Cns Infections

Front 1

Know the four mechanisms for CNS infections

Back 1

1. Hematogenous spread(most common)
2. Traumatic implantation
3. Local extension from nearby infection
4. Ascent of peripheral nerve

Front 2

Define meningitis

Back 2

Inflammation of pia matter covering the brain

Front 3

What is the pathogenesis of meningitis

Back 3

Usually due to hematogenous spread

Front 4

What are the clinical and CSF laboratory findings meningitis

Back 4

Clinical findings are fever, nuchal rigidity, headache.
CSF findings

Laboratory findings in viral meningitis
a.Increased CSF protein - due to ↑ vessel permeability
b. Increased total CSF leukocyte count - initially neutrophils then converst to lymphocytes in 24 hrs.

Laboratory findings in bacterial and fungal meningitis
a. Increased CSF protein
b. Increased total CSF leukocyte count
c. Decreased CSF glucose

Front 5

Identify the gross findings of meningitis

Back 5

Fever, nuchal rigidity, headache.

↑ CSF protein (viral, bacterial, fungal); ↓ CSF glucose (bacterial, fungal)

Front 6

Know the four mechanisms for CNS infections

Back 6

1. Hematogenous spread(most common)
2. Traumatic implantation
3. Local extension from nearby infection
4. Ascent of peripheral nerve

Front 7

Define meningitis

Back 7

Inflammation of pia matter covering the brain

Front 8

What is the pathogenesis of meningitis

Back 8

Usually due to hematogenous spread

Front 9

What are the clinical and CSF laboratory findings meningitis

Back 9

Clinical findings are fever, nuchal rigidity, headache.
CSF findings

Laboratory findings in viral meningitis
a.Increased CSF protein - due to ↑ vessel permeability
b. Increased total CSF leukocyte count - initially neutrophils then converst to lymphocytes in 24 hrs.

Laboratory findings in bacterial and fungal meningitis
a. Increased CSF protein
b. Increased total CSF leukocyte count
c. Decreased CSF glucose

Front 10

Identify the gross findings of meningitis

Back 10

Fever, nuchal rigidity, headache.

↑ CSF protein (viral, bacterial, fungal); ↓ CSF glucose (bacterial, fungal)

Front 11

Be able to differentiate the bacterial/fungus causes of meningitis from viral meningitis using CSF studies

Back 11

CSF Bacterial/Fungus
TCC 1,000 - 20,000 cells/μL
DifC >90% neutrophils & mononuclear
CSF glucose Decreased
CSF protein Increase
Gram Stain Frequently positive
sensitivity (75 to 80%)

CSF Viral
TCC <1,000 cells/μL
DiffC first 24-48 hrs, neutrophils then switches to monocytes after 48 hours.
CSF glucose normal, except Mumps, Herpes
CSF Protein increased
Gram Stain Negative

Front 12

Define encephalitis and the clinical findings that differentiate it from meningitis.

Back 12

1. Inflammation of the brain
2. Clinical findings
a. Fever, headache
b. Impaired mental status, drowsiness

Impaired mental status & drowsiness differentiate encephalitis from meningitis

Front 13

Know the pathogenesis of a cerebral abscess.

Back 13

- Spread from an adjacent focus of infection (e.g., sinuses)
- Hematogenous spread (e.g., infective endocarditis)

Front 14

What is this

Back 14

cerebral abscess

Front 15

Arboviruses

Back 15

Disease: encephalitis
Comments: Mosquitos are the vector. Wild birds are the reservoir for the virus. West Nile virus: crows and other birds are spreading the disease from New York to the west coast.

Front 16

Coxsackievirus

Back 16

Disease: Meningitis
Comments: Most common cause of viral meningitis. Viral meningitis peaks in late summer and early autumn

Front 17

Cytomegalovirus

Back 17

Disease: Encephalitis
Comments: Most common viral infection in AIDS. Primarily intranuclear basophilic inclusions. Periventricular calcification in newborns.

Front 18

Herpes simplex virus type 1

Back 18

Disease: Encephalitis & Meningitis
Comments: Causes hemorrhagic necrosis of temporal lobes

Front 19

HIV

Back 19

Disease: Encephalitis
Comments: Most common cause of AIDS dementia. Microglial cells to from multinucleated cells.

