Posts Tagged 'TIA'

Detecting cerebral microemboli with transcranial doppler.

 

David W. Newell, MDCerebrovascular Surgery, Neurosurgery, Swedish Neuroscience Institute 

 

 

 

 

Colleen Douville, RVT, Director, Cerebrovascular Ultrasound, Swedish Neuroscience Institute

 

 

Since its introduction in 1982, transcranial doppler ultrasound (TCD) has evolved into a por­table, multimodality, noninvasive method for real-time imaging of intracranial vasculature.

The detection of cerebral microemboli is among the more remarkable capabilities of TCD. Emboli create countable signals in the ultrasound display due to the higher reflection of sound waves compared to the blood cells. Experimental mod­els have shown a high sensitivity and specificity for detection of a variety of substrates, including thrombotic, platelet and atheromatous emboli.

Microembolic signals (MES) within the in­tracranial vasculature are most frequently identi­fied in patients with large-vessel atherosclerotic disease, such as carotid stenosis. They have also been reported in intracranial arterial stenosis, ar­terial dissection, cardiac disease and atheroaortic plaque. Additionally, they have been seen in arter­ies distal to coiled aneurysms.

There is strong evidence that MES detection predicts future ipsilateral stroke risk in patients with symptomatic carotid stenosis (Markus HS, et al.; King A, et al.). A recent study of patients with asymptomatic carotid stenosis demonstrated that MES predicted subsequent ipsilateral stroke and TIA, and also ipsilateral stroke alone, and that it is helpful in selecting patients who will benefit from carotid endarterectomy (Markus, HS et al.).

Identification of active embolization provides crucial patho­physiological information to the neurologist and can also aid in the selection of tailored therapy aimed at reducing the risk of stroke. Emboli from different sources have unique compositions and re­quire specific therapy, such as antiplatelet agents for emboli from large artery atherosclerotic plaque and anticoagulants for cardiac emboli.

Future advances in TCD technology will permit full automa­tion and better identification of the composition and size of circu­lating embolic materials, thus improving its value for patients with cerebrovascular disease.

Contact Colleen Douville, RVT, at colleen.douville@swedish.org or 206-320-4080, for more information about TCD for detec­tion of cerebral microemboli.

 

Emerging concepts in vascular neurology: TIA clinics help prevent strokes and unnecessary hospital admissions

Michael Fruin, ARNP, Swedish Neuroscience Institute

Tom Jaspee placed an anxious call to Dr. Lewis’s office at 9 a.m. sharp. He didn’t give many details, other than to say his wife was worried about problems he was having with his speech the previous night. Later that morning in Dr. Lewis’s office, Tom said he had trouble getting his thoughts out for a few minutes. He said he felt fine im­mediately afterwards and didn’t want to raise a ruckus. Tom’s wife added that his right face drooped and the episode took al­most 30 minutes to clear up. She was wor­ried that Tom had suffered a stroke.

Dr. Lewis was well aware of Tom’s high risk of stroke following his transient isch­emic attack (TIA). Realizing that he could not manage this urgent issue in his office, Dr. Lewis sent the patient to the emergency room and after a six-hour stay, Tom was admitted as an inpatient for a 24-hour ob­servation and evaluation.

This mock case study highlights the role a TIA clinic might have played in avoiding an emergency room visit and hos­pitalization, while still providing the TIA patient the necessary urgent care.

While hospital admission is appropri­ate for the subset of patients at high risk for having a stroke after TIA, significant num­bers of emergency room visits and admis­sions could be avoided by a recent advance in evaluating patients in a TIA clinic. TIA clinics are being pioneered in the United Kingdom, where patients with TIA can be seen by a stroke specialist in an urgent-care clinic setting in which a standardized pro­tocol of neurologic evaluation and diagnos­tic testing is administered.

The effectiveness of the TIA clinic is supported by findings from the EXPRESS Trial (Luengo-Fernandez R, et al.). In this trial, there was an 80 percent reduction of 90-day stroke risk when TIA and minor stroke patients received urgent evaluation and treatment in a standardized urgent-care clinic setting. Patients at high risk of stroke, such as those with high-grade ste­nosis of the internal carotid artery or with atrial fibrillation, are admitted to the neurology service as indicted. Patients at low risk of stroke receive patient education and a stroke prevention plan is implemented.

Reference

Luengo-Fernandez R, Gray AM, Rothwell PM. “Effect of urgent treatment for transient ischaemic attack and minor stroke on disability and hospital costs (EXPRESS study): a prospective population-based sequential comparison.” Lancet Neurology 8:235-243. 2009.

.