| Meningitis | |
|---|---|
 | |
| Meninges of the central nervous system: dura mater, arachnoid mater, and pia mater. | |
| Specialty | Infectious disease, neurology |
| Symptoms | Fever, headache, neck stiffness[1] |
| Complications | Deafness, epilepsy, hydrocephalus, cognitive deficits[2][3] |
| Causes | Viral, bacterial, other[4] |
| Diagnostic method | Lumbar puncture[1] |
| Differential diagnosis | Encephalitis, brain tumor, lupus, Lyme disease, seizures, neuroleptic malignant syndrome,[5] naegleriasis[6] |
| Prevention | Vaccination[2] |
| Medication | Antibiotics, antivirals, steroids[1][7][8] |
| Frequency | 8.7 million (2015)[9] |
| Deaths | 379,000 (2015)[10] |
Meningitis is an acute inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges.[2] The most common symptoms are fever, headache, and neck stiffness.[1] Other symptoms include confusion or altered consciousness, vomiting, and an inability to tolerate light or loud noises.[1] Young children often exhibit only nonspecific symptoms, such as irritability, drowsiness, or poor feeding.[1] If a rash is present, it may indicate a particular cause of meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a characteristic rash.[2][3]
The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs.[4] Meningitis can be life-threatening because of the inflammation's proximity to the brain and spinal cord; therefore, the condition is classified as a medical emergency.[2][8] A lumbar puncture, in which a needle is inserted into the spinal canal to collect a sample of cerebrospinal fluid (CSF), can diagnose or exclude meningitis.[1][8]
Some forms of meningitis are preventable by immunization with the meningococcal, mumps, pneumococcal, and Hib vaccines.[2] Giving antibiotics to people with significant exposure to certain types of meningitis may also be useful.[1] The first treatment in acute meningitis consists of promptly giving antibiotics and sometimes antiviral drugs.[1][7] Corticosteroids can also be used to prevent complications from excessive inflammation.[3][8] Meningitis can lead to serious long-term consequences such as deafness, epilepsy, hydrocephalus, or cognitive deficits, especially if not treated quickly.[2][3]
In 2015, meningitis occurred in about 8.7 million people worldwide.[9] This resulted in 379,000 deaths—down from 464,000 deaths in 1990.[10][11] With appropriate treatment the risk of death in bacterial meningitis is less than 15%.[1] Outbreaks of bacterial meningitis occur between December and June each year in an area of sub-Saharan Africa known as the meningitis belt.[12] Smaller outbreaks may also occur in other areas of the world.[12] The word meningitis comes from the Greek μῆνιγξ meninx, "membrane", and the medical suffix -itis, "inflammation".[13][14]