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Craniocerebral Trauma What Not To Miss

Craniocerebral Trauma What Not To Miss. Ellen G. Hoeffner, MD Neuroradiology Division Department of Radiology University of Michigan Health System. Goals and Objectives . Role of imaging in craniocerebral trauma Indications for head CT in trauma patients

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Craniocerebral Trauma What Not To Miss

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  1. Craniocerebral TraumaWhat Not To Miss Ellen G. Hoeffner, MD Neuroradiology Division Department of Radiology University of Michigan Health System

  2. Goals and Objectives • Role of imaging in craniocerebral trauma • Indications for head CT in trauma patients • Indications for MRI in trauma patients • Become familiar with the various types of craniocerebral trauma • Primary traumatic injuries • Acute and subacute secondary injuries

  3. Imaging Modalities • CT is first imaging study that should be obtained • Should use multiple window and level settings • Brain (W:80, L:40) • Bone (W:2500, L:500) • Intermediate or “blood” (W:150, L:75) • Liberal use of CT warranted even with relatively minor trauma • Lancet 2001;357:1391-96 • N Engl J Med 2000;343:100-5

  4. Imaging Modalities • MRI generally not needed emergently • MRI generally used for problem solving tool • Determine cause of unexplained neuro deficit • Help determine prognosis

  5. Classification of Head Trauma • Primary vs. secondary • Primary – injuries that are the direct result of the head trauma • Secondary – injuries that arise as complications of primary lesion • Some of these injuries may be preventable

  6. Primary Injuries • Extra-axial • Epidural hematoma (EDH) • Subdural hematoma (SDH) • Subarachnoid hemorrhage (SAH) • Intraventricular hemorrhage (IVH) • Intra-axial • Cortical contusions • Diffuse axonal injury (DAI) or traumatic axonal injury (TAI)

  7. Secondary Injuries • Acute and subacute • Cerebral swelling/edema • Brain herniation • Cerebral ischemia/infarction • Chronic • Hydrocephalus • Encephalomalacia • Cerebrospinal fluid (CSF) leak • Leptomeningeal cyst

  8. Head CT Scoring Systems • Marshall CT score • I - no visible pathology • II - cisterns are present with midline shift of 0–5 mm and/or lesions densities present; no high or mixed density lesion >25 mL, may include bone fragments and foreign bodies • III - diffuse injury, cisterns compressed or absent with midline shift of 0–5mm; no high or mixed density lesion >25 mL • IV - diffuse injury, midline shift >5 mm; no high or mixed density lesion >25 mL • V - any lesion surgically evacuated • VI - high or mixed density lesion >25 mL; not surgically evacuated • Rotterdam CT score • Basal cisterns • 0: normal • 1: compressed • 2: absent • Midline shift • 0: no shift or <= 5mm • 1: shift > 5mm • Epidural mass lesion • 0: present • 1: absent • Intraventricular blood or traumatic SAH • 0: absent • 1: present • The final score is the sum of the scoring items + 1.

  9. Epidural Hematoma (EDH) • Between inner table and periostealdura; biconvex • Skull fracture with disruption middle meningeal artery (85%) • Venous – injury to transverse sinus, sphenoparietal sinus, superior sagittal sinus (15%) • Rarely crosses sutures, where periostealdura firmly attached • Can cross falx and tentorium, where dura loosely attached Seminars in Roentgenology 2006:177-189

  10. “Swirl sign” – low attenuation areas within EDH • Likely reflects active bleeding • Predicts rapid expansion of EDH

  11. Subdural Hematomas (SDH) • Between meningealdura and arachnoid; crescent-shaped • Do not cross falx or tentorium; cross sutures • Laceration of bridging cortical veins • Increased incidence with brain volume loss • Increased motion between brain and clavarium • May develop after trivial trauma • Usually in elderly, pts on anticoagulants, pts with coagulopathy • Often associated with parenchymal injury that may or may not be apparent on CT Seminars in Roentgenology 2006:177-189

  12. Subdural Hematomas (SDH) • Acute (few days up to 1 week old) • Hyperdense • Isodense with severe anemia • Mixed attenuation – active bleeding, clotted and unclotted blood present, mixed with CSF • Subacute (1-3 weeks old) • Isodense • Chronic (> 3 weeks old) • Hypodense • Mixed attenution, bi-layered if rebleeding occurs

