Head Trauma Imaging

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Initial Imaging & Skull Fractures - Scan Smart, Spot Breaks

  • Primary Scan: NCCT head is crucial for acute trauma.
    • X-ray skull: Very limited role; mainly if CT unavailable.
  • Key CT Indications:
    • GCS < 15 (2h post-injury)
    • Suspected open/depressed fracture
    • Basal skull fracture signs (Battle's, raccoon eyes)
    • Vomiting > 1 episode
    • Age ≥ 65 years
    • Retrograde amnesia > 30 min
    • Dangerous mechanism
    • Focal deficit, seizure
  • Skull Fracture Types:
    • Linear: Most common.
    • Depressed: Fragment inward; surgery if > bone thickness.
    • Basal: Clinical signs vital; CSF leak risk.
    • Comminuted: Multiple fragments.
    • Diastatic: Sutural separation (children).
    • Growing: Leptomeningeal cyst (infants/young children).

⭐ NCCT head is the investigation of choice in acute head trauma, rapidly identifying life-threatening injuries.

EDH & SDH - Bleeds Between Layers

FeatureEpidural Hematoma (EDH)Subdural Hematoma (SDH)
LocationBetween dura & skull inner tableBetween dura & arachnoid
VesselMiddle Meningeal Artery (arterial); skull fracture (pterion)Bridging veins (venous); elderly/atrophy, coagulopathy
CT ShapeBiconvex (lentiform), hyperdense. 📌 "Lemon"Crescentic, density varies (acute hyperdense). 📌 "Banana"
SuturesDoes NOT cross suturesCROSSES sutures
MidlineCan cross midline reflections (falx/tentorium)Limited by dural reflections (falx/tentorium)
ClinicalLucid interval; rapid declineGradual onset; fluctuating consciousness

⭐ The "lucid interval," a temporary improvement in neurological status after head trauma followed by rapid deterioration, is a classic presentation of EDH.

SAH & ICH/Contusions - Blood In Spaces & Substance

  • Subarachnoid Hemorrhage (SAH): Blood in CSF spaces (sulci, cisterns).
    • NCCT: Hyperdense CSF. Key sites: Sylvian fissure, basal cisterns.
    • Causes: Trauma (overall #1), ruptured aneurysm (spontaneous #1).
    • Complications: Vasospasm (Day 4-14), hydrocephalus. Axial CT: Subarachnoid Hemorrhage
  • Intracerebral Hemorrhage (ICH) & Contusions: Blood in brain parenchyma.
    • ICH: Frank bleed. Common: frontal, temporal lobes.
    • Contusions: Cortical "bruises"; mixed density (hemorrhage + edema).
      • Locations: Inferior frontal, anterior temporal (coup-contrecoup).
      • May "blossom" (evolve) over 24-48h.

⭐ Overall most common cause of SAH is trauma; for spontaneous SAH, it's a ruptured berry aneurysm.

DAI, Herniation & Peds Pearls - Axons, Squeezes & Small Skulls

  • Diffuse Axonal Injury (DAI)
    • Mechanism: High-velocity rotational shear forces; axons stretch & tear.
    • Key sites: Grey-white matter junction, corpus callosum (esp. splenium), brainstem (dorsolateral midbrain/pons).
    • CT: Often normal or subtle petechial hemorrhages.
    • MRI: Modality of choice. SWI/GRE for microhemorrhages; FLAIR/DWI for non-hemorrhagic lesions.
    • 📌 Adams Staging: Grade 1 (lobar WM), Grade 2 (+corpus callosum), Grade 3 (+brainstem).
  • Herniation Syndromes
    • Subfalcine: Cingulate gyrus under falx → ACA compression.
    • Uncal (Transtentorial): Medial temporal lobe (uncus) → CN III palsy (ipsilateral dilated pupil), contralateral hemiparesis (Kernohan's notch phenomenon). PCA often compressed.
    • Central: Diencephalon/midbrain downward → Duret hemorrhages (secondary brainstem bleeds).
    • Tonsillar: Cerebellar tonsils through foramen magnum → cardiorespiratory arrest. Types of brain herniation
  • Pediatric Pearls
    • Non-Accidental Injury (NAI): Suspect with interhemispheric SDH, unexplained skull fractures (esp. complex/diastatic), retinal hemorrhages.
    • Growing skull fracture (Leptomeningeal cyst): Post-traumatic dural tear with CSF/brain herniation through fracture line.
    • Brain: ↑water content, incomplete myelination → greater susceptibility to diffuse injury.

⭐ DAI lesions are classically found at the grey-white matter interface, corpus callosum, and dorsolateral brainstem; MRI is crucial as CT can be normal in up to 50% of cases.

High‑Yield Points - ⚡ Biggest Takeaways

  • NCCT Head: Initial modality for acute trauma; identifies fractures, hematomas.
  • EDH: Lentiform, arterial (MMA), doesn't cross sutures, lucid interval common.
  • SDH: Crescentic, venous (bridging veins), crosses sutures, can be acute or chronic.
  • Traumatic SAH: Blood in sulci/cisterns; common, may indicate severe injury.
  • DAI: MRI superior for punctate hemorrhages (grey-white junction, corpus callosum, brainstem).
  • Signs of raised ICP: Effacement of sulci/cisterns, midline shift, herniation.

Practice Questions: Head Trauma Imaging

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What is the most common cause of subarachnoid hemorrhage?

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Flashcards: Head Trauma Imaging

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The investigation of choice for stroke is a _____.

NCCT

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