CNS infections Flashcards
(40 cards)
1
Q
Types of CNS infections
A
- meningitis: acute bacterial, aseptic, chronic
- encephalitis
- space occupying infectious lesions of CNS
- prion diseases
2
Q
Risk factors
A
- immunosuppression: leukemia, HIV/AIDS, steroids, spleneectomy
- cranial trauma: brain surgery, skull fx
- peds: premature, perinatal complications
3
Q
CNS infection organisms
A
- bacteria
- spirochetes
- viruses
- fungi
- protozoa
- prions (mad cow disease)
4
Q
bacterial meningitis epidemiology
A
- The age of the pt often suggest the likely etiologic organism
- neonates (acquired during vaginal birth): stretococcus, group B, E.coli, listeria
- 1 month to 4 yr: h. flu
- 4 to 30 yr: neisseria meningitidis (meningococcal meningitis)
- 30-65 yr: s. pneumo
- over 65 yr: s. pneumo, GNR, listeria
5
Q
Bacterial meningitis prevention
A
- H.flu vaccine
- strep pneumo vaccines
- minningococcal vaccines
- Rifampin (abx) for prophylaxis in contacts of those w/ meninogoccal infections
6
Q
Bacterial meningitis transmission
A
- exposure: birth canal and other routes
- colonization: nasopharynx colonization
- invasion: organism gains access and sustains itself in bloodstream
- Bad bug breaches BBB
- organism invades meninges, subarachnoid space and cerebrospinal fluid
- once organism gains access the CSF is very vulnerable b/c the organism is in a protected area where there are few WBC
- vein damage occurs causing proteins to seep in CSF
- brain edema results from inflammation of meninges and CSF outflow
- intracranial pressure rises and cerebral perfusion pressure drops
- causes brain hypoxia, seizures, hydrocephalus, brain herniation, death
7
Q
Bacterial meningitis clinical dx
MISSING ONE MORE SLIDE
A
- neurologic emergency which evolves over hours or quicker
- HA w/ nausea, vomting, anorexia
- fever
- stiff neck
- malaise
- rash: petechial rash
- meningeal signs: nuchal ridigity (stiff neck), Brudzinski sign, Kernig sign
- progression
- change in mental status
- LP reveals CSF abnormalities
- LP contraindicated if elevated intracranial pressure (look for papilledema in eyes)
- If ICP suspected: draw blood, start IV steroids and abx, get CT
- No ICP do LP
8
Q
CSF analysis
A
- cell count
- protein
- glucose
- opening pressure
9
Q
Normal CSF analysis
A
- cell count: 0-5 lymphocytes
- protein: 15-45 mg/dl
- glucose: 50-70% of blood glucose level
- opening pressure: 70-180 mm H2O
10
Q
Bacterial meningitis tx
A
- must use bactericidal abx
- causes cell lysis increased inflammatory meditors occur causing more problems
- so give steroids to help with the abx
11
Q
Bacterial CSF analysis
A
- cloudy or grossly purulent
- elevated protein: > 45mg/dL
- low glucose: <40 mg/dL
- high opening pressure
12
Q
Viral meningitis/encephalitis
A
- HA, fever, stiff neck, other nonspecific sx of viral infection
- HSV, VZZ, enterovirus, HIV, CMV, equine encephalitis virus, WNV, St. Louis encephaltis
- change in consciousness and localizing neurologic signs are rare in meninigits
- encephalitis has more LOC changes and neurological signs
13
Q
Viral CSF analsysis
A
- Cell count: increased WBC (100-1000)
- increased protein: >50 mg/dL
- glucose: normal or slightly changed
- opening pressure: normal to slightly elevated
14
Q
Viral meningitis workup
A
- CSF
- CXR
- TB skin test
- syphilis/HIV serology
- blood bacterial and viral cultures
- PCR of virus from the CSF is becoming the test of choice due to it s sensitivity
15
Q
Menigitis vs encecphalitis
A
- menigitis: infection of meninges, normal cerebral function
- encephalitis: infection of brain tissue itself, abnormalities in brain function (AMS, motor or sensory deficits, altered behavior, personality changes, speech or movement disorders)
16
Q
Rabies encephalitis transmission
A
- salivary transmission, usually via a bite from an infected animal
- scratches, mucus membrane exposures with infected animals
- recent cases show “casual contact” routes of infection
- salivary exchange to health care workers
- some cases linking to infected organ transplants
17
Q
Rabies manifestations
A
- tingling feeling at the site of inoculation
- incubation period of 10 days to 1 year
- acute viral syndrome with non-specific features
- progresses to anxiety, agitation, delirum
- spasms of the throat and frothing at the mouth at the sight of water, coma, and death
- if pt has become symptomatic, death is nearly certain, even if treated
18
Q
Prophylaxis and tx of rabies
A
- early prophylactic tx is needed to prevent death (when in doubt, treat)
- in absence of early tx, virtually all cases are fatal
- if pt presents w/ neurologic sx then supportive care only is given
- prevention: vaccinate all pets and livestock
19
Q
West Nile virus
A
- most affected are asymptomatic or mildly ill
- if symptomatic, usually flu like sx
- outdoor exposure at dawn or dusk increases risk for infection
- other mosquito-borne viruses (St. Louis Western equine, Eastern equine) can also cause encephalitis
- tx is supportive
20
Q
Chronic meningitis
A
-usually mycobacterial (TB) or fungal meningitis: can mimic viral
CSF findings: looks a lot like viral
21
Q
Chronic meningitis CSF findings
