Lecture 2 Neuropathology of CNS Infections Flashcards Preview

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Flashcards in Lecture 2 Neuropathology of CNS Infections Deck (52):
1

How do infectious organisms access the CNS?

1. hematogenous spread
2. local extension (middle ear)
3. retrograde transport
4. direct implantation (surgery)

2

Pachymeningitis

spread of infection into layers of the dura mater
-“pachy” = thick

3

Meningitis/Leptomeningitis

inflammation of the pia and arachnoid

4

What does lepto mean

“thin”…so leptomeningitis = thin

5

Encephalitis

inflammation of the brain parenchyma with MONONUCLEAR cells
-usually caused by VIRAL agent

6

Mononuclear infiltration of brain parenchyma

Encephalitis

7

Cerebritis

inflammation of the brain parenchyma with neutrophils
-usually caused by a bacterial agent

8

Polynuclear infiltration of brain parenchyma

Cerebritis

9

Myelitis

inflammation of the spinal cord

10

Poliomyelitis

inflammation of spinal gray matter (like the ventral root/horn)

11

Ganglionitis

inflammation of the dorsal root ganglia

12

Radiculitis

inflammation of the intradural spinal nerve roots

13

What is granulamatous inflammation associated with in brain?

-mycobacteria
-spirochetes
-fungi
-parasites

14

What are microglial nodules associated with?

Viral encephalitis

15

What are the most common bacterial infections?

1. Acute bacterial meningitis ACUTE
2. Bacterial abscess ACUTE
3. Mycobateria (tuberculosis) CHRONIC
4. Multisystem bacterial infections CHRONIC

16

What layer of the brain most commonly gets fucked in bacterial CNS infections?

Subarachnoid space (leptomeningitis/meningitis)

17

What are the most common bacteria that cause acute bacterial meningitis in NEONATES (0-6months)?

1. Group B Streptococcus
2. E. coli
3. Listeria monocytogenes

18

What are the most common bacteria that cause acute bacterial meningitis from 6mos – 60 years?

1. Streptococcus pneumonia
2. Neisseria meningitides
3. Haemophilis influenza
(accounts for 80% of all cases)

19

What are the most common bacteria that cause bacterial meningitis in >60 y.o. and immunosuppressed patients?

1. Strep pneumonia
2. Listeria monocytogenes

20

How does acute bacterial meningitis present in gross examination? histological examination?

1. Pus
2. Polys

21

What are abscesses?

Focal, destructive lesions of the brain parenchyma due to necrosis
Mediated by ACUTE inflammation in response to bacterial infection
Bacterial meningitis = second most common CNS infection?

22

What is most common CNS infection? Second most?

1. bacterial meningitis
2. bacterial abscess

23

What are the characteristics of brain abscesses and what are the most common organisms?

Transmitted either locally (sinusitis otitis) or hematogenously (septic or cardiac emboli)
-infectious emboli can travel from heart
Oragnisms:
-staph
-streptococci

24

-What are the three most common causes of bacterial chronic inflammation?

1. Mycobacterium tuberculosis (most common)
2. Neurosyphilis (Treponema pallidum)
3. Neuroborreliosis (Borrelia burgdoferi … Lyme disease)

25

What are the symptoms of CNS TB?

Meningitis present over 2-3 weeks
-combination of headache, lethargy, nausea and vomiting
-involves CRANIAL NERVE PALSIES
-lymphocytosis in CSF
-affects basal part of brain, hence cranial nerve involvement

26

What organism causes neurosyphilis?

Treponema Pallidum

27

What are the three symptomatologies of neurosyphilis?

1. Meningovascular neurosyphilis (chronic basal meningitis…lots of lymphocytes seen)
2. Paretic neurosyphilis (fucks with cerebral cortex, loss of neurons, gliosis and microglia proliferation
3. Tabes dorsalis (Treponema pallidum spirochetes invade the dorsal columns)

28

What are symptoms of neuroborreliosis (Lyme disease)?

Caused by spirochete Borrelia burgdorferi
-facial nerve palsy
-polyradiculitis
-encephalopathy
-aseptic lymphocytic meningitis

29

What are the four most classic manifestations of viral infections?

1. Aseptic meningitis (meninges)
2. Polioencephalitis/poliomyelitis (grey matter)
3. Panencephalitis/panmyelitis (grey and white matter)
4. Leukoencephalitis (white matter)

30

What are most cases of aseptic meningitis caused by?

