These are questions that doctors are frequently asked.

"People have heard about ruptured brain aneurysms and brain tumors, and they wonder if that could be what’s causing their headache,” says Andrew Ringer, MD, professor of neurosurgery and radiology at the University of Cincinnati (UC) College of Medicine and an endovascular specialist with the Mayfield Clinic.

"Fortunately, the odds are that an individual’s headache is not being caused by either an aneurysm or a brain tumor. The vast majority of headaches are benign, or what we call ‘primary headaches.’

"They are typically one of three types: a migraine, a tension headache or a cluster headache. Patients with these disorders often recognize a regular component to their headache. They know when it’s coming on, and they recognize it.”

Ringer acknowledges that these headaches can be disabling. They can cause people to miss work, and they can interfere with parents’ ability to take care of their children.

"Anyone suffering from disabling and recurring headaches should seek treatment,” Ringer says. "But if the headaches are primary headaches, they are not life-threatening.”

But what about a headache that is not a primary headache? What if it is in fact a ‘secondary headache,’ a headache that is being caused by something else? This brings us back to the original question: When does a headache warrant a trip to the emergency room or a call to 911?

Ringer, who has clipped, coiled and glued hundreds of aneurysms during his career, said the telltale sign is when the headache comes on very suddenly and is not your usual headache. He offers the mnemonic S-N-O-O-P as a guideline for identifying an emergency headache.

S stands for systemic or secondary symptoms. If the headache is accompanied by fever, nausea and vomiting,  or if the individual has secondary issues that might cause a headache—such as a history of cancer or HIV/AIDS, then this could be a sign of a secondary problem, such as a tumor of the head or meningitis. This is a sign of an emergency headache.

At this point, Ringer provides an exception: People who experience an aura with migraine headaches may have temporary, or transient, neurologic symptoms.

"They might see flashing lights or have a temporary loss of vision in one eye, for example,” Ringer says. "But those symptoms typically develop slowly and progressively over a period of minutes. And they usually go away before or as the headache is starting. But if those symptoms come on suddenly or they don’t go away after the headache is gone, that is a sign of an emergency headache.” 

O stands for onset. If the onset of the headache is sudden; if it comes out of nowhere; if you were fine one moment and then you feel as if you’ve been hit over the back of the head with a shovel; if you were going about your business and then you feel as though you’ve been shot in the head, that is a sign of an emergency headache. That’s the kind of headache that requires a visit to the emergency room.

O stands for "older.” A sudden, uncharacteristic headache in an individual over the age of 50 can be a sign of an emergency headache.  "The over-50 age group is where we see an increase in tumors and high blood pressure that can cause strokes,” Ringer says. "A sudden onset of a new or very unique headache in an older person should be checked out.

P stands for previous history. If you have had a previous history of headaches and you know what your typical headache is like, a headache that stands apart as new, more severe, and with an onset that is more sudden is a sign of an emergency headache.

Many people who develop emergency headaches related to brain tumors have no known risk factors. But risk factors for the development of aneurysms are well known.

·         People who have two first-degree family members who have suffered a ruptured brain aneurysm are more likely to develop or harbor a brain aneurysm than the general population.

 ·         People who smoke, drink excessively, or suffer from hypertension are at greater risk. A smoker is 4.5 times more likely to suffer a bleeding stroke than a nonsmoker.

 ·         People who suffer a ruptured aneurysm typically are between 50 and 75 years of age, although they do happen less commonly in other age groups.