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Imaging in head trauma
Brain imaging is important in trauma to identify injuries from primary impact and secondary complications. CT is best for acute trauma to detect fractures and hemorrhages while MRI is more sensitive for diffuse injuries. Common primary injuries seen include fractures, contusions, hematomas, shearing injuries and hemorrhages in various locations. Secondary complications can include swelling, infection and herniations putting pressure on vessels.
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Imaging in head trauma
- 1. Brain Imaging inTraumaBrain Imaging in Trauma
- 2. Level Of ConsciousnessLevelOf Consciousness Glasgow Coma Scale Eye Opening Best Verbal Best Motor Spontaneous 4 Oriented 5 Obeys Command 6 To Voice 3 Confused 4 Localizes 5 To Pain 2 Inappropriate 3 Withdraws 4 None 1 Incomprehensible 2 Flexion 3 None 1 Extension 2 None 1
- 3. Primary Brain InjuryPrimaryBrain Injury
- 4. Classification of TBIClassificationof 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. IMAGINGTECHNIQUEIMAGINGTECHNIQUE CT without contrastis 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)
- 6. Extraaxial fluid collectionsExtraaxialfluid collections Subarachnoid hemorrhage(SAH) Subdural hematoma(SDH) Epidural hematoma Subdural hygroma Intraventricular hemorrhage
- 8. EPIDURAL HEMATOMAEPIDURAL HEMATOMA Locatedbetween 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)
- 11. SUBDURAL HEMATOMASUBDURAL HEMATOMA Occursbetween 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)
- 12.
- 15. Subarachnoid hemorrageSubarachnoid hemorrage Canoriginate 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
- 19. Intraventricular hemorrhageIntraventricular hemorrhage Mostcommonly 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
- 21. INTRA-AXIAL INJURYINTRA-AXIAL INJURY Surfacecontusion/laceration Intraparenchymal hematoma White matter shearing injury/diffuse axonal injury Post-traumatic infarction Brainstem injury
- 22. CONTUSION/LACERATIONSCONTUSION/LACERATIONS Most common sourceof 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
- 24. Intraparenchymal hematomaIntraparenchymal hematoma Focalcollections 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
- 26. DIFFUSE AXONAL INJURYDIFFUSEAXONAL INJURY Rarely detected on CT ( 20% of DAI lesions are hemorrhagic) MRI:T1,T2,T2 GRE, SWI
- 27. DAIDAI Due to acceleration/decelerationto 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
- 28. DAIDAI Hours: ◦ hemorrhages andtissue tears ◦ Axonal swellings ◦ Axonal bulbs Days/weeks: clusters of microglia and macrophages, astrocytosis Months/years:Wallerian degeneration
- 31. Axial FLAIR imagesAxialFLAIR images
- 32.
- 33. T2 * &SWIT2 * & SWI
- 34. BRAINSTEM INJURYBRAINSTEM INJURY Bydirect or indirect forces Most commonly associated with DAI Involves the dorsolateral midbrain and upper pons and is usually hemorrhagic Duret hemorrhage is an example of indirect damage: tearing of the pontine perforators leading to hemorrhage in the setting transtentorial herniation <20% of brainstem lesions are seen on CT
- 40. SUBFALCIAL HERNIATIONSUBFALCIAL HERNIATION Subfalcial:displacement of the cingulate gyrus under the free edge of the falx along with the pericallosal arteries. Can lead to anterior cerebral artery infarction
- 44. UNCAL HERNIATIONUNCAL HERNIATION Displacementof the medial temporal lobe through the tentorial notch Displacement of the midbrain Effacement of the suprasellar cistern Displacement of the contralateral cerebral peduncle against the tentorium Widening of the ipsilateral cerebello pontine angle Compression of the posterior cerebral artery
- 46.
- 47. Kernohan - falseipsilateralKernohan - false ipsilateral
- 49. UPWARD HERNIATIONUPWARD HERNIATION Dueto posterior fossa mass causing superior displacement of the vermis through the tentorial incisura Compression of the 4th ventricle and effacement of the quadrigeminal plate cistern. Compression of the superior cerebellar artery & pca
- 51. TONSILLAR HERNIATIONTONSILLAR HERNIATION Inferiordisplacement of the cerebellar tonsils through the foramen magnum Can lead to posterior cerebellar artery infarction
- 53. Skull FracturesSkull Fractures Thinskull #’s common place. Risk of # associated intracranial injuries? CT to R/o 1. Open 2. Closed 3. Comminuted 4. Diastatic 5. Depressed
- 54. SIGNIFICANT SKULL FRACTURESSIGNIFICANTSKULL FRACTURES “Depressed”: inner table is depressed by the thickness of the skull. Overlie major venous sinus, motor cortex, middle meningeal artery Pass through sinuses Look for sutural diastasis (lambdoid)
- 57. TEMPORAL BONE FRACTURESTEMPORALBONE FRACTURES Look for opacification of the mastoid Longitudinal: 70%, parallel to long axis of petrous bone, conductive hearing loss (from ossicular dislocation), facial nerve paralysis (20%) Transverse: 20%, sensorineural hearing loss, facial nerve paralysis (50%) Complex Complications: meningitis, abscess
- 59.
- 60. SCALP INJURYSCALP 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.
- 61. POSTTRAUMATIC SEQUELAEPOSTTRAUMATIC SEQUELAE Carotid-cavernousfistula(CCF) Dissection/pseudoaneurysm Infarction Atrophy/encephalomalacia Infection Leptomeningeal cyst