Thunderclap headaches are not common in individuals in developed countries, such as the United States. In fact, they happen to about 43 out of 100,000 adults. This is a very severe (“first or worst”) headache of an abrupt onset, reaching maximum intensity in less than 1 minute and lasting for 5 or more minutes. This headache requires emergent evaluation at the nearest emergency department for testing and evaluation, especially the first time that it occurs. One of the main diagnoses that needs to be evaluated for is a blood vessel related headache such as subarachnoid hemorrhage from aneurysm rupture (brain bleed).
One of the more notable characteristics of a thunderclap headache is that there is not an obvious trigger. Thunderclap headaches are sometimes indicative of a sudden, serious medical condition that requires immediate treatment. Let’s take a look at some of the causes of thunderclap headaches, headaches that are typically secondary in nature. Before we do that, keep in mind that thunderclap headache is a medical emergency requiring an emergency evaluation by a physician, preferably by calling 911 and having an ambulance take you to the emergency department.
What Does a Thunderclap Headache Feel Like?
Imagine a thunderclap headache as a thunderbolt lightning strike to the head with immediate and maximum pain. Thunderclap headaches have a rapid onset that happens rather quickly. Some people who get thunderclap headaches will notice the pain reaches its greatest intensity within 1 to 5 minutes of the onset of the headache. Sometimes, thunderclap headaches are accompanied by other symptoms. These can include a fever, blurred vision, complete loss of vision, nausea, dizziness, difficulty standing, numbness, weakness, loss of speech, or other neurological symptoms, all of which require emergent evaluation by a physician.Some symptoms that may be associated with a thunderclap headache could also be related to the primary cause of the headache itself.
What Causes Thunderclap Headaches?
Subarachnoid hemorrhage
A common cause of thunderclap headaches is a condition known as subarachnoid hemorrhage. This is always the #1 condition that requires emergent evaluation to rule out because the death rate is so high if it is not evaluated and treated quickly. This is a condition where bleeding occurs in the membranes that are surrounding the brain. The bleeding happens between the arachnoid membrane, just above the pia mater (the innermost membrane of the brain). Subarachnoid hemorrhages are responsible for about 5% of strokes but cause twenty-five percent of deaths related to strokes. Ruptured aneurysms are a major cause of subarachnoid hemorrhages.
Ischemic or Hemorrhagic Stroke
Ischemic strokes can also cause thunderclap headaches. Strokes are the fifth leading cause of death in the United States and ischemic strokes are the most common type of stroke. Ischemic strokes happen when arteries become blocked in the brain. When plaque builds up in the arteries, it can block blood flow to the brain. Another common type of ischemic stroke happens when a blood clot forms in blood vessels in the brain, depriving it of oxygen. People with diabetes, high blood pressure, high cholesterol, smokers and carotid artery disease are at extreme risk for developing an ischemic stroke.
Hemorrhagic stroke is when there is a bleed into the tissues of the brain, rather than a blockage of an artery. Between ischemic and hemorrhagic strokes, hemorrhagic strokes are more commonly associated with a bad headache, although it is certainly possible with both.
Vasculitis
Vasculitis occurs when there is inflammation and narrowing of various arteries in the brain. It is often associated with thunderclap headache. It can be caused by a number of things including medications (over the counter decongestants are sometimes culprits, along with many other medicine types), infections, or autoimmune disorders. Reversible Cerebral Vasoconstrictive Syndrome (RCVS) is a common cause of this, and is often medicine induced.
Cerebral Venous Thrombosis
Cerebral venous thrombosis occurs when a large blood clot forms and blocks draining (venous) blood flow in the brain. The large cerebral venous sinuses drain the brain of blood after the blood has delivered oxygen to the brain. From the venous sinuses, they drain into the jugular veins, and back into the normal circulation. Sometimes a blood clot can be formed in one of these venous sinuses causing blood flow to back up. This leads to headache (sometimes can be thunderclap) and can cause a variety of other neurological symptoms as well.
Arterial Dissection
This can occur when there is a tearing of one of the arteries in the neck or brain such as the carotid or vertebral arteries.