Enteroviruses
-less severe than bacterial

31

What are arboviruses?

Arthropod Born viruses
RNA motherfuckers
Causes SEASONAL acute viral encephalitis

32

What are the common causes of ACUTE viral encephalitis?

SEASONAL, ARBOVIRUSES
-West nile virus, Japanese encephalitis, St. Louis encephalitis, Eastern/Western equine encephalitis
NONSEASONAL:
-HSV 1, 2, 6; VZV; EBV; CMV; Rabies; H1N1

33

What are the four pathological features of acute viral encephalitis?

1. perivascular lymphocytic infiltrate
2. neuronophagia (ingestion of dying neurons by macrophages)
3. Intranuclear viral inclusions
4. Microglial nodules

34

What are the delineating features of herpetic encephalitis (HSV-1)?

Necrosis of TEMPORAL LOBES
-bilateral, asymmetrical hemorrhagic necrosis

35

When you see bilateral, asymmetrical hemorrhagic necrosis of the temporal lobes, think what?

HSV-1
-most common cause of encephalitis

36

Where do you see CMV encephalitis most commonly?

1. Intrauterine infection (congenital CMV)
2. Immunosuppression (post-transplant, HIV)

37

What is the significance of VZV encephalitis?

Very rare viral cause of encephalitis
-seen in zoster patients of advanced age or immunosuppressed patients
-causes granulamotous arteritis mimicking CNS vasculiitis

38

What are key characteristics of rabies encephalitis?

1. negri bodies
2. can be furious (insomnia agitation, aggressive behavior) or dumb rabies (ascending paralysis of one or more limbs, simulating Guillain-Barre)

39

What do negri bodies look like histologically?

Round to oval eosinophilic inclusions in neuronal cytoplasm of Purkije cells, hippocampal pyramidal neurons

40

What is the DDx of ringed lesion in brain?

Bacterial Abscess OR fungal infection

41

What are the most common fungal infections of CNS?

1. Cryptococcus neoformans (in immunosuppressed hosts)
2. Aspergillosis (hemorrhagic infarcts)
-hemorrhage  abscess  capsule/granulomas
3. Zygomycosis (seen in diabetic ketoacidotic patients…seizures)
-immunocompromised patients

42

What are the most common parasitic infections?

1. Amoebic encephalitis (Naegleria fowleri)
2. Cysticercosis (cysticerci from taenia solium)

43

What is the classic helminthic (worm or worm parasite) organism that lives in brain?

Cysticerci
-larvae of Taenia solium, a tapeworm

44

What are Naegleria fowleri?

An amoeba that is transmitted through olfactory bulbs
-causes fulminant, acute meningoencephalitis

45

What is cysticerosis?

Most common helminthic CNS disease
Caused by cysticerci
Causes a shitload of cysts

46

What are the most common CNS infections of the immunocompromised hosts?

1. cryptococcal meningitis
2. taxoplasmosis
3. HIV encephalopathy
4. Progressive multifocal encephalopathy

47

What are the delineating characteristics of cyrpotococcal meningitis?

1. most common cause of fungal meningitis
2. Identified in CSF via India ink
3. Produces cystic dilations of VIRCHOW-ROBIN spaces (“bubbles) with little surrounding gliosis/inflammation
3. fever, debility, headache, irritability, insomnia…can worsen over weeks, months or years

48

Domestic Cats

Definitive host for toxoplasma gondii
-leads to ring-enhancing lesions/brain abscesses

49

What are key characteristics of HIV encephalitis?

1. multinucleated giant cells
2. leukoencephalopathy with patchy demyelination and variable gliosis
3. low-grade inflammation with perivascular and parenchymal lymphocytes/microglial nodules

50

What is leukoencephalopathy?

A type of change associated with WHITE matter

51

What are the delineating features that separate fungal and viral meningitis?

CSF composition

52

What are the key characteristics of progressive multifocal leukoenceophalopathy

Caused by: JC = John Cunningham Virus; Polyomavirus JC
-tropism for oligodendroglia…WHITE MATTER ONLY BITCHES
-ill defined demyelinating lesions; lipid laden macrophages; intranuclear viral inclusion; bizarre astrocytes with atypia