70% of subarachnoid hemorrhage patients develop vasospasm, a major complication & source of morbidity.
87% of all strokes are ischemic strokes, where blood flow to the brain is blocked.
A right-to-left shunt (RLS) is a known risk factor for stroke as it provides a conduit for a venous clot to travel to the brain.
A patent foramen ovale (PFO), also known as a hole in the heart, is present in 25% of the population and is the most common source of RLS.
Ask the person to smile. Does one side droop?
Ask the person to raise both arms. Does one arm drift down?
Ask the person to repeat a simple sentence. Do they slur?
Time is brain. Call 911 right away.
TCD is a noninvasive and painless ultrasound method that uses sound waves to evaluate blood flow in and around the brain. There is no special contrast or radiation involved in the test.
During the TCD exam, high frequency sound waves are transmitted through the tissues of the skull. These sound waves reflect off blood cells moving within the blood vessels, allowing the TCD system to measure the rate and direction of blood flow in the main cerebral arteries known as the Circle of Willis.
While most forms of ultrasonography deliver images of the tissue studied, TCD delivers audible sounds that can be heard, recorded, and examined.
Physicians recommend this highly accurate and sensitive test for patients with stroke or stroke-like symptoms. It is used to assist in the diagnosis of a wide range of conditions affecting blood flow to, and within, the brain.
For assessment of cerebral vasospasm after spontaneous or traumatic subarachnoid hemorrhage (SAH)
Delivers continuous real-time data on embolic activity and blood flow to enable immediate treatment decisions
Assessment of vascular shunting to provide insight into the underlying cause of a stroke
The transtemporal windowis a thin spot in the skull that allows the ultrasound waves to pass through through the bone
Similar to other ultrasound-based tests, TCD uses sound waves to evaluate structures inside the body, in this case the blood flow in the brain.
However, the brain is protected by the skull and ultrasound waves cannot easily pass-through bone. TCD testing requires the operator to be able to find the transtemporal window (thin part of the bone in the skull) that will allow the ultrasound waves to penetrate the skull and find the blood vessels that need to be evaluated.
Finding this window is one of the most difficult parts of the exam. It is unique to this form of ultrasound, resulting in a high learning curve compared to other ultrasound tests.
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