Looking for Lyme in the nervous system.
Physicians have suspected Lyme disease as the culprit behind an assortment of central nervous system (CNS) ailments. Some of these illnesses, such as meningitis, are known to result from infection with the Lyme-causing bacterium, but others may be coincidental. Now, for the first time in North America, researchers have demonstrated that analysis of spinal fluid can provide "a fairly straightforward way to fell whether someone's CNS symptoms are due to Lyme infection," says study leader John J. Halperin, a neurologist at the State University of New York at Stony Brook.
The study, involving 85 patients with antibodies to the bacterium in their blood, offers the first direct evidence that active Lyme-causing bacteria in the central nervous system can trigger a brain disorder, or encephalopathy, that results in the cognitive and memory deficits observed in many Lyme patients. The researchers found that many study subjects diagnosed with encephalopathy harbored the antibodies in their spinal fluid as well as in their blood. These patients' Lyme disease symptoms improved substantially after antibiotic treatment, the team reports in the June NEUROLOGY.
The new results also strongly suggest that Lyme disease does not cause multiple sclerosis, a finding corroborated by Patricia K. Coyle, also at Stony Brook, in a separate study described in the same issue. And they hint that Lyme disease does not cause psychiatric ailments such as depression and psychosis. The study is the first to test spinal fluid in groups of patients with five different classes of nervous system abnormalities to determine which might stem from Lyme disease.
"There's this notion that Lyme [disease] can cause everything under the sun. I'm trying to establish that there are very specific patterns to what Lyme produces," Halperin told SCIENCE NEWS.
Spinal taps are seldom used to diagnose Lyme disease in North America, and Halperin contends that most labs analyzing spinal fluid for Lyme-related antibodies do not use the optimal dilution. U.S. physicians typically look for a positive result from the somewhat unreliable blood-antibody test, coupled with the presence of telltale symptoms of Lyme disease (SN: 3/25/89,p.184), to infer that the Lyme-causing bacterium led to a CNS disorder, Halperin says.
Halperin's method enables physicians to distinguish between people whose spinal fluid antibodies originated in the bloodstream and those who are producing the antibodies within the central nervous system. This should result in more appropriate treatment, because people with the active CNS infection should receive antibiotics intravenously rather than orally, says Michael F. Finkel of the Western Wisconsin Lyme Disease Center in Eau Claire.
Halperin and his co-workers did spinal taps on 53 patients and tested various patients with brain magnetic resonance imaging and "evoked potentials," a measure of electrical activity in stimulated sensory nerve cells. They found abnormal evoked potentials in the multiple sclerosis patients only. Magnetic resonance images were abnormal in five of six multiple sclerosis patients and in seven of 17 encephalopathy patients but were normal in all others, they report.
The spinal tap was the only method yielding an abnormal result in a significant number of the patients with CNS disorders, Halperin says. The team found that 12 of 18 patients with encephalopathy, meningitis or a focal CNS disease (localized in one brain area) had Lyme-related antibodies in their spinal fluid. In contrast, none of the patients with either multiple sclerosis or a psychiatric illness, and only two of 24 patients with peripheral nervous system ailments, showed spinal fluid antibodies.
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|Title Annotation:||Lyme disease|
|Date:||Jun 24, 1989|
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