Cerebral and Lacunar Strokes B&B Flashcards
what are the etiologies of strokes (2)? what is the best first test for diagnosis?
- 80% ischemic - thrombosis, embolism, hypoperfusion —> symptom onset over hours
- 20% hemorrhagic —> sudden onset
first test: non-contrast CT of head
you suspect your patient is having a stroke - what is the first test you should run?
non-contrast CT of head
what part of the body will display symptoms from stroke of the ACA vs MCA vs PCA? (think of the homunculus)
ACA: lower limb (supplies superior overlying strip of the cortex and the medial sides of the hemispheres)
MCA: upper limb, face (supplies most of cerebrum, lateral portion)
PCA: vision (supplies occipital lobe)
how do MCA strokes present? (4)
most common site of stroke
- contralateral motor/sensory symptoms
- arms (>legs) + face (think of homunculus)
- spastic (UMN) paralysis
4a. left sided - aphasia (speech center is L in most patients)
4b. right sided - hemineglect
what is the most common site of stroke, and how does it present?
middle cerebral artery (MCA)
- contralateral motor/sensory symptoms
- arms (>legs) + face (think of homunculus)
- spastic (UMN) paralysis
4a. left sided - aphasia (speech center is L in most patients)
4b. right sided - hemineglect
Pt is 75yo M presenting with acute onset of loss of movement in his R arm and drooping of the R face with drooling from the corner of his mouth. Pt has difficulty speaking.
What is most likely going on? Be exact.
stroke of L MCA (MCA = most common site of stroke)
- contralateral motor/sensory symptoms
- arms (>legs) + face (think of homunculus)
- spastic (UMN) paralysis
4a. left sided - aphasia (speech center is L in most patients)
4b. right sided - hemineglect
how will MCA stroke affect facial function?
recall upper face has dual innervation by R and L UMN - unaffected by unilateral MCA stroke
lower face has single UMN supply from contralateral motor cortex fibers running in corticobulbar tract - MCA stroke will cause UMN damage (spastic paralysis)
how does ACA stroke present?
ACA (anterior cerebral artery) supplies medial cortex (midline portion) —> causes symptoms in lower extremities (think of homunculus with legs hanging over the edge)
legs > arms
Pt is 75yo M presenting with acute weakness in his R hip and leg. PE reveals decreased sensation to pinprick and vibration in his R leg. What is the most likely diagnosis? Be exact.
stroke of L ACA (anterior cerebral artery)
ACA (anterior cerebral artery) supplies medial cortex (midline portion) —> causes symptoms in contralateral lower extremities (think of homunculus with legs hanging over the edge)
how does a PCA stroke present? (3)
recall PCA (posterior cerebral artery) supplies posterior brain (duh!) and therefore visual cortex
- visual hallucinations
- visual agnosia
- contralateral hemianopia with macular sparing (dual innervation by PCA + MCA)
Pt is 80yo M presenting with acute visual loss on the R side. His wife reports he is seeing people not in the room. PE is negative for motor or sensory deficits. Visual exam shows loss of the L medial and R lateral fields with macular sparing. What is the diagnosis? Be exact.
stroke of L PCA (posterior cerebral artery)
recall PCA (posterior cerebral artery) supplies posterior brain (duh!) and therefore visual cortex
- visual hallucinations
- visual agnosia
- contralateral hemianopia with macular sparing (dual innervation by MCA + PCA)
explain why PCA strokes spare the macula
macula: central, high-resolution vision (reading)
has dual blood supply from middle (MCA) and posterior (PCA) cerebral arteries
PCA strokes (affecting occipital lobe) often spare the macula
stroke of which artery can present with thalamic syndrome? how will this present?
posterior cerebral artery (PCA) strokes
—> contralateral total sensory loss of face, arms, legs + proprioception deficit [recall thalamus is sensory relay]
but NO motor deficits
may result in chronic pain on contralateral (affected) side
what are 3 possible causes of hypoxic encephalopathy?
- shock
- anemia
- repeated hypoglycemia
loss of consciousness can occur in <10 seconds, permanent damage <4 mins (no glycogen storage in neurons!), can result in coma/ vegetative state
which 2 populations of neurons are highly susceptible to hypoxic encephalopathy?
- pyramidal cells of hippocampus
- Purkinje cells of cerebellum
hypoxic encephalopathy can be caused by shock, anemia, repeated hypoglycemia
what occurs in a “watershed infarct”?
most distal branches of major arteries of cerebrum (ACA, MCA, PCA) / where the zones of supply border each other are most vulnerable to ischemia
classic scenario - CNS damage after massive MI —> “man in a barrel” (bilateral proximal weakness with sparing of face, hands, feet)
what is the classic presentation of watershed infarct?
watershed areas: supplied by distal branches of cerebral arteries / border zones between cerebral arteries (ACA, MCA, PCA)
classic scenario - CNS damage after massive MI
—> “man in a barrel”: bilateral proximal weakness (shoulders/thighs) with sparing of face, hands, feet
what are lacunar strokes, and what are they associated with?
anatomically small strokes which resolve and leave lacunae (empty spaces) in brain - may not show on initial CT
associated with HTN!!, diabetes mellitus, smoking
what’s signs will NOT be present in a patient with a lacunar stroke?
“cortical signs” seen in ACA/MCA/PCA strokes such as aphasia, agnosia, hemianopia will NOT be seen in lacunar infarcts
this is because lacunar strokes are of small artery branches supplying very small regions of the brain
what are 4 common locations of lacunar strokes?
- internal capsule —> hemiparesis (arms = legs)
- thalamus —> sensory loss
- basal ganglia
- pons
how will hemiparesis caused by a lacunar stroke differ from that of an MCA or ACA stroke?
lacunar stroke causing hemiparesis would be affecting internal capsule, so symptoms of legs = arms
MCA would affect arms > legs, while ACA would affect legs > arms (think of homunculus!)
the following arterial branches are commonly affected by lacunar strokes - from which arteries are these branches derived?
a. lenticulostriate branches
b. anterior choroidal artery
c. recurrent artery of Heubner
d. thalamoperfornate branch
e. paramedian branches
a. lenticulostriate branches (most common) - MCA
b. anterior choroidal artery (also common) - ICA (internal carotid)
c. recurrent artery of Heubner - ACA
d. thalamoperfornate branch - PCA
e. paramedian branches - basilar artery
what is required for a lacunar stroke to develop?
arteriolar sclerosis (due to HTN)
proposed causes of lacunae (holes) left in brain are either lipohyalinosis (small vessel destruction + necrosis) or microatheroma (macrophages in vessels), but the jury is still out
what are the 5 types of lacunar strokes? what part of the brain is damaged as a result of each type?
- pure motor - posterior limb of internal capsule
- pure sensory - VPL (ventral posteriolateral) thalamus (sensory relay nucleus)
- sensorimotor - thalamus, internal capsule, caudate and putamen, pons
- ataxic hemiparesis - base of pons, internal capsule (weakness, dysarthria, ataxia out of proportion to weakness)
- dysarthria-clumsy hand syndrome - pons, internal capsule
