Week 2 Lecture
What is aphasia
Aphasia is the inability to use language correctly. - The area of the brain responsible for language is the left hemisphere (in most people). The left hemisphere is more commonly effected than the right, so aphasia is common after stroke. - I'm going to outline the typical examples of the two types, but each case can be different, and patients may just have some aspects of each type. - It's also possible to get both types at the same time, but you really need 2 strokes, or one effecting a huge portion of the left hemisphere for that to happen.
What is ataxia
Ataxia means the lack of co-ordination of muscle movements. It's a very broad term and so includes other specific stroke symptoms such as dysphagia, aphasia and nystagmus. It can also cause you to lose fine motor skills, or have difficulty walking, causing an abnormal gait. Limb ataxia is tested by asking patients to touch their finger to their nose, and they heel to their shin.
What can loss of balance be due to
Balance problems can be due to: - muscle weakness and paralysis - damage to the areas of the brain that help control balance (i.e. the cerebellum) - loss of sensation in the limbs - damage to the vestibular system - high tone (spasticity) or low tone (flaccidity) of limbs which cause muscular imbalance - impaired vision - medications - hypotension - ataxia (lack of coordination while performing movement) - poor proprioception (lack of awareness of body position).
what imaging is used
CT, MRI and carotid doppler
What are the DDxes of stroke
Complicated Migraine TIA Brain Tumour Hypoglycaemia Hypertensive encephalopathy Seizures, Epilepsy and Todd's palsy Bell's palsy Subarachnoid haemorrhage, acute/chronic subdural, sepsis, multiple sclerosis, abscess.
What is regional metabolic hyperaemia and how does it keep constant blood supply to the brain
Different behaviours result in increased perfusion on specific regions of the brain that are responsible for carrying out that action (e.g. if you are reading a book, you need to deliver extra blood flow to regions of the brain that control the required processes) • Increased neuronal activity in these regions dilates local arterioles by: o Releasing transmitters (e.g. NO, vasoactive intestinal peptide and PGE2) that cause vasodilation. o Astrocytes - these are glial cells that are close in contact with adjacent nerves/blood vessels and monitor the activity of synapses. In response to an increased synaptic activity astrocytes increase the intracellular calcium. This causes the release of vasodilators (K+, PGE2 etc.) - N.B. they can release a vasoconstrictor (20-HETE) which is important for setting the basal tone of blood vessels.
What are common issues with eye movement
Diplopia - this is double vision. It often be caused by a brainstem stroke, and usually due to an inability for the patient to move their two eyes in sync as a pair. It can also just be a neurological issue. Nystagmus - this is rapid involuntary eye movement Patients can also develop photo-sensitivity and inability to move their eyes in certain directions due to specific ocular muscles being affected.
How does the body react to haemhorrhage
Haemorrhage triggers cerebral artery vasospasm which reduces perfusion to cause a stroke. Factors that contribute to vasospasm include: • Serotonin - from shed platelets and perivascular nerves • Neuropeptide Y - sympathetic varicosities • Endothelin-1 • Ca2+ sensitization
What is hemiparesis
It is a paralysis or severe weakness on one side of the body occurs. Hemiparesis is weakness associated with one side of the body as well but is much less severe. Hemiplegia and hemiparesis are both common side effects of stroke.