  13. Subarachnoid Hemorrhage (SAH) andIntraventricular Hemorrhage (IVH) • SAH • Disruption pial vessels • Extension of contusion or hematoma into SAS • Diffusion of IVH into SAS • Often opposite site of impact • Adverse prognostic factor – vasospasm, communicating hydrocephalus • < or > 3mm • IVH • Tearing of subependymal veins • Extension of hematoma • Reflux of SAH • May lead to obstructive or communicating hydrocephalus

  14. Cortical Contusions • 44% of traumatic parenchymal injuries • Mechanism • Translational movement of brain along bony surfaces of calvarium • Location • Along gyral surface • Inferior frontal lobes, anterior temporal lobes, lateral temporal lobe, parasagittal convexities, adjacent to margins of skull fractures

  15. Cortical Contusions • 50% contusions hemorrhagic on CT • Non-hemorrhagic contusions may not be visible on initial CT • Become more apparent over a few days as edema develops and delayed hemorrhage may occur • On MRI contusions of variable signal due to edema and blood

  16. MRI obtained 3 days after injury

  17. 24 hour follow-up

  18. Diffuse Axonal Injury/Traumatic Axonal Injury • Mechanism • Rapid acceleration/deceleration often with rotational forces • Multiple small focal areas of axon disruption • Location • Corticomedullary junction, • Frontotemporal region • Corpus callosum • Posterior body and splenium • Dorsolateral brainstem • Patients are unconscious from the moment of injury • Usually have severe impairment or remain in persistent vegetative state

  19. Diffuse Axonal Injury/Traumatic Axonal Injury • Over 50% of patients have an initially negative head CT • Seen on CT if hemorrhagic • MRI more sensitive than CT • Gradient echo T2* sequences show hemorrhagic foci • T2/FLAIR identify non-hemorrhagic foci • DWI can show additional areas of injury not seen on above sequences

  20. Diffuse Cerebral Swelling/Edema • Swelling results from hyperemia and increased cerebral blood volume • Gray-white differentiation preserved • Edema results from hypoxia and cytotoxic edema, vasogenic edema or interstitial edema

  21. Subfalcine Herniation • Commonest form of herniation • Imaging findings • Cingulategyrus displaced across midline underneath the falx • Compression of ipsilateral lateral ventricle and enlargement of contralateral lateral ventricle • Asymmetric anterior falx and shift of septum pellucidum • Complication • ACA branches displaced to contralateral side • Can trap callosalmarginal branches and lead to ACA infarct

  22. Uncal or Medial Transtentorial Herniation • Imaging findings • Uncus and hippocampus displaced over the free edge of tentorium • Uncus extends into and truncates the suprasellar cistern • Ipsilateral ambient cistern and prepontine cistern widened • Compression of ipsilateral lateral ventricle and enlargement of contralateral lateral ventricle

  23. Brain Herniation • Complications • Compression of PCA and anterior choroidal artery (AChA) can lead to infarcts • PCA courses above tentorium and medial to temporal lobe • AChA courses between medial temporal lobe and tentorium • Duret hemorrhages in brainstem • From stretching and tearing of pontine perforator arteries vs. thrombosis of small veins

  24. Descending Transtentorial Herniation • Imaging findings • Downward displacement of both medial temporal lobes and brainstem through tentorial incisura • Effacement of suprasellar and perimesencephalic cisterns

  25. Cerebral Ischemia/Infarction • Compression of blood vessel by herniating brain • Thrombosis or embolization from dissection • Hypoxia /anoxia or hypotension due to systemic causes • Fat emboli from long bone fractures

  26. HI-RADS • Head Injury Imaging Reporting and Data System (HI-RADS) • Being developed by ACR Head Injury Institute (HII) • Standardize the reporting and data collection of imaging in patients with TBI • Goals • Apply consistent terminology • Reduce imaging interpretation variability and errors • Enhance communication with referring clinicians • Facilitate quality assurance and • Improve patient outcome

  27. Conclusion • Studies have shown the efficacy of non contrast head CT even with minor trauma • MRI used more in subacute phase • Determine cause of unexplained neuro deficit • Determine extent of injury better than CT and may help determine prognosis

  28. Conclusion • More than one type of primary injury can occur in a given patient • Findings may progress over first few days as injuries mature • Always look for signs of secondary injury on follow up scans

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