Last reviewed: 6 Jan 2023
Last updated: 25 Oct 2022

This page compiles our content related to meningitis. For further information on diagnosis and treatment, follow the links below to our full BMJ Best Practice topics on the relevant conditions and symptoms.

Introduction

Condition
Description

Viral meningitis is the most common cause of aseptic meningitis. Causative agents include human enteroviruses (most commonly), herpes simplex virus, mumps, varicella zoster virus, arboviruses such as West Nile, HIV, and (rarely) influenza.[2][3] Distinguishing viral from bacterial meningitis can be difficult and empirical antibiotic therapy might be necessary while awaiting the results of cerebrospinal fluid analysis.[1] Infants, immunocompromised patients, and those infected with herpes viruses or arboviruses are more likely to have complications. However, viral meningitis is typically self-limiting without serious sequelae.

Bacterial meningitis is a rare but serious inflammation of the meninges caused by various bacteria. Streptococcus pneumoniae, Neisseria meningitidis, andHemophilus influenzae type b (Hib) are the predominant causative pathogens in both adults and children.[4] It commonly affects extremes of age (<2 months and >60 years) because of impaired or waning immunity.[5] Rapid assessment and prompt antimicrobial therapy are essential.

Meningococcal infections are caused by Neisseria meningitidis, a gram-negative diplococcus that colonizes the nasopharynx. Bacteria invade the bloodstream or spread within the respiratory tract.[6] Meningococcal infection may progress rapidly to septic shock with hypotension, acidosis and disseminated intravascular coagulation. Prompt evaluation and treatment are essential, as the fatality rate are risk of severe complications are high.

A progressive, life-threatening, chronic or subacute meningitis that is most commonly caused by Cryptococcus species.[7] It is often accompanied by systemic involvement in immunosuppressed patients. Infants and neonates are also at increased risk. Other causative agents include Coccidioides species, Candida species, Histoplasma capsulatum, Exserohilum rostratum, Aspergillusspecies, and mucormycosis, but all major fungal pathogens have the capacity to cause meningitis.[8]

Children with acute-onset rash accompanied by fever or systemic signs require urgent evaluation and treatment. One of the most life-threatening differentials is meningococcal septicemia. Other infectious diseases presenting with skin rash in children that can result in meningitis as a complication include, for example, roseola infantum (sixth disease).

An infectious disease caused by Mycobacterium tuberculosis that occurs in organ systems other than the lungs. Almost any organ system may be affected by extrapulmonary tuberculosis, including the lymph nodes, central nervous system, bones/joints, genitourinary tract, abdomen (intra-abdominal organs, peritoneum), and pericardium. Tuberculous meningitis results from hematogenous spread of Mycobacterium tuberculosis with the development of submeningeal or intrameningeal foci called Rich foci. Delays in diagnosis and initiation of therapy are associated with increased mortality.[9]

An acute viral encephalomyelitis caused by negative-sense RNA viruses of the Lyssavirus genus. The virus enters the nervous system through unmyelinated sensory and motor terminals. Clinically, rabies has two forms: encephalitic (furious) and paralytic. Both forms have a prodrome of fever, chills, malaise, sore throat, vomiting, headaches, and paresthesias.

A common sexually transmitted infection caused by the spirochete bacterium Treponema pallidum, subspeciespallidum. Neurosyphilis is characterized by a chronic, insidious inflammation of the meninges, and is caused by central nervous system invasion by treponemes, which may occur at any stage of infection. Early neurosyphilis syndromes are usually the result of meningovascular involvement; infection may be asymptomatic or present with headache, meningism, hearing loss, seizures, or cranial nerve palsies.[10] Late neurosyphilis may occur due to meningovascular involvement or direct infection of the brain and spinal cord parenchyma.

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