Blunt Cerebrovascular Injury (BCVI):Spectrum of Imaging Findings

Joao Inacio, Ferco Berger, Daniel Hou, David Tso, Adrian Reagan, Savvas Nicolaou

Radiology Department, Emergency Trauma Section,University of British Columbia /Vancouver General Hospital

Vancouver, BC, Canada

www.ubcERradiology.com

ASER, Seattle, 11-14th August 2010

Objectives:

Scope of Blunt Cerebrovascular Arterial injury Rationale for Screening Screening Imaging Modalities CTA Technical Aspects BCVI: Spectrum of Imaging Findings Conclusion

Blunt Cerebrovascular Injuries (BCVI) [= Blunt Carotid/Vertebral Arterial Injury]

Introduction:

BCVI includes: Common and internal carotid arteries (71%)* Vertebral arteries (29%)* Both

BCVI is uncommon in the general blunt trauma setting but is more common than previously believed. Incidence of 0.1-1.55% of all blunt trauma admissions**

Stroke prevention is a feasible goal of early diagnosis and treatment of BCVI

* Bub- Trauma: 2005** Miller- Annals of Surg: 2003

Scope of the problem:

BCVI-related mortality rates of 23%, with 48%-80% of survivors suffering permanent severe neurological sequelae

The Denver group confirmed that many injuries are clinically occult at admission

The majority of injuries diagnosed after CNS ischemic symptoms, hours to days after the traumatic insult

Objectives:

Scope of Blunt Cerebrovascular Arterial injury Rationale for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

Blunt Cerebrovascular Injuries (BCVI)

Rationale for Screening :

Patients at risk for BCVI can be identified and diagnosed before the onset of symptoms with the application of an appropriate screening modality

Institution of medical therapy or revascularization has significant impact on prognosis

Screening BCVI : exceeds 1% of blunt trauma admissions

Incidence up to 2.7% in patients with Injury Severity Score ≥16

BCVI and Stroke:

Majority occur 10 – 72 hours post trauma

Effective screening criteria remain elusive

Blunt Carotid injury:Mortality - 28% Neurological Sequelae - 58%

Blunt Vertebral Artery Injury:Mortality - 8%Neurological Sequelae - 24%

BCVI and Stroke:

Screening for BCVI:

Identification of asymptomatic patients with BCVI and

prevent neurological complications.

Criteria for screening/ Risk FactorsDenver Modified BCVI Screening Criteria

Clinical Signs/Symptoms of BCVI

Risk factors for BCVI (High-energy transfer mechanism)

Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Criteria for screening/ Risk FactorsDenver Modified BCVI Screening Criteria (I)

Signs/symptoms of BCVI:

Arterial hemorrhage Cervical bruit Expanding cervical hematoma Focal neurological deficit Neurologic examination unexplained by neuroimaging

findings Ischemic stroke on secondary Head CT

Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Criteria for screening/ Risk Factors

Risk factors for BCVI: Lefort II or III fractures Cervical spine fracture patterns:

Subluxation Fractures extending into the transverse foramen Fractures of C1–C3

Basilar skull fracture with carotid canal involvement Diffuse axonal injury with Glasgow Coma Scale score <6 Seatbelt contusion on neck (not isolated)

Near hanging with anoxic brain injury

Criteria for screening/ Risk FactorsDenver Modified BCVI Screening Criteria (II)

Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Denver Modified BCVI Screening Criteria: Limitations

20-27% patients with BCVI may not fulfill the commonly reported screening criteria

Other liberal screening criteria: Thoracic Abbreviated Injury score of ≥3 Injury Severity Score ≥16 Skull/ C-spine Fracture line extending to vascular channel

Vancouver General Hospital Screening Criteria

Any blunt trauma patient with GCS ≤ 13 Any trauma patient with GCS > 13 plus:

Cervical spine injury Basal Skull fracture Diffuse Axonal injury LeForte II/III fracture Significant thoracic injury Abnormal neurological exam not explained by CT scan of the head

Discretion of attending Trauma Surgeon

Objectives:

Scope of Blunt Carotid/Vertebral Arterial injury

Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

What is the appropriate modality for the screening and diagnosis of BCVI?

Diagnostic digital subtraction (DSA) four-vessel cerebral angiography: remains the gold standard modality.