what will MRI show in haemhorragic stroke
MRI brain with diffusion-weighted imaging (DWI) and gradient-echo sequence (GRE) - acute haemorrhage appears hypointense (dark) in gradient-echo MRI brain with susceptibility-weighted imaging - Susceptibility-weighted imaging (SWI) is a newer MRI technique that may be more sensitive for identification of microbleeds than MRI gradient-echo sequence. [48] View image - Will show hypointense lesions
How is Cerebral perfusion pressure maintained by brainstem regulation of other circulations
Neural control: • Sympathetic and parasympathetic neurons supply the cerebral vessels • Sympathetic fibres from postganglionic neurons in superior cervical ganglia (located in C1) innervate cerebral arteries on the brain surface. Stimulation of sympathetic fibres reduces flow by a small amount. o Purpose to protect against high arterial pressures • Neural control of blood flow is weak because of the autoregulation mechanism. The sympathetic vasoconstrictive response is important to protect cerebral vessels from the high arterial pressures i.e. for preventing strokes.;
What is cartotid doppler
Non-invasive test that uses sound waves to measure the flow of blood through the large carotid arteries that supply blood to the brain. These arteries can become narrowed due to atherosclerosis or other causes, and this can lead to TIA or stroke. The carotid doppler test can help doctors determine stroke risk and the need for preventative measures
How is blood flow to the brain kept constant
The blood flow in the brain is relatively constant, this is bought about by structural adaptations (see LO 1) and functional adaptations
Why is this
The brain needs more substrate (e.g. glucose and oxygen) than other organs because it has high energy requirements to send the electrical impulses through neurons. This demand is met by the circulation in the brain
What area of the brain is responsivle dor this
The cerebellum is responsible for the integration of sensory perception and co-ordination & motor control Therefore, damage to the cerebella generally causes ataxia and loss of co-ordination
How does the body try to compensate for ischeamia
The cerebral autoregulatory mechanism tries to compensate for a reduction in cerebral blood flow by vasodilatation increasing the extraction of oxygen and glucose from the blood When the cerebral blood flow is severely reduced (i.e. <20 ml/100g min) synaptic activity is greatly diminished to preserve energy stores. In some cases, there is irreversible neuronal injury eventually leads to grey matter infarction in the artery's territory
What causes vasospasm in the brain?
- 5-hydroxytryptamine (serotonin) is abundant in perivascular nerves around cerebral arteries. - Its release contributes to the vasospasm of: o subarachnoid & intracerebral haemorrhage o migraine prodromal visual scotoma (possibly).;
What is a paradoxical embolus
- A clot in your leg goes to the brain instead of your lungs
How is stroke differentiated from Seizures, Epilepsy and Todd's palsy
- A history of seizures and/or a witnessed seizure followed by postictal deficits - ECG results may identify seizure activity - MRI shows no evidence of infarction.
What is a stroke?
- An acute focal neurological deficit resulting from cerebrovascular disease and lasting more than 24 hours (or causing earlier death) - Transient Ischaemic Attack o recovery in <24 hours - Cerebrovascular accident (CVA) = Stroke;
What are the possible speech disorders that can occur after stroke
- Aphasia - Dysarthria - Dysphonia - Dysphagia
What can go wrong with movement and sensation
- Ataxia - Hemiparesis/hemiplegia - Muscle tone - Loss of balance
What does the temporal lobe do
- Auditory processing - Contains primary auditory cortex, hippocampus (long term memory) - Process semantics in both speech and vision
What are the intrinsic mechanism by which blood flow is kept constant
- Autoregulation - Regional metabolic hyperaemia
What are the sensory pathways
- Spinothalamic tract - Dorsal (Posterior) column - Spinocerebellar tracts - Visual, Auditory, Olfactory pathways etc - Spinothalamic tract o Originate in spinal cord → thalamus → cerebral cortex o Pain, temperature, and crude touch o Cross at spinal entry
How is stroke differentiated from Brain Tumour
- Symptoms and signs more likely to have been on-going - May have a history of cancer if metastatic lesion causing symptoms - CT head would demonstrate lesion or lesions
When do you use a CT
All patients with TIA or possible ischaemic stroke should initially undergo a CT scan of the brain to rule out intracranial haemorrhage.
Define a 'stroke'
An acute focal neurological deficit resulting from cerebraoascualr disease and lasting more than 24 hours (or causing earlier death)'
Why are effects of ischemia in the brain seen quickly
The effects of ischaemia are seen very quickly in the brain because it does not store glucose (energy substrate) and cannot carry out anaerobic metabolism.
What can the ischeamia be due to
The ischaemia can be due to: • Thrombus formation on the atheromatous plaque in the internal carotid artery. • Embolism, dislodged thrombus that lodges into another part of the artery that is narrowed.
what will MRI show in ischaemic stroke
acute ischaemic infarct appears bright on DWI - at later stages, T2 images may also show increased signal in the ischaemic territory
what will MRI show in TIA
half will have positive diffusion images
What is homonymous hemianoia?
