10.1 Anatomy And Physiology Of Stroke Flashcards
What is the definition of a stroke?
An acute focal injury of the CNS due to a vascular pathology causing a sudden neurological deficit. Causes include cerebral infarction, intracerebral hemorrage (ICH), and subarachnoid hemorrhage (SAH). Symptoms and signs last longer than 24 hours.
What is the definition of a TIA?
a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction
What are the most common causes of stroke?
Ischaemic (85%) - thromboembolism Haemorrhagic (10%) - intracerebral - subarachnoid Other (5%) - dissection - venous sinus thrombosis - hypoxia brain injury
In a younger patient, what are the most likely causes of a stroke?
Vasculitis (autoimmune disease that causes inflammation and narrowing of blood vessels)
Thrombophilia (imbalance in naturally occurring blood-clotting proteins, or clotting factors)
Subarachnoid haemorrhage
Venous sinus thrombosis
Carotid artery dissection
In an older/elderly patient, what are the most likely causes of a stroke?
Thrombosis in situ Athero-thromboembolism Heart emboli CNS bleed Sudden blood pressure drop of more than 40mmHg Vasculitis Venous sinus thrombosis
What are the risk factors of stroke?
Hypertension Smoking Diabetes mellitus Heart disease (fibrillation/valvular/ischaemic) Peripheral arterial disease Post-TIA (high early risk of stroke) Carotid artery occlusion: carotid bruit Polycythemia Vera COCP Hyperlipidaemia Excess alcohol Clotting disorders.
What signs occurs in an infarct of the anterior cerebral artery?
Affects the medial areas of the primary motor and sensory cortex. Similar distribution of motor and sensory deficit in the contralateral lower limb.
Paracentral lobules may be affected in anterior cerebral stroke causing urinary incontinence
May have corpus callosum issues. Results in split brain syndrome or alien hand syndrome.
Frontal lobe features such as personality / apraxia changes.
What are the signs and symptoms of a proximal middle cerebral artery infarct?
Main trunk occlusion associated with mortality.
Contralateral full hemiparesis (face, arm and leg) as internal. capsule affected
Initial flaccid hemiparesis followed by spastic hemiparesis due to spinal shock
Lateral primary sensory cortex = Contralateral sensory loss in upper limb and face, could involve larger areas f the sensory components in the internal capsule are affected
Destruction of the superior and inferior optic radiations as they pass through the parietal and temporal lobes = Contralateral homonomous hemianopia
If left sided stroke and affecting Broca’s and wernickes area = aphasia / speech problems.
If lesion affects right parietal lobe = Neglect on left hand side
Why is proximal MCA occlusion not uncommon?
As the MCA is a continuation of the internal Carotid and therefore atherosclerosis emboli can easily enter from the internal carotid artery.
What is anosognosia?
literally does not acknowledge that they have had a stroke or neurological deficit, so will confabulate to explain disability.
What is tactile extinction?
if touch each side simultaneously doesn’t feel the affected side.
The failure to detect a stimulus only in the presence of another stimulus to certain parts of the body-is a well-known clinical sign of parietal lobe disease.
What are the manifestations of lenticulostriate arteries strokes?
Often destruction of internal capsule/ basal capsule.
Small deficits in motor or sensory function.
What are the manifestations of a distal MCA occlusion affecting the MCA superior division?
Supplies lateral frontal lobe - Primary motor cortex and Broca’s area if on left side.
Contralateral face and arm weakness
If on left side then may have Broca’s aphasia / expressive aphasia
What are the manifestation of a distal MCA occlusion affecting the inferior division of the MCA?
Supplies the lateral parietal lobe and the superior temporal lobe.
Have problems with the sensory cortex and wernickes area
May have problems with one or both optic radiations
Contralateral sensory problems
Wernickes aphasia/ fluent aphasia
Problems with vision - non macular sparing homonomous hemianopia or a quadrantopia.
What are the manifestations of a posterior cerebral artery occlusion?
Supplies the thalamus, midbrain and occipital lobe.
Contralateral homonomous hemianopia that is MACULA SPARING
As sensory pathways travel through the thalamus may get contralateral sensory loss.
What are the manifestations of cerebellar artery occlusions?
Ipsilateral DANISH symptoms / cerebellar deficit
nausea, vomiting, headache, vertigo
Ipsilateral Horners syndrome - affecting sympathetics running laterally from the brainstem
Contralateral sensory signs - sensory fibres run more laterally in the brain stem and contralateral as post-decussation
What are danish symptoms?