A
- Cell count: increased WBC (100-1000)
- protein: increased
- glucose: decreased
- opening pressure: moderately elevated
22
Q
Bacterial, chronic, and viral CSF finding
A
- Bacterial: high neutrophils, low glucose, high protein, markedly elevated opening pressure
- chronic: increased lymphocytes, low glucose, moderately elevated opening pressure
- viral: increased lymphocytes, increased protein, increased glucose, normal opening pressure
23
Q
Manifestations of chronic meningitis
A
- mild meningeal signs (stiff neck, HA)
- disease evolves over a prolonged period, weeks or months
- cranial nerve palsies
- invasion into the brain
- seizures
- CSF rhinorrhea
- chronic infections leads to arachnoid fibrosis, hydrocephalus, and underlying brain infarction
- often fatal
24
Q
Chronic meningitis tx
A
- culture is diagnostic
- multiple drug therapy for meningeal tuberculosis
- antifugal therapy for cryptococcal
- fungal infections by direct extension from sinuses require debridement of involved areas and systemic antifungal therapy as dictated by antifungal susceptibility testing
25
Cysticerocosis
- causes by the larval from Taenia Solium, the pork tapeworm
- transmission: obtained by eating the eggs of the tapeworm (not the larvae), associated w/ pica (dirt eating), poor handwashing, ingestion of T. solium eggs in contaminated water
26
Neuro-cysticerosis
- human is accidental intermediate host of the encysted larval form of the tapeworm
- most sx due to cysticerci in the CNS
- frequent causes of seizures in children
- with very large infection, extensive brain swelling leads to herniation and death
- in brain matter not just meninges
- if they are not causing problems then just leave them alone
27
Cysticercosis tx
- antihelminthic drugs may agument sx due increased CNS inflammation that occurs as the larvae die
- need to give steroids
- may need seizure meds
- albendazole or praziquantel are drugs of choice
- treat only acute CNS disease
- if you tx you end up w/ a lot of dead larvae and swelling and inflammation
28
Toxoplasmosis
- caused by parasite (toxoplasma gonii)
- transmission:
- ingesting raw beef
- oral fecal contamination usually via ingestion of sporazoites from handling the litter of an infected cat
- congential form: infected in utero through transplacental inoculation in the 3rd trimester
- exposure while pregnant is bad for fetus (1st exposure only - if exposed prior not an issue)
29
Toxoplasmosis disease manifestations
- asymptomatic infection
- respiratory disease
- CNS infection: space occupying lesions, seizures, mental status changes, fever, focal neurologic defects
- ocular infections
30
Toxoplasmosis dx
- serology IgM and IgG may be detected in CSF and serum
- no culture commercially available
- tissue biopsy demonstrates intracellular tachyzoites
- MRI demonstartes RING ENHANCING LESIONS in the brain
31
Toxoplamsosis tx
- trimethoprim/sulfamethoxazole (septra/bactrim)
| - long term prophylaxis may be needed for immunosuppressed pt
32
Brain abscesses
- caused by any number of bacteria, depending upon the cause of the infection
- often seen as mixed infections of anaerobes and aerobes if oral/HENT primary source
- GNR, s. aurea, coagulase negative staphlococci
- fungi: cause disease by direct extension from sinuses
- constant HA, stiff neck, possible focal neurological findings
33
Brain abscess pathogenesis
- infections start at non-CNS site and spread to CNS
- may occur secondary to seeding by infected heart valve or other sources of sepsis
- may occur by direct extension from abscessed teeth, otitis media, or sinus infection
- may occur from peritoneal seeding
- may occur from direct inoculation
34
Brain abscess clinical manifestations
- fever (low grade)
- drowsiness
- HA
- focal neurological deficits
- seizures
35
Brain abscess course
- indolent (slow) to fulminant (fast)
- 75% have sx for 2 weeks or less
- clinical picture: look for source
- lung, ear, or sinus disease with signs of intracranial infection and seizures
36
Brain abscess work up
- CBC: typically normal WBC count
- CT or MRI of the brain: localizes the abscess and determines the degree of capsule formation
- LP is contraindicated
- Aspiration of biopsy of abscess
37
Diagnostic testing for CNS abscesses
- MRI/CT scan show RING ENHANCING LESISONS
- CSF exam may not be informative if the abscess does not communicate w/ the meningeal space
- CT: guided FINE NEEDLE ASPIRATE of the abscess contents
38
CNS abscesses tx
- surgical drainage
- abx therapy should be guided by susceptibility testing and gram stain morphology
- intrathecal administration of drug may be required for adequate penetration into tissues
- tx underlying cause of infection
39
Brain abscess prognosis
- 40-60% mortality rate
- poor prognostic factors: delayed dx, ventricular rupture, fungal infection, coma, multiple and deep inoperable abscesses, inappropriate abx
40
Prions
- "protein infectious" causes
- mode of infection unclear
- "mad cow" disease is transmitted via eating infected nervous tissue
- Kuru and Creutzfeldt-Jakob disease preceded mad cow disease
- progressive encephalitis
- no tx, bad prognoses
