Can meningitis cause demyelination?

Meningitis and Demyelination: The Connection

Yes, meningitis can cause demyelination in the central nervous system. The inflammatory processes triggered during meningitis can lead to various demyelinating conditions through both direct and indirect mechanisms.

Mechanisms of Demyelination in Meningitis

• Meningitis can be associated with acute demyelinating processes, particularly when temporally related to a prior infection, known as acute disseminated encephalomyelitis (ADEM) 1
• Inflammatory responses during meningitis can trigger autoimmune reactions targeting myelin, leading to demyelination 1
• Both viral and bacterial meningitis can be associated with subsequent demyelination through post-infectious autoimmune mechanisms 2

Types of Demyelinating Conditions Associated with Meningitis

• Acute Disseminated Encephalomyelitis (ADEM): A post-infectious demyelinating condition that can follow meningitis 1, 2
• Tumefactive demyelination: Large demyelinating lesions that can occur following infectious processes including tuberculous meningitis 3
• Transverse myelitis: Acute inflammation of the spinal cord causing demyelination, reported following Streptococcus pneumoniae meningitis 2
• MOG antibody-associated demyelination: Cases of aseptic meningitis with demyelinating lesions associated with myelin oligodendrocyte glycoprotein antibodies have been reported 4

Clinical Presentations

• Patients may present with neurological deficits that develop during or after recovery from meningitis 2
• Symptoms can include motor deficits (12%), cognitive defects (9%), and visual loss (6%) 1
• Demyelinating lesions may be visible on MRI as T2 and FLAIR hyperintense areas 4
• Some patients may develop recurrent episodes of meningitis associated with central nervous system demyelination 5

Diagnostic Approach

• MRI is the imaging modality of choice to detect demyelinating lesions 1
• Early MRI is recommended as it may show abnormalities in approximately 90% of patients with encephalitis within 48 hours of admission 1
• Cerebrospinal fluid analysis may show elevated white cell count and protein, indicating inflammation 1, 4
• In cases of suspected demyelination following meningitis, testing for autoantibodies such as MOG antibodies may be warranted 4

Management Considerations

• Corticosteroids are often effective in treating post-infectious demyelination 3, 4, 2
• For viral encephalitis with suspected demyelination, intravenous aciclovir should be started if initial CSF and/or imaging findings suggest viral encephalitis, and definitely within 6 hours of admission 1
• In bacterial meningitis with subsequent demyelination, appropriate antimicrobial therapy for the underlying infection followed by immunomodulatory treatment may be necessary 2
• Plasma exchange therapy has been used in severe cases of myelitis following infection 1

Common Pitfalls and Caveats

• Demyelinating disorders may be misdiagnosed as recurrent or treatment-resistant meningitis 6, 5
• Non-infectious, autoimmune causes of meningitis should be considered when patients fail to respond to antimicrobial treatments 6
• The clinical presentation may not always correlate with the location of radiological lesions, making diagnosis challenging 2
• Differentiating between infectious meningitis and autoimmune demyelination with meningeal involvement is crucial as their long-term management differs significantly 6

In conclusion, clinicians should be aware of the potential for demyelination following meningitis and consider appropriate neuroimaging and immunological testing when patients develop new neurological symptoms during or after recovery from meningitis.