Bacterial and Viral Meningitis
Meningitis is another condition that can cause a thunderclap headache. This is usually associated with fevers, chills, bad neck pain, and often confusion. Caused by either bacteria or viruses, meningitis is an inflammation of the brain and spinal cord lining that puts pressure on the brain. Infections of the brain are responsible for about 7% of thunderclap headaches, according to the National Institute of Health.
Head Injury Or Trauma
A severe head injury can also bring about a thunderclap headache. By and far, the most common cause of a head injury are falls and motor vehicle accidents. Sports and other physical activities can often result in a head injury. Depending upon the severity of the injury, one may experience a thunderclap headache. Head injuries often result in a concussion, which may include some additional symptoms, such as confusion, a dislike of noise or light, memory problems, difficulty with balance, and an inability to concentrate.
Migraine
For some patients, their migraines can come on abruptly and wake them up, or they can come on during the day as well with fast onset. This cause is established after proper testing has been completed for thunderclap headaches, and after a recurring pattern has been observed.
What Should I Do If I Have a Thunderclap Headache?
You have very limited time to act if you notice the onset of a thunderclap headache. If you have a subarachnoid hemorrhage, it can start causing permanent brain damage in as little as three to four minutes. If a patient is able to secure treatment quickly, the odds of survival and recovery are better. Generally speaking, about 33% of patients who receive treatment for this type of hemorrhage have a favorable outlook of recovery, meaning that they experience no disability after the fact. This type of headache requires emergency evaluation in the emergency department.
How Do Doctors Investigate Thunderclap Headaches?
Emergency medical personnel and headache specialists have a unique challenge when diagnosing the cause of a thunderclap headache, as the investigation is often a race against time. If evaluated promptly, a physician will often do a CTA of the head and neck blood vessels (CT angiogram, which is a special CT scan with IV contrast to look at the brain and the arteries). An MRI and MRA of the brain and neck blood vessels is another option. They would be looking for an outpouching of blood vessels (indicating an aneurysm), tearing of an artery (dissection), blood vessel inflammation, or a tear. If a cerebral venous thrombosis is suspected, an MRV or CTV of the brain may also be done. The “V” in these tests is for venogram to look at the deep venous blood channels which the blood from the brain drain into, but can become blocked with a blood clot. If there is a high suspicion for an aneurysm rupture (tearing), a lumbar puncture may be done to look for blood in the spinal fluid. A lumbar puncture may also be done if there is concern for meningitis, along with blood tests looking for signs of infection.
How Do Doctors Treat Thunderclap Headaches?
Doctors deal with thunderclap headaches by immediately addressing the primary cause. For example, if a person is having a stroke, they may receive blood thinners to help break up a blood clot. Surgery can also attempt to repair brain bleeds by securing blood vessels, repairing aneurysms, and relieving pressure on the brain. Infections, such as meningitis, can be treated with antibiotics (if bacterial) and with antiviral drugs (in very rare instances of viral meningitis). For concussions, doctors can prescribe rest and the concussion will generally resolve itself within about 14 days. Pain relievers and nausea medications are typically prescribed for concussion.
What Are the Risk Factors for a Thunderclap Headache?
There are a plethora of risk factors for a thunderclap headache. For strokes and hemorrhage, diabetes, high blood pressure, genetic history, smoking, and age are all risk factors. The risk of a stroke doubles each decade for individuals who are over the age of 45. Over 70% of all strokes happen once a person reaches the age of 65. Smoking, alcohol, and hypertension (stress) are the major risk factors for a subarachnoid hemorrhage.
The Seriousness of Thunderclap Headaches
Thunderclap headaches are a medical emergency. In some of the primary causes of thunderclap headaches, a physician will have a matter of minutes to act to prevent brain damage and prevent loss of life. Also, physicians have to use all the diagnostic tools available to them. For example, a CT scan can miss around 25% of subarachnoid hemorrhages. However, the prevalence of thunderclap headaches is quite low. Less than .3% of people will experience a thunderclap headache during their lifetime. Additionally, lifetime prevalence of thunderclap headaches in emergency room patients is less than 6%.
There is a benign form of thunderclap headache called primary thunderclap headache, which is not caused by something bad. However, this cannot be diagnosed until examination, further history, testing, and a recurrent pattern of events have been established (never assume this during the first attack). Evaluations to exclude other more dangerous causes of the headache must have been performed with a physician first before considering this.
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