CNS Histology and Infections

Question 1

Inflammation restricted to the meninges, no sign of bacteria or fungi

Answer 1

Aseptic meningitis

Question 2

Viral encephalitis restricted to gray matter

Answer 2

Polioencephalitis/poliomyelitis

Question 3

Viral encephalitis of both gray and white matter

Answer 3

Panencephalitis/Panmyelitis

Question 4

Viral encephalitis restricted to white matter

Answer 4

Leukoencephalitis

Question 5

What virus is usually responsible for aseptic meningitis?

Answer 5

Enterovirus, accounts for over 80% of cases

Question 6

What 6 viruses are associated with polioencephalitis?

Answer 6

Poliovirus, coxsackievirus, echovirus, arbovirus, tick-borne encephalitis, rabies

Question 7

What viruses are associated with panenecephalitis?

Answer 7

Necrotizing herpesviruses (HSV) and non-necrotizing viruses (HIV)

Question 8

Lymphocytic meningitis, cranial nerve palsies, polyradiculitis (several months after erythema migrans) is associated with what?

Answer 8

Lyme disease (Borriela burgdorferi)

Question 9

Examples of leukoencephalitis?

Answer 9

JC multifocal leukoencephalopathy, infection of HIV

Question 10

What broad classification of viruses is involved in seasonal acute viral encephalitis?

Answer 10

Arboviruses

Question 11

What is the most common cause of non-seasonal acute viral encephalitis?

Answer 11

Herpes encephalitis

Question 12

Are the majority of human arbovirus infections symptomatic or asymptomatic?

Answer 12

Asymptomatic

Question 13

What are the natural hosts for most arboviruses?

Answer 13

Birds and small mammals

Question 14

What is an example of an amplifying host for arboviruses?

Answer 14

Pigs, for japanese encephalitis virus

Question 15

What are two examples of dead-end hosts for arboviruses?

Answer 15

Humans and horses (equine encephalitis)

Question 16

What is the most common form of arbovirus encephalitis?

Answer 16

St. Louis encephalitis

Question 17

List features of acute viral encephalitis pathology

Answer 17

1. Perivascular inflammatory infiltrates (lymphocytes) 2. Microglial nodules and neuronophagia, 3. Intranuclear viral inclusions

Question 18

Bilateral asymmetric hemorrhagic necrosis of temporal lobes. Patient presents with nonspecific features of encephalitis (headache, pyrexia, neck stiffness, drowsiness, coma) and focal neurological signs (dysphasia, hemiparesis, focal seizures) and a very high fever. Fatal within a few days without treatment.

Answer 18

HSV-1 most common cause. Also HSV-2, VZV, EBV, CMV, but these are much rarer causes.

Question 19

What is the treatment for HSV-1 encephalitis?

Answer 19

Aciclovir

Question 20

What are neurological sequelae if a patient does survive a HSV-1 encephalitis?

Answer 20

Behavioral abnormalities, memory disturbances, other neurologic deficits.

Question 21

In what two settings does CMV cause significant CNS pathology?

Answer 21

1. Interuterine infection, 2. Immunosuppression (post-transplant, HIV)

Question 22

Insomnia, agitation, aggressive behavior, biting, hypersalivation, hallucination, hydrophobia, dysphagia, dysarthria, nystagmus

Answer 22

Furious rabies. 70-80% of patients.

Question 23

Type of rabies with ascending paralysis of one or more limbs, simulating Guillan-Barre, sensory loss and incontinence

Answer 23

Dumb rabies. 20-30% of patients.

Question 24

What happens after a person gets bitten by an animal with rabies?

Answer 24

Rabiesvirus replicates in skeletal muscle –> taken up by axons –> transported centripetally to the CNS –> replicates and spreads within the CNS through the spinal cord to cerebellum and cerebrum

Question 25

What is the incubation period for rabies?

Answer 25

1-2 months, but can vary from 15 days - 1 year

Question 26

What is the most common neurological fungal infection? The second most common?

Answer 26

1. Cryptococcus, 2. Asprgilloma

Question 27

Two main ways that aspergilloma enters the brain?

Answer 27

1. Hematogenous spread (arising from the bloodstream) 2. Direct spread, arising from the cranial cavity, such as a sinonasal infection.

Question 28

What happens when you have hematogenous dissemination of aspergillosis?

Answer 28

Multiple lesions, often in the ACA or MCA territory. Often involve the cerebral cortex, white matter, and basal ganglia, but brain stem and cerebellar structures may also be affected. Early lesions resemble hemorrhagic infarcts, thrombosis, etc. These may then form abscesses.

Question 29

What happens when you have direct spread of aspergillus?

Answer 29

You are more likely to get chronic, relatively localized infection with a tendency toward fibrosis and granuloma formation.

Question 30

What are cysticerci?

Answer 30

Larvae of Taenia solium tapeworm

Question 31

How is Taenia solium transmitted?

Answer 31

Usually through eggs in uncooked pork

Question 32

How much of an inflammatory response do cysts from cysticercosis cause?

Answer 32

Almost no inflammatory response

Question 33

Cryptococcomas

Answer 33

Cryptococcal abscesses

Question 34

How common are cryptococcomas?

Answer 34

Much less common than cryptococcal meningitis, tend to form in non-immunocompromised patients

Question 35

Primary infection for cryptococcomas and cryptococcal meningitis is usually where?

Answer 35

Pulmonary, and then subsequent hematogenous spread to the CNS occurs.

Question 36

Poliomyelitis

Answer 36

Viral encephalitis restricted to gray matter

Question 37

Embolites from endocarditis that can cause infection are called

Answer 37

Septic emboli

Question 38

focal, destructive lesions (occasionally multifocal) of the brain parenchyma due to necrosis mediated by acute inflammation in response to bacterial infection

Answer 38

Abscess

Question 39

Symptoms of abscess

Answer 39

fever and focalizing neurological symptoms/signs related to the localization of the lesion

Question 40

purulent meningitis =?

Answer 40

Bacterial meningitis

Question 41

Most common meningitis bacteria in neonates

Answer 41

Group B strep E coli Listeria monocytogenes

Question 42

The primary infection for tb usually occurs in infancy or childhood in developing or developed countries?

Answer 42

Developing

Question 43

Presents over 2–3 weeks with a combination of headache, lethargy, nausea, and vomiting. Subsequently causes a variety of neurologic signs including cranial nerve palsies, other focal neurologic deficits, epilepsy, and increasing obtundation. May cause signs of raised intracranial pressure. Examination of the cerebrospinal fluid (CSF) usually reveals lymphocytosis, a reduced concentration of glucose, and an increase in protein. H&E section shows granulomatous inflammation with multinucleated giant cells surrounding a necrotic center.

Answer 43

TB meningitis

Question 44

Associated with fresh water swimming

Answer 44

Naegleria fowleri