A 58-year-old man from Delhi presents to the emergency department with acute onset left-sided weakness and slurred speech of 2 hours duration. Blood pressure is 165/95 mmHg, heart rate 88/min regular. Non-contrast CT head shows no hyperdensity. MRI brain performed 3 hours after symptom onset reveals restricted diffusion in the right middle cerebral artery territory on DWI sequences with corresponding low signal on ADC maps. What is the most appropriate next step in management?

Explanation

## Clinical Context This patient presents with acute ischemic stroke within the thrombolytic window (2–3 hours), confirmed by MRI showing acute infarction (restricted diffusion on DWI/ADC). The key clinical decision now is whether to pursue reperfusion therapy and which modality. ## Imaging Interpretation **Key Point:** DWI hyperintensity with ADC hypointensity is the hallmark of acute ischemic stroke (cytotoxic edema), appearing within **minutes** of symptom onset—far earlier than conventional CT or T2-weighted MRI. **High-Yield:** Non-contrast CT rules out hemorrhage (prerequisite for thrombolysis); MRI DWI/ADC confirms acute infarction and helps identify salvageable penumbra. ## Management Algorithm ```mermaid flowchart TD A[Acute ischemic stroke confirmed on DWI/ADC]:::outcome --> B{Time since onset?}:::decision B -->|< 4.5 hrs| C[IV thrombolysis eligible]:::action B -->|4.5-24 hrs + select criteria| D[Consider thrombectomy]:::action C --> E{Large vessel occlusion on CTA?}:::decision E -->|Yes| F[IV thrombolysis + mechanical thrombectomy]:::action E -->|No| G[IV thrombolysis alone]:::action D --> H[CTA/MRA to assess LVO]:::action H --> I{LVO present?}:::decision I -->|Yes| J[Mechanical thrombectomy]:::action I -->|No| K[Medical management + secondary prevention]:::action ``` ## Why CTA/Thrombectomy Assessment? 1. **Current guidelines** (AHA/ASA 2019, ESO 2019) recommend CTA or MRA in all acute ischemic stroke patients to identify large vessel occlusion (LVO). 2. **Thrombectomy benefit:** Mechanical thrombectomy has Class 1A evidence in LVO within 24 hours if patient meets criteria (DAWN, DEFUSE 3 trials). 3. **Time window:** At 3 hours, patient is in the IV thrombolysis window AND potentially eligible for thrombectomy if LVO is present. 4. **Rationale:** CTA identifies LVO and guides the decision to proceed with thrombectomy, which has superior outcomes compared to thrombolysis alone in LVO. ## Why Not Immediate Thrombolysis? **Clinical Pearl:** While IV thrombolysis is indicated, it should NOT delay CTA assessment for LVO. Modern practice is **"drip and ship"** or simultaneous CTA—thrombolysis can be given en route to the thrombectomy center or in parallel with CTA evaluation. Delaying CTA to give thrombolysis first may miss the thrombectomy window. **Warning:** Do NOT assume all acute ischemic strokes benefit equally from thrombolysis alone; LVO patients have better outcomes with thrombectomy ± thrombolysis. [cite:Harrison 21e Ch 436]