The Hidden Danger of a Sudden, Severe Headache

Medically Reviewed

Emergency room doctors treat more headaches than you might expect: It’s one of the top five reasons for an ER visit, according to the Centers for Disease Control and Prevention.

Most primary-type headaches like migraine, cluster, and tension headaches can be treated at home with over-the-counter pain relievers or prescription drugs. But a sudden, severe headache’s incapacitating pain can—and should—send some people to the hospital.

Headaches that require immediate medical attention are rare, but failure to treat them can be fatal. A sudden, crushing headache in adults older than 50 who have no history of headaches can be a sign of a serious or life-threatening condition, such as an ischemic stroke or an infection like meningitis; in fact, stroke symptoms can be mistaken for those of a migraine.

Recognizing a hemorrhage

An excruciating headache can also be a sign of a subarachnoid hemorrhage—deep bleeding between the brain and the thin tissues that cover it. A subarachnoid hemorrhage, considered a type of stroke, is often caused by a ruptured brain aneurysm, which occurs when a weakened blood vessel swells and bursts, cutting off blood supply to the brain.

Subarachnoid hemorrhages are rare: They account for only 1 percent of ER visits for headaches, but missed or delayed diagnoses are common, partly because of difficulty diagnosing one. A 2004 study reported that 12 percent of patients who had a subarachnoid hemorrhage were misdiagnosed—mostly with migraine or tension headaches—because of failure to perform proper testing.

Early diagnosis of subarachnoid hemorrhages is critical to survival and to preempting short-term complications like recurrent bleeding and vasospasm (reduced blood flow to the brain).

To help determine when a headache may be a subarachnoid hemorrhage that needs emergency care, researchers recently developed a decision-making tool identifying common key factors. Certain signs, say the researchers, warrant a computed tomography (CT) scan of the head—the cornerstone of diagnosis—and a lumbar puncture, or spinal tap, if the CT results are normal, to detect a hemorrhage. Anyone age 40 or older who experiences one or more of the following should be tested:

• A “thunderclap” headache—pain that comes on suddenly and becomes excruciating within seconds or minutes

• Neck pain or stiffness

• Headache onset during exertion

• Limited neck flexion

• A loss of consciousness

The researchers examined more than 2,000 people admitted to ERs with a severe headache. The tool, published in 2014 by the Journal of the American Medical Association, accurately pointed to a subarachnoid hemorrhage 98.5 percent of the time. The tool can help reduce the risk of overlooking a subarachnoid hemorrhage, but it doesn’t rule out other dangerous causes of a sudden, severe headache.

Along with an accurate diagnosis recovery depends on fast and aggressive intervention as well as the initial bleeding’s severity. Doctors treat a subarachnoid hemorrhage by stopping the bleeding with either aneurysm clipping, which involves surgery to close the burst aneurysm, or endovascular coiling, a less invasive treatment that uses stents, or small metallic coils, threaded through a blood vessel to the aneurysm to close it off.

Can you prevent a subarachnoid hemorrhage?

Most aneurysms have no symptoms until they burst. But about 20 percent of people have sentinel, or warning, headaches two to eight weeks beforehand. They tend to appear suddenly but are sometimes milder. They can last for hours or days and be accompanied by nausea and vomiting.

Although it’s impossible to predict who will have a subarachnoid hemorrhage, certain risk factors make you more prone to the condition: family history, smoking, excessive alcohol consumption, high blood pressure, illicit drug use, and diet pill use.

Headache danger signs

As a rule, you should seek immediate medical help if:

• Your headache comes on suddenly and feels like the worst headache you’ve ever had

• You have speech, vision, movement, or balance problems

• You have a stiff neck or fever

• Your headache is accompanied by nausea or vomiting

• Your headache develops upon exertion

• You have a head injury

• Your headache affects one eye, with redness in that eye