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Sem3 > Case 5 > Flashcards

Case 5 Flashcards

1
Q

What is a stroke?

A

Sudden attack of weakness usually affecting one side of the body due to interrupted flow of blood to the brain

Deficit Lasts more than 24hrs or leads to death

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2
Q

What are the two types of stroke?

A

Ischaemic - thrombus/embolism prevents flow (80%)

Haemorrhagic - rupture of a cerebral artery wall

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3
Q

What are stroke risk factors?

A

Asian and black African

Age (>40)

Male

Hypertension

Hypercholesterolemia

Diabetes

Cigarette smoking

Family history

CVD

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4
Q

What is ischaemic strokes linked to?

A

Neurological deficits, headaches, seizures

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5
Q

What is the penumbra?

A

Area surrounding immediate area of infarct

Blood supply is compromised but not cut off and cells are not dead but under threat

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6
Q

What three things cause ischaemic damage?

A

Neurotransmitters - glutamate

Ions - calcium and sodium

Free radicals - abnormal oxygen molecules

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7
Q

The mechanisms that lead to ischaemic damage are?

A

Excitotoxicity

Reperfusion injury

Free radical formation (oxidative stress)

Apoptosis

Inflammation

Peri-infarct depolarisation

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8
Q

What is excitotoxicity?

A

Hypoxia leads to decrease ATP production hence failure of pump channels

Influx of calcium and sodium ions causes increase glutamate release

Calcium ions cause formation of free radicals

Results in necrosis at onset of injury

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9
Q

How does calcium ion overload lead to free radical production?

A

Mitochondrial injury

Increased production of Nitric Oxide

Protease Activation

Phospholipase activation

All these lead to cell death via apoptosis

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10
Q

What does the production of free radicals result in?

A

Lipid ms and proteins peroxidation

DNA damage

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11
Q

How does apoptosis occur?

A

Oxidative stress > mitochondrial injury > cytochrome C released from mitochondria > paracaspases activated to cascades > DNA damage and apoptosis

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12
Q

Why does inflammation occur?

A

Due to potent inflammatory response caused by brain damage

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13
Q

What is the charesteristic of inflammation?

A

Heat (Calor); redness (rubor); swelling (tumor); pain (dolor); lost of function (function laesa)

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14
Q

What are investigations for stroke?

A
  • FAST

- CT and MRI - CT best for haemorrhage, MRI for infarction

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15
Q

What are the clinical features of a stroke?

A

Limb weakness on contralateral side, contralateral hemiplegia/hemiparesis w/ facial weakness, aphasia (when dominant hemisphere is affected); extensor plantar response

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16
Q

What is a Doppler ultrasound for?

A

Assessing blood flow to neck and head - if internal carotid artery stereos is present a carotid bruit is heard

Electrocardiogram identifies cardioembolic source

Echocardiogram looks for structural abnormalities or thrombi

Blood test for cardiac enzymes to detect myocardial infarction

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17
Q

How is an ischaemic stroke treated?

A

Drugs for hypertension, heart disease and diabetes (propranolol and ramipril)

Endarterectomy

Speech therapy

Anticoagulants (warfarin/heparin)

Antiplatelet agents (aspirin)

Thrombolysis (rule out haemorrhage with CT and then administer tPA w/in 4.5hrs of stroke onset)

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18
Q

How to treat haemorrhage stroke?

A

Anticonvulsant

Antihypertensive (reduce BP and other risks of heart disease)

Osmotic diuretic (reduce intracranial pressure)

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19
Q

What is a Transient Ischaemic Attack?

A

Focal neurological deficit lasting less than 24hrs and causing temporary ischaemia

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20
Q

What is amauroses fungax?

A

Sudden loss of vision in one eye due to embolus in retinal arteries

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21
Q

What is transient global amnesia?

A

Episodes of amnesia/confusion lasting several hrs due to posterior circulation ischaemia

More common in over 65yo

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22
Q

Over what period of time do some patients regain function affected by stroke?

