Bacterial meningitis is a serious condition, accounting for 80 percent of all meningitis cases, according to the Cleveland Clinic. When left untreated, bacterial meningitis can be a life threatening disease, causing brain tissue to swell, which can affect blood flow in the brain.
Brain Anatomy
The center location for bacterial meningitis is the sub-arachnoid space in the brain, according to the Merck Manual Home Edition. The sub-arachnoid space is in between the meninges, which covers the brain and spinal cord. Specifically, the sub-arachnoid space is between the arachnoid mater (the middle layer of the meninges) and the pia mater (the thin inner layer of the meninges).
Located in the sub-arachnoid space is the cerebrospinal fluid, or CSF. Besides being in the sub-arachnoid space, the Merck Manual Home Edition notes that the CSF also is found through the meninges, as well as in the internal spaces of the brain. The appearance of the CSF is a clear and colorless liquid. The main purpose of the CSF is to cushion the brain and spinal cord, thus acting as a shock absorber during impact to the head. The National Multiple Sclerosis Society adds that the CSF “circulates nutrients and chemicals filtered from the blood and removes waste products.”
Process of Infection
The inflammation in the sub-arachnoid space occurs when the immune cells combat the infection. The Merck Manual Home Edition adds that “severe inflammation can spread to blood vessels within the brain, sometimes causing clots to form.” Obstruction of the blood flow in the brain is another possibility, which can lead to paralysis or stroke. In addition, edema and bleeding can also result from brain tissue damage.
In cases of severe swelling, intracranial pressure can occur. “If these parts [of the brain caused by the intracranial pressure] are pressed through one of the small natural openings in the tissues that separate the brain into compartments, a life threatening disorder called brain herniation results,” according to the Merck Manual Home Edition.
A sample of the CSF, obtained through a spinal tap, can indicate the presence of bacterial meningitis. When first drawn, the normally clear fluid appears cloudy. High pressure in the fluid is another indicator of bacterial meningitis. Doctors may microscopically examine the sample for the presence of bacteria. To determine the appropriate treatment, the CSF sample is cultured for 24 hours, then tested with different antibiotics to see which is the most effective treatment.
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Elizabeth Stannard Gromisch received her bachelor’s of science degree in neuroscience from Trinity College in Hartford, CT in May 2009. She is the Hartford Women's Health Examiner and she writes about abuse on Suite 101.