32 - Infectious Diseases of the CNS

Question 1

Bacterial Meningitis

Answer 1

Most common infection of the CNS

Organisms reach the leptomeninges via hematogenous spread or direct extension

Spinal tap yields cloudy CSF with many PMNs and bacteria may be seen

Question 2

Bacterial Meningitis - Neonates

Answer 2

Group B Strep, E Coli

Question 3

Bacterial Meningitis - Infants and Children

Answer 3

H-Flu

Question 4

Bacterial Meningitis - Adolescents and young adults

Answer 4

N. Meningitidis

Question 5

Bacterial Meningitis - Elderly

Answer 5

Strep Pneumo

Question 6

Path - Large Thick-walled Vessels

Answer 6

Landmark for the leptomeningeal space

Question 7

Acute meningitis

Answer 7

Hella PMNs in the leptomeningeal space

Question 8

Brain Abscess

Answer 8

Second most common CNS infection

Local contiguous spread (sinusitis, otitis, mastoiditis)
Hematogenous (septic emboli from bacterial endocarditis, pulmonary infection, etc)

Question 9

Stages of Cerebral Abscess Formation

Answer 9

Early cerebritis (1 - 3 days)
Late cerebritis (4 - 9 days)
Early capsule formation (10 - 13 days)
Late capsule cofmation (14 days and later)

Question 10

Early Cerebritis

Answer 10

1 - 3 days

Acute inflammation & edema

Question 11

Late Cerebritis

Answer 11

4 - 9 days
+Necrosis
+Macrophages

Question 12

Early Capsule Formation

Answer 12

Fibrous capsule surrounds abscess (which has degenerated to pus)

Question 13

Cerebral Fungal Infection

Answer 13

Often opportunistic in immunocompromised patients
Hematogenous spread from other organs

May produce leptomeningitis, vasculitis, granulomas, or cerebral abscess

Question 14

Cerebral Fungal Infection - Common Organisms

Answer 14

Asbergillus
Mucormycosis
Candida
Cryptococcus

Question 15

Aspergillus

Answer 15

Opportunistic
Septate hyphae
Acute angle branches
Flowery body
Attacks vasculature
Perivascular inflammation
Massive hemorrhage

Question 16

Mucormycosis

Answer 16

Opportunistic

Nonseptate hyphae

Question 17

Candida

Answer 17

Opportunistic
Budding yeast
Pseudohyphae

Question 18

Cryptococcus

Answer 18

Opportunistic or previously healthy
Budding yeast
Encapsulated
Typically stays in leptomeninges
Extends along virchow robin spaces (projections of leptomeninges cuffing perforating vessels

Polysaccharide capsule (highlighted with mucy carmen stain)
Slippery brain. "Sugar coated brain"
Edema/fluid restricted to leptomeninges and in virchow robin spaces.

Question 19

See something all over the brain?

Answer 19

Hematogenous spread!!!!

Question 20

Parasitic Infections - Protozoa

Answer 20

Toxoplasma
Acanthamoeba
Naegieria
Plasmodium (malaria)
Trypanosoma
Trichinella
Toxocara

Question 21

Parasitic Infections - Metazoa

Answer 21

Cysticercosis
Echinococcus
Sparganum
Paragonimus
Schistosoma
Strongyloides
Angiostrongylus

Question 22

Neurocysticercosis

Answer 22

Cysts in brain tissue containing organisms

Humans are the definitive host
Tapeworms shed ova that get ingested by pigs
We eat pigs
If we eat the ova from poop, the intermediate stage will invade muscle, eye and brain. HEMATOGENOUS spread

Question 23

CNS Viral Infections - Manifestations

Answer 23

“Aseptic” Meningitis
Encephalitis
Meningoencephalitis
Myelitis

Question 24

Stereotypical Tissue Reactions

Answer 24

Inflammatory Cell Infiltrates
Microgliosis
Neuronophagia
Microglial nodules
Astrocytosis
Intracellular inclusion bodies
Neuronal cell degeneration
Cellular and tissue necrosis

Question 25

Rabies - Pathology buzzword

Answer 25

Negri bodies Intraneuronal cytoplasmic inclusions Brightly eosinophilic Inside purkinje cells

Question 26

Rabies

Answer 26

Transmitted via bite Virus proliferates at bite site Transaxial migration into nervous system Bat bites Aggression, violence Photophobia Vampires come from here.

