Brain Imaging in TraumaBrain Imaging in Trauma

Level Of Consciousness Level Of 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

Primary Brain InjuryPrimary Brain Injury

Classification of TBIClassification of TBIPrimary◦ 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 TECHNIQUEIMAGING TECHNIQUECT 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)

Extraaxial fluid collectionsExtraaxial fluid collectionsSubarachnoid hemorrhage(SAH)Subdural hematoma(SDH)Epidural hematomaSubdural hygromaIntraventricular hemorrhage

EPIDURAL HEMATOMAEPIDURAL HEMATOMALocated between the skull and

periosteumDue to laceration of the middle

meningeal artery or dural veinsCan cross dural reflections but is limited

by suture linesLentiform shape (but concave shape in

SDH)

SUBDURAL HEMATOMASUBDURAL HEMATOMAOccurs between the dura and arachnoidCan cross the sutures but not the dural

reflectionsDue to disruption of the bridging cortical

veinsHypodense(hyperacute, chronic),

isodense(subacute), hyperdense(acute)

W=33 L=41

Subarachnoid hemorrageSubarachnoid hemorrageCan 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

Intraventricular hemorrhageIntraventricular hemorrhageMost commonly due to rupture of

subependymal vesselsCan occur from reflux of SAH or

contiguous extension of an intracerebral hemorrhage

Look for blood-cerebrospinal fluid level in occipital horns

INTRA-AXIAL INJURYINTRA-AXIAL INJURYSurface contusion/lacerationIntraparenchymal hematomaWhite matter shearing injury/diffuse

axonal injuryPost-traumatic infarctionBrainstem injury

CONTUSION/LACERATIONSCONTUSION/LACERATIONSMost common source of traumatic SAHContusion: must involve the superficial gray

matterLaceration: contusion + tear of pia-arachnoidAffects the crests of gyriHemorrhage present ½ cases and occur at right

angles to the cortical surfaceLocated near the irregular bony contours: poles

of frontal lobes, temporal lobes, inferior cerebellar hemispheres

Intraparenchymal hematomaIntraparenchymal hematomaFocal 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 INJURYDIFFUSE AXONAL INJURYRarely detected on CT ( 20% of DAI

lesions are hemorrhagic)MRI: T1, T2, T2 GRE, SWI

DAIDAIDue to acceleration/deceleration to

whtie matter + hypoxiaPatients 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

DAIDAIHours: ◦ hemorrhages and tissue tears◦ Axonal swellings◦ Axonal bulbs

Days/weeks: clusters of microglia and macrophages, astrocytosis

Months/years: Wallerian degeneration

Axial FLAIR imagesAxial FLAIR images

AXIAL FLAIR AXIAL FLAIR

T2 * & SWIT2 * & SWI

BRAINSTEM INJURYBRAINSTEM INJURYBy direct or indirect forcesMost commonly associated with DAIInvolves the dorsolateral midbrain and upper

pons and is usually hemorrhagicDuret 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

SUBFALCIAL HERNIATIONSUBFALCIAL HERNIATIONSubfalcial: 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 HERNIATIONUNCAL HERNIATION

Displacement of the medial temporal lobe through the tentorial notch

Displacement of the midbrainEffacement of the suprasellar cisternDisplacement of the contralateral cerebral

peduncle against the tentoriumWidening of the ipsilateral cerebello pontine

angleCompression of the posterior cerebral artery

DuretDuret

Kernohan - false ipsilateralKernohan - false ipsilateral

UPWARD HERNIATIONUPWARD HERNIATIONDue 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 & pca

TONSILLAR HERNIATIONTONSILLAR HERNIATIONInferior displacement of the cerebellar

tonsils through the foramen magnumCan lead to posterior cerebellar artery

infarction

Skull FracturesSkull FracturesThin skull #’s common place.Risk of # associated intracranial injuries?

CT to R/o 1. Open 2. Closed3. Comminuted 4. Diastatic5. Depressed

SIGNIFICANT SKULL FRACTURESSIGNIFICANT 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)

TEMPORAL BONE FRACTURESTEMPORAL BONE FRACTURES

Look for opacification of the mastoidLongitudinal: 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%)

ComplexComplications: meningitis, abscess

SCALP INJURYSCALP INJURY

SCALP INJURYSCALP INJURYCephalohematoma: 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.

POST TRAUMATIC SEQUELAEPOST TRAUMATIC SEQUELAECarotid-cavernous fistula(CCF)Dissection/pseudoaneurysmInfarctionAtrophy/encephalomalaciaInfectionLeptomeningeal cyst