What is a key finding in viral meningitis on lumbar puncture?

In viral meningitis, a lumbar puncture, or spinal tap, typically reveals an increase in lymphocytes, which is a key finding. This is in contrast to bacterial meningitis, where neutrophils predominately increase. Lymphocytes are a type of white blood cell that play a crucial role in the body's immune response, particularly in viral infections. The increase in lymphocytes in the cerebrospinal fluid (CSF) indicates that the body is mounting an immune response to a viral pathogen.

In addition to the increase in lymphocytes, other findings in viral meningitis may include a normal glucose level and a modestly elevated protein level; however, the significant increase in lymphocytes is a hallmark differentiator for viral infections when analyzing CSF. This helps medical professionals distinguish between viral and bacterial meningitis, as the treatment and clinical management for these two conditions differ substantially.