5.1 Cerebrovascular Disease, Stroke & Transients

Hyperacute Evaluation & Initial Diagnostic Protocol

Acute cerebrovascular events represent a leading cause of long-term disability and mortality. Rapid, methodical assessment is required to restore cerebral perfusion while preventing catastrophic bleeding complications. The initial clinical priority in any patient presenting with acute focal neurological deficits is establishing the exact time of last known normal (LKN) and immediately obtaining a non-contrast computed tomography (NCCT) scan of the head.

Vascular Territory Stroke Syndromes

Localization of focal ischemia based on clinical presentation relies on understanding cerebrovascular anatomy:

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Reperfusion Therapies: Thrombolysis & Mechanical Thrombectomy

Therapeutic management of acute ischemic stroke depends heavily on time elapsed since LKN, blood pressure parameters, and vascular imaging.

                          [ Acute Focal Deficit / Suspected Stroke ]
                                              |
                                  (NCCT Head + Blood Glucose)
                                              |
                     +------------------------+------------------------+
                     |                                                 |
          [ Intracranial Hemorrhage ]                        [ No Hemorrhage (Ischemic) ]
                     |                                                 |
       (BP Control + Reversal of                               (Check Time & BP)
       Anticoagulation + Neurosurg)                                    |
                                              +------------------------+------------------------+
                                              |                                                 |
                                     [ LKN ≤ 4.5 Hours ]                              [ LKN > 4.5 Hours ]
                                              |                                                 |
                                  (Check rtPA Contraindications)                    (CTA / MRA for LVO)
                                              |                                                 |
                                  +-----------+-----------+                         +-----------+-----------+
                                  |                       |                         |                       |
                            [ Eligible ]            [ Ineligible ]            [ LVO Present ]         [ No LVO ]
                                  |                       |                         |                       |
                           (Lower BP <185/110;    (Aspirin 162-325 mg;     (EVT up to 24h if       (Aspirin + Statin;
                           Administer rtPA)       CTA for EVT)              perfusion mismatch)      Subacute Workup)

Intravenous Alteplase (rtPA) Criteria

Intravenous tissue plasminogen activator (rtPA) should be administered to eligible patients within 4.5 hours of LKN. Blood pressure must be lowered below 185/110 mmHg prior to initiation (e.g., using IV labetalol or nicardipine) and maintained below 180/105 mmHg for 24 hours post-infusion.

Absolute Contraindications to rtPA:

• Active internal bleeding or bleeding diathesis (platelets <100,000/mm³, INR >1.7, or use of direct oral anticoagulants within 48 hours)
• Evidence of intracranial hemorrhage on initial NCCT
• Head trauma or ischemic stroke within the preceding 3 months
• History of prior intracranial hemorrhage, arteriovenous malformation, or aneurysm
• Intracranial or intraspinal surgery within 3 months
• Severe uncontrolled hypertension (BP >185/110 mmHg unresponsive to acute antihypertensive therapy)
• Blood glucose <50 mg/dL (must correct hypoglycemia first as it mimics stroke)

Endovascular Thrombectomy (EVT)

Mechanical thrombectomy with a stent retriever is indicated for patients with a demonstrated large vessel occlusion (LVO) in the anterior circulation (internal carotid artery or M1 segment MCA). EVT can be performed up to 24 hours from LKN if CT perfusion or MRI demonstrates a favorable mismatch between a small core infarct and a large salvageable penumbra.

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Transient Ischemic Attack (TIA) & Risk Stratification

A TIA is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia without acute tissue infarction on magnetic resonance imaging (MRI) diffusion-weighted imaging (DWI).

ABCD2 Score Risk Stratification

Short-term stroke risk following a TIA is quantified using the ABCD2 score:

• Age ≥ 60 years: 1 point
• Blood Pressure ≥ 140/90 mmHg: 1 point
• Clinical Features: Unilateral weakness (2 points); Speech impairment without weakness (1 point)
• Duration of Symptoms: ≥ 60 minutes (2 points); 10–59 minutes (1 point)
• Diabetes Mellitus: 1 point

Therapeutic Management Based on Score:

• High Risk (ABCD2 Score ≥ 4) or Minor Ischemic Stroke (NIHSS ≤ 3): Initiate Dual Antiplatelet Therapy (DAPT) with aspirin (81 mg daily) plus clopidogrel (75 mg daily) within 24 hours of presentation and continue for 21 days, followed by single antiplatelet monotherapy.
• Low Risk (ABCD2 Score < 4): Single antiplatelet therapy (aspirin monotherapy 81 mg daily) is recommended.
• Carotid Endarterectomy (CEA): Indicated for symptomatic carotid artery stenosis of 70% to 99% if perioperative morbidity risk is <6%. CEA is performed within 2 weeks of symptom onset.

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Intracranial Hemorrhage & Subarachnoid Hemorrhage

Subarachnoid Hemorrhage (SAH)

SAH results predominantly from the rupture of a saccular (berry) aneurysm, most commonly located at the junction of the Anterior Communicating Artery with the anterior cerebral artery.

• Presentation: Sudden onset of an excruciating "thunderclap" headache ("worst headache of my life"), often accompanied by transient loss of consciousness, neck stiffness, and subhyaloid retinal hemorrhages.
• Diagnostic Algorithm: Perform urgent non-contrast head CT (>95% sensitive within 6 hours). If CT is negative but clinical suspicion remains high, perform a lumbar puncture (LP). LP finding of xanthochromia (pink/yellow supernatant after centrifugation due to hemoglobin breakdown) confirms SAH.
• Complications & Prevention:
  1. Rebleeding: Highest risk within 24 hours; control blood pressure with target SBP <160 mmHg; perform early surgical clipping or endovascular coiling.
  2. Vasospasm / Delayed Cerebral Ischemia: Occurs 3 to 14 days post-bleed. Administer oral nimodipine 60 mg every 4 hours for 21 days to prevent vasospasm.
  3. Hydrocephalus: Communicating hydrocephalus due to arachnoid villi plugging; managed via external ventricular drain (EVD).