Neuropathology IV

CNS Infections

bacteria, virus, fungi, parasite, prion

Routes of entry for CNS infections:

hematogenous

direct implantation

local extension

transport along peripheral nerves

Meningitis

inflammation of the meninges

of the brain and spinal cord

often life-threatening

Meningitis is caused by ...

bacterial and viral infections

can also be due to chemicals or carcinomatous

If caused by mycobacteria, fungus, or spirochetes, meningitis may be ___ in nature

chronic

Chronic meningitis is caused by ...

M Tuberculosis

cryptococcus

histoplasma

coccidioides immitis

syphilis

CNS ___ causes greyish, gelatinous, viscous exudate

tuberculosis

Tuberculosis CSF has elevated ___ and low ___

protein

glucose

___ is the most common form of fungal meningitis

Cryptococcus

What is the source of cryptococcus?

pigeon droppings

Cryptococcus is especially harmful in ___ and other immunocompromised hosts

AIDS

___ meningitis is bacterial

Acute pyogenic (APM)

___ meningitis is viral

Acute aseptic (AAM)

APM bacteria are mostly neonates that are commonly found in the ___

vagina

APM is common in patients with ...

shunt infections

neurosurgeries

skull fractures

APM clinical features include:

headache

clouding of consciousness

fever

irritability

APM has ... in CSF

neutrophils*

high protein

low glucose

bacteria on smear or culture

AAM clinical features are similar to APM, except usually less ___

fulminant

What is in the CSF of AAM?

lymphocytes*

slightly elevated protein — not as much as APM

normal glucose

viral culture/PCR positive

___ is most often caused by bacterial infections

Brain abscess

Predisposing factors for brain abscess include ___ and ___

acute bacterial endocarditis

colonic pulmonary infections

Brain abscesses may mimic ___ in function

brain tumors

How do you tell the difference between abscess and tumor?

abscesses have ring-enhancing lesions, that tumors don't have

Brain abscess is a discrete destructive lesion with ___

central necrosis

Do you analyze an abscess using CSF?

no, you use a direct culture of drained abscess fluid, instead

Brain abscess has ___ mortality rate

high

Brain abscesses can be treated by ___ and ___

surgery

antibiotics

What is encephalitis?

inflammation of the brain usually caused by a virus

Which viruses?

arbovirus (West Nile)

enterovirus

herpes simplex

EBV

CMV

mumps

JC

Encephalitis can lead to ...

edema, congestion, hemorrhage, and herniation

What is indicative of severe encaphalitis?

herniation

Parasitic infections can be caused by ...

protozoa

metazoa

rickettsia

These three are all ___

parasites (makes sense)

Examples of Protozoa:

toxoplasma

amebiasis

acanthamoeba

malaria

Examples of metozoa:

cysticercosis

echinococcus

Examples of rickettsia:

typhus

rocky mountain spotted fever

Toxoplasmosis

a parasite that is most commonly transmitted from pets to humans by contact with contaminated animal feces (especially cats)

also by consumption of undercooked meat

Toxoplasmosis is an indicator disease of ___

AIDS/HIV

Toxoplasmosis can be identified, via ___ scan, by presence of ___ lesion and surrounding edema

CT

ring-enhancing

We've seen ring-enhancing lesions before.. connect the dots:

toxoplasmosis can cause abscess

(non bacterial cause)

What is PML?

a CNS demyelinating disorder

What causes PML?

reactivation of latent JCV infection

PML mostly attacks immunocompromised (___) patients

AIDS

What is the treatment for HIV?

Natalizumab

JCV is the only ___ associated with CNS disease

polyomavirus

Clinical presentations of PML include ...

sensory deficits, hemianopsia, cognitive dysfunction, aphasia, gait disturbances, seizures

What is cysticercosis?

tissue infection after exposure to eggs of Taenia solium, the pork tapeworm

Cysticercosis is often obtained from ...

traveling outside of the U.S.

Cysticercosis causes ___ and ___ after the parasite dies

inflammatory response

calcification

Demyelinating Disorders

disorders that attack myelin capacity

Myelin

a fatty substance that helps insulate neurons and speeds the transmission of nerve impulses

CNS Myelin

oligodendrocytes

1 oligodendrocyte myelinates up to ___ axons

50

PNS Myelin

Schwann cells

1 Schwann cell myelinates ___ axon

1

Demyelination is a major feature of a broad range of pediatric and adult ___ diseases

neurological

Demyelination has ___ etiologies

multiple

Demyelination is associated with ___ clinical presentations and syndromes

diverse

Demyelinating diseases include ...

MS

neuromyelitis optica (NMO)

Guillain-Barre Syndrome (GB)

MS attacks the ___

CNS

MS is the ___ autoimmune demyelinating disorder

most common

MS is mostly in people aged ___

20-50 years old

Polysymptoms of MS include ...

motor

cognitive

sensory

How is MS autoimmune?

initiated by helper T cells acting against myelin antigens

MS has a ___ and ___ course

relapsing

remitting

MS features CSF with ...

mildly elevated protein

pleocytosis (elevated WBC count)

oligoclonal IgG bands

Which of these CSF features is an autoimmune hallmark?

oligoclonal IgG bands

NMO

bilateral optic neuritis and spinal cord demyelination

NMO was considered a variant of ___, but this is not the case as per contemporary research

MS

A majority of people with NMO have ___ in their blood

antibodies against aquaporin-4

Two extremely severe examples of demyelinating diseases are ___ and ___

ADEM

AHLE

What is CPM?

acute disorder with loss of myelin in the pons

(of the brainstem)

CPM is most commonly seen 2-6 days after rapid correction of ___

hyponatremia

GB

affects the PNS

GB leads to progressive ___ with mild ___ loss

weakness

sensory

CSF of GB has ___

protein without pleocytosis