Block 12 - Musculoskeletal and nervous system (nervous 2) Flashcards
(131 cards)
1
Q
What are the colours on a CT scan?
A
Black = fluid
Grey = brain
White = bone
Bright white = blood
2
Q
Where is an extradural bleed?
What shape is it?
A
In the extradural space (outside the dura)
Lens shaped bleed
3
Q
Where is subdural bleed?
What shape is it?
A
Between the dura
Bioconcave shape
4
Q
Give 3 examples of diffuse brain injuries
A
Swelling/inflammation
Hypoxia (neurones damages > reduced oxygen)
Axonal injury > decreased consciousness
5
Q
What can sheering forces cause to happen after a brain injury?
2 other ways progressive damage occurs
A
Sheering forces tear the lipid bilayer at the BBB > flux of elements (Ca), inflammation and axon death
Metabolic changes
Free radical formation
6
Q
Give 4 examples of secondary brain injuries
A
Increased intracranial pressure
Hypoxia/Ischaemia
Seizures/fits
Infection
7
Q
Which fracture has increased risk of infection?
Why?
A
Basal skull fracture
Bacteria enter through tympanic membrane
8
Q
Explain what happens to cerebral blood flow after a brain injury
A
Increased ICP in the brain due to increased mass
Brain loses CSF > spinal cord and blood to SVC to balance pressure
Eventually you can balance no more and pressure rises
9
Q
How does death occur in a brain injury?
A
Uncus of brain herniates though tentorium causing pressure on the brainstem
Brainstem cones through the foramen magnum
10
Q
Which nerves will the brain push on first?
What will this do to the eye?
A
Push on the parasympathetic (they’re outside)
Eye will dilate
11
Q
Why must you maintain blood pressure during a brain injury?
A
Blood Pressure - Intracranial Pressure = Cerebral Perfusion Pressure
Must maintain CPP and ICP is increased so BP needs to also increase
12
Q
What is Cushing’s reflex?
A
Increased blood pressure when the ICP increases
13
Q
Define lucid
A
No symptoms
14
Q
How long does an MRI scan take?
How expensive is it?
A
The scan is quick but there’s a little preparation time
The scanner is expensive but scans are cheap
15
Q
What is the resolution and sensitivity like in an MRI scanner?
A
Poor time resolution but good spatial resolution
Poor sensitivity
16
Q
Define precission
When does it occur
A
Change in the orientation of the rotational axis of a rotating body
Happens to protons in an MRI scanner
17
Q
How do you obtain an MRI image?
A
- Apply an electromagnetic radiofrequency pulse at the precision frequency
- Protons absorb energy and change their alignment in respect to the external field (same/opposite direction)
- Remove the RF pulse > protons realign with the external field and emit energy to the scanner to form an image
18
Q
What is the difference between a T1 and T2 weighted MRI?
A
T1: white matter white, grey matter grey, CSF dark
T2: white matter dark, grey matter light, CSF very white
19
Q
What can you use MRI contrast to look specifically for? (4)
A
Blood flow and volume
Vessel permeability and extracellular volume
Cell density and water movement
Biochemistry and metabolite disruption
20
Q
What happens to blood vessel permeability as a tumour develops?
A
Vessels become more ‘leaky’ and haemorrhage more
21
Q
What does water motion tell you about a cell?
A
Increased water motion = increased cell density
22
Q
What does magnetic resonance spectroscopy look at?
A
Chemicals and metabolites in the brain
23
Q
What is the spacial resolution of MRS like?
A
Low spacial resolution as it targets a specific area
24
Q
What do levels of choline and lactate indicate?
A
Choline shows normal cell division and density
Lactate indicates anaerobic respiration (tumour)
25
What is PET?
| How does it work?
Proton emission tomography
Patient injected with radioactive isotopes (e.g. glucose)
Brain uses lots of glucose so can see affected areas
26
What is PET dependent on?
The isotope half life
Long enough for scanning but short for the patient
(amino acids better than glucose but shorter half life)
27
Resolution, sensitivity and safety or PET
Low spacial resolution
High sensitivity
One scan a lifetime (risky)
28
What is SPECT?
| How does it work?
Single photon emission computed tomography
| Same as PET but photon not positron
29
Resolution, expense and safety or SPECT
Low spacial resolution
Less expensive (isotopes have longer half lives)
Less invasive
30
How long does an EEG take?
A long time, has a long preparation time
31
What is the resolution of an EEG?
Good time resolution
| Poor spatial resolution (don't know where signals originate)
32
What is ECoG?
Electrocorticography
33
What is the resolution of an ECoG?