Front 20

Lymphocytic choriomeningitis

Back 20

Disease: Meningitis & encephalitis
Comments: Endemic in the mouse population.
Transmission: food or water contaminated with mouse urine/feces.
Meningoencephalits: combination of nuchal rigidity and mental status abnormalities (encephalitis).
CSF Findings: increased protein, lymphocyte infiltrate, normal to decreased glucose.

Front 21

Polio virus

Back 21

Disease: Encephalits and myelitis (spinal cord)
Comments: Destroys upper and lower motor neurons (anterior horn cells). Causes muscle paralysis.

Front 22

Rabies

Back 22

Disease: Encephalitis
Comments: Most often transmitted by raccoon (40% of cases). Other vectors are dog, skunk, bat and coyote. Virus ascends peripheral nerves. Neurons contain intracytoplasmic Negri bodies. CNS excitability stage followed by flaccid paralysis.

Front 23

Creutzfeldt-Jakob disease

Back 23

Unconventional slow virus encephalitis due to prions (proteinaceous material devoid of RNA or DNA). Transmitted by corneal transplantation,contact with human brain, used of improperly sterilized cortical electrodes, or ingestion of tissues from cattle with bovine spongiform encephalopathy ("mad cow" disease).
Brain has "bubble and holes" spongiform change in cerebral cortex. Death usually occurs within 1 year.

Front 24

Progressive multifocal leukoencephaly

Back 24

Conventional slow virus encephalitis due to papovavirus.

Intranuclear inclusion in oligodendrocytes. Occurs in AIDS when CD4 T helper count <50 cells per μL.

Front 25

Subacute sclerosing panencephalitis

Back 25

Conventional slow virus encephalitis associated with rubeola (measles) virus.
Intranuclear inclusion in neurons and oligodendrocytes.

Front 26

Group B streptococcus (Streptococcus agalactiae)

Back 26

Disease: Neonatal meningitis
Comments: Gram positive coccus
-Most common cause of neonatal meningitis
-Spreads from a focus of infection in maternal vagina

Front 27

Escherichia coli

Back 27

Disease: Neonatal meningitis
Comments:
Gram negative rod
Second most common cause of neonatal meningitis

Front 28

Listeria monocytogenes

Back 28

Disease: Neonatal meningitis
Comments:
Gram-positive rod with tumbling motility
Pathogen found in soft cheese, hot dogs

Front 29

Neisseria meningitidis

Back 29

Disease: Meningitis
Comments:
Gram negative diplococcus
Most common cause of meningitis between 1 month and 18 years of age

Front 30

Streptococcus pneumoniae

Back 30

Disease: Meningitis
Comments:
Gram positive diplococcus
Most common cause of meningitis in patients > 18 years of age

Front 31

Mycobacterium tuberculosis

Back 31

Disease: Meningitis
Comments:
Complication of primary tuberculosis
Involves base of brain
Vasculitis (infarction) and scarring (hydrocephalus)

Front 32

Treponema pallidum

Back 32

Disease: Meningitis, encephalitis, and myelitis
Comments:
Spirochete
Types of neurosyphilis:
-Meningovascular: vasculitis causing strokes
-General paresis: dementia
-Tabes dorsalis: involves dorsal root ganglia and dorsal column. Causes ataxia, loss of vibration sensation, absent deep tendon reflexes, Argyll Robertson pupil (pupils accommodate but do not directly react to light).

Front 33

Cryptococcus neoformans

Back 33

Disease:Meningitis and encephalitis
Comments:
Occurs in immunocompromised host
Most common fungal CNS infection in AIDS

Front 34

Mucor species

Back 34

Disease: Frontal lobe abscess
Comments:
Occurs in diabetic ketoacidosis. Spreads from frontal sinuses

Front 35

Naegleria fowleri

Back 35

Disease: Meningoencephalitis
Comments:
Involves frontal lobes
Contracted by swimming in fresh-water lakes

Front 36

Taenia solium

Back 36

Disease: Cysticercosis
Comments:
Patient (intermediate host) ingests food or water containing eggs. Eggs develop into larval forms (cysticerci) that invade brain, producing calcified cysts causing seizures.

Front 37

Toxoplasma gondii

Back 37

Disease: Encephalitis
Comments:
Most common CNS space-occupying lesion in AIDS
Congenital toxoplasmosis produces basal ganglia calcification