Pathology of CNS Infections Flashcards
How can you grossly tell if brain tissue has a bacterial meningitis?
Loses transparency (filled with pus) –> adopts a cloudy/opaque coloration
How can bacteria spread into the meninges? (2 main ways)
Bacteremia (hematogenous spread via bloodstream)
Direct extension from mastoid, sinuses, skull, etc.
Signs/Symptoms of Meningitis
Fever and headache STIFF NECK Brain edema Brain ischemia/infarcts Inc. ICP Nerve palsies Communicating hydrocephalus (Meningeal fibrosis)
Difference between Acute vs. Subacute/Chronic Meningitis
Acute: onset in HOURS
Subacute: weeks to months
Organisms responsible for SUBACUTE/CHRONIC meningitis
TB (mycobacterium)
Fungi (Cryptococcus)
Spirochetes (Syphilis, lyme disease)
Sarcoidosis can cause chronic meningitis (True or False)
True
Tuberculous meningitis involves a (granulomatous/nongranulomatous) inflammation mainly affecting what part of the brain?
Granulomatous; Base of brain
What cells can histologically be seen in the granulomas of tuberculous meningitis? ____ stain can be used to visualize tuberculous meningitis?
multinucleate GIANT cells; acid-fast
Common cause of meningitis in immunocompromised patients
- Microscopy: single budding yeast with a thick capsule “halo”
- Gross: brain has outer slimy consistency, yellow-gray exudate in ventricles –> a gelatinous substance with multiple small cysts in brain (“soap bubbles”)
Cryptococcosis
How can brain abscess can occur?
- Direct extension (sinuses, middle ear, etc.)
- Implantation (head trauma)
- Bacteremia (hematogenous spread via bloodstream)
Frontal lobe abscess can occur when there is a direct extension of infection from the ________.
Paranasal sinuses (sinusitis)
Temporal lobe or cerebellar abscess can occur when there is a direct extension of infection from ________
Middle ear (or Mastoid air cells) (Otitis or Mastoiditis)
Cause of brain abscesses; usually results in MULTIPLE abscesses and preferentially localizes to gray-white junction
Bacteremia
Abscesses of the brain due to BACTEREMIA prefer what area?
Gray-white junctions
Consequences of Brain Abscesses
Fever
Leukocytosis
Mass effect (headache, nauses, vomiting and herniation due to inc. ICP)
Brain destruction
(Bacteria/Viruses) are most common cause of Encephalitis
Virus (Herpesviruses, Arboviruses, Rabies, HIV, etc.)
Viruses that can use retrograde spread along axons to infect the CNS (2 total)
HSV-1
Rabies
_____________ is a virus that commonly causes encephalitis or hemorrhagic necrosis of the Temporal and Frontal lobes
HSV-1 (remember is typically orally spread via saliva, so makes sense is centered around the mouth)
_____________ is a virus that commonly infects the Anterior Horns cells
Poliovirus
___________ virus commonly infects oligodendrocytes, causing Progressive Multifocal Leukoencephalopathy
JC (John Cunningham) virus
_____________ virus commonly infects the Hippocampus and Cerebellum
Rabies
________________ virus commonly infects the DRG
Varicella-Zoster virus
______________ virus usually infects the leptomeninges (Arachnoid and Pia mater)
Lymphocytic Choriomeningitis virus
Examples of Parasitic infections of the CNS
Cysticercosis
Toxoplasmosis
Amebiasis
MOST common parasitic CNS infection globally; etiologic agent is Taenia solium; due to ingestion of eggs (contaminated water or food); cysts can be either intra/extraparenchymal
Cysticercosis
Cysticercosis is caused by the ingestion of undercooked pork with Taenia solium (True or False)
False: due to ingestion of EGGS in contaminated water or food
- ingestion of undercooked pork leads to intestinal tapeworm (not CNS infection)
CNS pathogen that causes RAPIDLY fatal necrotizing encephalitis; due to swimming in fresh water containing amoebas; treat with Amphotericin B
Naegleria fowleri
2 main pathways for transmission of an infection to a fetus
- Ascending infection from vagina/cervix (usually bacterial)
- Transplacental infection (hematogenous)
What are the STORCH infections that are the common causes of congenital encephalitis via TRANSPLACENTAL spread
Syphilis Toxoplasmosis Other congenital infections (HIV) Rubella CMV HSV-2
