Scenario 25 Flashcards
1
Q
What is the incidence of stroke?
A
114/100,000 75% over 65
2
Q
What is the mortality of stroke?
A
64,000 deaths per year 12% of deaths
3
Q
What are the vascular risk factors for stroke?
A
High BP, Diabetes, Smoking, high cholesterol
4
Q
What is left hemiplegia?
A
Arm in flexion, leg in extension
5
Q
What should you do if suspected stroke?
A
CT to see if caused by a clot and can use thrombolytics in under 3 hours
6
Q
How much of the cardiac output does the brain receive?
A
17%
7
Q
What are the 2 main arterial routes to the brain?
A
ICA (carotid canal into middle cranial fossa adj to optic chasm) and Vertebral arteries (foramen transversaria entering via formamen magnum passing through cavernous sinus)
8
Q
What does the ICA give rise to?
A
Anterior and middle cerebral arteries and opthalmic artery
9
Q
What does the Anterior cerebral artery supply
A
Medial and superior aspects of the parietal and frontal lobes
10
Q
What does occlusion of the ACA cause?
A
Paralysis and sensory defecits to contralateral leg and perineum, mental confusion and sometimes contralateral fact, tongue and upper limb due to IC
11
Q
What does the MCA supply?
A
Lateral cerebral cortes, anterior temporal lobes and insular cortices
12
Q
What does occlusion of MCA cause?
A
(most common) paralysis of contalateral face and arm and sensory loss, hemianopia of contralateral visual fields
Damage to dominant hemisphere results in aphasia (Broca/ Wernickes) and non-dominant results in contralateral neglect syndrome
13
Q
Where does the posterior cerebral artery arise?
A
Intersection of post communicating and basilar
14
Q
Where does the PCA supply?
A
Posterior aspect of the brain (occipital lobe) and part of temporal lobe
15
Q
What does PCA occlusion cause?
A
Blindness in contralateral visual field, hippocampal memory may be affected but usually temp
16
Q
What does the vertebrobasiliar system supply?
A
Brainstep, cerebellum and posterior aspect of cerebral hemispheres
17
Q
What is the basilar artery formed from?
A
Union of the two vertebral arteries
18
Q
What does the basilar artery give rise to?
A
Splits into posterior cerebral arteries before this giving rise to superior cerebellar arteries, before this several small pontine arteries and before this the anterior inferior cerebellar arteries
19
Q
What do the vertebral arteries give rise to?
A
Posterior inferior cerebellar arteries, anterior and posterior spinal arteries
20
Q
Where do the 2 systems anastamose?
A
Circle of Willis
21
Q
What are the advantages of anastamoses?
A
Provide an alternative route if normal one is occluded
22
Q
What are the disadvantages of anastamoses?
A
Can cause aneurysms which can leak or explode causing a sub arachnoid haemmorhage
23
Q
What does occlusion of vertebral or basilar arteries lead to?
A
Cerebellar defects, instantly fatal due to coma and loss of resp control, cranial nerve defects, deafness, infarction of ventral pons leads to loss of all voluntary movements except eyes
24
Q
What is the blood supply to the IC?
A
Small perforating arteries from circle of willis mostly supplied by ACA and MCA (LENTICULOSTRIATE)
25
What is the venous drainage of the brain?
Intracranial veins drain into dural venous sinuses then to internal jugular via jugular foramen in post cranial fossa
26
Where is the superior saggital venous sinus
Down midline
27
Where is falx cerebri?
Between superior and inferior saggital sinus
28
Where are left and right transverse sinus?
at the back of the head horizontally
29
Where is the sigmoid sinus and where does it exit skull?
At the sides of the head a continuation of transverse, exits through jugular foramen
30
Where does the middle meningeal artery enter the intracranial region?
Foramen spinosum
31
What does the middle meningeal artery supply?
The bones of the vault
32
What could a leak from the MMA cause?
Extradural haemmorhage- prolonged
33
What is a subdural haemmorhage?
Caused by leak of superior cerebral vein, low pressure slow accumulation (between dura and arachnoid) pushes on the brain
34
What is a sub-arach?
Between arachnoid and pia eg from ruptured aneurysm form curcle of willis very sudden and painful
35
Intracerebral haemmorhage
Within the brain tissue itself
36
What is the blood supply to the spinal cord?
Posterior and anterior spinal arteries from vertebras and radicular arteries from segmental spinal arteries
37
What does the brain consume at rest?
60% of glucose, 20% of oxygen (120g glucose a day)
38
How do NTs work?
AP arrives at the cell presynaptic cell depolarises and releases vesicles which diffuse across the synapse and cause Na to enter the next cell and K to be released, depolarising the postsynaptic cell.
39
How is NT removed?
Uptake into astrocytes- powered by ionic gradients (Na/K ATPase) and then glutamate is converted into glutamine (requires another ATP) and glutamine is exported and taken up pre-synaptically, converted back and packed into vesicles (another ATP)
40
Why does glutamate need to be removed?
Highly active at receptors, depolarises post-synaptic cells
41
What is neurovascular coupling?