Good time resolution
| Better spatial resolution
34
How does an MEG work?
Current flow from neurones > magnetic field on sensors > computer interpretation
35
What is the resolution of an MEG?
How much does it cost? (what does this mean?)
How long does it take?
Good time and better spatial resolution
Expensive (not clinically established)
Quicker (reduced prep time)
36
What is the BOLD response?
What is its purpose?
Which imaging technique measures it?
Blood Oxygen Level Dependent response
Exploits the different magnetic properties of Hb and its oxygen status
fMRI
37
What is fMRI combined with?
EEG/MEG to improve information about neuronal actiivty
38
What imaging techniques does York University have?
MEG
| fMRI
39
What is brain plasticity and when does it occur?
When the brain recovers from a tumour, other parts of the brain take over the role of the damaged brain
40
What is fNIRS?
| Explain how it works
Function Near-Infrared Spectroscopy
Uses infrared light to measure blood flow by the different absorption properties of oxy / deoxy haemaglobin
Sensor detects the amount of infrared reflected
41
When is fNIRS used?
In research
| In children who cannot stay still in an MRI
42
Define hyperpolarisation (MRI)
Increased protons aligning with the field
43
Explain the purpose of single shot hyperpolarised MRI
| What is the sensitivity and resolution like (compared to normal MRI)
Enhances structural images based on proton distribution
| Increased sensitivity and resolution
44
Define primary prevention
| How can you do it?
Avoidance of disease before sign/symptoms develop
| e.g. genome sequencing
45
Define secondary prevention
Avoiding progression in people who already have signs and symptoms
46
2 risk factors for cardioembolism in the young
Patent foramen ovale
| Endocarditis
47
2 recreational drugs which increase the risk of stroke
| How?
Cocaine: vasoconstricts and increased bp
Amphetamine: increases blood pressure and irregular heart beat
48
How do you measure stroke risk?
CHADS2-VASc score
49
2 ways by which smoking increases the risk of stroke
Accelerates atherosclerosis
| Increases platelet adhesion
50
Explain why an effective large study may not actually benefit in a population?
1000 people = 100 benefit but in your 50 patients only 5 will benefit from the drug
51
What happens in a haemodynamic event?
| 2 symptoms
When you quicky stand up your blood pressure is not high enough to reach all of your arteries
Pale and clammy
52
What is reducing lipids better at preventing than stroke?
Better at preventing heart disease
53
What happens to the core of the plaque in atherosclerosis?
Becomes soft and unstable due to inflammation so parts break off`
54
Which part of the homulculus does the middle and anterior cerebral artery supply?
```
Cervical = middle
Sacral = anterior
```
55
Define dysgraphasthesia
Can feel but cannot interpret what an object is
56
Where is a lacunar stroke?
Basal ganglia
57
Define ischaemia penumbra
The brain is short of blood but the cells are not dead yet
| The brain is electrically silent but can be recovered
58
What are the 3 main causes of ischaemic stoke and %
50% atheromatous plaque
25% heart related (e.g. AF and endocarditis)
25% small end arteries
59
What are the 2 types of haemorrhages in strokes?
| Which has the worse prognosis and why?
Subarachnoid
| Parenchymal (poor prognosis as in the middle of the brain)
60
6 causes of haemorrhagic stroke
```
Aneurysm
Artero-venous malformation
Cerebral amyloid angiopathy (amyloid deposits weaken vessels)
Coagulation disorders/medication
Haemorrhage
Hypertension
```
61
Explain the 4 types of stroke
TACI: Total anterior circulation infarct
PACI: Partial anterior circulation infarct
LACI: Lacunar infarct
POCI: Posterior circulation infarct
62
What happens in a TACI?
Corticol dysfunction
Hemianopia
Hemi motor and sensory deficit
63
What happens in a PACI?
```
Corticol dysfunction
(with or without hemianopia and hemi motor and hemi sensory deficit)
```
64
What happens in a LACI?
Pure motor or sensory loss
Dysarthria (clumsy hand)
Ataxic hemiparesis (pyramidal signs on one side and cerebellar on the other)
65
What happens in a POCI?
Ataxia (cerebellar syndrome)
A/Dyspraxia (lack of motor integration and sequencing)
Vertigo
Hemianopia
66
Define hemiplegia
Paralysis (motor loss) in one side of the body
67
Define pyramidal symptoms
Increase in the muscle tone in the lower limb
Hyperreflexia
Positive Babinski
Decrease in fine motor coordination
68
What are the signs if there is a stroke in the middle cerebral artery?
