Neuroradiology (Brain, Spine, Head and Neck)
Neuroradiology (Brain, Spine, Head and Neck)
This domain covers acute stroke, hemorrhage, tumors, infection, demyelination, spinal emergencies, and head and neck spaces. The exam tests time-critical diagnosis and lesion localization.
Core rules
- Acute stroke: noncontrast CT excludes hemorrhage; CTA identifies large-vessel occlusion; CT perfusion or MRI mismatch estimates salvageable penumbra. ASPECTS ≤6 predicts a larger infarct core.
- Hemorrhage: hyperdense extra-axial collections; subarachnoid hemorrhage fills sulci and basal cisterns. Brain herniation syndromes depend on compartment and shift.
- Ring-enhancing lesions: glioblastoma has a thick irregular wall; abscess has a thin rim with restricted diffusion; metastasis is often multiple at the gray-white junction; toxoplasmosis favors basal ganglia in HIV.
- Spine: cord compression is a surgical emergency; look for epidural mass, disc extrusion, or fracture. Head and neck spaces include parotid, masticator, parapharyngeal, and retropharyngeal.
Worked example
A 70-year-old presents 3 hours after right hemiparesis. Noncontrast CT shows no hemorrhage and a hyperdense left M1. CTA confirms M1 occlusion; perfusion shows a small core and large penumbra. Endovascular thrombectomy is indicated. If CT instead showed a large established infarct with mass effect, thrombectomy would be futile and hazardous.
Traps
Missing posterior fossa hemorrhage on axial CT; interpreting DWI restriction as always acute ischemia; confusing tumefactive demyelination with tumor; overlooking epidural extension in spine infection; failing to search the retropharyngeal space in neck infection.