American Board of Psychiatry and Neurology (ABPN) Practice Exam

What cerebrospinal fluid finding is indicative of aseptic meningitis?

1. Moderately increased lymphocytes, decreased glucose

2. Slightly increased lymphocytes, normal glucose

3. Highly increased neutrophils, decreased glucose

4. Absent or few lymphocytes, normal glucose

The correct answer is: Slightly increased lymphocytes, normal glucose

The finding indicative of aseptic meningitis involves slightly increased lymphocytes and normal glucose levels in the cerebrospinal fluid (CSF). Aseptic meningitis is typically caused by viral infections, which tend to elicit a lymphocytic response rather than a neutrophilic one commonly associated with bacterial infections. In cases of aseptic meningitis, the lymphocytic predominance is a hallmark feature, and the glucose level remains within the normal range because, unlike bacterial meningitis, the organisms that primarily cause aseptic meningitis do not consume glucose in the CSF to a significant degree. This is in contrast to bacterial meningitis, where the CSF typically shows a marked increase in neutrophils and a decrease in glucose due to the consumption of glucose by the bacteria and the inflammatory process. Thus, the combination of slightly increased lymphocytes and normal glucose levels is characteristic of aseptic meningitis, validating the selection made.