MDCT is the best non invasive screening modality in place of DSA.

MRI Angiography is promising but with limited availability. Duplex ultrasound is not adequate for screening for BCVI.

Screening Imaging Modalities

Blunt Cerebrovascular Injury Practice Management Guidelines, J Trauma. 2010

Strokes are prevented by early diagnosis and antithrombotic therapy.

The harder you look for BCVI, the more injuries you will find Does CTA false-positive/ negative studies reflect the

technology or the interpretation? ≥16-slice MDCT CTA is the most accurate noninvasive

screening modality available More data needed to know if and when to submit patients

to confirmatory DSA, with its attendant risks and expense.

BCVI Screeninng: MDCT vs DSAControversy and Consensus

Biffl, Walter L., (editorial) J Trauma February 2010

Objectives:

Scope of Blunt Carotid/Vertebral Arterial injury

Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

CT Trauma EvaluationTechnical Aspects

STANDARD (Segmented) MDCT PROTOCOL: Scout head and C-spine

Nc Head CT

C-spine or CTA vertex to arch

- Arms Reposition-

CTA Chest + Abd (arterial)

CT Abd + Pelvis (venous)

- 5’ delay-

CT Delayed excretory phase

and

Focused CT:

Peripheral vascular injuries

Complex limb fractures

1st bolus IV contrast

2nd bolus IV contrast

3rd bolus IV contrast

VGH Blunt Neck Trauma CTA Protocol:Part of Segmented Trauma Series CT

Protocol Arterial phase Arch to COW

mAs(Tube A) kV 120 500

Kernel B B46(Mediastinum) 2 x1mm

Kernel B MIP recon thru COW and Carotids

Kernel B B75(Bone) 2x 1mm for C Spine

Collimation 128 mmx 0.6mm

Pitch 1.1

Rotation Time 0.28-0.5s

CTDIvol 25

Note: Bolus tracking at arch using 120 cc of 320 mgI/mL at 5.0mL/s for arterial phase acquisition.

WHOLE BODY (CONTINOUS) MDCT

PROTOCOL: Scout head to toe or NO SCOUT

Nc Head CT (1st scan)

CTA vertex to pelvis (arterial) (2nd scan)

CT Abd + Pelvis (venous) (3rd scan)

Pros: Faster acquisition Less radiation Less iodine contrast

Cons: Artifacts from arms position Lower signal to noise ratio Demanding post processing

1st bolus IV contrast

CT Trauma EvaluationTechnical Aspects

CTA Arch to vertex: Technical Aspects

POST-PROCESSING: Multiplanar reformation is applied for precise quantitative analysis of

lumen and vessel wall Routine reformatted series:

Axial source images 2mm MPRs 2mm:

Cervical Coronal Oblique sagital of carotid bifurcations

MIPs 3mm: Head and neck: axial Cervical: carotid bifurcations Head: coronal, sagital

Sagital Head to COW bone images 2mm

Objectives:

Scope of Blunt Carotid/Vertebral Arterial injury

Rational for Screening Screening Imaging Modalities CTA technical aspects BCVI: Spectrum of Imaging Findings

BCVI: Spectrum of Imaging Findings

Denver Grading Scale: Grade I – Minimal Intimal injury / intimal irregularity with

<25% narrowing Grade II - Dissection with raised intimal flap; intramural

hematoma with >25% narrowing; Intraluminal thrombus Grade III - Pseudoaneurysm Grade IV - Occlusion/ Thrombosis. Grade V - Transection with free extravasation

Arteriovenous fistula: ± Hemodynamic significance(Grade II or V)

Blunt carotid arterial injuries: implications of a new grading scale, Biffl et al. J Trauma 1999

Grade Injury and Prognosis

Denver Grading Scale:

Stroke incidence in Blunt Carotid Injury: Grade I - 3% Grade II - 11% Grade III – 33% Grade IV - 44% Grade V – 100%

Blunt carotid arterial injuries: implications of a new grading scale, Biffl et al. J Trauma 1999

Denver Grading Scale:

Stroke incidence in Blunt Vertebral Artery Injury: Grade I – 19% Grade II - 40% Grade III – 33% Grade IV - 13% Grade V – 0 cases

