1. Dr. Thanh Binh Nguyen University of Ottawa, Canada July 2009
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 Secondary
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

6. CANADIAN CT HEAD RULE
Minor head injury: patients with witnessed loss of consciousness, amnesia or disorientation and a Glasgow coma Scale(GCS) of
Prospective study of 3121 patients who presented with a GCS of (Stiell et al, Lancet 2001; 357: )

7. CANADIAN CT HEAD RULE
CT is required for patients with minor head injury and any one of the following:
High risk (for neurological intervention)
GCS score<15 at 2h after injury
Suspected open or depressed skull fracture
Any sign of basal skull fracture (hemotympanum, ‘racoon’ eyes, CSF otorrhoea…)
Vomiting  2 episodes
Age  65 years.
Sensitivity of these rules (100%), specificity (69%), CT ordering proportion (32%)

8. CANADIAN CT HEAD RULE Medium risk (for brain injury on CT)
Amnesia after impact > 30 min
Dangerous mechanism (pedestrian struck by motor vehicle, occupant ejected from motor vehicle, fall from height > 3 feet or five stairs)
Sensitivity of these rules (98%), specificity (50%), CT ordering proportion (54%)

9. 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

10. 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)

11. 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

12. 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)

20. SCALP INJURY

21. 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.

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

24. 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

29. 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)

31. W=33 L=41

35. 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.

36. 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)

39. 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

40. 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

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

45. 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

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

47. 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

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

49. 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

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

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

53. Sagittal T1-W images

55. Axial FLAIR images

56. AXIAL FLAIR

57. AXIAL T2 GRADIENT-ECHO

59. BRAINSTEM INJURY By direct 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

60. 18 biker hit by a car

65. BRAIN HERNIATIONS

66. SUBFALCIAL 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

71. UNCAL HERNIATION
Displacement of 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

75. DOWNWARD HERNIATION Caudal displacement of the thalamus and midbrain
Effacement of the perimensencephalic cistern and 4th ventricle.
Can cause a 3rd nerve palsy and disrupt pontine vessels leading to brainstem hemorrhage

76. UPWARD HERNIATION
Due to 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

77. TONSILLAR HERNIATION
Inferior displacement of the cerebellar tonsils through the foramen magnum
Can lead to posterior cerebellar artery infarction

78. EXTERNAL HERNIATION
Due to a defect in the skull in combination with elevated ICP
Venous obstruction can occur at the margins of the defect.

79. ANATOMY

80. BASE OF SKULL ANATOMY

81. BASE OF SKULL ANATOMY

82. BASE OF SKULL ANATOMY

83. BASE OF SKULL ANATOMY

84. SIGNIFICANT SKULL 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)

87. TEMPORAL BONE 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

89. POST TRAUMATIC SEQUELAE
Carotid-cavernous fistula(CCF)
Dissection/pseudoaneurysm
Infarction
Atrophy/encephalomalacia
Infection
Leptomeningeal cyst