Head Trauma Part 2

1

Emergency Radiology: Imaging of Head Trauma Rathachai Kaewlai, MD

Imaging of Head TraumaPart 2: Pathology

Rathachai Kaewlai, MDSpecialized in Body Imaging and Emergency Radiology

[email protected] 2006

The author is willing to receive any input, comments and corrections, Please do not hesitate to contact at the email address provided above.

2


Checklist for Trauma Brain CT

Have 3 different windows to look for different pathology(brain, subdural and bone windows)

First image includes foramen magnum Look first for the pathology that needs emergent Rx

Hydrocephalus Look for primary pathology (hemorrhage in different

compartments) Look for secondary pathology (brain herniation, midline shift) Look at the mastoid and sphenoid sinuses for hemorrhage

which implies skull base fractures Look at temporomandibular joints for fracture and/or dislocation

(this pathology causes significant long term complications)

3


Skull Fracture

• Etiology-Pathogenesis– Direct blow to the skull– Skull vault has 3 layers (outer table, diploe, and inner table)

but diploe does not form where skull is covered by muscles(thin area, prone to fracture)

– Areas prone to fracture:• Squamous temporal/parietal bones (most common)• Foramen magnum, skull bases, cribiform plates, orbital roofs

4


Skull Fracture

• Epidemiology– Fracture (fx) present in majority of severe head injury cases– Skull fx absent in 1/4 of fatal injuries at autopsy. Absence of

skull fracture not excludes brain injury– 1/3 of severely injured patients do not have skull fx– Concomitant cervical spine injury is 15% (cervical spine

radiograph or CT may be needed)

5


Skull Fracture

•Specific anatomiclocation

•Any locations•Lesser width•Greater in width

•Lighter•Darker on X-ray•Curvilinear•Angular turn•Curvilinear•Straight line•Serrated edge•Smooth or jagged edge

SutureFracture

6


Skull Fracture

• Imaging recommendation– When suspect skull fracture

• Head CT (in bone window, and edge enhancement algorithm*)AND Scout CT (to look for fracture ‘in plane’ with axial scan)

• Coronal and sagittal reformation is proven to be useful onlywhen the scans were performed in helical mode (most hospitalsscan the brain in conventional mode)

* Consult your radiologist about the different CT algorithm. Edge enhancement algorithm is useful to detect bony lesions (in bone window) and lung lesions (in lung window).

7


Skull Fracture - Linear,nondepressed

• Run through the entire thickness of bone• Look if the fx line runs through a vascular

channel, venous sinus. (This can cause epiduralhematoma, venous sinus thrombosis and occlusion)

• Almost always overlying soft tissue edema• Associated with extra-axial hematoma• Axial images of CT may miss fx that is ‘in plane’.

Always check scout CT for obvious fx

8


34-year-old man, fall from 10ft height

Retrospective review of theskull x-ray shows faint fractureline.

Axial CT: linear non-depressedfracture (red arrows) of leftparietal bone. Note soft tissuehematoma overlying the fracture.

9


Skull Fracture - Depressed

• Fragment (s) depressed inward• Consider open when

– Skin laceration over the fracture– Through paranasal sinuses, middle ear structures

• Potential surgical elevation in– Depressed > 5 mm and overlies motor or speech areas– Depressed > skull thickness

• Causes laceration of dura, arachnoid and possiblebrain parenchyma

10


Middle age man, MVA, severe head injury

Axial CT (bone window) showsopen depressed fractures (redarrows) of the right frontoparietalbone and presence ofpneumocephalus (blue arrow).Severe soft tissue edema orhematoma.

3D CT, although not needed for diagnosis, helpsradiologists and clinicians ‘see’ the complexity offractures and plan for treatment.

11


Skull Fracture - Diastatic

• Spreading of suture, 1-2 mm more than normalcontralateral side

• Coexisting linear fracture possible• May tear dural venous sinus, causing venous

epidural hematoma (venous EDH), venous sinusthrombosis or occlusion

12


Axial CT image showsdiastasis fractures (redarrows) through left coronalsuture and posterior portionof the sagittal suture.Normal suture is shown(blue arrow). Severe softtissue swelling orhematomas overly thefractures.

