CT Evaluation for Brain. Postgraduate Teaching Hospital

Evaluation of CT Brain is important.

1. CT EVALUATION OF TBI
YogessvaranKrishnan

2. CLASSIFICATION OF TBI
•Primary
•Injury to scalp, skull fracture
•Surface contusion/laceration
•Intracranial hematoma
•Diffuse axonal injury, diffuse vascular injury
•Secondary
•Diffuse edema, herniation, infarction

3. 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)

4. CT INTBI
•ALL moderate& severe acutehead injury
•Minorhead injury?

5. CANADIAN CT HEAD RULE
CT required for patients with minor head injuries with any one of the
following:
*Minor head injury is defined as witnessed loss of consciousness, definite amnesia, or
witnessed deterioration in a patient with GCS score of13-15
High risk (for neurosurgical intervention)
•GCS score <15 at 2 hours afterinjury
•Suspected open or depressed skullfracture
•Any sign of basal skullfracture
•Vomiting >twoepisodes
•Age >65years

6. CANADIAN CT HEAD RULE
CT required for patients with minor head injuries with any one of the
following:
*Minor head injury is defined as witnessed loss of consciousness, definite amnesia, or
witnessed deterioration in a patient with GCS score of13-15
Medium risk (for brain injury onCT)
•Amnesia before impact >30min
•Dangerousmechanism

7. NEW ORLEANS CT CRITERIA
CT required for patients with minor head injury with any of following
findings (criteria only apply for patients who have GCS of15)
•Headache
•Vomiting
•Age >60years
•Drug or alcoholintoxication
•Persistent anterograde amnesia (deficit in short-termmemory)
•Visible trauma above theclavicle
•Seizures

8. Canadian CTHeadvsNew OrleansCriteria

9. NEXUSII CT HEAD RULE
CT required for patients withfollowing
•Age ≥ 65years
•Evidence of significant skullfracture
•Scalphaematoma
•Neurologicdeficit
•Altered level ofalertness
•Abnormalbehaviour
•Coagulopathy
•Recurrent or forcefulvomiting

10. CT IN PAEDIATRIC GROUP
•California ACEP&PECARNS, PediatricsHead Injury CT DecisionGuide

13. APPROACH TO CT BRAIN
•Look at the film: systematically from scalp inwards
•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)

14. •Look for allthreewindows
Brain Subdural Bone

15. MIDLINE SHIFT
•Correlateswith worse outcome and associated with altered level of
consciousness
•Measured at level of ForamenMonroe
Midline Shift(MLS)=
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2
−SP
BPD –Biparietal Diameter (the width of intracranialcompartment)
SP –The distance from the inner table to Septum Pellucidum on the
side ofshift

16. MIDLINE SHIFT
Midline Shift(MLS)=
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2
−SP
Amount ofMLSLevel of
consciousness
0-3mm Alert
3-4mm Drowsy
6-8.5mm Stuporous
8-13mm Comatous

17. BASAL CISTERNS
•Basal cisterns in trauma –PerimesencephalicCisterns
•3limbs
•1 Posterior Limb
•2 Lateral Limbs
•Each limbs assessed individually; possible findings:
•Open –all 3 limbspatent
•Partially Effaced –1 or 2 limbsobliterated
•Completely Effaced –all 3 limbsobliterated

18. BASAL CISTERNS
BasalCistern
---Outcome---
MortalityVegetative
Severe
Disability
Moderate
Disability
Good
(GOS1)(GOS2)(GOS3)(GOS4)(GOS5)
Normal 22% 6% 16% 21% 35%
Compressed 39% 7% 18% 17% 19%
Absent 77% 2% 6% 4% 11%

19. CLOT VOLUME MEASUREMENT
•Volumetric measurement of ICH is made based on volume ofellipsoid
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4&#3627408436;&#3627408437;&#3627408438;&#3627408436;×&#3627408437;×&#3627408438;
3222 2
A = LargestDiameter
B = Largest Diameter Perpendicular to A on same level
C = Number of slice ×Thickness of eachslice
(if >75% = 1 slice, if 25%<x<75% = 0.5 slice, if <25% = 0slice)
π =3

20. SCALPINJURY

21. SCALP HEMATOMAS
SubgalealHaematoma
•Bleeding between periosteum
and galeaaponeurosis
•Crosses sutureline
•Soft and fluctuantmass
•Do notcalcify
Cephalohaematoma(Subperiosteal)
•Bleeding between skull bone and
periosteum
•Limited by sutureline
•Firm & less ballotable, scalp moves
freely aboveheamatoma
•Reabsorbed by bone and
occasionally maycalcify

