ABSTRACT
Laboratory techniques for the diagnosis of central nervous system (CNS) infections
are rapidly improving but at present have limitations that necessitate our guarded
enthusiasm. Enteroviruses are the most common infectious agents of viral meningitis
for which an etiology can be determined, and it is anticipated that the use of the
reverse transcriptase polymerase chain reaction (RT-PCR) technique should significantly
improve the identification of the etiologic agent of aseptic meningitis. The combination
of the polymerase chain reaction technique with laboratory methods for the determination
of intrathecal antibody production to herpes simplex virus and varicella-zoster virus
have improved the rapidity with which these viral infections can be diagnosed. The
pearls and pitfalls of the use of these laboratory techniques in the diagnosis of
viral meningitis, recurrent meningitis, and focal encephalitis are included. Recommendations
for the empiric therapy of bacterial meningitis in children and adults have changed
because of the emergence of penicillin and cepha-losporin-resistant pneumococcal organisms.
The currently recommended antibiotics and their dosages are included. The evidence
for the efficacy of dexamethasone therapy in bacterial meningitis is provided. Meningitis
due to Mycobacterium tuberculosis is increasingly recognized, and the initiation of empiric antituberculous
chemotherapy should not await the results of CSF cultures. Toxoplasma encephalitis
and primary CNS lymphoma are the most common cause of mass lesions in patients with
HIV, and the diagnostic techniques to distinguish between these two infections is
reviewed. A short discussion of the best test for the diagnosis of neurosyphilis is
provided.
Keywords
Central nervous system infectious diseases - meningitis - encephalitis
