Neuropathology: Circulatory Diseases

Question 1

What is the glymphatic system?

Answer 1

waste clearance system that utilises a unique system of perivascular channels formed by astroglial cells

Question 2

What is the function of the glymphatic system?

Answer 2

• efficent elimination of soluble proteins and metabolites from the CNS
• Helps distribute non-waste compounds

may be supressed in certain diseases

Question 3

What is vasogenic oedema?

Answer 3

Injury to the vascular endothelium -> breakdown of the blood-brain barrier -> permeability and leakage -> fluid spreads between cells

Question 4

Name 5 causes of vasogenic oedema

Answer 4

1. Inflammation
2. Tumours
3. Haemorrhage/ Contusions
4. Infarcts
5. Hypertension

Question 5

What does intracellular cytotoxic oedema look like

Answer 5

hydropic degeneration
* astrocytes, neurons, endothelial cells, swelling of the cytoplasm

Question 6

What causes cytotoxic intracellular oedema?

Answer 6

Cellular injury with disruption of the membrane- ATP-dependent NA+/ K+ pumps

Question 7

What is cytotoxic oedema related to?

Answer 7

• decrease in energy supply
• Ischaemia
• Hypoxia
• Metabolic inhibitors

Question 8

What is hydrostatic oedema?

Answer 8

Accumulation of fluid in the interstitial space

Question 9

What is hypo-osmotic oedema?

Answer 9

• Over consumption of water leading to dilution of plasma
• Fluid moves to brain plasma causing salt poisioning

Question 10

What is primary traumatic brain injury?

Answer 10

• Mechanical disruption of tissue
• Microvascular lesions

Question 11

What is secondary traumatic brain injury?

Answer 11

• Occurs within hours to days after injury
• Changes lead to ischaemia
• Frequently fatal

Question 12

What supplies oxygen to the brain?

Answer 12

O2 is supplied to the brain from the internal carotid and vertebral arteries which anastamose ventral to the brainstem and at the circle of willis

Question 13

What is an ‘end-artery’ ?

Answer 13

an arterial branch that penetrates the brain

Question 14

What is a cerebral infarction?

Answer 14

sudden occlusion of the arterial branch

Question 15

What causes a cerebrovascular accident ‘stroke’?

Answer 15

Central haemorrhage or infarction

Question 16

What is ischemic myelopathy?

Answer 16

herniation of the fibrocartilage from the intervertebral disc into the vasculature, forming occlusive emboli

Question 17

What does cytotoxic oedema look like?

Answer 17

Sweling of the cytoplasm +/- the nucleus
related to a decrease in energy supply (ischaemia, hypoxia, decreased metabolic inhibitors)

Question 18

What are the three sites where herniation occurs?

Answer 18

• Foramen magnum
• Falx cerebri
• Tentorium cerebelli

Question 19

Give 4 possible causes of vasogenic oedema

Answer 19

1. Oedema disease
2. Focal symetrical encephalomalacia
3. Mulberry heart disease
4. Thiamine deficiency

Question 20

Give two possible causes of cytotoxic oedema

Answer 20

1. Early stages of hypoxic-ischaemic injury
2. Ammonia toxicity in hepatic and renal encephalopathy

Question 21

What cells in the brain are the most susceptible to injury?

Answer 21

• Neurones (high metabolic activity) and high energy use
• Endothelial cells are the least sensitive

Question 22

What causes impaired cell utilisation of O2?

Answer 22

cyanide poisoning or fluroacetate

Question 23

Where do small emboli tend to lodge in the brain?

Answer 23

tend to lodge close to the grey/ white matter junction

Question 24

Where do the venous sinuses of the dura mater empty into?

Answer 24

Jugular veins and also communicate with the cranial bones

Question 25

Give 4 causes of cerebral infarction

Answer 25

Thromboembolism 2. Feline cardiomyopathy 3. Septic thrombosis 4. Parasitic (dirofilaria immitis) 5. Fibrocartilaginous emboli

Question 26

What does the consequence of vascular osbtrcution depend on?

Answer 26

* Type and size of the obstructed blood vessel * Speed and onset * Existence and capacity of the collateral circulation

Question 27

What do CNS infarcts tend to undergo?

Answer 27

* Liquefactive necrosis * Softening (malacia) * Swelling

Question 28

What colour do grey arterial infarcts tend to be?

Answer 28

red/ haemorrhagic

Question 29

What colour do white arterial infarcts tend to be?

Answer 29

pale

Question 30

What is fibrocartilaginous embolic myelopathy?

Answer 30

Herniation of fibrocartilage from the intervertebral disc into the vasculature, forming occlusive emboli Trauma to the nucleus pulposus causes it to fragment and the pressure of the trauma forces small fragments into damaged veins, venous plexus or small arterioles ## Footnote embolised fibrocart material resembels nucleus pulposus -> infarction

Question 31

Where does water in the brain come from?

Answer 31

* Water comes from the blood and ultimately returns to it by re-entry at the venous ends of the capillaries * little water passes through cerebrospinal fluid

Question 32

What are dura mater lymphatics?

Answer 32

Network of lymphatics in the meninges running alongside the dural venous sinuses and extending upon the dura mater surrounding the brain

Question 33

What are the three sites of herniation?

Answer 33

1. Falx cerebri 2. Tentorium cerebelli 3. Foramen magnum

Question 34

What is the pathophysiology of oedema?

Answer 34

* Compression and disrupted vessels go on to cause ischaemia * excitatory neurtransmitters * increased intracellular calcium * proteloytic enzymes -> neuronal necrosis * high levels of inflammatory mediators * vasospasm

Question 35

What are the 5 causes of hypoxic brain injury?

Answer 35

1. Vascular obstruction 2. Complete cessation of cerebral circulation 3. Sustained hypotension 4. Hypoxaemia 5. Impaired cell utilisation of O2

Question 36

What do abrupt changes in the calibre of the pia-arachnoid arterial vessels lead to?

Answer 36

large emboli to become trapped in leptomeningeal vessels

Question 37

Why are strokes less common in dogs?

Answer 37

* Difference in arterial supply * Decreased incidence of atherosclerosis

Question 38

Name 4 causes of cerebral infarction | Thromboembolism

Answer 38

2. Feline cardiomyopathy 3. Septic thrombosis 4. Parasitic 5. Fibrocartilaginous emboli