23. FRACTURES
•Skull fractures –detectable on plain Xrayimages
•GOLD STANDARD –Computer Tomography(CT)
•Complete CT scan of skull includes –Skull vault, base of skull, orbits,
sinuses and temporalbones
•Both bone & brain window should beevaluated
•Multiplanar views should beevaluated

24. Skull Fracture vs.Suture
FRACTURE SUTURE
Smooth or jaggededge Serratededge
Straightline Curvilinearline
Angularturn Curvilinearturn
Greater inwidth Lesser inwidth
(X-ray)darker (X-ray)lighter
Anylocations Specific anatomiclocation

26. SKULL
•3layers
–Outer table
–Diploe
–Inner table
•Parts without diploe prone tofracture
–Squamous temporal bone / Parietal bone
–Foramen magnum, skull bases, cribiform plates,
orbital roofs

27. TYPES OF SKULL FRACTURE
•Linearfracture
–Associated withEDH,SDH
•Depressedfracture
–Associated withfocal
parenchymal lesions
•Diastatic fracture
•Skull basefracture

28. Skull Fracture: Linear
Use subgaleal hematoma as aclue

29. Skull Fracture:Depressed
•In adults, criteria toelevate:
–>8-10 mm depression or>1 thickness
ofskull
–Deficit related to underlyingbrain
–CSFleak
•In children, twotypes:
–Simple depressed: usually remodelling
occurs withgrowth, surgery if dura
penetrated or persistent cosmeticdefect
–Ping-pongballfractures:treatif
underlyingbraininjuryordura
penetrated

30. Fracture -Depressed

31. Skull Fracture: Diastatic
•Fracture along suture lines “traumatic suturalseparation”
•Usually affected newborns and infants (unfusedsutures)
•Commonlyunilateral
•Most common location = lambdoid and sagittalsutures
•>2 mm separation that isasymmetric

32. Skull Fracture: SkullBase
•Most are extensions of
fracture of cranialvault
•Clinical clues:
–CSF otorrhea orrhinorrhea
–Hemotympanum or lacerationof
EAC
–Postauricularecchymoses
–Periorbital ecchymoses in
absence of direct orbitaltrauma
esp ifbilateral
–Cranial nerve injury (I, VI, VII,
VIII)

33. Skull Fracture: SkullBase
•Frontobasilar–Sakasdescribed 4types
•Type 1 –Cribriform
•Type 2 –Frontoethmoidal
•Type 3 –Lateral Frontal
•Type 4 –Complex (Combination)

34. Type1
Type2
Type3

35. Skull Fracture:Pneumocephalus
•Gas within cranialcavity
•In acute trauma setting, this is commonly due to fractures
of paranasal sinusesand temporal bones(open skull
fracture is anothercause)
•Most do not cause immediate danger but rapid expansion
can lead to brain compression (tensionpneumocephalus)
–Mount Fujisign
•Usually decreases by 10-15 days and almost never present
by 3 weeks

36. Pneumocephalus
•Bilateral pneumocephalus –
MountFujisign
•Twofrontalpolesappearpeaked
resemblingsilhouetteofthetwin
peaksofMountFuji

37. Haemorrhages
•Contusions
•Intraparenchymal haemorrhage
•IVH
•ExtraduralHaemorrhage
•SubduralHaemorrhage
•Traumatic SubarachnoidHaemorrhage

38. CerebralContusions
•Cerebral gyri impact inner tableof skull
•Characterizes coup andcontrecoup injuries
•Petechial hemorrhage of gyri / smallhematomas

39. CerebralContusionsn
•Anterior base frontal,
temporal lobes (esp tip),
cortex surrounding
Sylvianfissure
•Usually multiple and
bilateral

40. CerebralContusion
•Can be normal early; can benon-hemorrhagic
•Imagingmayworsen overtime, most evident after 24h
Day0 Day1

41. IntraparenchymalHaemorrhage
•Parenchymalvesselrupture
frombluntorpenetratingforces
•Orareasofcontusions
coalescingintocontusional
haematoma
•Haematomaatprimary trauma
site (usually frontal andtemporal)

42. Intraparenchymalhaemorrhage
•Well-circumscribed hyperdense
lesionwith or withoutperilesional
edema
•Up to 60% associatedwith SDHorEDH
•Not always easy to distinguish IPH from
contusion
Traumatic intraparenchymal hemorrhage withIVH

