Meningitis: Pathology, Causes, Symptoms, Diagnosis and Treatment, Animation
Meningitis: pathology, causative agents, symptoms, diagnosis and treatments. This video is available for instant download licensing here:
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Voice by : Marty Henne
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Meningitis is inflammation of the meninges - the membranes that enclose the brain and spinal cord. The meninges consist of 3 layers: dura, arachnoid, and pia mater. Between the arachnoid and pia mater is the subarachnoid space containing blood vessels that supply the brain. Meningitis typically affects the arachnoid, subarachnoid space, and pia mater.
Meningitis can be caused by a large number of various organisms. Different age groups are susceptible to different causative agents. In the majority of cases, the offending organism originates from an infection elsewhere in the body and gets to the central nervous system by several ways:
- it may invade the bloodstream, then disrupt the blood-brain barrier to gain access to the brain,
- or, it may spread directly by way of the nose, throat, or ear, following a respiratory or ear infection.
- some organisms can reach the brain by travelling along olfactory or peripheral nerves.
Early symptoms may include high fever, intense headache, and stiff neck. Patients may also experience altered mental status such as drowsiness, confusion, and delirium. If left untreated, infection may spread to the underlying brain tissue, causing loss of sensory and motor functions, coma or even death. Depending on the causative agent and patient’s age, death may occur as soon as within hours. Survivors may also be left with lifelong disability due to brain damage.
Bacterial meningitis is most serious, with Streptococcus pneumoniae causing the highest mortality and morbidity. It’s a medical emergency requiring immediate diagnosis and treatment.
A hallmark of bacterial meningitis is the presence white blood cells and bacteria in the cerebrospinal fluid - the CSF. Samples of the CSF can be obtained by making a lumbar puncture in a spinal tap procedure.
Meningitis with a negative microbiologic workup is known as aseptic meningitis and is most commonly caused by a virus. Most cases of viral meningitis are milder and self-limited.
Treatments for bacterial meningitis include prompt initiation of empiric antibiotic therapy, followed by directed antibiotic therapy once the pathogen is identified. Steroids, such as dexamethasone, are used to reduce inflammation. Patients must be closely monitored and treated for systemic and neurologic complications.
Viral meningitis may be treated with antiviral therapy, if available.
There are also specific treatments for fungal and parasitic meningitis.
Several vaccines are available for protection against most common types of meningitis.