27a - Ischemic Stroke Flashcards
define stroke
brain injury due to loss of blood supply or bleeding. Abrupt onset of FOCAL neurologic deficits. Often permanent disability or death
define transient ischemic attack (TIA)
abrupt onset of FOCAL neurological deficits that RESOLVE within 1 hour.
How can you tell the difference between ischemic and hemorrhagic stroke?
CT scan and??
Describe CBF autoregulation and relation to MAP
CBF = MAP/CVR. CVR = cerebral vascular resistance. Ideally unrelated to MAP. Occurs when MAP >50 and <150.
If MAP falls below 50 or rises above 150 then linear relationship between MAP and CBF develops.
CBF threshold for infarction is 20.
In ischemic areas, CBF directly related to MAP
what are risk factors for ischemic stroke?
nonmodifiable = age, gender, African amer, family history Modifiable = HTN, diabetes, hyperlipid, smoking, afib, obesity, and inactivity
What are signs and symptoms of ischemic stroke?
weakness or paralysis, loss of sensation, loss of vision in one eye or field, difficulty talking or understanding, difficulty with organization and perception, clumsiness and lack of balance
What is clinical presentation for anterior circulation stroke?
ipsilateral blindness or contralateral inferior quadrantanopsia.
Contralateral gaze paralysis.
Contralateral mono/hemiparesis and/or sensory loss.
Aphasia in dominant hemisphere or neglect in nondominant
What is clinical presentation for posterior circulation stroke?
unilateral, bilateral, or crossed (face/body) weakness and/or sensory defects.
Contarlateral homonymous hemianopsia or superior quadrantanopsia
Vertigo, N/V, gait ataxia, diplopia, dysphagia, Horner’s,
Altered consciousness and amnesia
What is major vascular supply to major brain divisions?
Anterior = ICA, MCA, ACA Posterior = PCA, VA, SCA, AICA, PAICA
what are three major causes for ischemic stroke
occlusions, emboli, vasospasm
What is differential diagnosis for ischemic stroke?
hemorrhagic stroke, subdural hematoma, syncope, radiculopathy, bell’s palsy, MS, brain tumor, migraine, seizure, glycimic problems, hypoxia
Most common type of stroke?
ischemic strokes are 80%
What is difference between focal necrosis and selective ischemic necrosis?
focal necrosis is death of all local cells.
selective is only death of brain neurons, and survival of suppporting glia
What is the penumbra?
boundary area around an ischemic infarct. Ischemic center dies within hour, but penumbra can be saved if restored within 4-6 hours
Is hyperglycemia good or bad for strokes?
bad. can accelerate brain injury
Patient presents with sudden frontal eye field disturbances, comprehends and follows commands but can’t speak, and has several focal sensory and motor parasthesias. Where would angiogram show occlusion?
middle cerebral artery occlusion
Patient presents with paralysis of an mostly entire side of the body: tongue, lips, face, thumb, fingers, hand, arm, shoulder, trunk, hip, ankle and toes. Where is the occlusion?
lenticulostriate arteries off of middle cerebral artery. Supplies the axons for almost entire motor cortex. Particularly bad.
Patient presents with paralysis of larynx, tongue, lips, face thumb, fingers, hand and arm. Where is the occlusion?
main stem of middle cerebral artery
CT scan shows necrosis of visual radiations, hippocampus, posterior corpus collosum, and thalamus. What artery was likely occluded?
posterior cerebral artery
Patient has paralysis and numbness of hip, leg and foot as well as sudden behavior changes and lack of executive capability. Where is the occlusion?
anterior cerebral artery. Will knock out frontal lobe and motorsensory to hip,leg,foot.
What is wallenberg syndrome?
medullary syndrome. stroke of PICA or vertebral artery.
Loss of pain/temp on ipsilateral face from lesion to spinal trigeminal nucleus/tract, loss of pain/temp on contralateral body due to lesion of spinothalamic tract, gait ataxia on ipsilateral side due to spinocerebellar tract lesion and dysarthria due to lesion of nucleus ambiguous
What is a pontine stroke?
occlusion of small penetrating arteries from basilar. Gaze disorder due to lesion of MLF and CN 6.
Contralateral epicritic and proprioception loss due to medial leminiscus lesion.
Cerebellar lesions on both sides due to pontine nuclei lesion and transverse cerebellar fibers from both sides.
Contralateral hemiparesis due to corticospinal tract lesion
What is Benedikt stroke?
Midbrain. Occlusion of PCA and or basilar artery.
ipsilateral CN 3 paralysis and pupil dilation due to loss of parasymp from edinger wesphal.
Contralateral epicritic loss due to medial leminiscus lesion.
Contralateral tremor and ataxia due to red nucleus lesion.
What would cause contralateral gaze paresis?
anterior circulation
What would cause aphasia in the dominant hemisphere or neglect in the nondominant?
anterior circulation
Contralateral homonymous hemianopsia. Where is the occlusion?
posterior cerebral artery
Vertigo, n/v, gait ataxia, diplopia, dysphagia, and horner’s syndrome. Where is the occlusion?
posterior circulation
altered consciousness and amnesia. Where is the occlusion?
posterior circulation
What is a lacunar stroke?
occlusion of small penetrating artery that causes small area of necrosis. Most common in internal capsule or pons.
Where are atherothrombotic plaques most common?
origins of carotid and vertebral arteries or at the bifurcations
What could cause multifocal occlusions?
CNS vasculitis such as collagen vascular diseases like lupus or giant cell arteritis
What drugs can precipitate stroke?
cocaine, LSD, amphetamines - street
ethanol
Oral contraceptives with estrogen
