CNS infections Flashcards
def. of empyema
accumulation of pus within a space of cavity (ie epidural space = epidural empyema)
def. of abscess
localized collections of pus
meningitis/leptomenigitis definition
inflammation of the pia and arachnoid in the subarachnoid space
def. of encephalitis
inflammation of brain parenchyma
def. of myelitis
inflammation of spinal cord parenchyma
def. of radiculitis
inflamm. of nerve roots
def. of neuritis
inflamm. of peripheral nerve
def. of encephalomyeltitis
generalized inflammation of brain and spinal cord
def. of ependymitis
inflamm. of ventricles
reactive leptomeningitis
response in the leptomeninges (subarachnoid space) due to infection in OTHER location (ie epiduarl, subdural spaces)… thus you have the changes in cell count, protein level, and pressure but will NOT find any organisms
CNS response to bacteria, fungi, and viruses
bacteria = purulent reactions with polymorphonuclear leukocytes and necrosis fungi = granulomatous inflammation viruses = lymphocytis response (and occasionally myelin breakdown via allergic response)
E. Coli in meningitis (g stain and group effected)
neonates most vulnerable (G neg rods)
Neisseria Meningitides in meningitis
adolescents and young adults (COLLEGE DORMS!)
(G neg diplococci)
Strep. pneumoniae in meningitis
elderly, children, infants (G pos diplococci)
group B strep (aka step. agalactiae) in meningitis
neonates (G pos cocci with Lancefield antigen B)
Listeria monocytogenes in meningitis
elderly aka immunocompromised (G pos rods)
What are the 3 main categories of meningitis?
1) acute pyogenic (usually bacterial)
2) acute lymphocytic aka aseptic meningitis (usually viral)
3) chronic (fungi, TB, and syphilis)
Acute pyogenic meningitis characterisics
Purulent exudate in subarachnoid space and along vessels, includes neutrophils and bacteria
acute lymphocytic meningitis
increase in lymphocytes (aka mononuclear cells aka B/T cells)
Chronic meningitis causes
Caused by:
fungi (candidiasis, cryptococcosis)
tubercle bacillus (TB)
T. pallidum (syphilis)
CSF changes characteristic of each of the 3 types of meningitis (pressure, glucose, and cells found)
Acute pyogenic = increased pressure, DECREASED glucose, and thousands of neutrophils ***CSF can actually appear cloudy, is normally clear
acute lymphocytic = normal/mild increase in pressure, NORMAL glucose, hundreds of mononuclear cells
chronic = increased pressure, sometimes decreased glucose, hundreds of mononuclear cells
Most common form of virus causing encephalitis
herpes simplex virus 1.
acyclovir is the treatment!
unique among other viruses causing encephalitis because there are often RBCs in the CSF
Rabies virus in CNS
enters peripheral nerve, goes retrograde to CNS
Negri bodies often found in hippocampal pyramidal neurons
Varicella zoster virus (VZV) aka herpes zoster in CNS
causes chickenpox in primary infection and establishes a latent infection in DRG or trigeminal ganglia.
Manifests a 2nd infection in a dermatomal distribution
in immunosuppressed, can cause encephalitis or myelitis
Cytomegalovirus in CNS
affects fetuses (part of TORCHES) or immunosuppressed. CMV is common opportunistic pathogen in AIDS patients*
Fungal infection patterns in CNS (3 of em)
1) chronic meningitis
2) vasculitis
3) parenchymal invasion (most commonly via Candida and Cryptococus)
Toxoplasma gondii in CNS
- from cat shit
- typically causes a ring-shaped lesion in brain
- common in patients who are immunocompromised
intracerebral abscesses (commonly bugs and their effects)
strep and staph are most common (fungi in immunocompromised)
resulst in a zone of fibrous tissue
seizures occur in 50% of cases
what are the 3 types of tertiary neurosyphilis?
1) meningovasculitis - mimics a stroke (via occlusion)
2) General paresis - spirochetes found in brain tissue… mental changes, progressing to dementia, headache
3) Tabes Dorsalis - Loss of axons/myelin in dorsal roots with wallerian degeneration of dorsal columns
- causes “lightning pains”, sensory deficits, argyll-robertson pupils (react to accomodation but not to light)
HIV-related CNS probs
50-70% develop AIDS-related cognitive-motor complex
primary: HIV-associated dementia & vacuolar myelopathy (swelling of myelin sheaths in dorsal and lateral columns thus MVP, CST probs)
secondary: CMV, cryptococcus, and toxoplasma infection & Progressive multifocal leukoencephalopaty (PML)
progressive multifocal leukoencephalopathy (PML)
- occurs in immunosuppressed
- slowly progressing encephalitis due to altered virus
- caused by JC polyomavirus
- intellectual decline and dementia, death within 2-6months
- inclusion bodies in oligodendroglia nuclei
Subacute sclerosing panencephalitis
slowly (years) progressive encephalitis associated with altered measles virus
- onset between 5-20 years old
- personality changes, intellectual decline, seizures, limb spasticity
- elevated IgG, antibody titer against measles elevated!*
perivascular cuffing by lymphocytes and plasma cells
death usually within several years
