WINSTON-SALEM, NC - A group of German neurologists reported today that ultrasound was more than 90 percent effective in distinguishing between ischemic and hemorrhagic stroke under emergency treatment conditions.
Dr. Mathias Maurer, senior resident in neurology at the University of Wurzburg in Wurzburg, Germany, said that a type of ultrasound called transcranial color-coded duplex sonography (TCDS) correctly identified the stroke type of 55 of 60 emergency stroke patients whose intracranial blood vessels could be imaged with ultrasound in a blinded comparison against computed tomography.
Maurer and other investigators of Wurzburg's Neurosonology Research Group will present their findings August 14th at the International Neursonology '97 meeting here sponsored by the World Federation of Neurology and the Bowman Gray School of Medicine of Wake Forest University.
While the results showed the CT is still the best imaging technique for making the critical distinction between ischemic and hemorrhagic stroke, Maurer said that the study shows that TCDS has a place in emergency stroke treatment--particularly in countries where CT machines are not readily available.
"When there is a CT machine in virtually every hospital in America, it is hard for Americans to understand that is not always the case elsewhere in the world," he said.
"In Germany, there may not be a CT machine in every hospital, but there is an ultrasound machine. With a clinical exam, you can do it (distinguish between strokes caused by clots or bleeding) in 91.6 percent of the cases and make the diagnosis in minutes."
Distinguishing between ischemic and hemorrhagic strokes is critical as stroke is increasingly viewed as the neurologic equivalent of a heart attack and such clot-busting drugs as t-PA, recently approved by the U.S. Food and Drug Administration, are employed in emergency rooms to dissolve the blockages and restore blood flow to the brain.
Indicated for use in a patients with ischemic stroke caused by bits of plaque, blood clots and other material that shut off blood flow to the brain, t-PA and other thrombolytics can increase bleeding and prove fatal to patients if incorrectly employed against hemorrhagic strokes caused by ruptured vessels.
In the Wurzburg study, sonographers correctly determined stroke type in 55 of the 60 patients whose skull structures were suitable for intracranial ultrasound. (Their stroke types had previously been confirmed using CT scanning.) Ultrasound could not accurately diagnose the other five patients because their problems were either high in the parietal lobe of the brain, where soundwaves from the probe cannot reach due to geometry, or microangiography, in which the brain's color is too uniform for sonographers to spot the hot white echoes that usually indicate bleeding.
Maurer said that 10 other patients could not be imaged because of bony tissue increasing the distance between layers of bone in the skull--a condition sonographers call a lack of an acoustic bone window. He said that about 10 to 15 percent of all elderly patients fall into this group.
Still, Maurer said that the results show ultrasound to be a fast and effective test in most cases and therefore useful in acute stroke treatment.
"Those patients who cannot be diagnosed can be sent to another hospital with a CT," he said. "If you think it may be a big bleed, you can send the patient to another hospital. Ultrasound is very important because you can sonify the vessels.
"Especially when you think of countries like India and China, where CT is very expensive, TCDS is another option that will become even more reliable in the future."
For further information, call Mark Wright (email: mwright@bgsm.edu) or Bob Conn (email: rconn@bgsm.edu) at 910-716-4587.
Once the International Neurosonology '97 has begun on August 13, call the conference press room at 910-724-6923.