Stroke Flashcards
List some DDx for sudden onset L hemiparesis?
• Vascular
- Infarct- subarachnoid infarct (MCA likely, R choroidal a affecting crus cerebri/motor tracts), extradural, subdural
- Haemorrhage (TBI, aneurysm)- subarachnoid
• Migraine with aura
• Seizure w post-ictal focal neuro deficit
• Metabolic- hypoglycaemic, hyponatraemic
• Toxins- ETOH
• Neoplastic- tumour
• Demyelinating disease- MS
• Infective- cerebral abscess
• Inflammatory- encephalitis
• Hydrocephalus (CSF flow blocked)
Describe the internal capsule?
Internal capsule- white matter structure separating caudate nucleus and thamalus from the putamen and globus pallidus
- Contains both ascending and descending motor fibers from cerebral cortex (most are from corticospinal tract)
o Anterior limb of internal capsule- contains fibers connecting cortex with striatum, connects thamalus to frontal lobe
- Supplies by lenticulostriate branches off MCA (superior half) and recurrent artery of Heubner off ACA (inferior half)
o Genu of internal capsule- contains corticobulbar tracts
- Supplied by lenticulostriate branches off MCA
o Posterior limb of internal capsule- contains corticospinal tract (anterior 2/3) an sensory fibers from thalamus (posterior 1/3)
- Supplied by lenticulostriate branches off MCA (superior half) and anterior choroidal plexus artery branch from ICA (inferior half)
Describe the pathological process of a stroke?
Ischaemic:
• Embolus
o Mural thrombus: CVS risk -> desynchronized heart wall contraction -> predisposes development of mural thrombus -> embolise -> lodge in lenticulostriate arteries -> ischaemia -> liquifactive necrosis -> neuronal death
o Atheromatous lesion: CVS risk -> atheromatous plaque develops (commonly in ICA) -> rupture -> showering fatty emboli -> occlude lenticulostriate arteries -> ischaemia
• Hyaline arteriosclerosis
o Chronic HTN -> artery hardening -> narrow lumen -> ischaemia
Haemorrhagic:
• Ruptured aneurysm
Chronic HTN -> Charcot Bouchard aneurysms in lenticulostriate arteries -> arteries harden and lose elasticity -> rupture -> intracerebral bleeding -> raise ICP and disrupt motor pathways
What are the centres for personality?
• Frontal lobes- higher executive function (e.g. decision making, considering rules)
• Limbic system- emotion regulation
- Includes: hippocampus, hypothalamus, amygdala, thalamus
• Hippocampus- memory formation
List possible causes of death following stroke?
- Cardiorespiratory failure: cerebral oedema (vasogenic and cytotoxic) -> raised ICP -> tonsillar herniation -> compression of respiratory centres -> death
- Septic shock: cerebral oedema-> raised ICP -> suppression of cough reflex (medulla) -> aspiration -> pneumonia
- Secondary stroke: basilar artery occlusion -> brainstem infarction -> dysfunction of cardiorespiratory centres -> death
What does the internal carotid a supply? What are the results of a deficit?
Internal carotid:
- Supplies: branches into MCA and ACA
- Deficits: similar to MCA (contralateral hemiplegia, hemisensory loss, homonymous hemianopnia)
What does the ACA supply? What are the results of a deficit?
ACA:
- Supplies: frontal and medial cerebrum (esp frontal and parietal lobes)-> motor and sensory cortices (lower limb)
- Deficits: contralateral hemiplegia and hemisensory loss (lower limb), mild upper limb symptoms
What does the MCA supply? What are the results of a deficit?
MCA:
- Supplies: lateral cerebrum- motor and sensory cortices (upper limb and face), frontal lobe (Broca), temporal lobe (Wernicke)
- Deficits:
• Contralateral hemiplegia and hemisensory loss of upper limbs and face
• Contralateral homonymous hemianopnia (optic radiation)
• Dysphagia (dominant side)
• Visuospacial disturbance (non-dominant side)
What does the PCA supply? What are the results of a deficit?
PCA:
- Supplies: occipital lobe
- Deficit: contralateral homonymous hemianopia (with macular sparing)
What do the Lenticulostriate a (of MCA), Heubner a (of ACA) and anterior choroidal a supply? What are the results of a deficit?
Lenticulostriate a (of MCA), Heubner a (of ACA) and anterior choroidal a:
- Supply: basal ganglia- lentiform nucleus, putamen, thalamus, internal capsule
- Deficits:
• Pure motor loss (internal capsule posterior limb, anterior 2/3)
• Pure sensory loss (internal capsule posterior limb, posterior 1/3)
• Ataxic hemiparesis- weakness, incoordination
What does the Basilar a supply? What are the results of a deficit?
Basilar a: - Supplies: pons, medulla, lower midbrain, corticobulbar and corticospinal tracts, ocular cranial nerve nuclei, paramedian pontine reticular formation - Deficits: • Preserved consciousness • Vertical eye movement • Blinking • Quadriplegia • Cardiorespiratory centres • Loss of voluntary movement (face/tongue/mouth) • “Locked in syndrome”
Compare the contents of the interior capsule anterior and posterior limb?
Anterior limb:
- Fibres connecting thalamus to frontal lobe
- Fibres connecting lentiform to caudate nuclei
- Fibres connecting cortex to corpus striatum
- Fibres connecting frontal lobe to peduncle and nuclei pontis
- Thalami pontine fibers
Posterior limb:
- Anterior 2/3- corticospinal tract
- Posterior 1/3- sensory fibers (from thalamus), optic radiation, acoustic fibers
What is the blood supply of the visual system?
- Retina: central retinal a, its 4 branches
- Optic nerve: ophthalmic a
- Optic chiasm: ICA branches
- Optic tract: anterior choroidal a
- Lateral geniculate nucleus (thalamus sensory relay nucleus): PCA deep branches
- Optic radiation: MCA inferior division
- Primary visual cortex: calcarine a (from PCA and MCA contributions)