Activity at the synapses leads to increased blood flow to deliver oxygen and glucose
42
How is glucose used for energy in the brain??
glucose transported from blood into glial cells where its converted into glucose-6-phosphate and then metabolised or stored as glycogen (very small store)
43
How is glucose metabolised in the presence of oxygen?
glucose gives 2 pyruvate, 2 ATP but uses 2 NAD and the pyruvate feeds into the next step, NAD regenerated elsewhere
44
How is glucose metabolised in the absence of oxygen?
Pyruvate is converted to lactate and NADH to NAD allowing glycolysis to continue using lactate
45
What happens in oxidative phosphorylation
In the mitochondrion pyruvate in the presence of oxygen gives CO2 and NADH which feeds into ox phos to give 34 ATP (overall 36ATP)
46
Without mitochondria how many ATP can be made?
2
47
What is the leptomeningeal collateral circulation made up of?
The A, M and P cerebral arteries
48
What happens if the MCA is occluded?
Blood flow initially drops but by 2 minutes the collateral circulation form the ACA takes oevr but cant reach the core of the MCA territory
49
What perfusion is below survival threshold (core)
50
What is the perfusion in the penumbra?
51
Why does the core expand?
The AP is potassium out sodium in as normal but the ECS is flooded with potassium and glutamate so the output is a massive release of potassium allowing the wave to propagate.All neighbouring neurons and astrocytes depolarise- massive ATP use
52
In the normal brain what is the response to spreading depolarisations?
Hyperaemia- increase in blood flow
53
Why do we need to reperfuse quickly?
After each wave lactate increases and glucose decreases
54
Why does the brain swell when reperfused?
Neuronal ATPase is lost and Na is accepted into the cell causing cerebral oedema. When reperfused whole territory dilares and more capillaries open and are weak and leak causing swelling
55
Where is the central sulcus
between frontal and parietal lobes
56
How many layers is the cerebral neocortex?
6 layers
57
What is the function of the supragranular layers?
Makes you you, controls cognitive function, executive for motor and sensory function and instructs the infragranular layer
58
What does the forebrain contain?
Cerebral hemispheres and diencephalon (thalamus, hypothalamus, epithalamus and sub thalamus)
59
What are the roles of the cerebral hemispheres?
Sensory integration, control of voluntary movement, higher intellectual functions like speech
60
What is the role of the thalamus?
Relay centre between the medulla oblongata an cerebrum
61
What is the role of the hypothalamus?
control centre for pain, hunger, thirst, BP, temp and produced hormones
62
What is the primary somatosensory cortex reponsible for
Touch and proprioception (lost in somatosensory anaesthesia
63
Supplementary somatosensory area injury
Superior parietal lobule- contralateral somatosensory agnosia- inability to recognise common objects by palpation
Inferior parietal lobule- in dominant hemisphere concerned with language, other hemisphere contralateral body neglect
64
Where is the olfactory cortex found?
Frontal and temporal lobe
65
What is the hippocampus critical for?
Critical for memory- large in taxi drivers, small in AD
66
What areas are either side of the central sulcus?
Precentral (in front)- primary motor cortex
| Postcentral (behind)- somatosensory cortex
67
Where are the visual cortex and association area?
Back of the brain
68
Where is Wernickes area?
Back of the brain
69
What ascending connections are there to the cortex?
Somatosensory from the thalamus (inputs via VPL and trigeminal via VPM), Auditory from the thalamus (inputs from cochlea via medial geniculate nucleus), Visual from the thalamus (inputs from retina via lateral geniculate nucleus), smell (direct into olfactory cortex and taste via VPM)
70
What descending connections are there from the cortex?
Motor to spinal cord (corticospinal)
Motor to brain stem motor nuclei (corico-bulbar tract)
To the motor control centres (targeted to the basal ganglia and cerebellum)
To the limbic system
71
What are the connections between the cortex on the same side
Association fibres
72
What are the connections between the cortex on the opposite sides
Corpus Callosum
73
What happens if there is a lesion to the primary visual cortex or retina?
Blindness
74
What happens if there is damage to the visual supplementary areas?
visual agnosia, disregard, facial recognition
75
Where is spoken language processed and sent to?
Mid brain then to Wernicke's rea
76
Where is written language prcessed and sent to?
Visual are then sent to angular gyrus in L hemisphere, changed to sound and sent to Wernicke's area
77
What happens in Wernicke's area?
extracts the meaning of language and sends to brocas area
78
What happens in Brocas area?
Information refined into grammatical form and sent to motor cortex to make speech
79
What happens if R hemisphere damage
loss of ability to interpret emotional content
80
What happens if Brocas area damage?
Know what to say but cant do it with grammar (no fluency)
81
What happens if Wernicke's area is damaged?
Perfect grammar but meaningless
82
What association fibres connect frontal and occipital lobes?
Superior longitudinal fasciculus
83
What association fibres connect occipital and temporal lobes (visual recognition)?
Inferior longitudinal fasciculus
84
What association fibres connect Wernicke and Brocas areas?
Arcuate fasciculus
85
What does a tumour of the corpus callosum cause?
