Pathology

Question 1

What does grey matter consist of?

Answer 1

Neurone cell bodies and a network of thinly myelinated axon, dendrites and glial cell processes - collectively known as neuropil

Question 2

What deos white matter consist of?

Answer 2

Primarily well myelinated axes, oligodendroglia and astrocytes. Support cells

Question 3

What parts is white matter split into?

Answer 3

Dorsal funiculus - ascending sensory axons
Ventral funiculus - descending motor axons
Lateral funiculus - mixture of sensory and motor axons

Question 4

What is the neurons response to injury?

Answer 4

Apoptois or necrosis and central chromatolysis

Question 5

What is the astrocyte response to injury?

Answer 5

Hyperplasia and hypertrophy = gemistocytic

Question 6

What is the oligodendrocyte response to injury?

Answer 6

Hypertrophy and hyperplasia

Question 7

What is the microglia response to injury?

Answer 7

Proliferate and can transform into brain macrophages.

Form aggregates at site of injury = microglial nodules/glial nodules

Question 8

Define gitter cell

Answer 8

Macrophages that have ingested degenerate myelin adn other debris.
Foamy cytoplasm.

Question 9

State the protective elements of the CNS

Answer 9

Calvarium and vertebrae
Skin
Meninges and CSF
Barrier systems
Microglia
Immunologic responses

Question 10

Describe the overall CNS response to injury

Answer 10

No fibrosis
Gliosis 
Wallerian degeneration
Central chromatolysis
Necrosis of any cell type
Inflammation
Vascular changes
CNS swelling and oedema

Question 11

Define ‘gliosis’

Answer 11

Proliferation of astrocytes, oligodendrocytes and microglia

Question 12

Define ‘wallerian degeneration’

Answer 12

Trauma occurs to axon. Distal segment of neurone degenerates and myelin is removed by phagocytosis. Forms spheroids (swollen axons) and digestion chambers (areas of axonal loss, myelin removal and clean up by gitter cells)

Question 13

Can cells recover from wallerian degeneration?

Answer 13

CNS - axons don’t regenerate
PNS - nerves can regenerate, Schwann cells proliferate and proximal stump generates multiple sprouts. One sprout persists and grows distally to reinnervate the muscle

Question 14

What are the portals of entry into the CNS?

Answer 14

1. Direct extension
2. Haematogenous
3. Via leukocyte trafficking
4. Retrograde axonal transport

Question 15

Describe direct extension

Answer 15

Penetrating injury
Extension of nasal cavity/sinus infection/neoplasia via cribiform plate
Compression from growths of calvarium and vertebrae
Can be sterile or infected
Spinal trauma (intrinsic or extrinsic)

Question 16

How are disc lesions classified?

Answer 16

1. Hansen type 1 - degenerative discs have chondroid metaplasia and mineralisation, disc ruptures through annulus fibrosis into vertebral canal. Disc extrusion into spinal canal is acute
2. Hansen type 2 - degenerative disc is more fibrotic, disc bulges but is intact. Disc protrusion into canal is slow and is retained by the annulus fibrosis

Question 17

What agents can enter via haematogenous entry?

Answer 17

Bacteria
Virus
Fungi
Protozoa
Metastatic neoplasia
Fibrocartilagenous embolism

Question 18

Describe leukocyte trafficking

Answer 18

Component of systemic immunologic surveillance. Macrophages and lymphocytes continually move in and out of capillary beds in the CNS. Some infectious agents have part of their lifecycle in the cytoplasm of sentinel cells.

Question 19

Describe retrorade axonal transport

Answer 19

Infectious agents replicate in richly innervated tissues (sensory receptors and motor endplates). Allows entry to CNS. e.g. listeria and rabies