43. Contusions/Intraparenchymal haemorrhage
•Indication for Surgery–
•Progressive neurological deterioration due to contusion/medically refractory
ICP/signs of mass effect onCT
•Contusion/haemorrhagevolume >50cm
3

44. IntraventricularHaemorrhage
•Uncommon, due to rupture of subependymal
vessels
•Consequence of severe trauma. Associated with
DAIand trauma of deep grey andbrainstem
•Poorprognosis

45. ExtraduralHaemorrhage(EDH)
•Haematomabetweeninner table of
the skull anddura
•Source ofbleeding
–Most common = middle meningeal
artery (90%) (squamous temporal
bone)
–Venous EDH fromdural venous
sinus
www.practicalhospital.com

46. Extradural Haemorrhage(EDH)
•Most urgent of all cases of cranialtrauma
–Requiring prompt treatment to relieve compression of brainstem, tentorial herniation,
acutehydrocephalus
–EDH in posterior fossa veryworrisome
•1-4% of head injury cases, 10% of fatalcases
•Young men (20s –40s). Rare in patients >60y
•Almost always with skullfracture
•Lucid interval in 40% ofcases

47. Extradural Haemorrhage(EDH)
•Delayed development in 10-25% ofcases (within 36hrs)
–Arterial EDH: blood can flow into epidural space only after resolution
of arterialspasm
–Venous EDH bleedsslowly

48. Extradural Haemorrhage
(EDH): CTAppearance
•Biconvex or lens shape hyperdense lesion
(rare to be isodense)
•May cross midline anddural attachment
•Do not cross suture (except diastatic
fracture, largeEDH)

49. Extradural Haemorrhage(EDH): SwirlSign
•Small rounded lesion isodenseto
thebrain, representing active
extravasation of unclotted
blood
•Clotted componentis
hyperdense

50. ExtraduralHaemorrhage
•Indication for Surgery –Volume >30 cm
3
, regardless ofGCS
•Conservativeif
•Volume < 30cm
3or
•Thickness<15mm
•MLS <5mm
•GCS >8/15
•No focal neurologicaldeficits

51. Subdural Haemorrhage(SDH)
•Blood collectsbetween dura and
arachnoid
•Torn cortical bridgingveins
•Direct tear of arachnoid layer +
vessel injury
•Extension from contused lobe
(burstlobe)
•10-20% of allcranial trauma
cases
•Demographics:
–Elderly (60-80y) withbrain atrophy
–“Shaken babysyndrome”

52. Subdural Haemorrhage(SDH)
•Usually co-existwith other brain
injuries
–Especiallycontusion-typed injuries >
skullfractures
•Indication for Surgery –Thickness >
10mm or MLS > 5mm, regardless of
GCS
•Acute: within0 to3days fromtrauma
•Subacute: within 3days to 3weeks
•Chronic: after 3weeks
Layer of acute blood on pre-existing CSF-likesubdural
collection in the right cerebralconvexity

53. Subdural Haemorrhage
(SDH): CTAppearance
•Crescentichyperdense collection
•Can crosssuture
•Can extend to interhemispheric
fissure, alongtentorium cerebelli
Note coup (Rt.) and contrecoup (Lt.) pattern.
This SDH is a contrecoupinjury.

54. Subdural Haemorrhage(SDH):
Value of CoronalReformats

55. “Isodense” Subdural Haemorrhage(SDH)
•Usually takes upto3weeks for
acuteSDH to becomeisodense
(subacute)
•ButatHb 8-10 g/dL,blood will be
isodense to grey matter
•Anemic patientscan present with
acute isodenseSDH

56. Chronic SubduralHaemorrhage
•Progression from AcuteSDH
•0 –3 days –AcuteSDH(A)
•3days –3 weeks –SubacuteSDH(B)
•> 3weeks –ChronicSDH(C)

57. Acute On ChronicSDH
•Newhaemorrhagesuperimposedon
chronicSDH
•Recurrenttrauma
•Can bespontaneous
•Blood-fluid level ,blood clot organization

58. Comparison of EDH andSDH
EDH SDH
Incidence 1-4% of trauma cases; 10% of
fatal traumacases
10-20% of all traumacases; 30% of
fatal traumacases
Etiology fractures in 90% of cases with lacerationof
MMA/venoussinus
Tearing of corticalveins
Site Between skull anddura 95%
supratentorial
Between dura andarachnoid 95%
supratentorial
Crosses dura but notsutures Crosses suture but notdura
CTfindings Biconvex (lens)shape
Shift grey-white matterinterface
Crescenticshape

