neurologic disorders
Lumbar Puncture (Spinal Tap)
CSF staining, testing, and culture
If infection is suspected, the centrifuged CSF sediment is stained for the following: Bacteria ( Gram stain ) Tuberculosis (TB) (acid-fast stain or immunofluorescence) Cryptococcosis species (India ink) Larger amounts of fluid (10 mL) improve the chances of detecting the pathogen, particularly acid-fast bacilli and certain fungi, in stains and cultures. In early Meningococcal Diseases or severe Latex particle agglutination and coagglutination tests may allow rapid bacterial identification, especially when stains and cultures are negative (eg, in partially treated meningitis). CSF should be cultured aerobically and anaerobically and for acid-fast bacilli and fungi. Except for enteroviruses, viruses are seldom isolated from the CSF. Viral antibody panels are available. Venereal Disease Research Laboratories (VDRL) testing and cryptococcal antigen testing are often routinely done. Polymerase chain reaction (PCR) tests for Herpes Simplex Virus (HSV) Infections and other CNS pathogens are increasingly available. Specialized CSF tests can be done; they include tests for specific antibodies in various disorders, such as autoimmune encephalitis (see alsoThe Diagnosis and Treatment of Autoimmune Encephalitis). The autoimmune encephalitides are antibody-mediated brain disorders that target specific neuronal antigens. 