35-year-old man,pedestrian hit by a car

13


Skull Fracture - Basilar

• Clue: opacified sphenoid or mastoid• Problem associated:

– Dural tear (patients come with CSF otorrhea or rhinorrhea)– Ear ossicles, labyrinth, cranial nerve (V, VI, VII) involvement– Vascular injury- laceration, dissection, occlusion, infarction,

carotid-cavernous fistula

• Presentation:– Temporal bone fx- CSF otorrhea, bruising over mastoid

(Battle sign)– Anterior cranial fossa fx- CSF rhinorrhea, bruising around

the eyes (raccoon eyes)

14


Axial CT image shows the mostcommon type of skull base fx;longitudinal fx (blue arrows)through the right temporal bone.Note disruption of the right earossicles (red arrow). Blood inbilateral sphenoid sinuses implyfractures through the sinuses.There is no fracture through theright carotid canal (C). If there is asuspicion of fracture throughthe carotid canal, CTangiography should beperformed to rule out vascularinjury.

Young man in high velocity MVAwith bleeding from the right ear.

15


Skull Fracture - Pneumocephalus

• Presence of air or gas in the cranial cavity• Principal cause = trauma• Indicates communication between intracranial

and extracranial spaces, e.g. paranasal sinuses orambient air

• Significant complications: meningitis, CSF otorrhea orrhinorrhea

16


Small pneumocephalus (red arrows) is seenin the subarachnoid space of the right frontalconvexity. This patient had right frontal sinusfracture as a source of pneumocephalus.Presence of pneumocephalus should raisethe suspicion of sinus fracture or openfracture to the ambient air.

17


Epidural Hematoma (EDH)

• Etiology-pathogenesis– Source of bleeding most commonly middle meningeal

artery (85-90%) > others (dural sinus - venous EDH)– Hematoma between inner table of the skull and dura– Underlying brain usually minimally injured. Good prognosis if

treated aggressively– May cross midline and dural attachment– Not cross sutures (exception: diastatic fx, large EDH)– Most common location = squamous part of temporal

bone

18



• Epidemiology:– Young men (20-40’s) - older people dura strongly adheres to

inner table of the skull– Majority has skull fx

• Clinical features:– Significant trauma– Loss of consciousness; Lucid interval found in 40% of

patients– Delayed development 10-25%, within the first 36 hours

19



• CT findings– Hyperdense biconvex extra-axial mass– Low density area inside hematoma represents active

bleeding (swirl sign)– Common to have herniation

• Potential indications for surgery– Size > 2 cm– Active bleeding– Pending herniation– Corresponding neurological deficit

20



• Venous EDH– Usually in posterior fossa– Depressed skull fx causes strip of the dura, giving potential

space for blood accumulation– Tear of venous sinus (lhigh flow, low pressure)– More benign course, subacute presentation, usually not

required surgery

21


Young patient in MVA

Axial CT image shows a largelentiform-shaped homogeneoushyperdense mass in the righttemporal convexity, consistentwith epidural hematoma (redarrows). Nonvisualized temporalhorn of the right lateral ventricleimplies mass effect from thehematoma and degree of brainedema. Fracture is identified atthe right squamous temporalbone (not shown).

22


35-year-old man, fall from 12ft

Axial CT image shows a smalllentiform-shaped homogeneoushyperdense mass in the leftparieto-occipital convexity,consistent with epiduralhematoma (red arrows). Theproximity of the hematoma tothe transverse sinus raises thepossibility of dural venous sinusinjury. Subsequent MRV andCTV show no evidence ofvenous sinus injury. The patientwas discharged home.

23


Subdural Hematoma (SDH)

• Etiology-pathogenesis:– Blood collects between dura and arachnoid– Source of blood - torn cortical bridging veins, artery may

also be torn

• Epidemiology:– Extremes of age - infant or elderly– Usually coexists with other brain injuries, i.e. subarachnoid

hemorrhage

24


Subdural Hematoma (SDH)

• CT findings:– Acute SDH - crescent blood collection over hemisphere,

displacing the cerebral cortex medially– Usually hyperdense (can be mixed due to unclottted blood

or torn arachnoid)– Can be isodense if patients are anemic or blood mixes with

CSF– Can cross suture– Can extend into interhemispheric fissure (thick falx), along

tentorium

25


35-year-old man, fall from height

Axial CT image shows a thinconcave hematoma along the lefttemporal convexity, representingsubdural hematoma (red arrows).

