Temporal Changes and Spectrum of Findings on Follow-up CT Angiogram in Patients with Suspected Post-traumatic Blunt Cerebrovascular Injury

Blunt cerebrovascular injuries (BCVI) are defined as injuries to the carotid and vertebral arteries as a sequela of blunt trauma. BCVI is uncommon but potentially devastating diagnosis. The purpose of this study is to examine the temporal changes and spectrum of radiological findings on follow-up CTAs for trauma patients with suspected BCVIs. The management and outcome of these patients including stroke cases are discussed in our study. As a result, the study can help explore the use of follow-up CTAs in monitoring the outcome in patients with suspected BCVIs.

In our institution, all severely injured polytrauma patients receive a rapid imaging protocol in trauma (RIPIT) scan upon admission into the emergency department. The RIPIT scan is a single acquisition whole body dual-source CT scan to obtain efficient imaging in a trauma setting. A CTA arch to vertex is conducted as a part of standard RIPIT protocol for patients when there are risk factors for BCVI.

For this retrospective, IRB-approved study, the hospital trauma registry was queried for all polytrauma patients undergoing CTA scans performed in the emergency department between January 1, 2010 to December 31, 2016 with ISS ≥ 16, yielding 3747 patients. Inclusion criteria: Adult patients with blunt trauma, ISS ≥ 16 and received CT angiogram (CTA) of the neck vessels on admission. A documented BCVIs on initial CTA and at least one follow-up CTA within 6 months from the initial CTA. Exclusion criteria: Patients with a normal initial scan. Patients who did not receive or has no record of a follow-up CTA within the study time frame.

Patient Demographics (n=128) Median age, years [IQR]   44.5 [24] Median follow-up, days [IQR] 7 [58] Sex Male 89 70% Female 39 30% Associated Injury Vertebral Fractures 73 57% Intracranial Hemorrhage 55 43% Skull Fractures 35 27% Facial Fractures 34 26.5% Cases without head and neck injuries 19 15% Mechanism of trauma Vehicular crash 96 75% Fall 25 20% Crush, assault & others 7 5% GCS 10-15 78 61% Unresponsive 37 29% 3-9 9 7% Intubated 4 3%

Incidence of BCVIs is 4.8 % in our study population. In the literature: BCVIs are diagnosed in approximately 1-2% of trauma injuries or even higher. In a recent study by Esnault et al., the stroke rate in patients with severe traumatic brain injury was 9.2%. were detected on initial scan of 128 cases. By adding 52 cases with positive CTA on admission but without a follow-up study, the overall number of cases with documented BCVI was 180 cases out of 3747

Motor vehicle accidents were the most common mechanism of injury (75%). The most commonly associated injuries were vertebral fractures (57%) and intracranial hemorrhages (43%). In 19 cases (15 %), there were no associated injuries within the head, neck or face. Absence of associated head and neck injuries has been recognized in 16-30% and even higher 37% in a recent study by Jacobson et al. were detected on initial scan of 128 cases. By adding 52 cases with positive CTA on admission but without a follow-up study, the overall number of cases with documented BCVI was 180 cases out of 3747

BCVI were graded according to Denver five-point grading scale: Grade I: intraluminal irregularities or dissections with less than 25% luminal stenosis Grade II: intraluminal thrombus, visible intimal flap, small arteriovenous fistula or dissection with greater than 25% luminal stenosis. Grade III: The presence of a pseudoaneurysm. Grade IV: complete vessel occlusions. Grade V: vessel transection or hemodynamically significant arteriovenous fistulas.

Grade I injury: The most common type (~ 50%) half of BCVIs with equal distribution between ICA and VAs. Most of grade I injuries have resolved or remained unchanged. Only 3 progressed to ICA pseudoaneurysms (grade III). Grade II injury: The second most common injury (25%). The majority majority improved or healed. Only 4 injuries progressed to grade III.

Grade III& IV injuries: 83% remained unchanged. These findings are consistent with a recent study by Wagenaar et al, that suggested that early repeat imaging injuries may not be necessary in higher-grade BCVI as most of them do not improve. Thus, the cost and radiation can potentially outweigh the benefits for these patients.

Grade V injury: One VAI on initial CT: complete transaction of the vertebral artery origin secondary to a subclavian artery injury that warranted a subclavian endovascular stenting. One ICAI on follow-up: A traumatic carotid-cavernous fistula that appeared initially as a grade II injury of the cavernous and supra-clinoid ICA. In this case, angiographic endovascular embolization was performed

For the different grades of injuries: 51% Unchanged. 44% Improved in with complete healing in 34%. 5% progressed to a higher-grade injury: Progression from grade I or II to grade III (pseudoaneurysm) was the most common scenario , 7 out of 8 (88%), that mainly involved the ICA.

