9/26 CNS Infections - Casey Flashcards
abscess
collection of pus that becomes walled off in tissues
encephalitis
inflammation of brian
encephalopathy
altered brain fx
meningitis
inflammation fo meninges
how can you get a brain abscess?
most common locations?
main pathogens?
- contiguous spread
- hematogenous seeding
- post-traumatic
- cryptogenic
- temporal/frontal
- frontal/parietal
- cerebellar
- occipital
- multiple locations → implies hematogenous seeding!
- streptococci 60-70%
- bacteroides 20-40%
- enterobacteriaceae 23-33%
- staph aureus 10-15%
clinical presentation of brian abscess
- fever might be absent
- indolent, slow progression more common than fulminate
- headache is common
- focal neuro findings/seizures
- nausea/vomiting
- nuchal rigidity is relatively uncommon
diagnostic test
MRI, CT, blood cultures, sterotactic biopsy for culture
- LP contraindicated if abscess suspected → dont want to risk herniation!
treatment of brain abscess
medical or med&surgical drainage
- choose antibiotics based on organisms theyll clear out AND ability to cross bbb
suppurative (pus-forming) foci
cranial subdural empyema
- neuro emergencies
- usually bacteriema
- headache/seizures common
- same bacteriology as in brain abscess
spinal subdural empyema
epidural abscess (most commonly seen)
- almost always related to sinus disease
- elliptical apprearance
paraspinal abscesses
gen features
- may be epidural or subdural
- usually due to bacteremia but can also be due to contiguous spread
- surgical almost always required to prevent spinal cord compression
*Staph aureus is most common infecting organism
spinal subdural abscess
presentation
radicular pain, urinary retention, constipation, leg weakness, hyperreflexia
dx:
- MRI with gadolinium
- CT myelogram essential
tx:
- steroids, antibiotics, surgical decompression
spinal epidural abscess
where (link to anatomy)
sx, dx
where?
- posterior > anterior
- true epidural space posterior and lateral to spinal cord below foramen magnum
- potential epidural space anterior to spinal cord bc dural is adherent to vertebral bodies
- thoracic > lumbar > cervical
- larger epidural spaces contain more inf-prone fat
sx of cord compression
dx:
- positive blood cultures
- often simultaneous vertebral osteomyelitis (vert bodies degen)
- CSF analysis:
- small number of polys with markedly elevated protein and normal/low glucose
- culture frequently negative
chronic meningitis
infectious causes
infectious: TB, cryptococcus, coccidioidomycosis, histoplasmosis, Lyme disease, syphillis
infectious chronic meningitis
TB
TB
- PPD often negative → anergy (lymphocytes not working bc you’re acutely infected)
- AFB smears rarely positive
- NEED HIGH INDEX OF SUSPICION
- CSF shows high protein, low glucose, low lymphocytes
infectious chronic meningitis cryptococcus
- CAN occur in normal host
- USUALLY occurs in immunodeficient host
- dx: India ink, cryptococcal antigens are useful
- other fungal meningitis present similarly but cant test using India ink exam equivalent
