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Air bubble drug illuminates blocked brain artery, prevents stoke damage
WINSTON-SALEM -- To Dr. Mathias Maurer, a senior neurology resident at a downtown German hospital, what happened is a textbook case for using ultrasound in acute stroke treatment: 63-year-old city resident is rushed to the nearby emergency room by paramedics shortly after developing right-sided weakness and other classic stroke symptoms.
Transcranial ultrasound reveals what could be the signs of a blockage in the cerebral arteries, but a buildup of bony tissue widening the gap between bone layers in the skull known as a poor acoustic bone window -- found in about 10 to 15 percent of elderly patients like him -- masks the needed information about the brain's vessels.
So neurologists quickly order an injection of Levovist, an ultrasound contrast agent, to try to clear up the sonic noise and reveal the basal arteries in question. The drug, air bubbles encased in sugar particles, does its job.
Excellent reflectors of sound waves, the air bubbles reflect the signal from the ultrasound probe to reveal the arteries and the problem: a blocked portion of the middle cerebral artery causing an ischemic stroke. Doctors dissolve the stroke-causing clot with 100 milligrams of the thrombolytic rTPA.
Blood flow is restored to the brain. Patient recovers fully. All within 40 minutes of admission to the hospital.
Maurer and colleagues in the Neursonology Research Group at the University of Wurzburg in Wurzburg, Germany, presented the case study today at the International Neurosonology 97 meeting here sponsored by the World Federation of Neurology and the Bowman Gray School of Medicine of Wake Forest University.
While the Wurzburg case is matched by similar stories in American academic medical centers and others in the world, Maurer said that such cases still don't occur often enough. The real-life drama comes amid a growing consensus by doctors that the window of opportunity for emergency stroke treatment with thrombolytics and other therapies may be as narrow as three hours after the first onset of symptoms.
"He was admitted half an hour after the onset of symptoms," Maurer said. "We didn't get a radiologist but were able to thrombolyse [dissolve] the occlusion very quickly with this method. We had a secure diagnosis and didn't need angiography, which would have taken an additional hour.
"You have to get the patient prepped, explain the procedure to them. What happened is not unique to our hospital, but does show that one can do more with ultrasound. Ultrasound has a big potential for the acute stadium of stroke."
While treating the patient with thrombolytic, Maurer said that both transcranial ultrasound and the contrast agent were used, both to watch for bleeding and other potential risks of thrombolytic drugs and to observe the drug's effect on reopening the blocked artery.
No bleeding occurred;the drug reopened the artery completely; and the patient recovered from his neurologic deficits with slight numbness in his fingertips the only reminder of the stroke.
"It is very rare to have such a patient," Maurer said. "There are no contraindications for this use of ultrasound and no side effects. It's very cost effective and, with a secure diagnosis, there's no need for more invasive procedures with greater risks to the patient." # For further information, call Mark Wright (email: [email protected]) or Bob Conn (email: [email protected]) at 910-716-4587. Once International Neurosonology '97 has begun on August 13, call the conference press room at 910-724-6923.
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