Neurological Conditions

Question 1

What is the blood brain barrier

Answer 1

The BBB helps to isolate the brain from the circulatory system

Protects against: toxins, pathogens, blood components

Question 2

Where is the blood brain barrier absent or ‘leaky’ in?

Answer 2

Choroid plexus (where CSF if produced)

Posterior pituitary and neurohypophysis (where hormones are released)

Question 3

What is bacterial meningitis?

Answer 3

Inflammation of the meninges - particularly in the arachnoid mater and the pia mater

Question 4

How does bacterial meningitis begin?

Answer 4

Bacteria invades the subarachnoid space, spreading to the ventricles of the brain.

Infection spreads to brain parenchyma and the spinal cord. Results in neuronal damage, particularly in the hippocampus.

Highly activated leukocytes in the cerebrospinal fluid.

Question 5

How does bacteria gain access to cerebral spinal fluid?

Answer 5

Through local defects, sites of infection or the choroid plexus

Question 6

What are the physiological consequences of menningitis?

Answer 6

Bacteria releases toxins that can cause immediate cell death, causing the inflammatory response.

This results in: edema, intracranial pressure and neuronal damage.

Question 7

What are the effects of inflammatory mediators being released in the brain?

Answer 7

Toxic inflammatory mediators trigger dangerous inflammatory responses, resulting in edema in tissues, pus in the subarachnoid space, spreading over the cerebrum, cerebellum and spinal cord.

Question 8

What is Cushing’s Triad?

Answer 8

The 3 main symptoms indicating extreme intracranial pressure =

Rising blood pressure
Bradycardia
Periodic or slow respiration rate

Question 9

How does the brain compensate for increased intracranial pressure?

Answer 9

Increase the venous drainage (reducing amount of blood)

Increase in the CSF drainage.

Question 10

What is the Monro-Kellie Doctrine?

Answer 10

A doctrine that describes the relationship between the contents of the cranium and intracranial pressure.

Tissue + Blood + CSF = Total volume

Question 11

What pathologies change tissue volume?

Answer 11

Meningitis
Brain tumour
Inflammation/oedema
Trauma

Question 12

What pathologies change CSF volume?

Answer 12

Choroid plexus tumour
Blockage retarding CSF flow
Reduced drainage into venous sinus

Question 13

What pathologies change blood volume?

Answer 13

Hypercapnia (local vasodilation)

Heart failure (leads to increased venous pressure)

Question 14

What is Alzheimer’s disease?

Answer 14

A cognitive impairment leading to dementia.

Question 15

How does Alzheimer’s disease present itself?

Answer 15

With deficits in:

Sensation 
Processing speed
Perception 
Motor skills 
Memory 
Language 
Executive functioning

Question 16

What does the sulki/gyri look like in a brain with AD?

Answer 16

Sulki widens

Gyri thins

Question 17

What are the anatomical features of cortical atrophy?

Answer 17

Loss of parenchyma

Narrow gyri & widened sulci

Atrophy of parahippocampal cortex

Question 18

What are two key ultrastructural features of AD?

Answer 18

Senile plaques (i.e. amyloid plaques or neuritic plaques)

Neurofibrillary tangles (formed from tau proteins)

Question 19

What are Amyloid plaques?

Answer 19

Extracellular deposits of beta-amyloid accumulating in areas of the brain.

Question 20

Why are Amyloid plaques dangerous?

Answer 20

There is a recruitment of activated astrocytes and microglia (involved in inflammatory response)

Behaves in a way as if there is some damage in the tissue, and inflammatory response is developing.

Question 21

True or False - the number and distribution of the amyloid disposition in the tissue is not well correlated with clinical signs.

Answer 21

True

You may present signs of Alzheimer’s, yet an MRI may not show any clinical signs of degeneration

Question 22

What make up the amyloid plaques that sits in brain tissue?

Answer 22

Fibrils.

Proteins will fold, sometimes incorrectly in the intracellular space and bind into protofibrils

Question 23

What is the Amyloid Cascade hypothesis?

Answer 23

amyloid accumulation may be the initial step in Alzheimer’s pathogenesis, leading to deposition of Tau protein (neurofibrillary tangles).

Tauopathy is linked to neuronal decline and synaptic loss. These in turn result in classical cognitive decline

Question 24

What is Tau protein?

Answer 24

A very soluble protein, encoded by MAPT gene.

Question 25

What is the Tau hypothesis of AD?

Answer 25

Tau pathology is the primary driver of neurodegeneration.

The spread of tau pathology correlated with cognitive decline and neuron loss.

Question 26

What does tauopathy do to neurons?

Answer 26

Disrupts functioning of cytoskeleton

Disrupts to receptor protein trafficking inside the cell

Disrupts to synapse function and formation.

In the end, these issues lead to neuronal death.

Question 27

What affects does ageing have on the brain?

Answer 27

Degeneration of neurons

Increase size of ventricles as we age

Develop pigmentation of neural tissue

Question 28

What is the dura mater?

Answer 28

Makes up the periosteal and meningeal layers.

Has a tough, outer layer that lines the skull that protects the brain

Question 29

What is the arachnoid mater?

Answer 29

The subarachnoid space is beneath the arachnoid mater and contains the cerebrospinal fluid

Question 30

What is the pia mater?

Answer 30

The nutritive layer that hugs the surface of the brain