26



Axial CT image (subdural window)shows thin bilateral hyperdenseblood along the right parietal andleft temporal convexities,representing acute subduralhematoma (red arrows). Smallsubarachnoid hemorrhage is alsonoted in the sulci of the rightparietal lobe (blue arrow). Bilateralsubdural hematoma can be subtleand easily missed on ‘brainwindow’.

27


Traumatic SubarachnoidHemorrhage (tSAH)

• Etiology-pathogenesis:– Tear of veins in subarachnoid space

• Epidemiology:– Most common cause of subarachnoid hemorrhage is trauma– tSAH usually associated with cerebral contusion, SDH, or

other lesions. Nearly all cases of tSAH have other lesions tosuggest traumatic cause

– Isolated SAH in trauma patients; there is a possibility ofruptured aneurysm causing sudden loss of consciousnessand then later trauma (ruptured aneurysm while driving, orhaving activities)

28


Traumatic SubarachnoidHemorrhage (tSAH)

• CT findings:– High density blood in sulci/cisterns– Location - next to contusion or under SDH/skull fx/scalp

laceration (otherwise, look similar to aneurysmal SAH)– Traumatic intraventricular hemorrhage (tIVH) can coexist

• Seen as blood-CSF level in the ventricles– Subtle tSAH

• Blood in the interpeduncular fossa may be the manifestationof subtle SAH

29


58-year-old man, found downat home

Coronal reformatted CT imageshows subarachnoidhemorrhage insinuated in thecerebral sulci of left parietaland right temporal lobes.Ruptured cerebral aneurysmis the main differentialdiagnosis in the patientspresenting with puresubarachnoid hemorrhage withequivocal history of trauma.

30


Cerebral Contusion

• Etiology-pathogenesis:– Initial injury causes the contusion due to cerebral gyri impact

inner table of the skull (rough edges and ridges)– Evolve from petechial hemorrhage -> small hemorrhage ->

large hematoma (imaging worsened with time)– More evident after 24h

• Epidemiology:– Most common parenchymal lesion in head trauma

31


Cerebral Contusion

• CT findings– Low density cortex (edema) mixed with high density

blood (petechial hemorrhage)– Classic location: anterior base of frontal and temporal

lobes– Multiple, bilateral– Can be normal early– Can be non-hemorrhagic

• MRI is better for detection, delineating extents ofcontusions

32



Axial CT image shows an ill-defined area of hypodensity andloss of grey-white matterdifferentiation in the tip of the lefttemporal lobe (red arrows); atypical location of this non-hemorrhagic contusion.Contusion without hematomais difficult to appreciate on CTscan. MRI is more sensitive.

33


Middle age man, fall from height

Hemorrhagic contusion (red arrows) at the frontal bases,right more than left, is noted as an ill-defined area ofhypodensity in CT and high signal intensity zone in MRI T2-WI. MRI is more sensitive to depict the extent of this injury.

34


Diffuse Axonal Injury (DAI)

• Frequent cause of persistent vegetative state andmorbidity in traumatic brain injury patients

• Etiology-pathogenesis– Traumatic deceleration injury: shearing/rotational forces in

areas of greater density differential in the brain (= grey-whitematter interface)

• Can be an isolated finding in traumatic braininjury– No (or little) association with presence of subarachnoid,

subdural hemorrhage, or skull fracture

35



• Clinical features– Usually results in instantaneous loss of consciousness.

Clinical symptoms worse than CT findings– Most patients (90%) remains in vegetative state (rarely

causes death because brainstem function typicallyunaffected)

• General imaging features– Can be either hemorrhagic or non-hemorrhagic (the latter is

more common)– Grey-white matter interface, brain stem, corpus callosum– Number and location of lesions predict prognosis (worst

when multiple, and in supratentorial location)

36



• CT findings– May be normal (microscopic, nonhemorrhagic lesions can

be missed by CT)– Small hemorrhagic foci in typical locations

• MR findings– MRI is the imaging of choice to detect DAI– Susceptibility sequence needed for detection of hemorrhagic

DAI (called T2 GRE, or T2*). Hemorrhagic lesions will bedark.

– Non-hemorrhagic lesions are bright on T2-WI and FLAIR

T2 GRE = T2 gradient echo, T2* = T2 star

37



• Imaging recommendation for suspected DAI– When initial brain CT is normal but the patient is in

vegetative state• MRI with susceptibility sequenceOR• Follow up brain CT in 24 hours (1/6 of DAI will evolve, may be

seen in subsequent CT)

38


24-year-old woman, MVA, severe head injury, GCS 4T

Axial CT image shows mild diffusebrain swelling without intracranialhemorrhage. Small subgalealhematoma is present (red arrow).