59. SubarachnoidHaemorrhage
(SAH)
•Blood collectsbeneath arachnoid
•Tear of veins in subaracnoidspace
•Usually associated with other brain injuries
(common withcontusions)
•‘Nearly all cases of traumatic SAH haveother
lesions to suggest traumatic cause’
–Isolated SAH in trauma patients –possibleruptured
aneurysm causingtrauma
SAH withSDH

60. SubarachnoidHaemorrhage
(SAH)
•Site
–Next to braincontusion, under
SDH/fracture
–Can be distantbecause blood diffuses
in subarachnoidspace
•IVH may co-exist dueto retrograde
flow through foramen of Luschka
and Magendie
SAH withcontusion

61. Diffuse AxonalInjury
•Result from differential rotational forces between grey & white
matter tract which leads to rupture of small bloodvessels
•Seen as punctate haemorrhages/petechial haemorrhage onimaging
•MRI > CT scan (T2W–appears as hypointensefoci)

62. Diffuse AxonalInjury

63. Diffuse AxonalInjury

64. SECONDARYLESIONS
•Herniation
•Ischemia and infarction
•Hydrocephalus
•Braindeath

65. BrainHerniation
•Due to raisedICP and differencein
the pressure gradient between two
compartment
•Types:
Supratentorial
•Uncal
•Central
•Subfalcine
•Transcalvarial
Infratentoral
•Upward (ascending) –vermis compressing
the
mesencephalon, SCA mayinvolved
•Tonsilar–post fossa lesion, tonsil compress
medulla andPICA

66. Herniation:Descending(uncal)Transtentorial
•Medial and caudal shift of uncus and
parahippocampal gyrus of temporal lobe
beyond tentorium cerebelli
•Asymmetric prepontine cisterns and CP
angle (wider on side oflesion)
•PCAmay becompressedagainst
tentorium

67. Herniation:DescendingTranstentorial
Beforesurgery Aftersurgery

68. adiology.com
Herniation: Subfalcineand Midline Shift
•Shift of cingulate gyrus across midline belowfalx
•Thinner ipsilateral ventricle, dilated opposite
ventricle (CSF obstruction at foramen ofMonro)

69. Herniation: Subfalcineand Midline Shift
•Measured at level of foramen of Monro
•Distal ACA may be compressed againstfalx

70. Herniation: Extracranial (Transcalvarial)

71. Herniation:AscendingTranstentorial
•Cranial shift of vermisand parts of
superomedial cerebellar hemisphere
through tentoriumincisura
•Compressed superior cerebellar,
vermian cisterns and forthventricle

72. w.RiTradiology.com
Herniation:Tonsillar
•Downward displacement of tonsils through
foramen magnum
•Seenwith
–Up to ½ of all descending transtentorialherniation
–Up to 2/3 of ascending transtentorialherniation

73. PosttraumaticIschemia/Infarct
•Most commoncause =herniation
•Most commonlocation = occipital
(PCA infarct from descending
transtentorialherniation)
•2
ndcommonest location = frontal
(ACA infarct from subfalcine
herniation)
At time oftrauma
3 monthslater

74. Hydrocephalus
•Acutehydrocephaluscanoccurdueto
brainherniationorIVH
•Delayed hydrocephalus usually secondary
to adherenceof meninges over cerebral
convexity, basal cisterns or aqueduct
resulting in obstruction at level of
ventricles and arachnoid granulations

75. BrainDeath
•Severe increased ICP decreases
cerebral blood flow, then irreversible
loss of brain function
•Clinical criteria: coma + absent
brainstemreflexes
+ apneatest
•No flow in intracranial
arteries/venoussinuses
•Diffuse cerebral edema, hyperdense
cerebellum

76. Conclusions
•CT = primary modality for headtrauma, enough for most
parts
–Skull x-rays still used in penetrating trauma, suspected child abuse
–MRIto help predicting prognosis by detection of subtle injuries i.e.,
contusion andDAI

78. MarshallGrading
Major limitations
•Lack of TraumaticSAH
•Does not classify type ofhaematoma
•Does not include extend of basal cisterneffacement
•Rotterdam score overcomes limitations

80. References
•Handbook of Neurosurgery, Mark S. Greenberg, 7
th
Edition
•Absent or compressed basal cisterns on CT scan:ominous predictors
of outcome in severe head injury, Steven et al, J. Neurosurgery,
1984
•The Canadian CT head rule for patient with minor head injury, Ian et
al, The Lancet,2001
•Comparison of the Canadian ct head rule and the new Orleans criteria
in patient with minor head injury, Ian et al, JAMA, 2005
•Radiopedia.org
•BTF —TBI Guidelines