neuro- TIA/CVA

Overview of Stroke and Transient Ischemic Attack (TIA)

• Global Impact: Stroke is a leading global cause of mortality. Its incidence is increasing in correlation with aging demographics, as people are living significantly longer than in previous decades.

• Basic Definitions:

  • Cerebral: Relating to the brain.

  • Ischemia: A lack of oxygenation to tissues.

Transient Ischemic Attack (TIA)

• Definition: A TIA is characterized by cerebral ischemia where the brain lacks oxygen for a few seconds, resulting in transient neurological deficits. It is caused by the cessation of blood flow.

• The "Warning Stroke": Often referred to as a "mini-stroke" or "warning stroke," it serves as a disruption of blood flow resulting in focal neurological symptoms.

• Pathophysiology:

  • Can be caused by stenosis (narrowing of vessels) or small emboli blocking vessels, depriving tissue of oxygen.

  • The body attempts to autoregulate when it recognizes a blockage, often through vasodilation to overcome the "clog."

• Clinical Criteria for TIA:

  • All neurological deficits, signs, and symptoms must resolve within $24\,\text{hours}$.

  • There must be no evidence of brain infarction on brain imaging.

• Relationship to Full Stroke: If neurological signs and symptoms last for greater than $24\,\text{hours}$, it is classified as a stroke. A TIA is a significant warning sign for an impending stroke in the future.

Types of TIAs

• Embolic TIA:

  • Occurs when a clot travels from elsewhere in the body to the brain.

  • The most common source is the heart, specifically due to Atrial Fibrillation (AFib).

  • In AFib, stagnant blood in the heart becomes "clotty" and can eventually stenose a vessel in the brain.

• Lacunar TIA:

  • Affects the lacunar arteries, which are very small arteries deep inside the brain that branch off larger vessels.

  • This is considered a small vessel disease where a tiny vessel gets clogged, causing temporary symptoms before the body compensates.

• Large Artery TIA:

  • Involves the blockage of a major, larger vessel in the brain.

  • While more concerning and harder for the body to overcome than small vessel disease, the common denominator for all TIAs is that the patient's symptoms improve and resolve.

Risk Factors and Assessment

• Common Risk Factors (TIA and Stroke):

  • High blood pressure (Hypertension).

  • Diabetes.

  • Smoking.

  • High cholesterol.

  • Atrial Fibrillation (AFib): A major risk factor.

• AFib Management:

  • Prevention involves blood thinners (anticoagulants).

  • Rate control is achieved using medications like Beta-blockers.

  • The CHA2DS2-VASc (referred to as Chad-Vas) score is used to determine a patient's risk and the necessity for anticoagulation.

• The FAST Mnemonic:

  1. F (Face): Facial drooping.

  2. A (Arms): Extremity weakness.

  3. S (Speech): Slurred or difficult speech.

  4. T (Time): Time to call EMS immediately; "Time is brain."

Symptoms of TIA and Stroke

• General symptoms include weakness, speech difficulties, vision changes, dizziness, difficulty swallowing, and confusion.

• Amaurosis Fugax:

  • Described as a "TIA of the eye."

  • Presents as acute, temporary, and painless blindness in one eye, often described as a "curtain coming down" that resolves quickly.

  • It is considered a major warning sign for a full-on stroke, which could lead to permanent vision loss.

TIA Treatment and Diagnostics

• Immediate Action: Patients with transient symptoms (e.g., right arm weakness for $5\,\text{minutes}$) must be admitted for a full stroke workup.

• Neurovascular Imaging:

  • CT Head: The first step upon arrival.

  • CT Angio (CTA): Includes the head and neck (to check carotids) with perfusion.

  • MRI: More sensitive than CT; should be obtained within the first $24\,\text{hours}$ to $48\,\text{hours}$.

• Cardiac Evaluation: To ensure no clots are originating from the heart.

• Laboratory Testing: CBC, CMP, Coagulation panels, and Lipid panels.

• Hypoglycemia Screen: Low blood sugar can mimic a stroke (e.g., a finger stick of $36\,\text{mg/dL}$). Checking glucose can avoid unnecessary "stroke codes."

• Blood Pressure Management:

  • Do not immediately lower blood pressure unless it is extremely high (cutoff is often $220\,\text{mmHg}$).

  • Permissive hypertension (e.g., $170-180\,\text{mmHg}$) helps with brain perfusion/pushing the clot through.

• Medications: Antiplatelet therapy including Aspirin and Clopidogrel (Plavix).

• ABCD2 Score: A risk assessment tool for stroke following a TIA based on:

  • Age.

  • Blood pressure.

  • Clinical symptoms.

  • Duration of symptoms.

  • Diabetes.

  • Risk Statistics:

    • Score $0-3$: $3.1\%$ 90-day risk.

    • Score $7$: Approximately $20\%$ 90-day risk.

Ischemic Stroke

• Definition: A vessel is blocked, leading to a lack of oxygen and brain tissue death.

• Types of Causes:

  • Thrombus: A clot that forms locally due to atherosclerosis/hyperlipidemia ($2/3$ of cases).

  • Embolus: A clot that travels from elsewhere ($1/3$ of cases), often the heart.

• Cardioembolic sources: AFib, Left ventricular thrombus, or PFO (Patent Foramen Ovale). PFO is a congenital bypass seen in children that can cause stasis and subsequent clots.

Neuroanatomy: Carotid Circulation Strokes

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