Contralateral motor, sensory and vision loss
Agnosia (cannot integrate sensory information)
Dominant: Agraphia, Acalculia, Aphasia
Non-dominant: Neglect, dressing apraxia, cannot recognise faces
69
What are the signs if there is a large vessel occlusion in the carotid?
Contralateral motor and sensory loss
Ipsilateral homonymous hemianopia
Global aphasia
Gaze palsy
70
Hemianopia
Blindness in half the field of vision
71
What are the 8 stages of stroke rehabilitation?
Admission > Assessment > Goal setting > Education > Reassessment (may go back) > Monitor progress > Plan discharge > Discharge
72
Define early onset dementia
Diagnosed before the age of 65
73
What does normal and abnormal amyloid do?
Normal: Protects nerves from Ca and glutamate toxicity
Abnormal: Ca influx and plaques around nerves > inflammation and death
74
What does normal and abnormal tau do?
Normal: Maintains brain cell strcrure and communication
Abnormal: hyperphosphorylated tau disrupts cell integrity and function > reduced communication
75
8 symptoms of Alzheimer's
```
Anxiety and withdrawal
Cannot perform everyday tasks or recognise faces
Disorientation in time and place
Frontal lobe problems
Language difficulties
Mild symptoms which gradually worsen
Recall recent events but not past ones
Reduced spatial awareness
```
76
4 risk factors for Alzheimer's
| Is it preventable?
Above 65 and Female
Poor physical health e.g. uncontrolled diabetes or heart disease
Lifestyle e.g. smoking, alcohol, exercise
It is preventable
77
4 risk factors of Vascular dementia
Above 65 and Male
| Family history and poor physical health
78
What are Lewy bodies?
| What do they do?
Proteins which disrupt how brain cells communicate by reducing nerve cell connections and reducing Ach/dopamine
79
7 symptoms of dementia with lewy bodies
```
Fluctuating alertness
Frontal lobe problems
Mood changes
Reduced memory
Reduced spatial awareness
Sleep disturbance
Visual hallucinations and delusional beliefs (upsetting
```
80
Which type of dementia has parkinson features?
Lewy Body
81
2 risk factors for dementia with Lewy bodies
| 3 ways of prevention
Above 65 and equal
Rare genetic mutations
Can be prevented by being socially active, hearing/eye checks, sleep routine and physical health
82
Which dementia is linked to genetics so cannot be modified?
| What age does it occur at?
Frontotemporal dementia
| Diagnosed between 45 and 65
83
What causes frontotemporal dementia?
Mutation in tau gene
| Nerves in the frontal and temporal lobes die> reduction in chemical messengers and lobe shrinkage
84
What are the 3 main types of frontotemporal dementia?
Behavioural variant frontotemporal dementia
Primary progressive aphasia
- Semantic dementia
- Progressive non-fluent aphasia
85
What is Behavioural variant frontotemporal dementia also known as?
What symptoms does it have?
5 examples
Pick's disease
Frontal and temporal lobe changes
e.g. emotional blunting, withdrawal
e.g. rude, personality change, sweet tooth
86
Main symptom in Primary progressive aphasia
| 3 examples
Speech and language difficulties
| Cannot understand, speak gramatically correct or recognise objects/people
87
Explain what happens in Semantic dementia (3)
Describe objects as they don't know the name
Fluent speech but doesn't understand meaning
Cannot recognise people
88
Explain what happens in Progressive non-fluent aphasia (3)
Slow and hesitant speech with gramatical errors
Telegraphic speech (leave out linking words)
Know the words but not the sentences
89
How many seizures do you need to have in a year to be diagnosed with epilepsy?
2
90
4 characteristics of an epileptic seizure
Spontaneous, Brief, Stereotypical, Non-situational
91
What is the most common origin of an epileptic seizure?
Temporal lobe
92
3 characteristics of status epilepticus
Active part of the seiure lasts 5 mins or longer
Person goes into the 2nd seizure with no recovery from the 1st
Repeated seizures for 30 minutes or longer
93
7 causes of epilepsy
```
Cerebrovascular disease
Corticol development malformations
Genetic
Hippocampal sclerosis
Trauma
Tumour
Vascular malformations
```
94
3 characteristics of a frontal lobe seizure
Twitching and shaking
Consciousness retained
Difficulty speaking
95
2 characteristics of a parietal lobe seizure
Body tingling
| Reduced motor control in the affected area
96
4 characteristics of the visual disturbances in occipital lobe seizures
Unformed, circular, coloured and continued to 1 hemisphere
97
11 symptoms which occur DURING a temporal lobe seizure
```
Dejavu
Fear
Hallicuinations (all senses)
Lip smacking, fidgeting, undressing
Motionless stare
Pallor/flushed - heart rate increase/decrease
Speech arrest/repeitive speech
```
98
4 symptoms which occur after a temporal lobe seizure
Confusion, headache, dysphasia, nose rubbing
99
How long do seizures usually last?
| How many happen a month?