hemiaopnpa is the loss of field of vision. Homonymous hemianopia is the loss of field of vision in BOTH eyes. However, the patient describes they can't see out of one eye, because it looks like the picture on the right. They assume they can't see out of the left eye, but they actually can't see out of the same side of both eyes. Quadranopia is the same thing but in a quarter of each eye. the optic nerve that comes right the left side of the brain controls the left sides of both eyes;
what will CT show in haemoragic stroke
hyperdense lesion
what will CT show in ischaemic stroke
hypoattenuation (darkness) of the brain parenchyma
What are the CT findings in an acute stroke (<24hours)
• Acute infarction may be seen as hypodense dark area relative to surrounding normal brain • Haemorrhagic stroke may look like a large white area • HOWEVER, Can look completely normal • Loss of gray-white matter differentiation • Blurred basal ganglia • Insular ribbon sign (blurred insular cortex due to oedema) • Hyperdense middle cerebral artery • CT is better than MRI in detecting haemorrhagic transformation within an infarct
What is autoregulation
• Autoregulation - constant flow despite changes in perfusion pressure. A number of factors are involved in autoregulation. o Metabolic - Increased neuronal activity leads to increased metabolism. The by products of metabolism e.g. H+, K+, O2 and adenosine cause vasodilation o Myogenic - cerebral arteries constrict due to increased pressure and dilate due to decreased pressure.
What is the result
• Ischaemia results in a decrease in cerebral blood flow
How oxygen hungry is the brain
• The brain uses roughly 20% of available oxygen for normal function and receives 14% of the resting CO.
Why does grey matter recive most of the blood
• The grey matter in the brain receives the most blood because of its function: o It is largely composed of nerve cell bodies o Processing occurs in the grey matter whilst the white matter is responsible for communication to and from the grey matter to other parts of the body.
How is ion transport in the brain different?
- Cerebral capillaries form a tight blood-brain barrier - Lipid soluble molecules such as oxygen and carbon dioxide freely cross the BBB via passive diffusion and some drugs that target the such as general anaesthetics are also design to penetrate the barrier in this way. - Other substances, such as those that are water soluble require facilitated diffusion for example glucose enters the brain via GLUT 1 receptors. - The other mechanism by which substances can cross the BBB are via carrier mediated. There are specific carriers within the endothelial cell that help remove amino acids produced in the brain back out into the circulation.;
How is brain perfusion pressure maintained
- Cerebral perfusion pressure maintained by brainstem regulation of other circulations o Sympathetic mediated vasoconstriction of peripheral tissues (except myocardium) o Cardiac Output regulation via autonomic NS
How is the brian anatomically adapted to protect its blood supply
- Circle of Willis helps safeguard the O2 supply from interruption by arterial blockage - A high capillary density optimises O2 transport (3000-4000 /mm2 same as myocardium) - The major blood supply to the brain comes from two pairs of arteries o The internal carotid arteries anteriorly o Vertebral arteries posteriorly - The circle of Willis is an arterial loop lying at the base of the brain. o It is formed by the junction of the two internal carotid arteries and the basilar artery by an anterior communicating artery and a pair of posterior communicating arteries. - The brain relies on continuous flow for adequate function o Interruption of blood flow for only 5-10 seconds causes a loss of consciousness o Circulatory arrest for only 3-4 minutes results in irreversible brain damage. - Circle of Willis helps safeguard against arterial blockage in that a stenosis develops in one of the source arteries, the others can provide alternate flow - A high capillary density optimises O2 transport (3000-4000 /mm2 same as myocardium)
What does occlusion of the vertebrobasilar artery cause
- Combinations of: o Hemiparesis o Hemisensory loss o Vertigo, vomiting o Diplopia o Facial weakness /numbness o Dysphagia o Cerebellar ataxia o Respiratory failure o Coma & Death
What is the structure of vascular smooth muscle
- Contains actin and myosin, but not aligned as in skeletal/cardiac muscle - Run roughly parallel to long axis of cell - Attached at dense bodies - Dense bodies linked by intermediate filaments - Vascular tone is maintained by vascular smooth muscle cells o These are located in the tunica media of the vessel wall o They are spindle shaped non-striated (unlike skeletal muscle) considered to be involuntary in that they contract without conscious control • like that of cardiac muscle. They are joined by gap junctions. - Like cardiac and skeletal muscle they contain the proteins actin and myosin o BUT unlike these other types of muscle they do not contain troponin, instead the calcium binding protein is calmodulin. - The ends of the actin filaments are connected to the inner surface of the cell membrane by dense bodies. - Intermediate filaments provide further integrity to the cell structure by cross linking dense bodies through separate connections to the cell wall
