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
infectious chronic meningitis
Lyme disease
can occure in any stage of Lyme disease
- nonspecific lymphocityic meningitis
- often accompanies Bell’s palsy → uni or bilat
dx: simultaneous serum analysis & CSF analysis
infectious chronic meningitis
syphilitic
can occur as secondary syphilis 40% of time
meningitis most frequent manifestation of tertiary syphilis
asymptomatic approx 30% of time
common: headache + HIV (secondary), psych behavior ward pts (tertiary)
meningovascular syphilis
endarteritis obliterans → infarction of small vessels
- stroke-like syndrome
- seizures
parenchymatous neurosyphilis
destruction of nerve cells in cerebral cortex manifesting as general PARESIS or TABES DORSALIS
- psych and neuro manifestations
PARESIS: personality, affect, reflexes, eye, sensorium, intellect, speech
tabes dorsalis
- shooting pain
- ataxia
- sphincter disturbance
- periph neuropathy (decr vibration sense)
- cranial neuropathy
other manifestations: uveitis, deafness, optis neuritis or atrophy
neurocysticerocosis
most common presentation as seizures
- may or may not have live parasites
dx:
- CSF: lymphocytic pleocytosis, maybe low glucose
- serology + hx + CT finding is most common way to make a dx
noninfectious chronic meningitis
- neoplasms/paraneoplastic syndromes
- sarcoidosis
- vasculitis
- drug-induced
meningitis vs. encephalitis
altered mental status diffs are key
- early meningitis → no AMS
- encephalitis → AMS early
region of inflammation: meninges vs. brain
CSF exam: similar in both
stiff neck more common in meningitis (but most adults with meningitis dont have one either)
viral encephalitis
CSF exam
cell count <500 in 90% of cases
- lymphocytic predominance
- more polys in EES and some enteroviruses
- RBC > 500 in HSV, CTFV, CEV
- low glucose??? consider alt diagnosis
HSV vs non-HSV encephalitis
clinical features do not reliably distinguish
infero-medial and frontal-parietal localization? acyclovir initiation
EEE hits basal ganglia and thalami
- highest mortality
St Louis enceph
WEE
California enceph
West Nile enceph
less common: varicella zoster, EBV, HIV, HHV6
Eastern Equine encephalitis
avian reservoir - daytime feeding mosquito vector
Atlantic and Gulf states
all ages, especially children
- high incidence of neuro sequellae
- up to 75% mortality
West Nile virus
avian reservoir - Culex pipiens mosquito vector
- incubation period 5-5 days
- usually self limited
- fatality rate up to 3-15% in elderly
non-viral encephalitis
bacterial pathogens: Listeria, Salmonella, Nocardia
lots of others: Spirochetes, Rickettsia, parasites, Mycoplasma, drugs, vasculitis, carcinomatosis
PML : progressive multi-focal encephalopathy (JC virus)
Naegleria fowleri
fresh, non-Cl warm water
cause acute hemorrhagic encephalitis
CSF: high PMN count, low glucose, bloodies within days
tx: amphotericin, rifampicin, fluconazole, miltefosine, azithromycin
99% mortality
postinfectious encephalitis
Acute Disseminated Encephalomyelitis (ADEM)
- demyelination in white matter
- no direct infection
usually follows viral illness by 5-21 days
nonspecific neuro symptoms
CSF shows inflammation
tx: glucocorticoids
