Washington: According to a new American Heart Association scientific statement published today in the Association's journal Stroke, the symptoms of stroke that disappear in under an hour, known as a transient ischemic attack (TIA), need emergency assessment to help prevent a full-blown stroke.
The statement offers a standardized approach to evaluating people with suspected TIA, with guidance specifically for hospitals in rural areas that may not have access to advanced imaging or an on-site neurologist.
TIA is a temporary blockage of blood flow to the brain. Each year, about 240,000 people in the U.S. experience a TIA, although this estimate may represent underreporting of TIA because symptoms tend to go away within an hour.
While the TIA itself doesn't cause permanent damage, nearly 1 in 5 of those who have a TIA will have a full-blown stroke within three months after the TIA, almost half of which will happen within two days. For this reason, a TIA is more accurately described as a warning stroke rather than a "mini-stroke," as it's often called.
TIA symptoms are the same as stroke symptoms, only temporary. They begin suddenly and may have any or all of these characteristics, symptoms typically last less than an hour; facial droop; weakness on one side of the body; numbness on one side of the body; trouble finding the right words/slurred speech; or dizziness, vision loss or trouble walking.
The F.A.S.T. acronym for stroke symptoms can be used to identify a TIA:
F Face drooping or numbness;
A Arm weakness;
S Speech difficulty;
T Time to call 9-1-1, even if the symptoms go away.
"Confidently diagnosing a TIA is difficult since most patients are back to normal function by the time they arrive at the emergency room," said Hardik P. Amin, M.D., chair of the scientific statement writing committee and associate professor of neurology and medical stroke director at Yale New Haven Hospital, St. Raphael Campus in New Haven, Connecticut.
"There also is variability across the country in the workup that TIA patients may receive. This may be due to geographic factors, limited resources at health care centres or varying levels of comfort and experience among medical professionals."
For example, Amin said, "Someone with a TIA who goes to an emergency room with limited resources may not get the same evaluation that they would at a certified stroke centre. This statement was written with those emergency room physicians or internists in mind -- professionals in resource-limited areas who may not have immediate access to a vascular neurologist and must make challenging evaluation and treatment decisions."
The statement also includes guidance to help health care professionals tell the difference between a TIA and a "TIA mimic" -- a condition that shares some signs with TIA but is due to other medical conditions such as low blood sugar, a seizure or a migraine. Symptoms of a TIA mimic tend to spread to other body parts and build in intensity over time.
Who is at risk for a TIA?
People with cardiovascular risk factors, such as high blood pressure, diabetes, obesity, high cholesterol and smoking, are at high risk for stroke and TIA. Other conditions that increase the risk of a TIA include peripheral artery disease, atrial fibrillation, obstructive sleep apnea and coronary artery disease. In addition, a person who has had a prior stroke is at high risk for TIA.
Which tests come first once in the emergency room?
After assessing for symptoms and medical history, imaging of the blood vessels in the head and neck is an important first assessment. A non-contrast head CT should be done initially in the emergency department to rule out intracerebral haemorrhage and TIA mimics. CT angiography may be done as well to look for signs of narrowing in the arteries leading to the brain. Nearly half of the people with TIA symptoms have narrowing of the large arteries that lead to the brain.
A magnetic resonance imaging (MRI) scan is the preferred way to rule out brain injury (i.e., a stroke), ideally done within 24 hours of when symptoms began. About 40% of patients presenting in the ER with TIA symptoms will actually be diagnosed with a stroke based on MRI results. Some emergency rooms may not have access to an MRI scanner, and they may admit the patient to the hospital for MRI or transfer them to a centre with rapid access to one. (ANI)