What does the occipital lobe do
- Contains primary visual cortex - Lesions in parietal- temporal-occipital area o Colour agnosia - loss of the ability to interpret colours o Agraphia - loss or impairment of the function of language
What does occlusion of the posterior cerebral artery cause
- Contralateral o Hemianopia o Amnesia o Sensory loss (thalamus) o Thalamic pain
What does occlusion of the MCA lead to
- Contralateral o Hemiparesis, arm worse than leg o Facial weakness o Sensory loss o Dysphasia o Dysarthria o Hemianopia
What does occlusion of the anterior cerebral artery cause
- Contralateral o Hemiparesis, leg worse than arm o Incontinence o Apathy o Disinhibition o Mutism
What is the process of smooth muscle contraction in blood vessels
- Controlled by intracellular Ca, but lacks troponin - Increase in Cai leads to binding of calmodulin (CaM) - CaM then activates myosin light chain kinase (MLCK) - MLCK phosphorylates light chains on myosin head - Crossbridge formation occurs - As with other types of muscle vascular smooth muscle contraction occurs due to shortening of actin and myosin bundles through increased overlap of their filaments o The dense bodies are pulled together so the whole myocyte shortens. - This is an involuntary process that consumes ATP. - The contraction is dependent on the rise in intracellular calcium o BUT unlike in cardiac muscle, it is caused by a phosphorylation of myosin rather and an interaction between calcium and troponin. - There are two different mechanisms by which contraction can occur: o electromechanical coupling this is related to the opening of voltage sensitive calcium channels by action potentials causing depolarisation of the cell membrane o Pharmacomechanical coupling in which changes of tension development are caused by drugs or hormones. Sometimes this can occur in the absence of significant changes in membrane potential. It involves the continuous entry of calcium into the myocyte through receptor operated non-selective cation channels. - Both result in the activation of myosin light-chain kinase (MLCK) to facilitate contraction. - So the process is: o Calcium enters the cell via one of these mechanisms or can be released from internal stores in the sarcoplasmic reticulum o Calcium binds to calmodulin which is a calcium binding protein o This activates the enzyme MLCK which phosphorylates the light chains of the myosin head o The phosphorylated myosin head forms a cross bridge with the actin filaments which pulls the actin filaments alongside the myosin chain and shortens the myocyte. - Unlike skeletal muscle vascular smooth muscle is not capable of rapid contraction. As its function is in providing vascular tone is has a basal state of low level contraction which is supported by the fact that o Vascular smooth muscle can maintain contraction for long periods o Can achieve this without consuming large amounts of ATP - This means there is always some degree of contraction in blood vessels which gives it the ability to contract or relax further when flow demands change. -
What are the motor pathways
- Corticospinal & Corticobulbar tracts - Many other motor tracts - Note the concentration of wiring - internal capsule - Note fibres cross over in brain stem - It crosses over at the medulla o So if you damage it abouve that point then it effects the opposite side o If you get damage beflow that pint then it will effect the same side
What is the role of the frontal lobe
- Executive functions o organisation - Personality o Can make people aggressive or non reasonable if damaged o Keeps people to function within social norms does this partly through modifying emotions - Retaining longer term memories Not task based - Higher functioning
How is stroke differentiated from Hypertensive encephalopathy
- HTN significantly above patient's normal levels and associated with headaches. - Decreased consciousness and cognitive abnormalities, visual changes or loss, and signs of increased intracranial pressure. - Cerebral oedema seen on CT or MRI. Certain patients present characteristic changes in the posterior aspect of the brain
what is the role of the parietal lobe
- Sensory cortex - Integrates sensory information from different modalities, particularly determining spatial sense and navigation o stops you getting anxious in the world
What are the functional adaptations in the brain that work together to maintain flow
- Instrinsic mechanisms of blood flow o The cerebral circulation is tightly auto-regulated to ensure that blood flow to the brain is kept relatively constant. o A number of factors including neural metabolic and myogenic factors all contribute to vasoconstriction and dilatation to keep flow constant. o Reactive hyperaemia: local changes in brain metabolism accompany diverse types of mental activity, causing enhanced local production of metabolites. The increased presence of such factors in the interstitium causes a powerful vasodilatation, termed metabolic or functional hyperaemia , allowing the rises in blood flow necessary to supply the increased metabolic demand. This is particularly important for local blood flow to specific regions of the brain. o There is some degree of neural and hormonal control of blood flow but these are not as strong as the metabolic mechanisms.
