. Headache is in the form of one or more attacks.
2. Pain starts suddenly and reaches its highest severity within 1 minute.
3. Each attack lasts at least 5 minutes.
4. Headache is not associated with any of the following (i.e., the presence of these causes must be excluded):

• Subarachnoid hemorrhage
• Cerebral venous thrombosis
• Cervical or intracranial artery dissection
• Posterior Reversible Encephalopathy Syndrome (PRES)
• Reversible Cerebral Vasoconstriction Syndrome (RCVS)
• Pituitary apoplexy
• Spontaneous intracranial hypotension
• Other intracranial causes (e.g., tumor, infection, etc.)

1. Headache cannot be explained by another headache disorder.

How is Thunderclap Headache Diagnosed?

In a patient applying to the emergency room with thunderclap headache, the diagnostic process is a marathon raced against time. The goal is to rapidly exclude subarachnoid hemorrhage (SAH), the most dangerous and treatable condition, and investigate other possible causes.

1. Emergency Brain Imaging (CT): The first and most important test to be performed is non-contrast brain computed tomography (CT). Brain CT is quite sensitive in detecting subarachnoid hemorrhage and can rapidly show bleeding.
2. Lumbar Puncture (Spinal Tap): If brain CT is normal but SAH suspicion is still very high (for example, if it’s the patient’s most severe headache in their life and there is neck stiffness), the next step is lumbar puncture. With this procedure, a sample is taken from cerebrospinal fluid (CSF). Detection of blood cells or blood breakdown products (xanthochromia) in CSF can diagnose bleeding too small to be seen on CT. When CT is normal, lumbar puncture is mandatory to exclude SAH.
3. Advanced Imaging Methods: After SAH is excluded in the first two steps, more advanced imaging methods are used to investigate other possible causes:
   • CT Angiography (CTA) and/or MR Angiography (MRA): Used to detect vascular pathologies such as aneurysm, vessel tear (dissection), or vasoconstriction (RCVS) by imaging brain and neck vessels in detail.
   • MR Venography (MRV): Used to diagnose cerebral venous sinus thrombosis by imaging brain veins.
   • Brain MRI: Performed to evaluate conditions such as tumor, infection, or stroke by examining brain tissue in more detail.

Who Gets Thunderclap Headache?

Thunderclap Headache itself is not specific to an age or gender group, because it is a warning symptom. Its frequency of occurrence varies depending on the underlying cause. For example:

• Subarachnoid Hemorrhage: Generally seen in individuals between 40-60 years of age and is slightly more common in women. The most important risk factors are hypertension and smoking. Aneurysm (balloon) rupture is the most common cause. Starts with sudden headache described as “the worst headache of my life”; nausea, vomiting, and neck stiffness may accompany.
• RCVS: Mostly seen in middle-aged women and risk is higher in those with migraine history. Some medications (e.g., serotonergic or sympathomimetic agents) and postpartum period can be triggers. Recurrent, thunderclap-type headaches are typical and generally regress within a few weeks.
• Cervical Artery Dissection: One of the important causes of stroke in young and middle-aged adults. Most often develops after sudden neck movement, coughing, sports activities, or minor traumas. Can occur with unilateral neck pain, headache, or Horner syndrome. Diagnosis is generally made with MR angiography.

Thunderclap Headache Treatment

Treatment is entirely directed at the underlying cause. Therefore, correct and rapid diagnosis is life-saving.

• Subarachnoid Hemorrhage (SAH): Treatment includes closing the aneurysm to prevent recurrence of bleeding. This is done by clipping (closing) the aneurysm with open brain surgery or by filling the inside of the aneurysm with materials called “coils” through angiographic methods entered through the groin (endovascular coiling).
• Reversible Cerebral Vasoconstriction Syndrome (RCVS): Treatment includes medications that regulate blood pressure such as calcium channel blockers to relieve narrowing in brain vessels. Additionally, discontinuation of medications triggering the syndrome is also important.
• Cerebral Venous Sinus Thrombosis (CVST): The basis of treatment consists of blood thinning medications (anticoagulants) that prevent clot growth and formation of new clots.
• Cervical Artery Dissection: Generally blood thinning medications are used in treatment to prevent clot formation.

If no underlying cause is found despite all comprehensive investigations and “Primary Thunderclap Headache” is diagnosed, treatment is generally directed at alleviating pain and the patient’s complaints.

Thunderclap Headache is an urgent medical condition that should never be ignored. Every headache that starts suddenly and reaches its most severe level within one minute can be a harbinger of an underlying life-threatening cause. When such a headache is experienced, instead of thinking “let me rest a bit, it will pass,” immediately calling 112 or applying to the emergency room of the nearest hospital will be a life-saving decision.

Of course, here are 5 frequently asked questions and answers summarizing the most important points about the article I prepared:

Frequently Asked Questions About Thunderclap Headache

1. I’m experiencing a pain described as “the worst headache of my life.” What should I do?

If you are experiencing this situation, the single and most important thing to do is to immediately call 112 without any delay or ask someone close to you to take you to the nearest hospital’s emergency room. Thunderclap Headache can be the first sign of a life-threatening condition such as brain hemorrhage. Waiting thinking “let me rest a bit, it will pass” or trying to sleep after taking a painkiller is extremely dangerous. This is a medical emergency and racing against time is vitally important.

2. A very severe headache suddenly started. How can I tell whether this is a dangerous “Thunderclap Headache” or just a bad migraine attack?

The most basic distinguishing feature is the speed at which pain reaches peak. Migraine or other type headaches generally intensify slowly over minutes or even hours. In Thunderclap Headache, pain suddenly and explosively reaches its most severe level within seconds, generally in less than one minute. If your pain went from “0 to 10” instantly, you must definitely accept this as a Thunderclap Headache and get emergency help.

3. I went to the emergency room and my brain tomography (CT) came out clean. Does this mean the danger has passed?

Brain tomography (CT) coming out clean is good news and shows there is no large hemorrhage in the brain. However, this may not mean the danger has completely passed. Especially a very small portion of subarachnoid hemorrhages can be missed on initial tomography. Therefore, even if tomography is normal, if your doctor’s suspicion continues, they may want to perform a lumbar puncture (spinal tap) procedure to confirm diagnosis. This test can detect blood not visible on tomography. Therefore, it is very important to fully comply with your doctor’s recommendations.

4. Is such an explosive headache always due to a terrible cause like brain hemorrhage?

No, it doesn’t always have to be the worst scenario. Although the most common and dangerous cause of Thunderclap Headache is subarachnoid hemorrhage, it can also have other serious causes such as temporary narrowing in brain vessels (RCVS), tear in vessel wall (dissection), or clot in brain veins. In very rare cases, no underlying cause is found despite all detailed investigations. This condition is called “Primary Thunderclap Headache” and is considered benign. However, this diagnosis can only be made after all other dangerous possibilities have been definitively excluded.

5. Is there any activity or situation that can trigger Thunderclap Headache?

Yes. Depending on the underlying cause, some activities or substances can trigger this headache. It can occur in situations that suddenly increase intracranial pressure such as coughing, straining, intense exercise, sexual intercourse, hot shower or bath. Additionally, some medications and substances (for example, symptomatic medications, serotonergic agents, ergotamines, triptans, amphetamine or cocaine use) can similarly trigger Reversible Cerebral Vasoconstriction Syndrome (RCVS) and related thunderclap-type headaches. However, it should not be forgotten that pain can sometimes start suddenly even during complete rest; therefore, there may not always be an obvious trigger.