Reporter's death prompts worry: How common are brain aneurysms?

Lisa Colagrossi, a 49-year-old reporter for WABC-TV in New York City who died suddenly of a brain aneurysm on Friday, is a prime example of how terrifying the condition is. On Thursday, Colagrossi had just returned from an assignment covering a fire when she collapsed and was rushed to the hospital.

How could an otherwise healthy and relatively young person with no symptoms die so quickly and never know they were suffering from a life-threatening condition?

A cerebral aneurysm is a thin or weak spot that can occur on a blood vessel of the brain. The aneurysm causes that area of the vessel to enlarge and fill with blood. As a result, the blood vessel may begin to bulge and put stress on nerves or surrounding brain tissue. It can burst and cause devastating bleeding in the brain.

The condition most typically occurs in people between the ages of 35 and 60. It also more commonly strikes women. Like Colagrossi, patients who suffer from brain aneurysms often seem perfectly healthy and don't show warning signs prior to a rupture.

Though scary, brain aneurysm ruptures are relatively rare. According the Brain Aneurysm Foundation, about one in 50 people develops a brain aneurysm, but most do not rupture. Ruptures occur in about 30,000 people in the U.S. each year, and 40 percent of those cases result in death within 24 hours. Another 25 percent of patients may die of complications within 6 months. Up to two-thirds of those who survive will be left with some sort of neurological deficit.

Cerebral aneurysms can be caused by abnormalities in the artery wall that occur before birth. They also tend to be more common in people with genetic conditions such as connective tissue disorders and circulatory problems. Sometimes a history of head trauma can put a person at higher risk for developing an aneurysm. Other health conditions commonly linked to higher risk for aneurysm include high blood pressure, infection, brain tumors, disease of the blood vessels.

Certain factors such as drug and alcohol abuse and cigarette smoking may increase one's risk as well, according to the National Institute of Neurological Disorders and Stroke, a division of the National Institutes of Health.

Most cerebral aneurysms will go unnoticed until they become very large or burst. A large aneurysm may press against the brain or nerves and cause a headache, pain above or behind the eye, blurred or double vision, weakness, numbness or difficulty speaking.

Symptoms of a ruptured aneurysm can be similar to those typically found in stroke patients, including a sudden severe headache (sometimes called a "thunderclap headache"), pain above or behind the eye, numbness, weakness and paralysis on one side of the body. Symptoms can also look similar to those found in concussion patients, including double vision, nausea, vomiting, stiff neck and loss of consciousness.

Unfortunately, death from an aneurysm can occur frequently once there is a rupture. Whether or not a patient survives may depend on a number of factors such as their age and overall health, the location of the aneurysm and also how quickly they receive medical care. Rapid emergency medical treatment is essential, but the Brain Aneurysm Foundation estimates that up to 25 percent of patients encounter a delay or are initially misdiagnosed, potentially costing lives.

When doctors do detect an aneurysm early -- before it bursts -- they may recommend monitoring and MRI imaging to detect signs of growth or change. Sometimes surgery may be done that involves clipping or cutting off the blood flow to the aneurysm to prevent rupture.