di-imaging of head traum 2009 (tn)

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IMAGING OF HEAD TRAUMA

Dr. Thanh Binh Nguyen

University of Ottawa, CanadaJuly 2009



OUTLINE

Clinical indications for imaging

Imaging technique

Extraaxial hemorrhage

Intraaxial injury

Brain herniations Skull fractures



INTRODUCTION

Head trauma is the leading cause of

death in people under the age of 30.

Males have 2-3 x frequency of braininjury than females

Due mainly to motor vehicle accidents

and assaults



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



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



IMAGING TECHNIQUE

CT without contrast is the modality of

choice in acute trauma (fast, available,

sensitive to acute subarachnoidhemorrhage and skull fractures)

MRI is useful in non-acute head trauma

(higher sensitivity than CT for corticalcontusions, diffuse axonal injury,

posterior fossa abnormalities)



APPROACH TO CT BRAIN

Look at the scout film: ? Fracture of uppercervical 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)



SCALP INJURY



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.



Extraaxial fluid collections

Subarachnoid hemorrhage(SAH)

Subdural hematoma(SDH)

Epidural hematoma

Subdural hygroma

Intraventricular hemorrhage



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 fromaneurysm)

Can lead to communicatinghydrocephalus



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)



W=33 L=41



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.



EPIDURAL HEMATOMA

Located between the skull andperiosteum

Due to laceration of the middlemeningeal artery or dural veins

Can cross dural reflections but is limitedby suture lines

Lentiform shape (but concave shape inSDH)



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



Intraventricular hemorrhage

Most commonly due to rupture of

subependymal vessels

Can occur from reflux of SAH orcontiguous extension of an intracerebral

hemorrhage

Look for blood-cerebrospinal fluid levelin occipital horns



INTRA-AXIAL INJURY

Surface contusion/laceration

Intraparenchymal hematoma

White matter shearing injury/diffuse

axonal injury

Post-traumatic infarction

Brainstem injury



CONTUSION/LACERATIONS

Most common source of traumatic SAH

Contusion: must involve the superficial graymatter

Laceration: contusion + tear of pia-arachnoid Affects the crests of gyri

Hemorrhage present ½ cases and occur atright angles to the cortical surface

Located near the irregular bony contours:poles of frontal lobes, temporal lobes, inferiorcerebellar hemispheres



Fromhttp://neuropathology.n

eoucom.edu/

Dr.Agamanolis

http://neuropathology.neoucom.edu/






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 brainDDx: DAI, hemorrhagic contusion



DIFFUSE AXONAL INJURY

Rarely detected on CT ( 20% of DAI

lesions are hemorrhagic)

MRI: T1, T2, T2 GRE, SWI



DAI

Due to acceleration/deceleration towhtie matter + hypoxia

Patients have severe LOC at impactGrade 1: axonal damage in WM only -

67%

Grade 2: WM + corpus callosum(posterior > anterior) – 21%

Grade 3: WM + CC + brainstem



DAI

Hours:

hemorrhages and tissue tears

Axonal swellings Axonal bulbs

Days/weeks: clusters of microglia and

macrophages, astrocytosisMonths/years: Wallerian degeneration



From

http://neuropathology.neou

com.edu/

Dr.Agamanolis







Sagittal T1-W images



Axial FLAIR images



AXIAL FLAIR



AXIAL T2 GRADIENT-ECHO



BRAINSTEM INJURY

By direct or indirect forces

Most commonly associated with DAI

Involves the dorsolateral midbrain and upperpons and is usually hemorrhagic

Duret hemorrhage is an example of indirectdamage: tearing of the pontine perforators

leading to hemorrhage in the settingtranstentorial herniation

<20% of brainstem lesions are seen on CT



18 biker hit by a car



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



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 pontineangle

Compression of the posterior cerebral artery



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



UPWARD HERNIATION

Due to posterior fossa mass causingsuperior displacement of the vermisthrough the tentorial incisura

Compression of the 4th ventricle andeffacement of the quadrigeminal platecistern.

Compression of the superior cerebellarartery



TONSILLAR HERNIATION

Inferior displacement of the cerebellar

tonsils through the foramen magnum

Can lead to posterior cerebellar arteryinfarction



EXTERNAL HERNIATION

Due to a defect in the skull in

combination with elevated ICP

Venous obstruction can occur at

the margins of the defect.



SIGNIFICANT SKULL

FRACTURES “Depressed”: inner table is depressed

by the thickness of the skull.

Overlie major venous sinus, motorcortex, middle meningeal artery

Pass through sinuses

Look for sutural diastasis (lambdoid)



TEMPORAL BONE



TEMPORAL BONE

FRACTURES Look for opacification of the mastoid

Longitudinal: 70%, parallel to long axis

of petrous bone, conductive hearingloss (from ossicular dislocation), facialnerve paralysis (20%)

Transverse: 20%, sensorineural hearing

loss, facial nerve paralysis (50%)Complex

Complications: meningitis, abscess



POST TRAUMATIC



POST TRAUMATIC

SEQUELAECarotid-cavernous fistula(CCF)

Dissection/pseudoaneurysm

Infarction

Atrophy/encephalomalacia

Infection

Leptomeningeal cyst

di-imaging of head traum 2009 (tn)

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