Definition of ischemic stroke
Ischemic injury to the brain causing a persistent clinical deficit at 24 hours. Even mild residual deficits are classified as strokes. The severity of the deficit is not the determinant, only that the deficit is present at 24 hours.
Definition of TIA
Transient Ischemic Attack: ischemic neurological deficits that have completely resolved by 24 hours, regardless of their severity or relative duration (seconds or hours).
Presentation of a large-vessel ischemic stroke
Large vessel ischemia causes deficits in multiple systems.
Ex.: large vessel ischemic stroke in the middle cerebral artery territory will have a hemiparesis, a hemi-sensory loss, and a homonymous hemi-anopsia contralateral to the ischemic side of the brain.
This type of stroke requires a large vessel mechanism causing partial or complete occlusion of a major artery.
Presentation of small-vessel ischemic stroke
An isolated motor (or isolated sensory) deficit on one side of the body
Caused by occlusion (atheromatous, lipohyalinosis) of the small penetrating vessels that arise from large arteries deep into the brain.
Small vessel ischemic strokes that cause lacunar infarctions and contribute to the stepwise process of multi-infarct dementia, from multiple lacunar strokes that can accumulate over many years
Traditional non-modifiable atherosclerosis risk factors for stroke
Age, men, race (white people less)
Traditional modifiable atherosclerosis risk factors for stroke
HTN, lipid disorders, homocysteine elevation (treatable with folate, vit b12, and vit B6), smoking, obesity, physical inactivity, diabetes, alcohol abuse
Structural risks for stroke
Arterial Stenosis, Dissection, Occlusion
Atrial myxoma (cardiac tumor)
Less Common Mechanisms of Stroke (“Young Stroke” mechanisms)
- The Vasculopathies: (Fibromuscular Dysplasia (FMD), Moya-Moya, Arterial Dissection)
- Hematological Disorders: (Deficiencies of Protein C, Protein S, or Antithrombin, or the presence of Factor V Leiden, or Prothrombin Gene, Malignancies, Sickle cell anemia, Hyperviscosity States, oral contraceptive use, Antiphospholipid antibodies
- Inflammatory: (Vasculitis, migraine)
- Venous infarction
Reducing risk of stroke
Treat all risk factors possible
“good health” approach (sleep, eat healthy, exercise, fitness, low stress, high happiness) as well as specific dietary, vitamin and medication therapies where needed.
Plus antithrombotic agent
Single agents that reduce the long term risk of recurrent ischemic stroke
Aspirin, Thienopyridines (Clopidogrel, Prasurgrel, Ticlopidine) and Anticoagulants
Use of anticoagulants after stroke
Warfarin is highly effective in primary prevention of stroke with atrial fibrillation or mechanical heart valves.
Injected/Intravenous Anticoagulants are commonly used in the hospital setting and for short term (i.e. trays to weeks) needs (heparin).
What is the surgical therapy for symptomatic patients with high grade (70-90%) stenosis
Endarterectomy (highly beneficial)
Emergency management of stroke
Don’t lower bp
TPA (thrombolytic agent) if 0-4.5 hr
Only give glucose if pt is hypoglycemic
Lumbar puncture and stroke
Useful to exclude neurosyphilis, vasculitis, other inflammatory conditons, and the occasional stroke mimic.. Otherwise, it is not a routine part of the evaluation of ischemic stroke. Perhaps the greatest utility of lumbar puncture is in the determination of subarachnoid hemorrhage, which can occur with a normal CT scan in two situations.
Acute prophylaxis for stroke
ASA and heparin (controversial)
Heparin is only considered to prevent recurrent embolization or progression of large vessel syndromes in patients with a high recurrence risk. Second, delaying the institution of anticoagulation for 48 hours (the high risk period for hemorrhagic CNS catastrophes) and repeating the CT scan, will still reduce the bulk of the re-embolization risk for a few days to a week. Delaying makes sense in larger strokes, which are more susceptible to secondary hemorrhage.
Symptoms of stroke in the different arteries
Anterior cerebral- legs (leg weakness)
Middle cerebral artery- weakness in one side of arm and face; aphasia;
Posterior cerebral artery- vision; visual inputs and sensation
Ataxia- cerebellar signs
Basilar stroke- worst kind of stroke to have (coma and death)
Stroke in cortex
Motor + sensory findings in similar distribution Motor findings variable Aphasia Cognitive issues Apraxia Visual field deficits Gerstmann’s syndrome Higher level sensory processing
Face + arm + leg symmetrically Acute onset movement disorders Common syndromes: Clumsy hand dysarthria Ataxia hemiparesis Pure motor hemiparesis Hemi sensory loss Mixed sensory-motor