Page 28 - Human Lyme Neuroborreliosis

12 David S. Younger

synthesis of anti-B. burgdorferi antibody was considered positive when the
ratio of CSF to serum OD was ? 1.0 [20]. Neuropsychological evaluation
consisted of measures to assess global intellectual ability, verbal fluency,
conceptual reasoning, visual spatial ability, and memory functioning. In
addition, subjects were screened for depressive symptoms and fatigue by
appropriate scales. The results of neuropsychological testing were compared to
a cohort of 10 healthy controls matched for age and years of education.
Altogether, neuropsychological evaluation revealed evidence of cognitive
impairment in 9 (60%) patients that was rated as mild in 1, moderate in 6, and
severe in 2 patients. In 6 other patients, the neuropsychological evaluation was
normal. CSF in 11 patients showed positive anti-B. burgdorferi titers that
exceeded the negative serum cutoff values in 5 patients, only one of whom
was considered positive for intrathecal synthesis; and in 6 whose CSF
antibody titer was less than the negative serum cutoff value. MRI of the brain
performed in 8 patients showed normal results in 6, while 2 patients
demonstrated one or more small areas of increased signal intensity on T2-
weighted images in subcortical white matter. The study and control groups
differed significantly in verbal memory functioning with the former showing
substantially poorer performance. Among the 9 patients who received oral
antibiotic therapy, 3 demonstrated normal cognitive functioning and 6 showed
impaired cognitive function. Of the 6 patients treated with intravenous
antibiotic therapy, cognitive therapy was equally normal and impaired in 3
patients respectively. There was no relation between neuropsychological
function and either MRI or CSF findings, however depression and fatigue
were both correlated with memory performance, with depression inversely
related to memory deficits. The authors conceded that patient selection might
have been biased and generalizability of the results was limited. In the absence
of a correlation between encephalopathy and intrathecal production of anti-B.
burgdorferi antibody, the authors [36] suggested that encephalopathy might
have been caused by the immunological consequences of systemic infection
including release of pathogenic cytokines or other toxic-metabolic factors.
Since some of the treated patients had entirely normal neuropsychological
results but high scores on a depressive symptom scale, the encephalopathy in
such patients might have been confounded by concomitant depression.

The next year, Luft and coworkers [37] conducted a prospective study of
CNS involvement in acute disseminated B. burgdorferi infection by
measurement of Borrelia-specific deoxyribonucleic acid (DNA) using the
polymerase chain-reaction (PCR) assay with comparison to standard
serological tests. Among 12 patients with acute disseminated Lyme borreliosis

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