A

3-6months

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23
Q

What is neuroplasticity?

A

Extraordinary ability of the brain to modify its own structure and function following changes within the body or in external environment

It is strongest during childhood (this is a why childhood stroke recovers quickly)

This is built upon synaptic pruning - removing weak synaptic connections and keeping strong ones

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24
Q

Where are ischaemic events more common?

A

Middle cerebral artery

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25
Q

What is the different types of intracranial haemorrhages?

A
  • subarachnoid: headaches, Nuchal rigidity, photophobia, neurologic deficits
  • subdural: headaches, drowsiness, confusion caused by rupture of bridging veins
  • extradural: ipsilateral dilated pupil and contralateral hemiparesis caused by rupture of middle meningeal artery second to temporal bone fractures
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26
Q

What is carotid stenosis ?

A

Narrowing of internal carotid caused by atherosclerotic disease or sudden drop in systemic blood pressure

Leads to:

MCA - contralateral face-arm or face-arm-leg weakness

ACA - leg weakness

Ophathalmic artery - amauroses Fungax

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27
Q

What is muscle tone?

A

Continuous and passive partial contraction of muscles

28
Q

Where are skeletal muscle movements initiated?

A

Lower motor neurones in the spinal cord and brainstem that directly innervate skeletal muscles

29
Q

What are gamma motor neurones?

A

They innervate specialised intramural muscle fibres and function to regulate sensory input by setting the intramural muscle fibres to an appropriate length

Muscle tone and tension

30
Q

What are intrafusal muscle fibres?

A

aka muscle spindles

Specialised muscle fibres that serve proprioceptors

31
Q

What are alpha motor neurones?

A

They innervate extrafusal muscle fibres for posture and skeletal movement

Muscle Power and Strength

32
Q

What is a motor unit?

A

A single alpha motor neurone and all the muscles fibres it innervates

33
Q

What are slow twitch muscle fibres?

A

Slow oxidative fibres (Type I)

Innervated by small alpha motor neurones

Rich blood and myoglobin supply

Lots of mitochondria

Resistant to fatigue

Good for posture maintenance

34
Q

What are intermediate muscle fibres?

A

Fast oxidative-glycolytic fibres (Type IIA)

ATP generated by substrate-level phosphorylation (glucose > lactic acid)

Used in walking and slow pace running

35
Q

What are fast twitch muscle fibres?

A

Type IIB - fast glycolytic fibres

Innervated by large alpha motor

Release energy via glycolysis

Fewer mitochondria

Easily fatigued

Used for jumping and running

36
Q

How do stretch reflex work?

A

type Ia and type II afferent neurones innervate spindle > info relayed to alpha motor neurones (one to extensor and other to flexor muscle) > muscle tone

Gamma motor fibres maintain the contraction (tension) in the intrafusal fibre

37
Q

What is the job of golgi tendon organs?

A

These are proprioceptive that sense muscle tension caused by active contraction of the muscle

38
Q

How does the golgi tendon circuit work?

A

1b axons to 1b inhibitory interneurones > alpha motor neurones to the same muscle

Negative feedback regulating muscle tension

39
Q

What is the flexion reflex pathway?

A

A sensory stimulus via a nociceptor (A-delta afferent fibre) causes motor neurones to extensor and flexor muscles (one inhibits and other excites) to withdraw the foot from stimulus

The opposite thing happens on the contralateral half to allow for postural support

40
Q

What does damage to lower motor neurones cause?

A

Paralysis/paresis in affected muscle

Loss of reflexes

Loss in muscle tone

Atrophy of affected muscles

Fibrillations and fasciculations (spontaneous twitches)

41
Q

What is the premotor cortex?

A

Area of motor cortex lying within frontal lobe

It uses information from other cortical regions to select movements appropriate to the context of the action

42
Q

What does medial premotor cortex do?

A

It mediates selection of movement

It responds more so to internal cues rather than external

43
Q

What does an Upper Motor Neurone Déficit cause?

