CNS infections Flashcards
(26 cards)
4 mechanisms of CNS infection
- Haematogenous spread via epithelium (most common - e.g. Meningococcus via respiratory epithelium)
- Direct spread (surgery or accident)
- Local extension (ear infections)
- PNS into CNS (rabies)
Meningitis organisms
Fever, headache, stiff neck Meningococcus (N meningiditis) S pneumoniae Hib - Infants: Listeria, GBS, E coli
Encephalitis organisms
Disturbed brain function Rabies, arbovirus Trypanosoma species Prions Amoeba
Myelitis organisms
Disturbed nerve transmission
Poliovirus
Neurotoxin organisms
Paralysis, rigid (tetanus) or flaccid (botulinum)
Clostridiom tetani
Clostridium botulinum
- Acute bacterial meningitis
Rapid deterioration
3 main organisms (N meningiditis, S pneumoniae, Hib + in infants Listeria, E coli, GBS)
N meningiditis - 50% meningitis, 10% septicaemia, 40% both
CSF: High neutrophils, high protein, low glucose, turbid
- Chronic bacterial meningitis
No rapid deterioration, gradually worsening headache
TB
Immunosuppressed patients
Granuloma formation
CSF: Very high protein, neutrophils / lymphocytes,
- Aseptic (viral) meningitis
Most common CNS infection
Coxsackie B and echoviruses in 80-90%; HSV2
Self-limiting, resolves in 1-2w
CSF: High lymphocytes
Meningitis vs. encephalitis
Brain function disturbance more common in encephalitis
Headaches, fever, speech disturbance
Loses consciousness
Encephalitis
Meningitis with incomplete vaccinations
Gram negative coccibacilli
Hib
HIV
High opening pressure on LP
India Ink stain of CSF = yeast cells with halos
Pigeon droppings
Cryptococcus neoformans
Meningitis in baby
Gram positive rods
Listeria monocytogenes
2wk worsening headache
Ziehl-Neelson stain
TB meningitis
Forgetful + doesn’t make sense
Ataxia
Muscle spasms
EEG - periodic sharp waves
CJD
Positive microscopic agglutination test
Farming project in Africa
Aerobic spirochaetes
Leptospirosis
(Characterised by initial non-specific leptospiraemic phase then meningitis, liver damage + renal failure when IgM forms
Causes of encephalitis
Enteroviruses (Coxsackie A+B, echovirus, polio)
Herpes Simplex 1 + 2
Mollaret’s
Recurrent meningitis
Meningitis in baby
K1 antigen, lack of circulating IgM
E coli
CSF: Colourless, raised lymphocytes
Viral meningitis
CSF: Turbid, raised neutrophils, high protein, low glucose
Bacterial meningitis
CSF: Turbid, raised neutrophils / lymphocytes, low glucose, high protein
TB meningitis
Xanthochromia (straw coloured CSF)
SAH
Tx meningitis
Ceftriaxone (+ Amoxicillin to cover listeria)