Biffl WL, et al, Blunt carotid and vertebral arterial injuries. World J Surg 2001

Grade Injury and Prognosis

BCVI: Spectrum of Imaging Findings

Major segments involved: Distal Cervical segments of ICA Petrous and Cavernous ICA Vertebral arteries C1-C2 and C6

18-36% Multiple Arteries Are Injured

Left Internal Carotid Minimal Intimal Injury(Grade I)

Figure 1. Left Internal Carotid Minimal Intimal Injury. 39y Male, MVC. Sagital Cervical MPR. MRI axial T1 image. Left Internal Carotid Minimal Intimal Injury with high intensity Intramural hematoma, <25% luminal narrowing.

Right Vertebral Minimal Intimal Injury(Grade I)

Figure 2. Right Vertebral Artery multofocal Minimal Intimal Injury.

Left Internal Carotid Dissection(GRADE II)

Figure3. 40y Male, MVC. Sagital Cervical MPR and axial source image. Left Internal Carotid Artery dissection with raised intimal flap.

Figure 4. 34 y female, MVC . Whole body CT trauma protocol with coronal cervical MPR and posterior fossa axial image. Left vertebral artery dissection with raised intimal flap, and left cerebellar ischemic infarct. DSA correlation with long vertebral artery dissection from C2 to C6.

Vertebral Artery Dissection(GRADE II)

Right Internal Carotid Dissection/Intramural Hematoma >25% Luminal Stenosis/Pseudoaneurysm (GRADE II AND III)

Figure 5. Grade II Injury. Snowboarding injury with 15 minutes loss of consciousness at the scene. CTA with oblique sagittal and coronal MIP reformats with bilateral wall hematoma resulting in >25% stenosis, with extension to the petrous segment on the right. There is also a pseudoaneurysm in keeping with a grade III injury.

Right Internal Carotid Pseudoaneurysm(GRADE III)

Figure 6. Grade III Injury. Distal Right Internal Carotid Pseudoaneurysm. CTA coronal, sagital , axial images with DSA correlation.

Bilateral Occlusion of Vertebral Arteries(Grade IV)

Figure 7. Grade IV Injury. Bilateral Occlusion of the Vertebral Arteries. MVA with seat belt sign neck, > 50% subluxation of C5/C6 with locking facets: two associated risk factors for BCVI.

Figure 8. Grade IV Injury. 30 y male, MVC . RIPIT protocol with coronal neck MPR and posterior fossa axial image. Left vertebral artery traumatic thrombosis and left cerebellar infarct.

Unilateral Occlusion of Vertebral Artery(Grade IV)

Figure 9. Grade V Injury. 35 y Male, MVC ; Whole body CT trauma protocol with cervical VR. Atlantoaxial dissociation, left vertebral artery transection with active contrast extravasation.

Left Vertebral Artery Transection with active contrast extravasation (Grade V)

Left Vertebral Artery Transection with active contrast extravasation (Grade V)

Figure 10. Grade V Injury. Left Vertebral Artery transection with active contrast extravasation.

Follow-up imaging:

Both untreated and medically treated injuries can either heal or progress

Standardized follow-up regimens are mandatory ≥7-10d post trauma

2

Western Trauma Association Critical Decisions in Trauma: Screening for and Treatment of Blunt Cerebrovascular Injuries. Biffl, Walter et all, J Trauma December 2009.

Conclusion

Diagnostic Imaging plays a vital role in diagnosis of cerebrovascular injuries

Prompt diagnosis and treatment impacts prognosis DSA is the gold standard for BCVI screening CTA as proved especially valuable CTA technical aspects and Interpretation must be

considered in management decisions Screening and treatment of BCVI is effective

References

Biffl, Walter et all, J Trauma December 2009

Biffl WL, Ray CE, Moore EE, et al. Ann Surg 2002

Miller PR, Fabian TC, Bee TK, et al. J Trauma 2001

Biffl et al. J Trauma 1999

Silker et al. AJR 2008

McKevitt et al. Am J Surg 2002

Sliker. Radiographics 2008

Sliker CW, Shanmuganathan K, Mirvis SE. AJR 2008

Goodwin, Robert et al., J Trauma, 2009

Josser E. Delgado Almandoz, Radiology 2010

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