Flashcards in Ischemic Stroke Deck (45):
Injury to the brain caused by interruption of bloodflow or by bleeding into or around. Produces teh abrupt onset of focal neurologic defects that frequently result in permanent disability or death.
Transient Ischemic attack
abrupt onset of focal neurological deficits that resolve in less than an hour.
What percentage of strokes are hemorrhagic and describe a hemorrhagic stroke
about 20%... Hemorrhagic strokes may be caused by bleeding into the parenchyma of the brain or around the surface of the brain.
Bleeding into parenchyma of brain called
Bleeding around the surface of the brain called
Ischemic stroke may have what 4 potential underlying causes?
1) Atherosclerotic occlusion of an intra/extracerebral blood vessel
3) Lacunar infarcts ( disease of the lumen of small arterioles
4) 30% are cryptogenic (unknown cause)
Stroke risk factors
- Age: doubles each decade
- Gender: male at one and a half times higher risk
- Race: african americans
- Family Hx
Modifiable stroke risk factors
- Carotid Artery Stenosis
- Atrial Fib
- Physical inactivity
In the absence of blood supplying glucose to the brain, each 100gm of brain has sufficient energy stores to last how long?
two and a half minutes. The brain has very little energy storage. Thus, important to keep blood flowing to it.
Hyperthermia and hyperglycemia accelerate and worse stroke brain injury
Under normal conditions, neurons metabolize glucose delivered by the blood almost exclusively through what type of metabolism
Within minutes of the loss of blood supply, brain energy stores are depleted through the metabolism of glucose via glycolytic pathways with the accumulation of lactic acid.
Lactic acid is bad. High temps will accelerate glycolytic lactic acid production as will high blood glucose levels. Body temperature and blood glucose should be brought down asap.
The central area downstream of an embolus most affected by loss of bloodflow, fewer collaterals providing circulation.
Peripheral areas with less severe ischemia.
Ischemic core suffers irreversible injury how fast?
Within 1 hour or less
Ischemic prenumbra may survive for how long?
Therapeutic window for stroke intervention is generally recognized as being
CBF (Cerebral blood flow) in norma individuals?
around 55ml/100gm brain/ minute
Neurologic signs and symptoms produced by stroke include
- weakness or paralysis
- loss of sensation
- loss of vision in one eye
- difficulty talking or understanding what is being said
- difficulty with organization or perception
Anterior circulation stroke involves occlusion of:
Internal Carotid Artery
Posterior Circulation stroke involves occlusion of:
Superior Cerebellar Artery
Anterior Inferior Cerebellar Artery
Besides vessel location, what is the other way to classify ischemic stroke?
Middle Cerebral Artery
Small penetrating branches of the MCA called
Know slide 21...anterior and middle cerebral and what parts of the brain they provide vasculature to
What are the three clinical brainstem stroke syndromes?
- Lateral Medullary Syndrome
- Pontine syndrome
- Midbrain syndrome
Medullary Stroke Syndrome features
- Loss of pain and temperature from the ipsilateral side of the face due to lesion of the trigeminal nucleus and tract
- Dysarthria and Dysphagia due to lesion of nucleus ambigus
- Loss of pain and temperature on the contralateral side of the body due to lesion of spinothalamic tract
- Gait ataxia on the ipsilateral side of the body due to lesion of the spinocerebellar tract
Medullary stroke syndrome due to
occlusion of the PICA or vertebral artery?
Pontine Stroke Syndrome
- Gaze disorders due to a lesion of the medial longitudinal fasiculous
- Loss of epicritic sensation and proprioception on the contralateral side of the body due to a lesion of the medial lemniscus.
- Cerebellar lesions on both sides of the body due to lesion of the pontine nuclei and transverse cerebellar fibers
- Contralateral hemiparesis due to lesion of corticospinal tract
Midbrain stroke syndrome
see slide 27 for symptoms
Anterior Circulation Stroke
- Ipsilateral blindness or contralateral inferior quadrantanopsia ( blindness in 1 quarter of the visual field)
- Contralateral gaze paresis
- contralateral mono/hemiparesis and/or mono/hemisensory deficit
- Aphasia in the dominant hemisphere or neglect in the non-dominant
Posterior Circulation Stroke
-unlateral, bilateral, or crossed weakness or sensory deficits
- contralateral homonymous hemianopsi or superior quadrantanopsia
- vertigo, nausea/vomitting, gait ataxia, diplopia, dysphagia, horner's syndrome
- Altered consciousness and amnesia
The middle cerebral artery supplies blood to what functional brain areas
- Obviously the pre and post central gyri- so motor and sensory to just about every part of the body
- The frontal eye fields (field of vision)
- Broca's area (speech)
- Wernicke's area (comprehension)
- Visual Radiations (visual)
Anterior Cerebral Artery supplies blood to what functional parts of the brain
Supplies to the motor and sensory portions (pre and post central) for the hip, leg, and foot
Visual radiations of occipital lobe
occlusion of vertebral and PICA
- Loss of pain and temperature from ipsilateral side of face due to lesion of the spinal trigeminal nucleus and tract
- Dysarthria and Dysphagia: lesion to nucelus ambiguus
- Loss of pain and temperature on teh contralateral side of the body- spinothalamic tract
- Gait ataxia on the ipsilateral side of the body- spinocerebellar tract
Important to distinguish cerebral infarction from selective ischemic necrosis.
Cerebral infarction- Focal brain ischemia leading to focal necrosis of all cellular elements
Selective Ischemic Necrosis- Only brain neurons injured. Most frequently seen in pts suffering from cardiac arrest and cardiac resuscitation. Affects only specific populations of highly vulnerable neurons...Like the CA1 pyramidal neurons of the hippocampus or the cerebellar purkinjee cells
Common sites for atherothrombotic plaque buildup
- Origins or carotid and vertebral arteries
- Bifurcation of common carotid artery
- Internal carotid arteries at the carotid siphon
- M1 segment of the middle cerebral
Most common cause of cardiogenic emboli affecting the brain is
Other causes include: mitral stenosis, bacterial endocarditis, and prosthetic heart valves
CNS vaculitis presentation
multiple cerebral blood vessels involved so typicaly pts present with multiple focal defects
Giant cell temporal arteritis
causes unilateral headaches over the temoral artery. Untreated can lead to strokes and blindness. Respondes well to steroids so catch it early
Polycythemia and multiple myeloma are examples of
hyperviscosity syndromes (blood becomes thick)
Also be on the look out for hypercoagulable conditions such as
antiphospholipid syndrome, protein C and S deficiency, cancer, pregnancy, thrombocytosis