IM18.8-9 | Stroke Diagnostic Testing — Summary & Reflection

KEY TAKEAWAYS

Stroke diagnostic testing follows a logical sequence driven by two questions: what type of stroke is this (ischaemic vs haemorrhagic)? And what is the aetiology (to direct secondary prevention)?

Acute imaging:
- NCCT brain (always first): exclude haemorrhage; ASPECTS score for ischaemic extent
- CTA: vessel occlusion site (thrombectomy), carotid stenosis, dissection
- CT perfusion: core-penumbra mismatch for late-window thrombectomy (6–24 h, DAWN/DEFUSE-3)
- MRI DWI: ischaemia within minutes; DWI-FLAIR mismatch for wake-up stroke

Aetiological workup (all ischaemic stroke):
- ECG + prolonged cardiac monitoring (paroxysmal AF)
- TTE → TOE (LV thrombus, valvular disease, PFO with bubble contrast)
- Carotid duplex (≥70% symptomatic stenosis → CEA within 2 weeks)
- Labs: FBC, glucose/HbA1c, lipids, coagulation, ESR/CRP, TFTs

Young stroke (age <45) — EXTENDED workup:
- T1 fat-sat MRI neck (dissection — #1 cause <45 years)
- TOE bubble contrast (PFO — 40–50% of young cryptogenic)
- Thrombophilia screen (protein C/S, AT-III, factor V Leiden, prothrombin mutation)
- APS panel × 2 occasions ≥12 weeks apart
- Vasculitis screen (ANA, ANCA, Takayasu — CTA/MRA aorta)
- MRI+MRV (CVST — treat with anticoagulation despite haemorrhage)
- Haematological screen (sickle cell, polycythaemia, thrombocythaemia)

ICH workup: location = aetiology clue (putaminal = hypertensive; lobar elderly = CAA; young atypical = AVM/tumour); CTA spot sign = expansion; MRI GRE microbleeds; coagulation screen mandatory; DSA if structural lesion suspected.

SAH: NCCT → LP for xanthochromia if NCCT negative → CTA/DSA for aneurysm.

REFLECT

Return to the 38-year-old man from the hook. The NCCT was normal — haemorrhage excluded. You now know the next steps: CTA brain and neck (is there a large vessel occlusion? is there a dissection?), CT perfusion (how much penumbra remains?), ECG, and simultaneously draw blood for a young stroke extended panel — thrombophilia, APS, vasculitis markers, FBC — because in a 38-year-old, this workup starts in parallel with acute management, not weeks later.

The broader reflection: diagnostic testing in stroke is an expression of clinical reasoning. Each investigation you order should complete the sentence: 'I am ordering this because the clinical picture suggests X, and this test will confirm or refute X.' A student who understands this reasoning will adapt it to any future patient, including presentations not yet described in any textbook. What is the one test in the young stroke extended workup that would permanently change the long-term management strategy if it comes back positive — and what management change would it trigger?