Dysdiadochokinesia Ataxia (gait and posture) Nystagmus Intention tremor Slurred staccato speech Hypotonia/heel-shin test
What are the manifestations of basilar artery occlusions?
Can lead to sudden death as supply the brain stem
If affecting the superior aspect then may get visual and oculomotor defects.
Below CN III = Complete bilateral motor loss - locked in syndrome, complete paralysis of the body.
What system is used to classify strokes?
Oxford stroke classification system
What are the 4 classifications of stroke according to the Bamford (oxford) stroke classification system?
TACS
PACS
POCS
LACS
What is the CHADS2 stroke assessment tool used for?
CHADS2 is used to estimate the stroke risk in patients who have AF.
What is the rosier stroke assessment tool used for?
Recognition of stroke in the emergency room
Is a 7 item stroke tool that incorporates the FAST elements and leg weakness and visual field deficit.
If symptoms are indicative of a stroke the patient scores a 1
What imaging is used in a suspected stroke?
CT
CT angiogram.
How long is the thrombolysis window?
Four and a half hours from the onset of the stroke.
Why is SALT. Involved after stroke?
Salt is the speech and language therapists. Help patients improve speech deficits they may have suffered during a stroke
How is a patients cognitive function assessed after a stroke?
MMSE - mini-mental state examination
Used to serially assess a patients cognitive function. Used repeatedly to indicate a decline in function. The lower the score, the less the cognitive function
What is the phq9 used to examine?
Depression test used to indicate presence and severity of depression. Scored from 0 to 27 with 27 being the most severe
What is a TACS
Total anterior circulation stroke All 3 of: 1. Unilateral weakness (+/- sensory deficit) of the face, arm and leg 2. Homonymous hemianopia 3. Higher cerebral dysfunction • Dysphasia / aphasia • Visuospatial disorder
What is a PACS?
Partial anterior circulate stroke Only 2 of: 1. Unilateral weakness (+/- sensory deficit) of the face, arm and leg 2. Homonymous hemianopia 3. Higher cerebral dysfunction • Dysphasia / aphasia • Visuospatial disorder
What is a POCS?
Posterior circulation stroke
One of the following:
• Cranial nerve palsy and contralateral motor/sensory deficit
• Bilateral motor/sensory deficit
• Conjugate eye movement disorder
• Cerebellar dysfunction
• Isolated homonymous hemianopia (with macular sparing)
What is LACS?
Lacunar stroke One of the following: • Pure sensory deficit • Pure motor deficit • Senori-motor deficit • Ataxic hemiparesis
What are the 4 motor nuclei are in the midline of the brainstem?
3,4,6, 12
What 4 M’s are on the mid-line of the brainstem?
Motor pathway (corticospinal tract) Medial lemniscus (dorsal columns Medial longitudinal fasciculus Motor nuclei ( only 3,4,6 and 12)
What are the 4 side Ss of the brainstem?
Spinocerebellar pathway
Spinothalamic pathway
Sensory nucleus
Sympathetics
What key features indicate brainstem pathology?
Ipsilateral cranial nerve signs
Contralateral sensory and motor tract deficit.
The anterior cerebral artery supplies the paracentral lobule and the prefrontal cortex. In an occlusion what would be the resulting signs?
Contralateral motor and sensory deficit. More in legs than arms
Cognitive/behavioural/personality changes
The middle cerebral artery supplies many key aspects of the brain. What are these and in an occlusion what would be the resulting manifestations
Primary motor and sensory cortex = contralateral deficit, more affecting face and arms
Wernickes area = receptive aphasia
Broca’s area = expressive aphasia
Internal capsule = contralateral pure motor deficit
Optic radiations = contralateral homonomous hemianopia
What areas does the posterior cerebral artery supply, and in an occlusion how does it manifest?
Primary visual cortex = contralateral homonymous hemianopia, blindness if bilateral
Thalamus = contralateral sensory deficit
Midbrain = contralateral Hemiplegia and ipsilateral CN III palsy
Inferior temporal lobe = amnesia
What are the 2 main principles of treatment of a stroke?
Within window for thrombolysis
Do head CT to determine if it is an infarct or haemorrhage?
How does a stroke appear on a CT?
• Ischaemic area of brain not visible early on (as infarct becomes more established the ischaemic area will
become hypodense)
• A bleed will show up as a bright white area, maybe with mass effect
How will a stroke appear on an MRI?
Sometimes performed
Ischaemia shows up as a high signal area
