CNS infections Flashcards
sites/types of bacterial infections
- scalp, sinus, or ear infection - osteomyelitis - epidural abscess - leptomeningitis aka meningitis - brain abscess - encephalitis
pathology of acute bacterial meningitis shows
subarachnoid space filled with neutrophils, bacteria, necrotic debris
pathogenesis of bacterial meningitis
Direct extension or bacteremia
________ of a parameningeal cranial infection from the mastoid air cells, paranasal sinuses, skull, etc.
direct extension
a hematogenous dissemination of the bacteria
Bacteremia
clinical signs of acute bacterial meningitis
presents clinically with fever, headache, stiff neck, and mental status changes
meningeal inflammation means
stiff neck and headache
communicating hydrocephalus
the obstruction is within the subarachnoid space or arachnoid vili
non communicating hydrocephalus
the obstruction is within the ventricular system
type of bacterial infection in meningitis is ___ dependent
age
neonate bacterial meningitis infectious agents
Group B strep, Listeria, enteric bacilii
agents that cause bacterial meningitis in children
S. pneumonia, N. meningitidis, H. influenzae
agents that cause bacterial meningitis in adults
S. pneuomiae, N. meningitidis
onset of acute meningitis
hours to days
onset of subacute/chronic meningitis
weeks to months
Organisms associated with subacute/chronic meningitis include
mycobacteria (tuberculosis), fungi (cryptococcosis), and spirochetes (syphilis, Lyme disease)
idiopathic cause of meningitis
sarcoidosis
Granulomatous inflammation, mainly involving base of brain, causing brain infarcts from verse involvement
tuberculous meningitis
tuberculous meningitis can cause ____ mainly involving the base of the brain
granulamtous inflammation
multinucleate giant cells in the granuloma
stain of tuberculous meningitis
acid fast stain
common cause of brain infection in immunocompromised individuals
cryptococcosis
macroscopic findings of cryptococcosis
»Meninges thickened/opacified
»Slimy consistency
»Yellow-gray exudate in ventricles/perivascular spaces in immunocompromised.
»Subacute cases produce leptomeningeal fibrosis
- multiple small cysts in brain
subactue cryptococcosis cases produce _______ fibrosis
leptomeningeal fibrosis
50% cases show multiple _______ (“soap bubbles”) secondary to exuberant capsular material in brain (basal ganglia)
intraparenchymal cysts
tuberculous meningitis can result in brain infarcts from vessel invovlement, leading to _____ damage and meningeal fibrosis. Meningeal fibrosis can cause ________.
- cranial nerve damage
- hydrocephalus
microscopic findings on cryptococcosis
- single budding yeast forms
- surrounded by thick capsule, may shrink in tussue prep and leave “halo” around organisms
- leptomeningeal inflammation: lymphocytes, plasma cells, gianet cells
Types of neurosyphilis
- subacute leptomeningitis
- chronic leptomeningitis with associated vasculitis and vasculopathy (meningovascular syphilis)
- chronic spinal arachnoiditis with degerneration of dorsal roots and the posterior columns of the spinal cord (tabes dorsalis)
- chronic low grade encephalitis
- congenital neurosyphilis
what is this
brain abscess
pathogenesis of brain abscess
- direct extension
- implantation following head trauma
- bacteremia from distant focus of infection
direct extension from a parameningeal (cranial infection) can come from the _____ and cause a frontal lobe abscess
paranasal sinuses (sinusitis)
direct extension from a parameningeal (cranial infection) can come from the __________ and cause temporal-lobe or cerebellar abscess
middle ear or mastoid air cells (otitis or mastoiditis)
Direct extension may also cause an epidural abscess, subdural empyema, or ______
leptomeningitis
bacteremia often creates how many brain abscesses?
multiple
location of abscesses in brain
preferentially localizes to the gray-white junction
focus of cerebritis after penetration of BBB by bacteria happens within ____ days
4-9 days
formation of fibrous capsule happens day ____ in pathogenesis of a brain abscess
day 14
a brain abscess typically presents as a _______
mass lesion
in brain abscess, Patient may also have fever or _______.
leukocytosis
clinical consequences of mass effect
- headache, nausea, and vomiting from increased ICP
- potential for herniation
a brain abscess causes local brain destruction that may result in __________
neurological deficits
A diffuse inflammation of brain
encephalitis
A diffuse inflammation of brain and spinal cord
encephalomyeiltis
most common cause of encephalitis
viruses
common viruses that cause encephalitis
- HSV 1 and other herpesviruses
- arboviruses
- HIV
- rabies
- enteroviruses
Hematogenous Pathogenesis of CNS viral infection
from viremia after initial viral replication in GI tract (enteroviruses) or innoculation site (arboviruses)
when viremia travels and infects leptomeningeal cells it causes
Stiff neck, headache, & fever;
lymphocytic leptomeningitis
infectino of cells in the brain (viral encephalitis) causes
Headache, coma, seizures, & fever;
lymphocytic infiltrates & brain necrosis
pathogenesis of viral infection can also be spread along axons by _________
retrograde spread
HSV1 infection of oral cavity retrograde spread of virus goes to the ______ gangiion
trigeminal
HSV 1 encephalitis primary involves the ____ and ____ lobes after infection
temporal and inferior frontal lobes
initial infection of HSV1 occurs in ______ of cases and reactivation later occurs in ______ of cases
30%
70%
viral trophism of poliovirus
anterior horn cells
viral trophism of JC virus
oligodendrocytes - progressive multifocal leukoencephalopathy
viral trophism of rabies virus
— hippocampus and cerebellum
viral trophism of Varicella-Zoster virus
— dorsal root ganglia
viral trophism of Lymphocytic choriomeningitis virus —
leptomeninges
