Aseptic meningitis is a condition in which the layers lining of the brain, or meninges, become inflamed and a bacterial source is not to blame.

Aseptic meningitis often results as a side effect of medications or vaccines, and can be an early finding in autoimmune disease.

Meningitis is diagnosed on a history of characteristic symptoms and certain examination findings (e.g. Kernig’s sign). Investigations should show an increase in the number of leukocytes present in the cerebrospinal fluid (CSF), obtained via lumbar puncture.