What does the cerebellum do
- Integration of sensory perception - Co-ordination & Motor control - Integrates spino- cerebellar tracts and connections with cerebral cortex o Tract = big bundle of similar axons that run together and branch off at different levels
What is a lacunar stroke
- Lacunar stroke - occlusion of one of the penetrating arteries that provides blood to the brain's deep structures. - Effects the basal ganglia and thalamus - Effects area around the interal capsule - A effect on a small area makes a big issue - Can be: o Pure motor o Pure sensory o Sensorimotor o Ataxic hemiparesis o Aosocated with deep structures Frontal lobe - Function o Contralateral (opposite side) motor control o Personality, emotional control o Social behaviour o Speech - broca's area o Mictruition - Effects of damage o Contralateral hemiparesis o Lack of inhibition/antisocial behaviour o Expressive dysphasia o Incontinence o Memory loss Parietal lobe - Function o Primary sensory cortex - sensory perception o Language - on dominant hemisphere o Numerical calculation o Spatial orientation - non-dominant hemisphere o Construction skill - Effects of damage o Contralateral hemi-sensory loss o Dysphasia o Dyslexia o Spatial disorientation o Dressing and construction apraxia Temporal - Function o Auditory perception (Wernicke's area) o Balance - primary vestibular cortex o Limbic system - memory and emotional processing - Effects of damage o Receptive dysphasia o Impaired balance o Impaired memory Occipital - Function o Visual processing - Effects of damage o Visual inattention (of contralateral side), homonymous hemianopia
What does the brainstem do
- Midbrain o Eye movement nuclei o Convergence of tracts everything is being funnelled down a small area • so if you damage a bit of this, it will have a big effect because lots of different axons are there - Pons o Relays sensory information o Controls arousal o Respiratory centres - Medulla o Corticospinal tracts o Relays nerve signals between brain and SC
What are the key stroke mimics
- Migraine - Tumour - Abscess - Subarachnoid - Subdural - Cerebral vein thrombosis - Epilepsy and Todd's palsy - Multiple sclerosis - Myasthenia gravis - Bells palsy Functional - There is no physical problem but they just have symptoms - Some of these people aren't actually ill, they are just after attention - Hypoglycaemia/ other metabolic disorder - Hypothermia - Sepsis Old strokes who are unwell - Peoples symptoms temporarily get worse if the patient is unwell for another reason - Dementia
What is the role of the thalamus
- Multiple functions - Process and relay sensory information - Regulate state of sleep and wakefulness
What are the changes that occur in the brain during a stroke
- Normal cerebral blood flow is approximately 50-60 mL/100g/min - In a stroke you get reduced cerebral blood flow, which stimulates the autoregulatory system of the brain to try and minimise the effects of this as mentioned above. - Cerebral blood flow <20 mL/100g/min - synaptic activity is diminished to preserve energy stores - Cerebral blood flow <10 mL/100g/min - irreversible neural damage
How is stroke differentiated from Bell's palsy
- Paralysis or weakness to an entire side of the face as for stroke it affects the lower face usually. - Bell's palsy only targets the facial area while stroke can target the entire side of your body. - MRI would show no evidence of infarction
What is dysarthria
- Patients struggle physically to speak - This is more common than aphasia - It results from the loss of motor power to the system which control speech. It might affect the ability to move the mouth to articulate words, or may be due to issues in being able to force out air to make a sound. - Appearance: slurred speech
How is stroke differentiated from Complicated Migraine
- Repetitive history of similar events: preceding aura, headache in a marching pattern differentiates migraines - Stroke often presents with negative symptoms such as visual loss, numbness and weakness - Positive symptoms will be present such as visual hallucinations, abnormal motor manifestations and marching paraesthesia - MRI shows no evidence of infarction
How does the brainstem regulate other systems to protect its own blood supply
- The brain can safeguard its own perfusion by manipulating the rest of the circulation - Baroreceptors in the carotid sinus (which are stretch receptors) monitor the pressure of arterial blood supplying the brain. o If carotid sinus pressure falls, for example, if you jump up quickly from lying down to standing) o the reduced baroreceptor input into the nucleus tractus solitarius of the brainstem elicits an autonomic-mediated increase in heart rate and stroke volume resulting in an increase in cardiac output and peripheral vasoconstriction, - This helps to restore arterial pressure and thus blood flow to the brain. - Thus, the brain can be thought of as a selfish organ, manipulating the rest of the circulation to optimise its own survival.
