2-Minute Neuroscience: Meningitis

Meningitis is a potentially deadly disease characterized by an inflammation of the meninges. In this video, I discuss the meninges and the pathophysiology of meningitis.

TRANSCRIPT:

The term meninges refers to 3 membranes that surround the brain and spinal cord: the dura mater, the arachnoid mater, and the pia mater. The meninges protect and provide structural support for the brain as well as contain cerebrospinal fluid. Meningitis is an inflammation of the meninges. This inflammation is typically caused by an infection, although there are non-infectious causes of meningitis as well. A variety of pathogens can cause meningitis, but the most severe cases tend to involve bacterial infections.

Although the central nervous system is separated from the bloodstream by barriers like the blood-brain barrier and blood-cerebrospinal fluid barrier, meningitis can occur when pathogens evade these types of barriers and enter the meninges. When a pathogen enters the cerebrospinal fluid, an immune response causes the inflammation that characterizes meningitis. As a consequence of the immune response, the blood-brain barrier is made more permeable. This causes an influx of white blood cells and constituents of blood plasma into the cerebrospinal fluid, which contributes to inflammation and increases the volume and viscosity of the cerebrospinal fluid. These changes contribute to the development of cerebral edema, or the accumulation of fluid in the brain, as well as to the build-up of the pressure inside the skull, known as intracranial pressure. The increased intracranial pressure can disrupt cerebral blood flow and result in damage to brain tissue. Common symptoms of meningitis include headache, neck stiffness, fever, and altered mental status, but the disease can cause serious long-term complications or death. A lumbar puncture, or spinal tap, is typically done to diagnose meningitis. Although treatment will vary depending on the cause of the disease, antibiotics are often started before a diagnosis is made if bacterial meningitis is suspected, as bacterial meningitis is typically fatal if left untreated.

REFERENCES:

Hasbun R, van de Beek D, Brouwer MC, Tunkel AR. 2010. Actue Meningitis. In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas, and Bennett’s Principles and Practice of Infectious Diseases, 7th ed. Philadelphia: Elsevier.

Kurrus TA, Tauber MG. 2012. Meningitis. In: Jong EC, Stevens DL, eds. Netter’s Infectious Diseases. Philadelphia: Elsevier.

Sáez-Llorens X, McCracken GH Jr. Bacterial meningitis in children. Lancet. 2003;361(9375):2139-2148. doi:10.1016/S0140-6736(03)13693-8

Scheld WM, Koedel U, Nathan B, Pfister HW. Pathophysiology of bacterial meningitis: mechanism(s) of neuronal injury. J Infect Dis. 2002;186 Suppl 2:S225-S233. doi:10.1086/344939