IM18.1-2 | Stroke Foundations — Summary & Reflection

KEY TAKEAWAYS

Stroke is a time-critical emergency defined as focal neurological dysfunction >24 hours (or death) from vascular brain pathology. The vascular anatomy organises stroke localisation: the anterior circulation (ICA → MCA, ACA) supplies the frontal, parietal, and temporal cortex; the posterior circulation (vertebral → basilar → PCA) supplies the brainstem, cerebellum, and occipital lobes; perforating arteries supply the basal ganglia, capsule, and thalamus (lacunar territory).

Classification:
- Ischaemic (80%): TOAST subtypes — large artery atherosclerosis (20–25%), cardioembolism (20–25%; AF most common, rheumatic mitral stenosis important in India), small vessel lacunar (20–25%; lipohyalinosis in hypertension/diabetes), other determined aetiology (5%; young stroke — dissection, thrombophilia, vasculitis), cryptogenic (30–35%)
- Haemorrhagic (20%): ICH (hypertensive Charcot-Bouchard microaneurysms → putamen, thalamus, cerebellum, pons; CAA → lobar); SAH (ruptured berry aneurysm at Circle of Willis bifurcations)

Key pathophysiology: ischaemic core (CBF <10–15 mL/100g/min, irreversible) surrounded by salvageable penumbra (CBF 15–25 mL/100g/min) — rationale for thrombolysis (≤4.5 h) and thrombectomy (≤6 h, selected ≤24 h with penumbra imaging).

Risk factors: hypertension (most important), AF (CHA₂DS₂-VASc ≥2 → anticoagulate), diabetes, dyslipidaemia, smoking, family history.

Initial approach: FAST/BEFAST screening → check blood glucose (exclude hypoglycaemia) → NIHSS → NCCT brain (exclude haemorrhage before thrombolysis) → TIA: ABCD2 score → dual antiplatelet if score ≥4.

REFLECT

The opening hook described a 62-year-old with left hemiplegia at 3 am — 40 minutes after onset. You now have the knowledge to understand exactly what is happening inside his brain: a thrombus has occluded the proximal right MCA, cutting off flow to the lateral right hemisphere. Every passing minute, a portion of the penumbra — previously hypoperfused but still viable neurons — is crossing the threshold into irreversible death. You know that the blood pressure of 182/104 mmHg is a calculated permissive hypertension: lowering it too aggressively now would reduce perfusion pressure to the already-ischaemic penumbra and expand the infarct. You know the NCCT must be done, not to see the infarct, but to confirm there is no blood before you give alteplase.

Now reflect: in your first week of internship, you are covering the casualty overnight when a patient arrives with these features. What is the first thing you do? Not the CT — the first thing. What if the blood glucose returns at 40 mg/dL? How does that change everything? And what is the conversation you will have with the patient's wife, who is standing at the door asking, 'Will my husband walk again?' This module has built the knowledge base for that encounter — the clinical reasoning and the communication are yours to develop in the wards.