2-5 minutes
| 2-10 times a month
100
3 characteristics of visual disturbances in a migraine
Zigzag, black and white, transverse visual fields
101
Define postural hypotension
Blood pressure decreases when you stand up
102
7 red flags for epilepsy
```
Auras/dejavu
Drugs/alcohol
Event sequence
Early morning myoclonic jerks
Family history
Other medical problems
Trauma
```
103
Explain the history of someone who experiences a single seizure
```
Feeling strange for a few days
Aura for seconds > minutes
Tonic: cry and fall
Clonic movements for a minute
Altered consciousness
```
104
4 investigations for epilepsy
Blood
CT (reliable)
MRI (reliable)
EEG (not reliable)
105
What does the EEG look like in epilepsy?
Double wave
106
What is the 'pacemaker' used to treat epilepsy called?
| What does it do?
Vagus nerve stimulator
| Controls brain electrical waves
107
Define sleep
Period of rest with reduced bodily functions
| Immune and reduced (but reversible) sensitivity to the environment
108
Define sedation
| When is it used?
Verbal contact maintained but reduced anxiety and discomfort
Toleration of unpleasant procedures
109
Define coma
Extreme unresponsiveness
| No voluntary behaviour
110
4 characteristics of general anaesthesia
Coma, Hypnosis, Areflexia, Analgesia
111
```
What happened in anaesthesia development in the:
1500s
1700s
1800s
1900s
```
1500s Curare discovered
1700s NO discovered as laughing gas
1800s Curare if maintain ventilation, Ether, Chloroform (childbirth)
1900s Rapid development e.g. propofol
112
What was discovered in the polio epidemic
Positive pressure ventilation
113
Which receptors do GA target?
GABA - A
114
4 side effects of anaesthesia
Reduced heart contractility and blood pressure
Sympathetic inhibition
Respiratory depression
Brain functions depressed
115
What is the onset of volatile anaesthetics?
| Why?
Slow - alveolar gas exchange
116
What are the characteristics of A, B and C fibres?
```
A = large and myelinated
B = small and myelinated
C = small and unmyelinated
```
117
Which fibres do you lose first?
C fibres then B then A
118
What are the 3 types of A fibres?
```
alpha = motor and proprioception
beta = light touch and pressure
delta = pain and temperature
```
119
What do you administer when you overdose on local anaesthetic?
Lipid solution to dissolve the anaesthetic
| 'Intralipid'
120
Which Ach receptor is blocked by NMJ blocking drugs?
Nicotinic (sympathetic)
121
6 risks of GA
CNS, CVS, RS depression
Aspiration of gastric contents
Can be hard to ventilate (e.g. asthma/airway problem)
Post op nauesea, vomiting and resp problems
Continued awareness (rare)
Death (very rate)
122
4 benefits of GA
Patient unconsciousness
Surgical access
Total control of the patient
Easily treated complications
123
6 risks of LA
```
Often not suitable
Contraindications
Anticoagulation
Nerve injury > paralysis (e.g. epidural)
Can fail
Toxicity
```
124
5 benefits of LA
```
Avoid GA risks
Post op analgesia
Reduced blood loss
Reduced DVT risk
Reduced death
```
125
3 ways to know that someone is asleep
Clinical signs
Measure exhaled anaesthetic concentrations
Bispectral index monitor (EEG on the forehead)
126
3 examples of reliable signs
| 4 examples of unreliable signs
Reliable: heart rate, resp rate and bp
Unreliable: movement, muscle tone, eye reflexes, lacrimation
127
What are the 4 stages of anaesthesia
1. Induction
2. Excitement
3. Surgical/Operative
4. Overdose/Danger
128
Explain what happens in induction
Analgesi > Amnesia
Patients can talk
Ends when patient unconscious
129
Explain what happens in excitement
Excited after loss of consciousness
Irregular heart and resp rate
Uncontrolled movements e.g. vomiting, pupil dilation, holding breath
Can lead to airway compromise
130
Explain what happens in surgical/operative
Muscles relax and vomiting stops
Resp depression
Eye movements slow and stop
- eyes roll > fixed
- loss of corneal and laryngeal reflex
- pupils dilate and lose light reflex
- intercostal paralysis > shallow abdominal resp
131
Explain what happens in overdose/danger
Brain stem depression
Stop breathing
Cardiovascular collapse
