In a paper to be presented August 15th at an international medical conference in Winston-Salem, N.C., Dr. B. Martin Eicke of Johannes Gutenberg University in Mainz, Germany, reported that 80 percent of the patients he studied continued to have microembolisms in their brains up to four weeks after having been treated with antibiotics.
Microembolisms are small particles in the blood. In the brain they can induce brain abscesses and lesions that can lead to stroke.
In the case of endocarditis the microembolisms result from bacteria growing on the lining of the heart and its valves. Standard practice is treatment with antibiotics. The new research suggests that antibiotics alone are not sufficient because microembolisms continue to form, Eicke said.
"Physicians should be aware that even if they have treated the endocarditis there's still an increased risk of stroke for a prolonged time," Eicke said. "So these patients should be followed very carefully."
Bacterial endocarditis is caused by systemic bacterial infection such as streptococcus (the cause of strep throat) or staphylococcus. The disease killed 2,048 Americans in 1993, according to the American Heart Association. About 22,000 Americans suffered from the disease in 1994, the latest year for which statistics are available.
Additional research is needed to determine what additional treatment would reduce the risk of stroke in these patients, Eicke said. He suggested that one possible approach may be to treat patients with blood thinners.
Eicke will present his findings at International Neurosonology '97. The conference, which is being held August 12 through August 17, will draw doctors and researchers from around the world to present the latest research on the medical uses of ultrasound. It is being sponsored by the World Federation of Neurology and the Bowman Gray Medical School of Wake Forest University.
Using transcranial Doppler ultrasound, Eicke and others studied 10 patients suffering from acute bacterial endocarditis for four weeks after they were admitted to the hospital. By passing ultrasound waves through the patients' brains, the researchers were able to use the higher density of microembolisms to detect their presence.
All 10 were treated with antibiotics upon admission. Six of the 10 had microembolisms during an initial screening within 72 hours of admission. After one week, four patients had microembolisms, including two who had none during the initial screening.
Two weeks after admission, three patients continued to suffer from microembolisms. At four weeks, two patients tested positive for microembolisms even through they had none at two weeks. None of the patients died. However, the patient with the most microembolisms in the first three screenings recovered poorly and suffered from persistant neurological problems.
To search for microembolisms, the study authors used a relatively new form of ultrasound called transcranial Doppler. Patients were exposed to the ultrasound for 45 minutes during each session.
Transcranial Doppler is one of several new forms of ultrasound that are being used for diagnostic purposes. Unlike X-rays, which pose a radiation hazard, and blood dyes, which require insertion of a catheter up into the blood vessel, ultrasound gives physicians a safe, non-invasive method for looking inside the body.
Eicke said that it is only because of ultrasound that medical researchers can now look for microembolisms.
For further information, call Mark Wright (email: mwright@bgsm.edu) or Bob Conn (email: rconn@bgsm.edu) at 910-716-4587. Once International Neurosonology '97 has begun on August 13, call the conference press room at 910-724-6923.