What changes occur during the brain immediately after a stroke
- The brain has a high metabolic rate and little room for energy storage - ATP levels are depleted within 3 mins of complete ischaemia due to reduced oxygen perfusion - Decreased energy levels leads to a process called excitotoxicity which involves the release of glutamate (which is normally stored inside the synaptic terminals) into the extracellular space. This causes persistent depolarisation of the neuron. - This results in the opening/closing of ion channels ultimately leading to: o Influx in calcium, sodium and chloride ions o Efflux of potassium - The influx of calcium is responsible for the activation of destructive enzymes including proteases, lipases and endonucleases which then leads to the release of cytokines and other mediators ultimately resulting in loss of cell integrity. - Further cell damage occurs through triggering of necrotic or apoptotic cell death. - Necrosis occurs following cell swelling due to loss of the mitochondrial membrane potential, collapse of the inner and outer membranes and inability to conduct oxidative phosphyralation.
What changes occur in the brain after a stroke longer term
- There is on-going inflammation following a stroke due to the activation of specific genes that leads to the release of cytokines and other mediators which bring about inflammation. - The infarcted tissue is then removed by macrophages. - The normal blood flow is restored following treatment but in most cases there is irreversible damage due to the infarcted tissue which leads to the problems we see in patients who have had a stroke
How are capiliaries in the brain different to normal?
- These astrocytes help support the cell to form these tight junctions that prevent unwanted substances from crossing into the brain. - This is unlike a regular capillary which has a number of pores that allow some degree of passive transport;
Why is it so important
- Third leading cause of death - Incidence 150,000 per year - Annual cost £7 billion - Lifetime risk 1 in 6 - ~1-2 / 1000 per year in UK
Why is the structure the circle of willis important?
- This is a defence mechanism o if there's a blockage in the ring, you can just go round the other way the issues come if there's a bloackage in one of the branches off the ring ;
How is stroke differentiated from TIA
- Transient neurological symptoms last less than 24 hours with no evidence of acute infarct - CT or MRI may be normal or may reveal evidence of old infarcts
How is stroke differentiated from Hypoglycaemia
- Usually a history of diabetes with use of insulin or drug that promotes production of insulin. - Decreased level of consciousness - Low serum glucose at time of symptoms
What is the venous supply to the brain?
- drains into sinuses o little cavities within the meningies of the brain ;
What is the difference between grey and white matter?
- grey o neuronal cell bodies o business end o descisoin making - White o myelinated axon o wiring - Stroke doesn't differentiate between grey and white - If you cut off the blood supply, they both die Tumours may stop at the grey/white interface;
What areas of the brain do the different arteries supply?
- the cerebrum is supplied by the anterior, middle and posterior cerebral vessels o anterior cerebral medial surface A tiny bit of the anterior outer surface o Middle cerebral Most of the lateral aspect of the brain o Posterior lower part of the brian - look at the diagram - the cerebellum is also supplied by 3 vessels o the superior, anterior inferior and the posterior inferior cerebellar arteries off the Basiliar o Superior cerebellar = supplies the superior cerebellar o the cerebelum and brain stem is supplied by the o branches coming off the basilar and the vertebral arteries ;
What is the internal capsule
- this is where all the things in the hommunculus pic converge - It's the most common area for strokes
What % of stroke surviors get vison loss?
1/3;
What is expressive aphasia
Patients have issues with sentences, not words. These patients tend not to use grammar, connectives or words like 'is, the, a' etc. They have very disjointed sentences, just saying a few simple words. It can often take patients a long time to find the words they want. These patients can become very frustrated. Patients may also repeat back what you've said to them, or get stuck saying the same word or sound repeatedly. Sometimes patients can't understand sentences either. They get the words, but not the context or ordering. Example: If you told a patient 'I was bitten by a dog', they would just get the words 'I bite dog' and think that you'd bitten your dog. Patients can also use the wrong word, but one that is closely related to the word they want to use. Example: a patient may call a lorry a car. using pictures or just handwriting can be helpful for these patients. Appearance: interrupted, disjointed speaking.
