Brain Damage

Question 1

What are the two broad types of cerebrovascular disorders that can lead to brain damage?

Answer 1

The two broad types are hemorrhagic stroke (cerebral haemorrhage) and ischaemic stroke (cerebral ischemia)

Question 2

What are the main mechanisms that can cause cerebrovascular disorders - differences between hemorrhagic and Ischaemic strokes?

Answer 2

The main mechanisms include cerebrovascular injury, such as rupture of a blood vessel leading to bleeding (hemorrhagic stroke)

and disruptions in blood supply caused by thrombosis, embolism, or arteriosclerosis (Ischaemic stroke).

Question 3

What neurotransmitter is involved in ischemia-induced brain damage?

Answer 3

Glutamate, the brain’s most excitatory neurotransmitter, is involved in ischemia-induced brain damage.

Question 4

What are the two types of cell death that can occur in brain damage?

Answer 4

The two types are apoptosis, which is an active but gradual self-destructive process. It is an adaptive process limiting brain damage. A cell body shrinks and remainder neurons die, any debris is cleared.

Necrosis, which is a passive and fast but more generally destructive process whereby neurons swell up and break.

Question 5

What is the pathomechanism of brain injury and broadly the two primary classifications?

Answer 5

The mechanism is typically shearing, stretching and tearing at the neuron level.

The two classifications are penetrating head injury and close head injury

Question 6

What is the difference between primary and secondary impact in closed head injury?

Answer 6

Primary impact refers to the initial force applied to the head (coupe), while secondary impact refers to the brain hitting the opposite side of the skull due to the movement of the brain within the skull (contra coupe).

Question 7

What is a concussion in the context of traumatic brain injury?

Answer 7

A concussion is a disturbance of consciousness without evidence of structural damage, and it can have significant impacts on brain functioning, particularly in the case of repeated concussions.

Question 8

What is a cerebral haemorrhage?

Answer 8

It is bleeding within the brain tissue, and it can cause the collection of blood in the convex or dish-shaped part of the brain.

Question 9

What are some imaging findings associated with closed head injury?

Answer 9

Imaging findings may show contusions (damage to the cerebral circulatory system resulting in internal bleeding), collections of blood around the cisterns and fissures of the brain, and bleeding within the brain tissue itself.

Question 10

What is the qualities of subdural hematoma in the brain?

Answer 10

Cresent-shaped
Blood collection between dura and arachnoid mater
Tear in bridging veins
Alcoholics and elderly are prone

Question 11

What are the qualities of an epidural hematoma?

Answer 11

Biconvex (lens) shaped
Blood between dura and skull
Tearing of middle meningeal artery
Adolescents and young adults (trauma)

Question 12

What are the qualities of a subarachnoid haemorrhage?

Answer 12

Blood in circle of Willis, cisterns, and fissures
Rupture of berry aneurysm
Polycystic kidney disease (risk factor)

Question 13

What are the qualities of intracerebral haemorrhage?

Answer 13

Blood in parenchyma and ventricles
Hypertensive vasculopathy
Territory of penetrator arteries

Question 14

Is it better to have a brain injury as a child or an adult?

Answer 14

Brain injuries in children can have a greater impact on development and organisation, while injuries in adults may lead to a narrowing gap in trying to recover compared to their peers.

Question 15

What are the classifications of severity for traumatic brain injury (TBI)?

Answer 15

The classifications of severity include Glasgow Coma Scale (GCS), loss of consciousness (LOC), and post-traumatic amnesia (PTA).

Most TBI’s are classified as mild, with a smaller percentage classified as moderate or severe.

Question 16

What are the four neuroplastic responses to brain damage?

Answer 16

The four responses are neural degeneration, neural regeneration, neural reorganisation, and recovery of brain function

Question 17

What is Anterograde and retrograde degeneration and how does it occur?

Answer 17

Anterograde degeneration = distal portion of a neutron degenerates quickly

retrograde degeneration may affect the proximate portion depending on the reaction of the cell body.

Question 18

What is Transneuronal degeneration and how does it occur?

Answer 18

where degeneration is transmitted from damaged neurons to intact neurons via synaptic connections.

Question 19

Is neural regeneration successful in mammals and higher vertebrates?

Answer 19

Neural regeneration is not successful in mammals and higher vertebrates, except for in the peripheral nervous system (PNS) where it is possible to some extent.

Question 20

What are the factors that determine the course of neural regeneration in the PNS?

Answer 20

The nature of the injury determines whether regeneration axons can grow through intact Schwan cell myelin sheaths (if intact) - yellow neuron to yellow neutron.

Grow into incorrect sheaths and incorrect destinations (if the nerve is severed and ends are separated) - blue neuron connection severed, cannot connect to blue so connects to yellow neuron.

Or no meaningful regeneration will occur (if ends are widely separated) - all neurons that are severed will tangle their axons, leaving the neuron with no axon terminal.

