Non-traumatic Neurological Emergencies

Non-traumatic Neurological Emergencies

Non-traumatic Neurological Emergencies

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Acute Stroke Imaging - Brain Attack Basics

  • Goal: Rapidly differentiate ischemic vs. hemorrhagic stroke; guide reperfusion therapy. "Time is Brain!"
  • Initial Imaging: Non-Contrast CT (NCCT)
    • Primary: Exclude hemorrhage (hyperdense).
    • Early ischemic signs: Loss of grey-white differentiation, sulcal effacement, hyperdense MCA sign.
    • ASPECTS score (0-10) on NCCT for MCA stroke.
  • Ischemic Stroke Workup:
    • MRI: Gold standard.
      • DWI: Positive within minutes.
      • ADC map: Confirms restricted diffusion. Acute Ischemic Stroke MRI: DWI, ADC, Perfusion
    • CTA: Detects Large Vessel Occlusion (LVO).
    • CTP: Identifies core infarct vs. penumbra (target for reperfusion).

⭐ DWI hyperintensity with corresponding ADC hypointensity signifies restricted diffusion, visible within minutes (<30 min) of acute ischemic stroke onset.

CNS Infections - Brain Invaders

  • Bacterial Meningitis:
    • CT: Often normal; may show hydrocephalus, basal cistern effacement. Post-contrast: meningeal enhancement.
    • MRI: Superior for leptomeningeal enhancement (FLAIR, T1+C); DWI for restricted diffusion of pus in sulci.
  • Viral Encephalitis (Herpes Simplex - HSV):
    • Typically affects temporal lobes, insula.
    • CT: Early stages often normal; later may show hypodensity, edema.
    • MRI: Characteristic T2/FLAIR hyperintensity, DWI restriction, petechial hemorrhages.
    • Herpes simplex encephalitis DWI restriction
  • Brain Abscess:
    • CT/MRI: Central area of liquefaction necrosis, surrounded by a thick, enhancing rim and vasogenic edema.
    • DWI: Central restricted diffusion is key for pyogenic abscess.
    • Brain MRI showing ring enhancing lesions
    • ⭐ DWI restriction in the core of a pyogenic abscess is typical.

  • Tuberculous Meningitis:
    • Features: Thick basal meningeal enhancement, hydrocephalus, tuberculomas (ring-enhancing lesions). Infarcts common due to associated vasculitis.

Seizures & Status - Electric Storms

  • Imaging Goal: Identify structural causes (e.g., tumor, stroke, infection, malformation) or complications.
  • New-onset seizure: Non-contrast CT (NCCT) head initially to exclude acute bleed/mass.
  • MRI: Superior for subtle epileptogenic lesions (e.g., mesial temporal sclerosis, cortical dysplasia, encephalitis).
  • Status Epilepticus: May show reversible cortical/subcortical DWI restriction, T2/FLAIR hyperintensity, ↑perfusion; hippocampal changes common. image

⭐ MRI is superior to CT for detecting subtle epileptogenic lesions; CT is often first-line in emergency new-onset seizures to exclude acute bleed/mass effect immediately threatening life or requiring urgent neurosurgical intervention (e.g. large hematoma, hydrocephalus).

Raised ICP & Hydrocephalus - Pressure Cooker Brain

  • Raised ICP: Symptoms: Headache, vomiting, papilledema. Late: Cushing's triad. CT findings: Effaced sulci, compressed ventricles/cisterns.
  • Hydrocephalus: ↑CSF volume causing ventricular dilatation (Evan's Index > 0.3).
    • Acute sign: Transependymal CSF flow (periventricular lucency on CT / T2 hyperintensity on MRI).
    • Axial CT brain: Hydrocephalus pre- and post-shunt
    • Transependymal CSF seepage (periventricular lucency on CT / T2 hyperintensity on MRI) indicates acute/uncompensated hydrocephalus.

  • Differentiating Types:

Other Vascular Crises - Vessel Vendettas

AspectSubarachnoid Hemorrhage (SAH)Cerebral Venous Thrombosis (CVT)
Key NCCT Sign(s)Hyperdense blood (cisterns)"Cord sign", "Dense triangle sign"
Key CECT Sign(s)- (CTA for aneurysm)"Empty delta sign" (esp. SSS)
Grading / Gold Std.Fisher Grade (CT blood); CTA (aneurysm)MRV/CTV: Filling defect (gold)

⭐ The "empty delta sign" on contrast-enhanced CT is a classic finding in superior sagittal sinus thrombosis.

High‑Yield Points - ⚡ Biggest Takeaways

  • AIS: NCCT head first (no bleed); MRI (DWI) is most sensitive for early infarct.
  • ICH: NCCT shows type, location, mass effect; CTA for underlying vascular causes.
  • SAH: NCCT for acute blood; Angiography (CTA/DSA) vital for aneurysms.
  • CVT: MRV/CTV are diagnostic; look for "empty delta sign" on CECT.
  • CNS Infections: Contrast MRI for complications (e.g., abscess); DWI is key for herpes.
  • PRES: MRI (FLAIR/T2) shows posterior reversible edema, typically parieto-occipital.

Practice Questions: Non-traumatic Neurological Emergencies

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Earliest clinical sign of raised intracranial pressure is:

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Flashcards: Non-traumatic Neurological Emergencies

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What is the best modality to identify cocaine packets in a body packer?_____

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