Ischemic Stroke

Clinical Classification

Pathophysiology

Autoregulation

Treatments

Prevention

Definition

Focal disturbance in cerebral function that due to vascular cause, acute ischemia or hemorrhage

Transient Ischemic Attack

Focal, Transient, due vascular cause, Supported by evidence of risk of acute ischemia

Ischemic vs Hemorrhagic

Ischemia: Loss of blood flow to certain areas of brain

Hemorrhagic: Bleed from blood vessel in brain

Ischemia

Failure of cerebral blood flow to part of the brain

Interruption to blood supply

Hypoxia

Stresses metabolic machinery of brain cells -> Malfunction

Damage can result from edema, depending on size, location of the stroke

Brain will auto regulate itself to maintain a certain blood flow at a certain MAP

Localization

Anterior Cerebral Artery -> Hemiparesis, hemianesthesia, Apraxia, Apathy

Middle Cerebral Artery -> Hemianesthesia, hemiparesis, conjugate deviation, visual ifeld defect, aphasia, apraxia, hemineglect

Anterior Choroid Artery

Hypokinesea, Hemiparesis, hemianopsia, hemianesthsia

Posterior Cerebral Artery

Hemianopsia

Basillar Braches

Mid-Brain: 3, 7, 12, Parkinson's, hemiparesis

Pons: 5,6,7 hypacussi, ataxia, nystagmus, Horner's syndrome, tetraplegia, pseudobulbar paralysis

Medulla Oblangata: 5,10, nystagmus, horner's syndrome, hemiataxia, hiccough, hemianesthsia, ageusiss, hypacusis, 12 hemiparesis, hemihypesthesia

Acute Ischemic Stroke

Artery to artery embolism, local arterial thrombosis, small vessel disease, Cardiac embolism, Hypoperfusion, Hypercoagulable states, Arterial Dissection

Investigations

Blood Pressure, vascular risk factors, Vascular Imaging, cardiac monitoring, Other tests

Paradigmn

Remove the initiating facotrs (antihypertensives, glycemic control, smoking cessation, statins)

Mitigate Inflammation and Stabilize Fibrous Cap (Statins)

Revascularize (endarterectomy/stent)

Antiplatelets

ASA- COX1 inhibitor

Clopidogrel - ADP antagonist

Dipyrimadole - PDE inhibitor

Ticagrelor - P2y12 Receptor antagonist

Dual antiplatelets for 3 weeks followed by single antiplatelet maximizes stroke prevention

generally treat dual antiplatelets for three months for Intracranial disease

Smoking Cessation, Blood Pressure <140/90, Diabetes, dyslipidemia, Alcohol, exercise, diet

Small Vessel Disease

Changes in small vessels -> Tend to cause lacunar stroke

Proliferation of smooth muslce, degeneration of smooth muscle and collagen, Fribrinoid necrosis and occlusion

Anticoagulants

Vitamin K Antagonist - Warfarin

Antithrombin-meidated inactivation - Heparin

Direct thrombin inhibition - Dabigatran

Factor Xa inhibition - Rivaroxaban, apixaban, edoxaban

Risk Factors in Young

Low physical activity, Hypertension, Episodic Binge drinking, Cigarette smoking

Oral Contraceptives, Hormones and Pregnancy

1.7-6 fold increase in risk with estrogen-containing OCP

Pregnancy can also be. arisk factor for storke - especially in 3rd trimester + postpartum

Dissection

Generally causes thrombotic events, treated similarly to ischemic strokes

LMWH can be considered in complicated, but antiplatelets are more typical in less complex scenarios

Can consider prophylactic antithrombotics in patients with dissection in highest risk time periods

Mimics and Chameleons

Mimic: Ishcemic stroke-like symptoms that are caused by another issue

Seizures

Chameleon: Ischemic stroke caused by atypical symptoms, increasing risk of stroke being missed

Cortical overactivity, commonly described as paresis

Pro: Stereotyped events followed by weakness

Caution: First onset seizures may be caused by stroke

Migraine

Pro: Typical spreading neurological symptoms may have prodrome associated with irritability

Caution: Migrane aura can be associated with risk of ishcemic stroke

Syncope/Sepsis

Associated with hypoperfusion but not necessarily

Pro: Altered level of consciousness without accompanying brainstem findings

Caution: May see systemic changes in context of stroke, medical conditions may predispose to prothrombotic states

Amyloid Spells

In context of cerebal amyloid angiopathy, and associated with microbleeds/subarachnoid hemorrhage

Pro: Recurrent spells despite appropriate therapy, absence of epileptic findings

Caution: Overlap risk with stroke population

Vertigo

Isolated vertigo may have higher risk of stroke in elderly

Decreased level of Consciousness

Abrubt onset of decreased LOC can be a feature of particular localizations (Tip of basilar, Bilateral Thalamic infarcts)

Consider especially if abrupt onset or if accompanied by other neurological findings (Quadriparesis, pupillary abnormatliesi)

Acute Confusional State

Abrupt onset of confusion, restlessness or agitation, reflect a localizing

Stroke Therapies

Thrombolysis

Tenetabplase given within 4.5 hrs of onset

Endovascular Thereapy

Removal of clot with catheter angiogram up to 24 hrs from onset

Best Medical Therapy

Antiplatelets, stroke unit, management of etiologies

Should be administered within 30 minutes of presentation to ED

Exclusion Criteria

Active hemorrhage, or condition that could increase major hemorrhage

Hemorrhage on brain imaging

Relative Exclusion

History of ICH, Stroke or serious trauma in past 3 months, Major surgery in past 14 days