CNS infections and intoxications

Question 1

What is the difference between meningitis and encephalitis?

Answer 1

Meningitis is inflammation of the leptomeninges whereas encephalitis is inflammation of the brain parenchyma (usually accompanied by meningitis: meningoencephalitis)

Question 2

What is a localized CNS infection called?

Answer 2

Brain abscess

Question 3

What are the different types of meningitis?

Answer 3

Bacterial, fungal, amebic/tuberculous, viral, and non-infectious

Question 4

What are the common causative pathogens of bacterial meningitis in a newborn?

Answer 4

E. coli

Group B streptococci

Question 5

What are the common causative pathogens of bacterial meningitis in a patient between 1-12 months old?

Answer 5

Strep pneumoniae

Haemophilus influenzae

Question 6

What are the common causative pathogens of bacterial meningitis in a patient between 1 yr and 16 y/o?

Answer 6

Neisseria meningitidis
Haemophilus influenzae
Strep pneumoniae

Question 7

What are the common causative pathogens of bacterial meningitis in a patient between 16 y/o and 50 y/o?

Answer 7

Strep pneumoniae

Neisseria meningitidis

Question 8

What are the common causative pathogens of bacterial meningitis in patients at age extremes?

Answer 8

Listeria

Pseudomonas

Question 9

Describe the gross appearance of bacterial meningitis

Answer 9

The suparachnoid space is full of pus, which gives the meninges a yellow/cloudy appearance compared to the normal transparent appearance. Edema is also visible as flattened gyri and sulci.

Question 10

A CSF tap reveals cloudy fluid full of PMNs with high protein and low glucose. What type of meningitis is this?

Answer 10

Bacterial

Question 11

A CSF tap reveals clear fluid full of lymphocytes with slightly high protein and normal glucose. What type of meningitis is this?

Answer 11

Viral

Question 12

A CSF tap reveals lymphocytes, moderately high protein and mildly low glucose. What type of meningitis is this?

Answer 12

TB

Question 13

List the causative agents of chronic meningitis

Answer 13

Tuberculosis
Fungal
Parasitic
Syphilis
Borreliosis
Neurosarcoid

Question 14

What meningitis types can cause granuloma formation?

Answer 14

TB and fungal

Question 15

What are the parasitic CNS infections?

Answer 15

Cysticercosis
Toxoplasmosis
Amoebiasis (Naegleria fowleri, Entamoeba histolytica)

Question 16

What are the common causes of viral meningitis?

Answer 16

Eneterovirus (75% of all cases)
Arboviruses (West Nile)
HSV 2
WNV

Question 17

What viruses target the meninges?

Answer 17

Mumps
Enterovirus
Coxsackie
HIV

Question 18

What viruses target motor neurons?

Answer 18

Polio

Enterovirus

Question 19

What viruses target neurons and glial cells?

Answer 19

Herpes
Rabies
Measles

Question 20

What viruses target neurons, glial cells and endothelium?

Answer 20

CMV (in immunocompromised)

Question 21

What viruses target oligodendroglia?

Answer 21

Papovirus (in immunocomprimised)

Question 22

What viruses target microglia?

Answer 22

HIV

Question 23

What viruses target dorsal root ganglia?

Answer 23

HSV

VZV

Question 24

What viruses target the fetal nervous system?

Answer 24

Rubella

CMV

Question 25

What are the microscopic findings associated with viral encephalitis?

Answer 25

Perivascular inflammation Leptomeningeal inflammation Microglial clusters/nodules Neuronophagia *T-lymphocytes predominate

Question 26

What is the pathogenesis of polio encephalitis?

Answer 26

Fecal-oral transmission, replicates in oropharynx and small intestine Causes destruction of anterior horn cells

Question 27

What is the pathogenesis of rabies?

Answer 27

Caused by exposure to rabid animals (dog, bat, raccoon, skunk) Prodrome of flu-like symptoms Negri bodies are seen in neurons of brainstem, hippocampus and cerebellum

Question 28

What is the pathogenesis of herpes encephalitis?

