Viral meningitis/Encephalitis Flashcards
What is the definition of Meningitis?
inflammation of the meninges
What is the definition of Encephalitis?
inflammation of the brain
What is the definition of Meningo-encephalitis?
inflammation of brain and meninges
What is the microbiology of Aseptic Meningitis?
White cell count >5x106/L in CSF - allowed to be higher in children Negative bacterial culture of the CSF
What causes Aseptic Meningitis apart from viruses?
Bacteria e.g. TB, Syphilis non infectious agents e.g. malignancy, drugs etc.
What is the name of a Basic infectious virus particle?
virion
What does the Simple virus structure consist of?
Nucleic acid Capsid - protein coat possibly lipid envelope possibly other proteins/enzymes
Who is Viral Meningitis most common in?
neonates Around the age of 5 More common that bacterial meningitis
What is the leading cause of Viral Meningitis?
Enteroviruses e.g. echovirus HSV2
What is important to ask about in Viral Meningitis?
travel history sexual history check if the patient is immunocompromised
How does the virus enter the CNS?
Via cerebral microvascular endothelial cells Via choroid plexus epithelium from blood Spread along the olfactory nerve
What are the general Clinical features of Viral Meningitis in adults?
Fever Headache Neck stiffness Photophobia Sometimes ‘viral’ prodrome (e.g. lethargy, myalgias, arthralgias, sore throat, Diarrhea And Vomiting, rash)
What are the Clinical features of Viral Meningitis in children?
In neonates/infants meningeal signs may be absent Look for nuchal rigidity (neck stiffness) and bulging anterior fontanelle - sign of increased intercranial pressure
What are the two Examination signs for meningitis?
Kernig’s sign - hip and knee flexed to 90 degrees, the knee cannot be extended Brudzinski’s sign Flexing the neck causes the hips and knees to flex
What is the first investigation that should be carried out when suspecting meningitis?
Lumbar Puncture
When is the only time that care should be taken before doing a Lumbar Puncture for meningitis?
suspected raised inter-cranial pressure removing csf = herniation of the brain through the foramen magnum - can cause arrest perform CT head to check suspecting viral encephilitis
What are the CSF findings of Lymphocytes in viral meningitis?
Lymphocytic, usually
What does Pleocytosis stand for?
white cells in CSF
What are the CSF findings of protein in viral meningitis?
Protein (0.2-0.4 g/L) Normal, mildly elevated (0.5-1.0)
What are the CSF findings of Glucose in viral meningitis?
(ratio of CSF:plasma) Normal ratio is 50-66% In viral meningitis it is normal, or slightly low
What are the CSF differences to distinguish between bacterial and viral meningitis?
↑ opening pressure in bacterial ↑↑ WBC in bacterial ↑ protein in bacterial ↑ glucose in viral bacterial = gram stain
When is it useful to do a Throat swab and/or stool sample?
for enterovirus/ anything transmitted by a faecal oral route
What are the treatment options for meningitis?
Start appropriate IV antibiotics (e.g. cefotaxime) if any risk of bacterial meningitis - after LP preferred Mainly supportive therapy NOTIFIABLE - inform local public health dept
What time of the year does the enteroviral epidemic occur?
late summer/autumn
What are the symptoms of enteroviral meningitis?
fever vomiting anorexia rash upper respiratory tract symptoms
What is the treatement of enteroviral meningitis?
No specific treatment Full recovery normal
What is the 2nd most common cause of Viral Meningitis?
Herpes Simplex Virus - HSV2
What is Mollaret’s meningitis?
recurrent aseptic meningitis wide differential but major cause = HSV2
What is primary (varicella)?
chickenpox
What is secondary (zoster)?
shingles
When does meningitis develop in relation to Varicella zoster virus?
during chickenpox/shingles look for rash look after vaccination
When does CNS symptoms develop after mumps?
5 days after onset of parotitis
What are other features of Mumps meningitis?
Abdominal pain Orchitis - inflammation of one or both of the testicles
What is the treatment of Mumps meningitis?
No specific treatment Full recovery normal Preventable with vaccination
When can meningitis occur during HIV?
as part of primary infection
What are the associated features of HIV meningitis?
Fever Lymphadenopathy Pharyngitis Rash = like glandular fever
Which is more serious out of viral meningitis and viral encephalitis?
viral encephalitis - medical emergency
What is the most common cause of viral encephalitis?
Herpes Simplex Virus (HSV1)
what are the clinical presentations of viral encephalitis?
Altered mental state (confusion/bizarre behaviour -> coma - look at GCS) Fever Headache Meningism (may be absent) +/- Focal neurology i.e. seizures
What does an EEG of a person with HSV encephalitis show?
75% will show abnormal temporal lobe activity
What are the differences between viral encephalitis and viral meningitis?
They are the same!
What is the treatment for viral encephalitis?
High dose IV aciclovir 10mg/kg tds 14-21 days
Where does direct transmission of the virus that causes encephalitis occur?
along neural/olfactory pathways
Where does reactivation of the virus that causes encephalitis occur?
trigeminal ganglia
What does viral encephalitis cause?
Acute focal necrotising encephalitis Inflammation / swelling of brain tissue
What are the neurological consequences of viral encephalitis?
Paralysis Speech loss Personality change
What is Acute disseminated encephalomyelopathy (ADEM)?
autoimmune condition of CNS nerve demyelination Can follow viral illness or vaccination (e.g. influenza)
What are the clinical features of Acute disseminated encephalomyelopathy (ADEM)?
same as encephalitis
What are the CSF findings of Acute disseminated encephalomyelopathy (ADEM)?
same as viral meningitis.
What is the treatement for Acute disseminated encephalomyelopathy (ADEM)?
Treatment is steroids/other immunosuppressants
What other sample should you always take when taking a LP?
serum glucose sample