Question 21

What is neural reorganisation and where has it been observed?

Answer 21

It is the reorganisation of primary sensory and motor systems following damage to peripheral nerves or primary cortical areas. Examples include remapping of V1 neurons in animals and the larger auditory and somatosensory cortex in vision-impaired humans.

Question 22

What are the mechanisms of neural reorganisation?

Answer 22

release from inhibition strengthens existing connections, and collateral sprouting results in new connections.

Question 23

Why is the recovery of brain function poorly understood?

Answer 23

It is difficult to differentiate between compensation and true recovery, as improvements can be influenced by factors such as reduction in brain swelling after injury.

Question 24

explain and outline long-term consequences of repeated impact forces (chronic traumatic encephalopathy) (i.e., CTE).

Answer 24

Repeated concussions or subconcussyve impacts lead to CTE, a neurodegenerative condition associated with cognitive, emotional, and behavioural impairments.

Question 25

What are some causes of brain damage?

Answer 25

Cerebrovascular Disorders
Traumatic Brain Injury
Tumours
Infections
Neurotoxins

Question 26

In Ischaemic strokes, how is blood supply disrupted by Thrombosis, Embolism and Arteriosclerosis?

Answer 26

1. Thrombosis: At formation thrombus blocks artery
2. Embolism: Traveling thrombus lodges in narrower artery
3. Arteriosclerosis: Thickening of blood vessel walls
4. Also, Sudden drop in blood pressure.

Question 27

What is the difference between a thrombotic and embolic stroke?

Answer 27

Thrombotic is where a blood clot (thrombus) blocks the flow of blood in the brain

An Embolic stroke, is where fatty plaque or blood clot (embolism) breaks away and flows to brain where it blocks an artery.

Question 28

In Cerebral Ischemia and brain damage, how does the resulting damage occur?

Answer 28

1. blood-deprived neurons become overactive and release too much glutamate
2. Glutamate over-activates postsynaptic glutamate receptors esp. NMDA
3. results in an influx of Ca2+, Zn2+ and Na2+ into postsynaptic neurons (concentration abnormally high)
   Triggers release of glutamate from postsynaptic neuron (domino/cascade effect)
4. Triggers internal reactions that lead to cell death (apoptosis)

Question 29

In Cerebral Ischemia and brain damage, how does the resulting damage occur?

Answer 29

1. blood-deprived neurons become overactive and release too much glutamate
2. Glutamate over-activates postsynaptic glutamate receptors esp. NMDA
3. results in an influx of Ca2+, Zn2+ and Na2+ into postsynaptic neurons (concentration abnormally high)
   Triggers release of glutamate from postsynaptic neuron (domino/cascade effect)
4. Triggers internal reactions that lead to cell death (apoptosis)

Question 30

What is the definition of a tumour or neoplasm?

Answer 30

An independently growing cell mass without any physiological function.

Question 31

Meningiomas, infiltrating and metastatic are all different types of tumours. Where do they all grow?

Answer 31

Meningiomas:
~ 20% of tumours, grow between meninges; encapsulated (within own membrane), usually benign

Infiltrating:
Most tumours are infiltrating. Grow diffusely through surrounding tissue, typically malignant, difficult to remove or destroy

Metastatic
~10% of brain tumours, originate elsewhere, usually lungs, skin and breast tissue.

Question 32

If a traumatic brain injury is GCS: 13 - 15, LOC: <30mins and PTA: <24h. What level of severity is the TBI?

Answer 32

Mild

Question 33

If a TBI is; GCS: 9 - 12, LOC: 30mins - 24hr, PTA: 1- 7 days. What is the severity?

Answer 33

Moderate

Question 34

If a TBI is; GCS: 3 - 8, LOC: >24hrs, PTA: >7 days. What is the level of the TBI?

Answer 34

Severe

Question 35

In Neural degeneration, what is axotomy? and what does it result in?

Answer 35

It is cutting axons and a method to study responses to neuronal damage. Cutting results in two forms of neural degeneration:
1. Anterograde degeneration
2. Retrograde degeneration

Question 36

How can CNS neurons regenerate?

Answer 36

They can regenerate if transplanted into the PNS, while PNS neurons will not regenerate in the CNS to PNS environment. This is because oligodendrocytes in the CNA release substances actively blocking regeneration.

Question 37

How do Schwann cells (PNS) promote regeneration?

Answer 37

Neurotrophic factors - stimulate new axon growth
CAMs (Cell Adhesion Molecules) - provide a pathway

Question 38

Meningiomas are tumours that grow where? and what does it mean when meningiomas are encapsulated tumours?

Answer 38

They are tumours that grow between the meninges, the three membranes that cover the central nervous system.

Encapsulated means they grown within their own membrane - as a result, they are very easy to identify in CT and almost always benign.