Answer 28

Transmitted via saliva Causes latent infection of trigeminal ganglion. Can cause focal encephalitis: medial temporal lobe edema, hemorrhage and necrosis

Question 29

What is the characteristic appearance of a cell infected with HSV-1?

Answer 29

Intranuclear inclusions look like Owl's eyes

Question 30

What are the infectious agents that can cross the placenta?

Answer 30

``` ToRCHeS: Toxoplasmosis Rubella CMV Herpes Syphilis (And now Zika virus) ```

Question 31

What is the presentation of congenital CMV encephalitis?

Answer 31

Moderately dilated ventricles with several foci of periventricular calcifications

Question 32

What is the pathogenesis of progressive multifocal leukoencephalopathy?

Answer 32

``` Caused by JC virus (papovirus) Usually affects immunocompromised Disease of white matter Causes loss of myelin with axonal sparing, bizarre appearing astrocytes and oligodendroglial inclusions Untreatable ```

Question 33

What is the characteristic finding of HIV encephalitis?

Answer 33

Multinucleated giant cells with predilection to gray matter

Question 34

What is HIV leukoencephalopathy?

Answer 34

Subacute onset cognitive impairment and apathy related to diffuse white matter myelin degeneration. Etiology poorly understood.

Question 35

What predisposes patients to brain abscesses?

Answer 35

Direct introduction of organisms via trauma or surgery Infection elsewhere (brain or distant site) Diabetes EtOH

Question 36

What are the stages in evolution of an abscess?

Answer 36

Day 1-3: Early cerebritis Day 2-7: Confluent necrosis Day 5-14: Early encapsulation Days 14+: Late encapsulation

Question 37

How does tetanus affect the CNS?

Answer 37

C. tetani exotoxin binds to interneurons of the brain, brainstem, and spinal cord preventing the release of inhibitory glycine and GABA resulting in motor disinhibition, painful muscle spasms and generalized convulsive seizures

Question 38

How does botulism affect the CNS?

Answer 38

C. botulinum exotoxin binds to presynaptic nerve terminals preventing ACh release leading to paralysis presenting as ptosis, diplopia, dysphagia, facial/limb/respiratory weakness

Question 39

What is the affect of lead poisoning on adults? What about children?

Answer 39

Adults get peripheral neuropathy | Children get encephalopathy, abdominal pain

Question 40

What drugs are commonly associated with drug-related stroke syndromes?

Answer 40

Cocaine, amphetamines, PCP and LSD

Question 41

What are the stages of alcohol withdrawal syndrome?

Answer 41

Early hypersympathetic stage for up to 3 days | Delirium tremens 3-4 days after cessation of drinking

Question 42

What is Wernicke-Korsakoff syndrome?

Answer 42

Often associated with chronic alcoholism Thiamine deficiency leads to encephalopathy (nystagmus, ophthalmoplegia, gait ataxia and confusion) and Korsakoff psychosis (amnesia, confabulation)

Question 43

Which is more severe: acute bacterial meningitis or viral meningitis?

Answer 43

Bacterial is more severe than viral. Can be fatal if not treated early and aggressively.

Question 44

What are the complications of bacterial meningitis?

Answer 44

Hydrocephalus due to pus obstructing the CSF pathway Secondary edema of the cortex Infarction from inflamed vessels Deafness

Question 45

What is the presentation of Herpes simplex encephalitis?

Answer 45

Frontal and temporal lobe degeneration can cause aphasia, behavioral changes and memory impairment

Question 46

What is shingles?

Answer 46

Reactivation of latent varicella-zoster virus in the dorsal root ganglia causes vesicular rash with severe pain within a dermatomal distribution

Question 47

What are prion diseases?

Answer 47

Infectious proteins (no nucleic acid) that cause transmissible spongiform encephalopathies in humans and animals. Misfolded prions trigger conformational changes in normal proteins which trigger neuronal death without inflammation.

Question 48

What is Creutzfeldt-Jakob disease?

Answer 48

Prion disease that is rapidly progressive, untreatable and fatal within months. Presents as dementia with myoclonus. Can have corticospinal, extrapyramidal, cerebellar or lower motor neuron signs.