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IMAGING OF HEAD TRAUMA

IMAGING OF HEAD TRAUMA. Dr. Thanh Binh Nguyen University of Ottawa, Canada July 2009. OUTLINE. Clinical indications for imaging Imaging technique Extraaxial hemorrhage Intraaxial injury Brain herniations Skull fractures. INTRODUCTION.

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IMAGING OF HEAD TRAUMA

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  1. IMAGING OF HEAD TRAUMA Dr. Thanh Binh Nguyen University of Ottawa, Canada July 2009

  2. OUTLINE • Clinical indications for imaging • Imaging technique • Extraaxial hemorrhage • Intraaxial injury • Brain herniations • Skull fractures

  3. INTRODUCTION • Head trauma is the leading cause of death in people under the age of 30. • Males have 2-3 x frequency of brain injury than females • Due mainly to motor vehicle accidents and assaults

  4. Classification of TBI • Primary • Injury to scalp, skull fracture • Surface contusion/laceration • Intracranial hematoma • Diffuse axonal injury, diffuse vascular injury • Secondary • Hypoxia-ischemia, swelling/edema, raised intracranial pressure • Meningitis/abscess

  5. IMAGING TECHNIQUE • The presence of a skull fracture increases the risk of having a posttraumatic intracranial lesion. • However, the absence of a skull fracture does not exclude a brain injury, which is particularly true in pediatric patients due to the capacity of the skull to bend. • NO ROLE FOR PLAIN FILMS IN ACUTE HEAD TRAUMA

  6. IMAGING TECHNIQUE • CT without contrast is the modality of choice in acute trauma (fast, available, sensitive to acute subarachnoid hemorrhage and skull fractures) • MRI is useful in non-acute head trauma (higher sensitivity than CT for cortical contusions, diffuse axonal injury, posterior fossa abnormalities)

  7. OUR CT PROTOCOLS • “ROUTINE”: posterior fossa and supratentorial region (slice thickness = 5mm) • “TRAUMA”: posterior fossa (2.5mm), supratentorial region (5mm) • “TEMPORAL BONE”: <1mm in axial or coronal plane • “ORBITS/FACIAL BONES”: 1.25 mm axial/coronal orbits

  8. APPROACH TO CT BRAIN • Look at the scout film: ? Fracture of upper cervical spine or skull • Look for brain asymmetry • Look at sulci, Sylvian fissure and cisterns to exclude subarachnoid hemorrhage • Change windows to look for subdural collection • Look at bone windows to see fractures • Determine if mass is intraaxial (in the brain) or extraaxial (outside)

  9. SCALP INJURY

  10. SCALP INJURY • Cephalohematoma: blood between the bone and periosteum. Cannot cross the suture lines. • Subgaleal hematoma: blood between the periosteum and aponeurosis. Can cross the suture lines. • Caput Succ: swelling across the midline with scalp moulding. Resolves spontaneously.

  11. Extraaxial fluid collections • Subarachnoid hemorrhage(SAH) • Subdural hematoma(SDH) • Epidural hematoma • Subdural hygroma • Intraventricular hemorrhage

  12. Subarachnoid hemorrage • Can originate from direct vessel injury, contused cortex or intraventricular hemorrhage. • Look in the interpeduncular cistern and Sylvian fissure • Usually focal (but diffuse from aneurysm) • Can lead to communicating hydrocephalus

  13. SUBDURAL HEMATOMA • Occurs between the dura and arachnoid • Can cross the sutures but not the dural reflections • Due to disruption of the bridging cortical veins • Hypodense(hyperacute, chronic), isodense(subacute), hyperdense(acute)

  14. W=33 L=41

  15. MANAGEMENT OF aSDH • Acute SDH with thickness > 10 mm or midline shift > 5mm should be evacuated • Patient in coma with a decrease in GCS by >2 points with a SDH should undergo surgical evacuation.

  16. EPIDURAL HEMATOMA • Located between the skull and periosteum • Due to laceration of the middle meningeal artery or dural veins • Can cross dural reflections but is limited by suture lines • Lentiform shape (but concave shape in SDH)

  17. MANAGEMENT OF aEDH • EDH > 30 cm3 should be evacuated. • EDH < 30 cm3 and <15 mm thickness and < 5 mm midline shift and GCS >8 may be managed nonoperatively with serial CT

  18. Intraventricular hemorrhage • Most commonly due to rupture of subependymal vessels • Can occur from reflux of SAH or contiguous extension of an intracerebral hemorrhage • Look for blood-cerebrospinal fluid level in occipital horns

  19. INTRA-AXIAL INJURY • Surface contusion/laceration • Intraparenchymal hematoma • White matter shearing injury/diffuse axonal injury • Post-traumatic infarction • Brainstem injury

  20. CONTUSION/LACERATIONS • Most common source of traumatic SAH • Contusion: must involve the superficial gray matter • Laceration: contusion + tear of pia-arachnoid • Affects the crests of gyri • Hemorrhage present ½ cases and occur at right angles to the cortical surface • Located near the irregular bony contours: poles of frontal lobes, temporal lobes, inferior cerebellar hemispheres

  21. From http://neuropathology.neoucom.edu/ Dr.Agamanolis

  22. Intraparenchymal hematoma • Focal collections of blood that most commonly arise from shear-strain injury to intraparenchymal vessels. • Usually located in the frontotemporal white matter or basal ganglia • Hematoma within normal brain • DDx: DAI, hemorrhagic contusion

  23. DIFFUSE AXONAL INJURY • Rarely detected on CT ( 20% of DAI lesions are hemorrhagic) • MRI: T1, T2, T2 GRE, SWI

  24. DAI • Due to acceleration/deceleration to whtie matter + hypoxia • Patients have severe LOC at impact • Grade 1: axonal damage in WM only -67% • Grade 2: WM + corpus callosum (posterior > anterior) – 21% • Grade 3: WM + CC + brainstem

  25. DAI • Hours: • hemorrhages and tissue tears • Axonal swellings • Axonal bulbs • Days/weeks: clusters of microglia and macrophages, astrocytosis • Months/years: Wallerian degeneration

  26. From http://neuropathology.neoucom.edu/ Dr.Agamanolis

  27. Sagittal T1-W images

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