Viral meningitis Flashcards
What is aseptic meningitis?
Clinical meningitis but not bacterial source
What are possible causes of aseptic meningitis? (8)
Viruses Partially treated bacterial meningitis Listeria TB Autoimmune Malignancy Syphilis Drugs
2 peak ages of viral meningitis?
Neonate and about 5yo
Viruses that cause meningitis (18)
Enteroviruses (echoviruses, coxsackie, parecho, enterovirus 70/71, poliovirus) Herpes viruses (HSV 2, VZV, CMV, EBV, HHV6/7) Arboviruses Mumps HIV Adenovirus Measles Influenza Parainfluenza type 3 Lymphocytic choriomeningitis virus
Pathogenesis of viral meningitis?
colonisation of mucosal surfaces
invasion of epithelial surface
replication in cells
dissemination and cns invasion (cerebral microvascular endothelial cells, choroid plexus epithelium, olfactory nerve)
Inflammation in CNS=symptoms
What are the 3 features of meningism?
Stiff neck
Headache
Photophobia
What signs are present in infants (possibly in the absence of meningism)
Nuchal rigidity
Bulging anterior fontanelle
What are two clinical tests/signs?
Kernig’s sign (hip and knee flexed to 90 degrees, knee can’t be extended due to pain/stiffness in hamstrings)
Brudzinski’s sign (flexing neck causes hips and knees to flex)
What would viral meningitis blood tests show?
WBC count and CRP normal
What 4 investigations?
Bloods (tests and culture, MC&S)
CT head
Lumbar puncture ASAP
Viral PCR
What does the head CT look for?
Raised ICP- contraindicates an LP as removing CSF can cause brain to herniate through foramen magnum (‘coning’) and also to look for other diagnoses
What is the gold standard test for viral meningitis?
Viral PCR
CSF findings in viral meningitis?
Lymphocytic
Protein normal/mildly elevated
Glucose normal/slightly low
Most common and second most common cause of viral meningitis in uk?
Enterovirus
HSV2
Treatment of viral meningitis?
Supportive
If any risk that it is bacterial then IV Abx
NOTIFIABLE
Is aciclovir effective against HSV2 and VZV meningitis?
No evidence that it is
Mollaret’s meningitis is what?
Recurrent aseptic meningitis, major cause is HSV2
4 associated symptoms of HIV meningitis
fever
lymphadenopathy
pharyngitis
rash
Prognosis of viral meningitis
Full recovery expected
4 causes of viral encephalitis that are not also causes of meningitis?
HSV1
Rubella
Rabies
Acute disseminated encephalomyopathy
Major presenting features of encephalitis
Altered mental state Fever Headache Meningism Focal neurology (seizures, weakness, dysphagia, CN palsy, ataxia)
Investigations of viral encephalitis (5)
Blood tests CT MRI LP (MC&S, protein and glucose, viral PCR) EEG
What would EEG show in HSV encephalitis?
75% show abnormal temporal lobe activity
Rx viral encephalitis?
High dose IV aciclovir- start on clinical suspicion as is a medical emergency
CSF results?
Same as viral meningitis
HSV encephalitis prognosis?
High mortality if untreated (70%), even if treated remains high. Best if aciclovir within 4 days
HSE peak age?
50
HSE pathogenesis
Virus moves along neural/olfactory pathways, reactivated in the trigeminal ganglia
Acute focal necrotising encephalitis
What often happens to survivors of HSE?
neurological sequelae e.g. paralysis, speech loss, personality change
What is acute disseminated ecephalomyopathy?
Immune-mediate demyelination of CNS, can follow virus or vaccination.
Clinical features same as encephalitis
CSF findings = viral meningitis
MRI helpful
Rx ADEM
Steroids/immune suppressants
