Lecture 16- Stroke 1/2 Flashcards
Stroke
“a neurological deficit attributed to an acute focal injury of the central nervous system (CNS) by a vascular cause, including cerebral infarction, intracerebral hemorrage (ICH), and subarachnoid hemorrhage (SAH)”
TIA
“a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, without acute infarction.”
Types of stroke
- Ischaemic (85%)
- thromboembolic
- Haemorrhagic (10%)
- Intracerebral
- Subarachnoid
- Other (5%)
- Dissection
- Venous sinus thrombosis
- Hypoxic brain injury
Causes of stroke
In the young…
- Vasculitis
- Thrombophilia
- Subarachnoid haemorrhage
- Venous sinus thrombosis
- Carotid artery dissection e.g. via near strangling or fibromuscular dysplasia
causes of stroke in
In the old…
- Thrombosis in situ
- Athero-thromboembolism e.g. from carotid arteries
- Heart emboli (e.g. atrial fibrillation, infective endocarditis or MI)
- CNS bleed associated with hypertension, head injury, aneurysm rupture)
- Sudden blood pressure drop by more than 40 mmHg
- Vasculitis e.g. giant cell arteritis
- Venous sinus thrombosis
Risk factors
Classic stroke syndrome
a list of “classical” stroke syndromes arranged by arterial territory e.g. cerebral artery perfusion territorirs
label this circle of willis
Anterior cerebral artery
- Arises as one of the branches of the internal carotid
- Doesn’t supply many anterior structures
- Supplies medial areas of the brain
- grey and white matter distribution
grey matter dist of ACA
- Grey matter distribution: ACA loops back all over the superior surface of the corpus callosum and sends multiple branches to the medial aspect of the cerebral hemisphere (mostly frontal and parietal lobes)
white matter distribution of the ACA
- White matter distribution: as the ACA loops around the CC it will send lots of branches into the white matter of the CC
example of areas affected in a stroke affecting the ACA
- Medial areas of the sensory and motor homunculus affected
- Paracentral lobules
- Corpus callosum
- Frontal lobe
ACA stroke sensory and motor deficits
-
Medial areas of the sensory and motor homunculus affected
- Contralateral lower limb more affected
ACA stroke and paracentral lobules
-
Paracentral lobules containing M centre- found in the medial portion of the frontal lobe
- Incontinence
ACA stroke and corpus callosum
-
Corpus callosum
- Split brain syndrome- Both hemispheres cant communicate meaning limbs wont work together
ACA stroke and frontal lobe
-
Frontal lobe
- Personality changes
- Apraxia changes- coordinating motor plans e.g. doing laces up
Middle cerebral artery
- Arise as continuations of the internal carotids
- Run laterally and go over the insular cortex and energy through sylvian fissure onto the surface of the cerebral hemisphere
- Branches of the MCA = lenticular striate arteries which supplies the basal ganglia
- Supplies more lateral aspects of the cerebral hemispheres
- Frontal
- Parietal
- Temporal
Proximal MCA occlusion
- Will affect everything downstream too e.g. lenticulate striate arteries, inferior and superior arteries of the MCA
- Common –> internal carotid directly supplies the MCA
- Usually more common on right side because left parietal region has dual bilateral blood supply
signs of a proximal occlusion
face and arms–> lateral part of homonculus affwcted
aphasia if left sided (only found in left hemisphere) due to problem with either brocas, wernickes or arcuate fasiculus
proximal MCA occlusion and problems with the lateral motor homunculus
Contralateral upper limb and face motor problems
with proximal MCA occlusion we predict contraltateral and upper limb and face motor problems but usually see
- a complete hemiparesis à flaccid à spastic hemiparesis
- Why? Because the MCA also supplies the internal capsule (lenticulate striate arteries) which carries fibres from the face, arm and leg
proximal MCA occlusion and problems with the lateral sensory homunculus
- Upper limbs and face sensory problems
- Like likely to be full body sensory problems
- Because the posterior parts of the internal capsule are supplies by the PCA- therefore mismatch between sensory and motor deficits
proximal MCA occlusion and problems with vision
- Contralateral homonomous hemianopia
- Destruction of both superior and inferior optic radiations as they run through the temporal and parietal lobes
proximal MCA occlusion and problems with speech
- Broca’s aphasia (frontal)
- Reduction in speech fluidity
- Wernicke’s aphasia (temporal/parietal)
- Problems with understanding language
- If proximal occlusion= both Broca’s and Wernicke’s
proximal MCA occlusion and Neglect-like symptoms
- Lesions which affect the right parietal lobe
- Pt has issue with acknowledging what is going on, on the LHS
- E.g. may only eat half of the meal
Examples of affected areas with lenticulate artery occlusion
- Usually smaller deficits
- Deficits depends where the lacunar stroke occurs
- In the thalamus= sensory deficits
- In the internal capsule
- E.g. could occur on the posterior arm of the internal capsule and cause motor problems with the leg, trunk or arm
- E.g. At the genu= face motor problems
- If in both thalamus and internal capsule= mixed sensory and motor deficits
if lenticulate artery occlusion is in the internal capsule
- E.g. could occur on the posterior arm of the internal capsule and cause motor problems with the leg, trunk or arm
- E.g. At the genu= face motor problems
distal MCA occlusions
think in terms of superior division and inferior division problems
distal MCA occlusion: Superior division problems
- Supplies the lateral frontal lobe e.g. primary motor cortex and the Broca’s area
- Examples of superior division problems
- Contralateral face and arm weakness
- Broca’s (Expressive) aphasia
- Only if occurs on the LHS
distal MCA occlusion: Inferior division problems
- Examples of inferior division problems e.g. primary sensory cortex and Wernicke’s area
- Contralateral face and arm loss of sensation
- Wernicke’s aphasia
- Homonomous hemianopia if both optic radiations are damaged or a quadrantanopia if just one radiation is affect
- Without macula sparing
Posterior cerebral artery
- Posterior areas of the brain, thalamus and midbrain supply
Examples of affected areas with PCA occlusions
-
Contralateral Homonomous hemianopia with macula sparing
- If MCA damaged- everything will be destroyed (doesn’t matter if we have a contralateral supply by the PCA to the macula)- the damage is done
- If PCA occlusion causes damage to the optic radiations, you still have contralateral supply to macula from the MCA therefore macula sparing
-
Contralateral sensory loss due to thalamic involvement
- More likely to be PCA which supplies the oxygen to the thalamus where the sensory (and motor) pathways go through