Alexia without agraphia (speak and write but not read)
86
What happens if a focal cortical lesion?
Epilepsy, sensor and/or motor defects and psychological defecits
87
Bilateral cortical degeneration
AD- temporal parietal and limbic (loss of language and memory)
88
Left parietal damage
Anomia, acalculia, alexia and agraphia
89
Right parietal damage
Constructional apraxia (skilled movements)
90
Left temporal damage
Absenses, deja vu, Wernickes aphasia
91
Occipital damage
Single- hallucinations, contralat visual field loss
| Bilateral- blindness
92
What is the brainstem made up of
Midbrain, pons, medulla
93
What are surface markings on the midbrain part of the brainstem?
Anterior- mamillary body and crus cerebri
| Posterior- sup and inf colliculi
94
What are the surface markings on the pons?
Ant- middle cerebellar peduncle laterally
| Post- sup, mid and inf peduncles and floor of 4th ventricle
95
What are the surface markings on the medulla?
Ant- pyramid and olive (med to lat)
| Post- Gracile and cuneate tubercle (med to lat) and below the fasciculus cuneatus and fasciculus gracilis
96
Where does the corticospinal tract dessucate?
Level of the pyramids (80% of the fibres)
97
Which cranial nerves join to the brainstem?
3-12
98
Where is the occulomotor nerve attatched to the BS?
Motor- Edinger-Westphal nucleus and occulomotor nucleus- exit at level of crus cerebri
99
Where is trochlear nerve attached to BS?
Trochlear nucleus then decussates controlling sup oblique exiting at level of crus cerebri
100
Where is the trigeminal nerve attached to BS?
Trigeminal motor nucleus motor to muscles of mastication, sensort to trigeminal sensory nucleus
101
Where is abducens nerve attached to BS?
Abducens nucleus controls lateral rectus (abducts eyeball)
102
Where is the facial nerve attached to BS?
sensory form nucleus solitarius, motor from facial motor nucleus and superior salivatory nucleus
103
Where is the vestibulococchlear nerve joined to BS?
Sensory from cochlear and vestibular nuclei for hearing and balance
104
Where is the glossopharyngeal nerve joined to the BS?
Lateral to the olive. General sensation from trigeminal sensory nucleus, taste and visceral sensation from nucleus solitarus, inferior salivatory nucleus for parotid salivary gland, nucleus ambiguous and hypoglossal nucleus for pharynx and back of tongue
105
Where is the vagus nerve joined to BS?
Trigeminal sensory nucleus, nucleus solitarus for visceral sensation, nucleus ambiguous for muscles of soft palate, pharynx, larynx and upper part of oesophagus, dorsal motor nucleus of the vagus
106
Where is the accessory nerve joined to BS?
2 roots cranial and spinal, exits neurocranium via jugular foramen, motor nucleus ambiguus
107
Where is hypoglossal nerve joined to BS?
motor to tongue from hypoglossal nucleus to extrinsic and intrinsic tongue muscles, rootlets emerge between pyramids and olives
108
What is motor neurone disease?
Chronic degeneration of corticobulbar tracts
109
Which nucleus' degenerate in MND?
Nucleus Ambiguus and hypoglossal nucleus
110
What are the signs and symptoms of MND?
Dysphonia, dysphagia, dysarthia, weakness, spacisity of tongue
111
What happens is CN9-12 are compressed by tumours?
Dysphonia, unilateral weakness, wasting and fasciculation of tongue, suppression of gag reflex, unilateral wasting of sternomastoid and trapezius muscles
112
What is the reticular formation?
Has widespread ascending and descending projections and involved in normal and pathogenic processes
113
Brain stem lesion unilaterally causes
ipsilateral cranial nerve dysfunction, contralateral spastic hemiparesis, hyperreflexia, ipsilateral incoordination, contralateral hemisensory loss
114
Brain stem bilateral lesion causes
coma, death
115
What part of the brain initiates voluntary movement?
Basal ganglia
116
Which part of the brain controls messages and actual position?
Cerebellum
117
Which part puts the breaks on movement
Basal ganglia and cerebellum
118
Which area of the brain has the idea and motivation to move
Prefrontal cortex
119
What area of the brain controls conceptualisation of the plan
Premotor cortex (MCA)
120
What area of the brain plans and strategises?
Supplementary motor area (ACA)
121
What does the posterior parietal cortex do?
Analyses sensory information and activates the motor areas
122
What does the cerebellum do?
Balance, co-ordination, motor memory (3 cerebellar arteries)
123
What does the basal ganglia do?
Amplitude, timing, programming (MCA ACA)
124
How are the spinal motor neurons activated?
Via corticospinal tracts from the primary motor cortex
125
What is the process of repair after a stroke?
Initially contralateral flaccid paralysis but the motor cortex reorganisation and extrapyramidal pathways take control then speciosity (change in gamma motor neurone and regulatory interneurons and increase in alpha motor neurone activity)
126
How can you identify the ventral side of the spinal cord?
Median fissure is prominent
127
What is the denticulate ligament?
Extensions of pia matter onto arachnoid to anchor the cord
