Lecture 12 - Cerebral Blood Supply Flashcards
Circle of Willis
Made by Ant. cerebral artery, Middle cerebral artery (internal carotid artery), Post. comm. artery, and Post. cerebral artery, which joins together to form basilar artery
-PCA just anterior to CN3
Middle Cerebral Artery
- blood supply to most of the cerebral hemisphere
- lateral frontal, parietal, temporal lobes
- most of BG
- most of deep white matter (usually including internal capsule)
Anterior Cerebral Artery
- medial frontal and parietal lobes
- wraps around corpus callosum
Posterior Cerebral Artery
- medial temporal and occipital lobes
- most or all of thalamus
Variable arterial supply
deep branches of the ACA, MCA or PCA
-posterior limb of the internal capsule and lateral thalamus
Border zone
AKA watershed zone
- meeting between MCA and other (ACA or PCA) supply territory
- anastomosis
Cerebral arterial imaging
Ultrasound - carotid duplex (fast, safe, variable resolution) Magnetic resonance angiogram -slow, safe, good resolution -magnet contraindications Computed tomographic angiogram (CTA -fast, better resolution -iodinated contrast and radiation Catheter angiogram -best resolution -iodinated contrast, radiation, catheter risks
Cerebral venous sinuses
between dural layers
Syndrome: Retinal artery
internal carotid –> ophthalmic –> retinal
- common
- complete (or entire retina) or branch (infarct)
- monocular visual loss
- altitudinal (shade coming down)
- transient (amaurosis fugax)
- **vision flipped
- -> superior infarct = lower vision field affected
Syndrome: Left MCA
-common
lateral frontal (face & arm) affected
-motor cortex (hemiparesis, dysarthria, dysphagia, apraxia)
-frontal eye field (gaze preference/paresis)
> eyes rest IPSI, paresis is CONTRA
-broca’s area (Broca’s aphasia)
-prefrontal cortex (decreased motivation, attention, exec fx)
lateral parietal (face & arm)
- somatosensory cortex (hemisomatosensory loss, apraxia)
- optic radiation (quadrantanopsia - inf. vision, CONTRA loss)
Lateral temporal
- Wernicke’s area (Wernicke’s aphasia)
- Optic Radiation
Deep white matter
-Long tracts (hemiparesis, hemisomatosensory loss)
Syndrome: Right MCA
lateral frontal same as left MCA, except not aphasia (language is mostly on left side)
Lateral parietal
-add association cortex (hemineglect, anosognosia) to left MCA
Lateral temporal = optic radiation, no Wernicke’s
Syndrome: ACA
UNCOMMON
Medial frontal
-motor cortex (leg weakness, apraxia)
-prefrontal/cingulate cotex (decreased motivation, attention and exec fx)
Medial parietal
-somatosensory cortex (leg somatosensory loss)
Syndrome: PCA
common
Medial occipital
-visual cortex (hemianopsia with macular sparing)
>macula is more central and superficial, so there is enough collateral flow from MCA to keep macula alive
Medial temporal - usually nothing obvious
Thalamus - somatosensory loss
Syndrome: Lacunes
small subcortical cerebral arteries
common
internal capsule = subcortical weakness
thalamus = subcortical somatosensory loss
lacunes are left as arteries deteriorate and are often asymptomatic