What are the 2 types of aphasia
Receptive aphasia (Wenicke's aphasia.) Expressive aphasia (broca's aphasia
What can go wrong with muscle tone
SPASTICITY spasticity when the muscles are tight and stiff, making movement, especially of the arms or legs, difficult or uncontrollable. The common patterns seen after stroke are - Arm flexion pattern: arm resting against body, elbow bent with forearm across the abdomen, wrist bent, and fingers closed. - Arm extension pattern: elbow, wrist, and fingers rigidly straight. - Leg flexion pattern: hip bent and adducted (thigh pulled in toward the other leg), knee bent, and ankle bent. - Leg extension pattern: hip, knee and ankle straight (toes are pointed). FLACCIDITY - The opposite of spasticity, this is when there is decreased or no tone in a muscle. This condition is often present immediately after a person has experienced a stroke. The leg or arm will appear limp as if just hanging on the body. Some stroke victims will have permanent flaccidity, but most will acquire improved muscle tone as time progresses. FOOT DROP - This condition is the inability to lift the front part of the foot due to muscle weakness or paralysis. A person with foot drop is at an increased risk for falling because the foot will drag increasing the likelihood of tripping or stumbling. SHOULDER SUBLUXATION - This occurs when the upper arm bone drops out of the shoulder socket due to weak shoulder musculature or spasticity. It is important to properly support the arm to prevent further subluxation.
What is a stroke
Stroke is a clinical syndrome characterised by rapidly developing clinical symptoms and/or signs of focal neurological deficit lasting more than 24 hours and thought to be of vascular origin
What are the types of stroke
Strokes can be caused by ischaemia (80%) or haemorrhage (20%) - they both cause changes in circulation but in different ways.
What is the difference between subarachnoid and intercerebal haemorrhage
Subarachnoid haemorrhage = bleeding on the surface of the brain, below the arachnoid membrane (often caused by rupture of a saccular aneurysm in the circle of willis) Intracerebral haemorrhage - bleeding within the brain parenchyma (caused by rupture of micro aneurysms)
What can you use to asses higher mental function
There are many screening tools for cognitive function in patients in the acute setting, but NICE recommends: Abbreviated mental test score (AMTS) The patient is asked 10 questions such as their age, the time, their address, the year, where they are, their date of birth, and to count backwards from 20. Each correct answer scores 1 point MoCA http://dementia.ie/images/uploads/site-images/MoCA-Test-English_7_1.pdf This is the link to the test. It contains: visuospatial tests - here you copy a picture of a cube, connect dots in order and draw a clock face naming tests - there are pictures of animals to name memory tests - getting the patient to repeat back a list of random words attention tests - subtracting 7 repeatedly down from 100 (93,86,79 etc.) - getting patients to say a list of numbers you've given them backwards abstraction - connecting the link between words delayed recall - has to recall words you have told them, but after waiting for a period of time orientation - asking the patient, the date, month, day etc. RBANS This stands for Repeatable Battery for the Assessment of Neuropsychological Status. It assesses immediate memory, visuospatial/constructional, language, attention and delayed memory, just like MoCA. There is a big issue with all of these though - if the patient has issues communicating, they may have normal cognitive function, but not be able to answer any of the questions given. raven's coloured matrices this is a nonverbal test. It is used to assess cognitive ability and has lots of abstract reasoning questions. This means patients who can't communicate can just point to an answer. It's a pretty hard test, so young well on it suggests that the patient has totally normal cognitive ability, they just can't communicate. An OT will work alongside patients to watch them undergo normal daily activities. This helps the stroke team to assess if the patient is struggling with cognitive or motor/sensory issues.
What is the blood supply to the brain - (draw a diagram)?
