25 Viral meningitis Flashcards
Differentiate between meningitis and encephalitis.
Meningitis: inflammation of meninges.
Encephalitis: inflammation of brain.
Define aseptic meningitis.
Clinical meningitis with white cell count >5x10^6/L. Negative bacterial culture for CSF.
Epidemiology of viral meningitis:
Neonates and 5 year olds.
Aetiology of viral meningitis. (5)
Enteroviruses (leading) - echoviruses, cockasackie, parecho viruses Herpes: VZV, HSV2>>HSV1. Mumps. HIV. Unknown in 35%.
How do viruses invade the CNS to cause meningitis?
Cerebral microvascular endothelial cells.
Choroid plexus epithelium.
Olfactory nerve.
Clinical presentation of viral meningitis?
Presentation in neonates?
Fever. Headache. Neck stiffness. Photophobia. Possible viral prodrome.
Neonates: nuchal rigidity + bulging anterior fontanelle.
What are the examination findings in viral meningitis?
Kernels sign: hip and knee at 90o, knee cannot be extended.
Brudzinski’s sign. Neck flexion causes hip and knee flexion.
Nuchal rigidity: resistance to neck flexion.
What is a lumbar puncture used for in meningitis?
Why CT beforehand sometimes?
MC&S. Protein. Glucose (+blood glucose). Viral PCR.
CSF removal may cause herniation through foramen magnum.
What are the CSF findings in viral meningitis?
Lymphocytic WCC .
What is the treatment for viral meningitis?
IV antibiotics if bacterial risk.
Supportive therapy - analgesis and antipyretics.
What is the most common cause of viral meningitis in the UK?
Extra symptoms with this cause? (5)
Enteroviruses.
Fever, vomiting, anorexia, rash, URT symptoms.
What is mollaret’s meningitis?
Cause?
Recurrent aseptic meningitis.
Major cause is HSV2.
When can meningitis occur in VZV infection?
During chickenpox, singles, on its own or after vaccination.
What is the aetiology of enchepalitis? (10)
HSV1»>HSV2.
VZV, EBV, measles, mumps, enteroviruses.
Bacteria: strep pneumoniae, neisseria meningitidis, TB.
Acute disseminated encephalomyopathy.
What is the clinical presentation of encephalitis? (5)
Altered mental state, fever, headache, meningism (may be absent).
± focal neurology: seizures, weakness, dysphasia, ataxia.
Why are MRI and EEG used to investigate encephalitis.
MRI - changes in HSV encephalitis.
EEG: HSV encephalitis shows abnormal temporal lobe activity.
What is the treatment for viral encephalitis?
High dose IV acyclovir on clinical suspicion for 14-21 days.
No oral switch recommended.
What is the epidemiology of herpes simplex encephalitis?
Pathogenesis?
Bimodal - under 20 + over 50.
Reactivation in trigeminal ganglia -> acute focal necrotising encephalitis.
What is the outcome of herpes simplex encephalitis?
30% mortality at 18months even if treated.
Survivors: paralysis, speech loss, personality change.
What is acute disseminated encephalomyopathy?
CSF findings?
Rx?
Immune mediated CNS demyelination. May follow viral illness/vaccination. Clinical features of encephalitis.
CSF findings=viral meningitis.
Rx: steroids.
