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Pam Mace was a healthy nurse who enjoyed golfing, skydiving, and running twice a day, but when she developed stroke-like symptoms at only 37, she struggled to get medical answers for a year.
In July 2000, after experiencing excruciating headaches, numbness, fainting spells and high blood pressure, Mace learned she had dissections or tears in three arteries, as well as two aneurysms.
“It felt like someone was tightening my head with a screwdriver,” said Mace, now 50 and living in Michigan. “I was a nurse, and I knew something was wrong. I thought I was going to die.”
Mace finally got a diagnosis: fibromuscular dysplasia or FMD, a poorly understood cardiovascular disorder that strikes women up to 10 times more than men and can trigger life-threatening stroke and heart attacks.
As attention focuses on heart health during February, Mace, now executive director of the Fibromuscular Dysplasia Society of America, wants younger women to be aware of a serious, often hidden or misdiagnosed condition.
“Anytime a young woman has high blood pressure or a spontaneous coronary artery dissection, doctors should think FMD,” she said.
FMD is characterized by abnormal cell development in the artery wall, causing narrowing, aneurysms or tears. It differs from atherosclerosis, in which plaque causes the stenosis.
About 65 percent of the time, it affects the renal arteries, which lead from the heart to the kidneys, causing uncontrolled hypertension. But in Mace’s case, the stenosis was in the carotid and vertebral arteries.
Mace was diagnosed in 2001 at the Cleveland Clinic, but when she looked for resources and support among the nation’s major heart and stroke organizations, none had even heard of FMD, she said.
For a year, doctors prescribed medications and dismissed her fears, some even telling her she was depressed and to “get on with [her] life.”
“To me, knowledge is power, but nobody cared to look for the cause,” said Mace.
The disorder was first described in a European medical journal in 1938, and sporadic research was conducted in the United States in the 1950s and 1960s.
FMD is “more common than thought,” said Dr. Heather Gornik, a Cleveland Clinic cardiologist and director of its FMD clinic.
“Until a decade ago, it was relegated to the realm of medical zebras, or very rare diseases,” said Gornik, who treats Mace. “Not many people were writing about it. It was not taught well in medical school and there was a huge problem with awareness and detection.”
“Now, we are making great strides,” she told NBC News.
There are no statistics on how many Americans have FMD, but as doctors learn more, diagnoses are increasing.
Women aged 30 to 50 are at greatest risk for FMD, but it can also affect children and the elderly. Causes are still poorly understood, but recent studies suggest hormonal influences and genetics.
In 2009, the FMD Society of America funded a registry based at the University of Michigan, which now tracks 1,200 patients at 14 medical centers, one of them the Cleveland Clinic.
Of those in the registry whose carotid arteries were affected, 40 percent went on to have a “major vascular event,” such as a stroke, said Gornik.
Because it is a variable disorder, some have no symptoms at all. Studies of kidney transplants show that 4 to 6 percent of healthy donors may have FMD on their CT scans, according to Gornik.
Affected arteries are easy to recognize as they take on a “string of beads” appearance. Symptoms of an affected carotid artery include a pulsating noise or “bruit” that can be heard in the neck.
“A classic example is a woman in her 40s or 50s with migraines or a whooshing noise in her ear that might be dismissed,” said Gornik. “But if you listen carefully to hear the bruit, doctors can make the connection.”
Treatment may include medications for blood pressure and clots, or vascular procedures such as angioplasty or surgery.
“FMD may not be curable,” she said. “But it is not a death sentence.”
Today, Mace has stents in her carotid arteries and is on medication to prevent clots and stroke. She is as active as ever. She ran a 5K, and went on a medical mission to Haiti.
Thanks to her efforts, the National Organization for Rare Disorders, the National Stroke Association and the American Stroke Association, which featured Mace on its 2007 cover, now recognize FMD as a cause of stroke.
“I am determined,” said Mace, “that no one else goes through what I did.”
This article was originally published Feb. 17, 2015 at 2:14 a.m. ET.