A

Weakness of muscle on contralateral side

Abnormal babinski sign

Increased muscle tone (spasticity)

Hyperactive reflexes

Clonus (sustained)

[the later 3 causes loss of ability to perform fine movements]

44
Q

What is the babinski sign?

A

Stroking the sole of the foot resulting in flexion of big toe

UMN damage causes extension of big toe and fanning of the other toes

45
Q

What does clonus mean?

A

Involuntary contractions and relaxations of muscles in response to muscle stretching

46
Q

What is decerebrate rigidity?

A

Extensive UMN damage causes rigidity of extensor muscle of the leg and flexor muscle of the arm

47
Q

When does anxiety become abnormal?

A

When it is:
• excessively intense/ disproportionate to stimulus

  • continues beyond exposure to danger
  • triggered by harmless situations
  • occurs without cause
  • can’t be controlled
  • impairs function
48
Q

What structure is anxiety disorder associated with?

A

Dysfunction of the amygdala

49
Q

What are the different types of anxiety?

A

Panic disorder, phobias, OCD, generalised anxiety disorder (GAD) and PTSD

Each include symptoms of anxiety

50
Q

What is GAD?

A

a state of inappropriate and sometimes severe anxiety, without adequate cause that lasts for at least six month

It’s long term condition

51
Q

What are the characteristics of GAD?

A

free floating anxiety not linked to a specific cause or situation

Excessive, uncontrollable and often irrational worry about everyday things - disproportionate to the actual source of worry

52
Q

When is the common onset of GAD?

A

20s

53
Q

What are the causes of GAD?

A

Genetics, anxious personality, negative life events, childhood traumas, major stress in life, physical illness and drug harm (alcohol)

54
Q

What are the three types of signs and symptoms seen with GAD?

A

Psychological

Physical

Behavioural

55
Q

How is GAD diagnoses?

A

Operation diagnoses - a person must experience a number of symptoms for a minimum amount of time and symptoms must cause: significant disease and be associated with impairment in everyday function

DSM-5

ICD-10

56
Q

How does ICD-10 diagnose GAD?

A

6 out of 12 diagnostic criteria in ICD-10

Symptoms >6months in DSM-5

Not restricted or focused to a particular circumstance

57
Q

How is GAD treated?

A
  • Short-term treatment = benzodiazepines
  • long-term = beta-blockers/SSRI/SNRI
  • long term = Pregabalin
58
Q

What is the stress response?

A

Reaction to stressors (threatening stimuli)

Avoidance behaviour, increased vigilance and arousal, activation of sympathetic division of ANS, release of cortisol (stress hormone) from adrenal glands

59
Q

What responses is the hypothalamus involved in?

A

Humoral

Visceromotor

Somatic motor

60
Q

Which structures control the Corticotrophin-releasing-hormone (CRH) neurones of the hypothalamus?

A

Amygdala - fear response

Hypocampus - suppresses CRH release

61
Q

What does Benzodiazepines do?

A

Increases the inhibitory effect of GABA between gamma-2 and alpha-1 subunits of the GABA-A receptor

Diazepam is the choice for acute anxiety

62
Q

What is memory?

A

Mental capacity to store and later recall or recognise events that were previously experienced

63
Q

What is the process of memory?

A

Receive, encode, modify and retrieve information

Stage:
Perception, storage and retrieval

64
Q

What is short term memory?

A

Lasts seconds to minutes

Limited capacity 7 (+/- 2) pieces of information

Acoustic code (Engram)

Areas of activity include frontal and parietal lobe

65
Q

What is long term memory?

A

Capacity is possibly unlimited

Semantic code

Activity spread throughout the brain but hippocampus is essential for consolidation (learning)

66
Q

What are the four types of memory?

A
  • Procedural - memory for actions, skills (acquired through practicing)
  • Declarative - conscious effort of explicit information
  • implicit - non-conscious form of learning from unaware experiences
  • explicit - conscious process of remembering (attention is crucial)

Sem3 (10 decks)

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