Question 27

Herpes Encephalitis

Answer 27

Neurotropic virus Hemorrhagic inflammatory partially necrotic legions in medial temporal lobe Inflammatory lesion, microglial nodules, perivascular lymphocytes

Question 28

Herpes Encephalitis - Path Buzzword

Answer 28

Cowdry bodies intranuclear inclusions Viral particles growing inside nucleus

Question 29

HIV-1 - Primary Complications

Answer 29

HIV encephalitis or AIDS dementia complex HIV-associated myelopathy (vacuolar myelopathy) HIV-associated neuropathy (distal sensory neuropathy) HIV-associated myopathy

Question 30

HIV-1 - Secondary complications (due to immunodeficiency)

Answer 30

Opportunistic Infections Cryptococcosis Toxoplasmosis Progressive Multifocal Leukoencephalopathy Cytomegalovirus Infections Primary CNS Lymphoma

Question 31

HIV Encephalitis

Answer 31

Lymphocytic Encephalitis | Multinucleated giant cells (infected monocytes with multiple nuclei)

Question 32

Toxoplasma

Answer 32

Large necrotic lesions Can sit dormant for years, then flare up when immune system is compromised. Well circumscribed mass MRI - Ring-enhancing lesion

Question 33

Differential for Ring-Enhancing Lesion on MRI

Answer 33

Glioblastoma Metastatic Carcinoma Lymphoma Toxoplasmosis

Question 34

Toxoplasma - Path Buzz Word

Answer 34

``` Tissue Cysts (bradyzoites) Cysts burst with tachyzoites (more active form) ```

Question 35

JC Virus

Answer 35

Progressive Multifocal Leukoencephalopathy

Question 36

JC Virus (PML) - Path Buzz Word

Answer 36

Oligodendrocyte infected, gets big and glassy | Astrocytes start to look like astrocytomas

Question 37

Cytomegalovirus Ventriculitis

Answer 37

Predilection for ependymal cells Typically CMV leads to ventriculitis Microscopically, cells are hugesies!

Question 38

Transmissible Spongiform Encephalopathies - Prion Diseases

Answer 38

``` Creutzfeldt-Jakob Disease Gerstmann-Straussier-Scheinker disease Fetal familial insomnia Kuru New Varient CJT (Mad Cow) ``` Animal Prion Diseases: Scrapie Bovine spongiform encephalopathy Others

Question 39

Creutzfeldt-Jakob Disease

Answer 39

``` Worldwide incidence of approximately 1 per million Peak incidence in seventh decade of life Sporadic (85%) Familial (15%) Iatrogenic (Rare) Rapid progressive dementia Myoclonus Ataxia Usually Fatal ```

Question 40

Prion Hypothesis

Answer 40

PrP is a normal protein present EVERYWHURR Exists in a healthy alpha helix-rich state Exists rarely in an unhealthy beta pleated sheet state (more likely to layer like amyloid) Sporadic cases of switchy switchy through mutation cause folks to be susceptible Beta pleated sheet serves as a nidus for more to convert

Question 41

Kuru

Answer 41

``` Rapid progressive disease myoclonus ataxia seizures death ``` To honor them, bitches ate the body Women and children ate the brain Eating the brain gives you kuru

Question 42

Spongiform encephalopathy - Histo/path

Answer 42

Holes in the gray matter. Give spongy appearance. Holes are INTRACELLULAR spaces. End stage = Residual astrocytosis with dying neurons around