Same day MRI (Susceptibilitysequence) shows multiple tiny areasof blood products (red arrows) in thegrey-white matter junctions and deepgrey nuclei consistent with DAI.Blue arrow represents a vascular flowvoid. Blue star is an artifact.

39


Vascular Effects of Trauma

• Hemodynamic alterations common with traumaticbrain injury

• Spectrum of vascular abnormalities due to trauma– Vasospasm, ischemia, infarction– Pseudoaneurysm, arterio-venous fistula– Laceration, dissection

• Ischemia/infarction due to…– Vasospasm– Embolism from vascular injury– Secondary to brain herniation

40



Axial CT image done at day 2after the injury shows a largeright middle cerebral arteryterritory infarction (redarrows), in conjunction withacute subdural (blue star) andintraparenchymal hemorrhage inthe right frontal base. The highdensity structure in the leftparasagittal region is a part ofan intracranial pressuremonitoring device.

41


Cerebral Edema

• Increased brain water (astroglial swelling)• Two types (vasogenic and cytotoxic edema) often

coexists• In trauma:

– Vasogenic edema occurs immediately then cytotoxic edemawithin hours

– Usually adjacent or mixed with brain contusion– Generally resolves within 2 weeks

42


23-year-old woman, MVA

Axial CT image showsedematous brain with loss ofgrey/white matter interface(red stars), compressedventricle (arrow) andeffacement of the sulci (notseeing any cerebral sulci) in thispatient who had DAI confirmedby MRI.

43


Herniations

• Usually more deteriorating than primary injury• Etiology-pathogenesis

– Hemorrhage accumulates within closed space, CSF spacescompressed then mechanical displacement of brain occurs

– May cause secondary ischemia or infarction– If not correct, brain death

44


Axial CT image shows a midlineshift to the left due to large rightextra-axial hemorrhage (red stars)and intraparenchymal hemorrhage.The degree of midline shift (red line)is usually measured at the level ofmaximal deviation of the midlinestructure (septum pellucidum is auseful anatomy).

Subfalcine herniation is definedas herniation of cingular gyrus (bluestar) underneath the falx cerebri.Presence of midline shift usuallysignify subfalcine herniation, andvice versa. ACA occlusion maybecome occluded.

Midline Shift & Subfalcine Herniation

45


Obstructive Hydrocephalus &Descending (central)

transtentorial herniation

Hydrocephalus is one of themost emergent finding to lookfor, because it is treatable. Thispatient had dilated left lateralventricle from asymmetric brainedema (right more than left).Central herniation is defined asboth temporal lobes descendthrough the tentorial incisura,which can be seen aseffacement of the cisternaround the midbrain (star).

46


Make sure the lowest cut of CTimage includes foramenmagnum! Presence of space-occupying lesion in the brain,cerebellar tonsils (red stars) in thesame cut as foramen magnum,obliteration of CSF space anddisplaced portions ofcervicomedullary junction (M) aresigns of tonsillar herniation.Tonsils can be low lying as anormal variation or a Chiarimalformation.

Tonsillar Herniation

47


Brain Death

• Etiology-pathogenesis:– Severe increased ICP decreases cerebral blood flow, then

irreversible loss of brain function• Clinical criteria: coma + absent brainstem

reflexes + apnea test• Imaging may confirm but does not substitute for

clinical criteria• CT findings:

– No flow in intracranial arteries/venous sinuses– Diffuse cerebral edema– Hyperdense cerebellum (much denser than cerebrum)

48


Contrast-enhanced axial CT (Left) shows diffuse SAH (blue stars)in the cerebral cisterns, diffuse cerebral edema. There is nointracranial blood flow either in arteries or venous sinuses.Both images show normal enhancement of extracranial vessels(red arrows). The patient had bilateral ventricular shunt placement.

49-year-old woman, ruptured cerebral aneurysm

49


• The information provided in this presentation…– Does not represent the official statements or views of the

Thai Association of Emergency Medicine.– Is intended to be used as educational purposes only.– Is designed to assist emergency practitioners in providing

appropriate radiologic care for patients.– Is flexible and not intended, nor should they be used to

establish a legal standard of care.

Head Trauma Part 2

Health & Medicine

Transcript of Head Trauma Part 2