Meningitis is a condition in which the protective membranes (meninges) around the brain and spinal cord become inflamed, potentially causing damage to the central nervous system. To diagnose meningitis, doctors perform a lumbar puncture to collect cerebrospinal fluid (CSF) for testing.

Meningitis can have different causes, including bacterial, viral, fungal, parasitic, or autoimmune disorders. Bacterial meningitis is a medical emergency that requires prompt treatment with antibiotics and can be caused by various types of bacteria, such as Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae.

Other types of meningitis, such as those caused by viruses, fungi, parasites, or autoimmune disorders, are usually less severe and may require less intense treatment, or sometimes no treatment at all.

Cross section of a head showing the brain which fills most of the space inside the skull. The brain is separated from the skull by a layer of fluid called cerebrospinal fluid (CSF) and a layer of meninges. Below the brain is a yarn-like structure that extends down from the head to the spine, forming the spinal cord.

Figure 1: Figure 1: Cross section of a head showing the brain, spinal cord, CSF and meninges