There are two main paired arteries responsible for the blood supply to the brain- the vertebral arteries and the internal carotid arteries (ICA). Internal carotid arteries: They arise from the common carotid arteries where these bifurcate into the internal and external carotid arteries at cervical vertebral level 3 or 4; the internal carotid artery supplies the brain, while the external carotid nourishes other portions of the head, such as face, scalp, skull, and meninges. Once in the cranial cavity, the internal carotids pass anteriorly through the cavernous sinus. Distal to the cavernous sinus, each ICA gives rise to: • Ophthalmic artery - Supplies the structures of the orbit. • Posterior communicating artery - Acts as an anastomotic 'connecting vessel' in the Circle of Willis. • Anterior cerebral artery - Supplies part of the cerebrum. The ICAs then continue as the middle cerebral artery to supply lateral parts of the cerebrum. Vertebral arteries: They arise as branches from the subclavian arteries and merge to form the single midline basilar artery. As the vertebrobasilar system, they supply blood to the upper spinal cord, brainstem, cerebellum, and posterior part of brain. The right and left vertebral arteries arise from the subclavian arteries, medial to the anterior scalene muscle. They then ascend up the posterior side of the neck, through the holes in the transverse processes of the cervical vertebrae. The vertebral arteries enter the cranial cavity via the foramen magnum. Within the cranial vault, some branches are given off: • Meningeal branch - supplies the falx cerebelli, a sheet of dura mater. • Anterior and posterior spinal arteries - supplies the spinal cord, spanning its entire length. • Posterior inferior cerebellar artery - supplies the cerebellum. The terminal branches of the vertebral and internal carotid arteries all anastomose to form the Circle of Willis- this a circular blood vessel. There are three main (paired) constituents of the Circle of Willis: Anterior cerebral arteries: These are terminal branches of the internal carotids. Internal carotid arteries: Present immediately proximal to the origin of the middle cerebral arteries. Posterior cerebral arteries: These are terminal branches of the vertebral arteries. To complete the circle, two 'connecting vessels' are also present: Anterior communicating artery: This artery connects the two anterior cerebral arteries. Posterior communicating artery: A branch of the internal carotid, this artery connects the ICA to the posterior cerebral artery;
What is receptor aphasia
This is an issue with the patient's comprehension. So with this type of aphasia, the patient doesn't understand what's being said to them AND they use the wrong words. They can often understand the tone of voice, and body language - they could tell if the person talking to them was angry, upset, giving an order or asking a question. They often don't understand many words, but may be able to pick out one word in a sentence that they understand. Therefore, when asked questions, they often give unrelated answers as they only pick up on one word. Example: You might ask a patient 'what do you want to eat today?'. They might only understand the word 'today' and so say 'Monday', or whatever day of the week it is. On top of this, these patients often use the wrong words for things (which can be made up words), and not realise that they are saying the wrong word. Patients can get frustrated because they don't understand why people aren't reply to their questions because they don't know that the sentences they are saying don't make sense. The area of the brain that holds our 'dictionary' of words is in a similar region to the area used for understanding words Appearance: fluent speaking but nonsensical.
What is dysphagia
This is difficulty swallowing. It affects half the people who have had a stroke. Swallowing is actually a very complicated process, which requires co-ordination of many different muscles. This co-ordination can be affected in stroke.
What is dysphonia
This is paralysis of the vocal cords, leaving you unable to speak.
What is visual inattention
This is when you subconsciously ignore objects in a certain area. it can cause you to eat food from only one half of your plate or shave only half your face
When do you use MRI
Unconfirmed diagnosis and you want more info Some specialised stroke centres are using MRI as the initial imaging of choice, replacing CT.
what will CT show in TIA
Ususally normal
How do hypocapnia and hypercapnia affect blood supply to the brain
o Hypercapnia - cerebral vasodilation o Hypocapnia - cerebral vasoconstriction - Local hypoxia causes cerebral vasodilation - This figure here gives an overview of autoregulation of cerebral blood flow. o You can see that between arterial pressures of 60-140mmHg there is no significant changes in CBF under normocapnic conditions. - When mean pressures drop lower than 60, you get cerebral hypoxia o this can result in mental confusion, and syncope. o An example might be those who suffer from orthostatic hypotension, where when blood pressure drops quite low upon standing and syncope occurs to eliminate the hydrostatic pressure gradient and restore cerebral oxygen. - Raised CO2 will cause vasodilation and increased flow, decreased CO2 will cause vasoconstriction. - The dashed black line shows that local sympathetic stimulation only affects flow when arterial pressure is quite high
