CNS Flashcards
What is Meningitis?
Meningitis – infection of cerebrospinal fluid
Acute fever, headache, neck stiffness +/- rash
Fully conscious, no focal neurological signs
Usually viral but may be bacterial
What is Encephalitis?
Encephalitis – infection of the brain tissue
Acute fever, headache, neck stiffness
Altered conscious level, seizures +/- focal neurological signs
Usually viral
What is a brain abscess?
abscess within the brain tissue
Insidious onset of fever, headache, +/- neck stiffness
+/- Altered conscious level, seizures, focal neurological signs
Usually bacterial, may be parasitic
What are the two most common causes of viral meningitis?
Enteroviruses
HSV 2
What is Meningism?
Headache
Neck stiffness
Photophobia
What clinical signs do you look for in infants with suspected meningism?
Look for nuchal rigidity (neck stiffness)
and bulging anterior fontanelle
What is Kenig’s sign?
With hip and knee flexed to 90o, the knee cannot be extended due to pain/stiffness in the hamstrings
Positive = Meningism
What is Brudzinski’s sign?
Flexing the neck causes the hips and knees to flex
Positive = Meningism
Lumbar puncture:
What is the normal opening pressure compared to bacterial meningitis?
Normal =
Lumbar puncture:
What is the normal WBC count (mm3) compared to viral and bacterial meningitis?
WBC normal = 0-5
Viral = 5-500 (mean 80)
Bacterial = 100-20,00 (mean 800)
Lumbar puncture:
What is the normal protein (mg/dl) compared to viral and bacterial meningitis?
Protein normal = 15-50mg/dl
Viral = 30-150mg/dl
Bacterial = 100-500mg/dl
What is Mollaret’s meningitis?
Recurrent aseptic meningitis
wide differential but major cause = HSV2
What is the main cause of Viral encephalitis?
HSV 1
What is the main difference between presentation of meningitis and encephalitis?
Encephalitis will also have:
Altered mental state
confusion/bizarre behaviour -> coma
Focal neurology eg. Seizures
What is the treatment for Viral encephalitis?
High dose IV aciclovir
What disease has the same clinical features as encephalitis? Can follow viral illness or vaccination (e.g. influenza)
Acute disseminated encephalomyelopathy (ADEM)
Immune-mediated CNS demyelination
Which bacteria causes meningococcal disease and how is it treated?
Neisseria meningitides
- Meningitis
- Fulminant septicaemia
Ceftriaxone, cefotaxime
Penicillin
Close contacts given Rifampicin
How do you treat meningitis caused by Haemophilus influenza and who normally gets it?
Ceftriaxone, cefotaxime
Ampicillin
Close contacts given Rifampicin
2months – 2 years
How do you treat meningitis caused by Streptococcus pneumoniae and who normally gets it?
Ceftriaxone, cefotaxime
no prophylaxis for close contacts required
more common and severe in the elderly and immunocomprimised
Which steroid is given with antibiotics to treat meningitis in adults?
Dexamethasone
What are possible differential diagnosis for lymphocytic meningitis?
TB meningitis
- Rx TB antibiotics and steroids
Cryptococcal meningitis
- Rx amphotericin, flucytosine or fluconazole
What is the most common cause of encephalitis worldwide?
Japanese encephalitis
One third die in the acute illness
One third left with severe long term neurological disability
One third recover
What bacteria do brain abscesses contain?
Brain abscesses are often mixed (polymicrobial)
Streptococci (60-70%)
Staphylococcus aureus (10-15%)
Anaerobes
Gram negative enteric bacteria eg. E.coli, Pseudomonas spp.
Which antibiotics can achieve therapeutic concentrations in intracranial pus?
ampicillin, penicillin, cefuroxime, cefotaxime, ceftazidime, metronidazole
What are the possible complications of a brain abscesses?
Raised intracranial pressure, mass effect, coning
Rupture (usually into ventricles) causing ventriculitis
What is Subdural empyema?
Infection between dura and arachnoid mata - often polymicrobial
Pathogenesis: spread of infection from sinuses (50-80%), middle ear and mastoid (10-20%)
Which bacteria are usually responsible for Ventriculoperitoneal shunt and external ventricular drain infections?
coagulase-negative staphylococci
Diagnosis: CSF microscopy and culture