A 27-year-old female with a history of fall from 40 ft presented with multiple calvarial, skull base and cervical spine fractures. Initial Arch-vertex CT angiogram with axial (a) and coronal reformatting (b) demonstrate multiple facial and orbital fractures with entrapment the clinoid portion of the left ICA “long black arrow by a fractured bone fragment of the orbital apex “short black arrow” resulting in a grade II injury. 15 days later, a follow-up Arch-vertex CT angiogram with axial (c) and coronal reformatting (d) demonstrate a 7 mm pseudoaneurysm “dotted black arrow” arising from the medial aspect of the supraclinoid ICA indicating grade III injury which was confirmed by oblique digital subtraction angiography image (e) demonstrates a pseudoaneurysm arising from the clinoid ICA “white arrow”.

A 29-year-old female with history of a motorcyclist trauma initial CT: Initial Arch-vertex CT angiogram with axial image (a) that demonstrate a focal traumatic dissection of the left vertebral artery at C4 level (grade II) “black arrow” and sagittal reformatted image (b) that demonstrate grade I injury of the cervical ICA “white arrow”. Follow-up Arch-vertex CT angiogram with axial (c) and sagittal (d) images that show interval resolution of left VA and ICA and injuries with no residual vascular abnormality seen.

A 33-year-old male with a history of falling from 20 ft A 33-year-old male with a history of falling from 20 ft. Initial Arch-vertex CT angiogram with axial image (a) grade II injury of the right VA at C5-6 and “dotted white arrow”. Axial image (b) at the level of the occipital condyles with grade I injury of the ICAs bilaterally “white arrows”. After 30 days, a follow-up Arch-vertex CT angiogram with axial image (c) demonstrates complete recanalization of the right vertebral artery “dotted white arrows”. Axial image (d) demonstrates upgrading of the ICA injuries bilaterally from grade I to III with pseudoaneurysms “black arrows”.

A 20-year-old male with a history of bike versus car collision A 20-year-old male with a history of bike versus car collision. Initial Arch-vertex CT angiogram with axial MIP (maximum intensity projection) reformatting image (a) demonstrates grade II of the clinoid/petrous portion of the right ICA “black long arrow”. Ethmoid, sphenoid and orbital apex fractures are noted. 23 days later, a follow-up Arch-vertex CT angiogram with axial MIP reformatting image (b) demonstrates a fullness of the right cavernous sinus “black short arrows” that appears enlarged compared to the left one suggesting the diagnosis of carotid cavernous fistula. Frontal (c) and lateral (d) projections of a 4-vessel digital subtraction angiography image, confirms the diagnosis of the carotid cavernous fistula with shunting of contrast to fill the cavernous sinus “white short arrows”.

For 69% of injuries: medical treatment was received via anticoagulation or antiplatelet therapy. 29% of injuries received neither medical nor endovascular treatment 5 patients (2%) warranted non-medical treatment: Angioplasty with stenting for a grade II cervical ICA injury. Carotid endarterectomy for grade I injury of the proximal ICA with concomitant injury of the common carotid artery. Subclavian endovascular stenting: complete transaction of the vertebral artery origin because of concomitant vascular injury of the subclavian artery. Surgical clipping of the supraclinoid ICA pseudoaneurysm. Endovascular embolization of carotid-cavernous fistula.

12 patients developed stroke with injuries included: (6) ICAIs, (6) VAIs with (4) low grade injuries (I &II) and (8) high-grade (III&IV). The stroke rate in our study is 9.4%. All patients received the appropriate medical treatment immediately after the initial diagnosis of BCVI. The reported stroke rates can approach (40-60%) in untreated patients and as low as 4% in treated patients. In the study by Esnault et al., 82% of patients received treatment and stroke rate was 19%. The stroke related injuries included three grade III, two grade II and one grade IV for the ICA and three grade IV, one grade III, one grade II and one grade I for the VA.

Limitations: Patients with abnormal initial CTA without a follow-up imaging scan were excluded from the study. Our study data is based on the imaging findings that have been reported by different radiologists and lacks reassessment of the radiological images; however, the reported findings have a standard reference of Denver classification that minimizes the variability among readers. As a retrospective studies, there may be confounding factors that cannot be fully accounted for if not measured or indicated on initial scan.

Conclusion: Understanding the temporal changes and spectrum of findings is crucial for the proper screening, diagnosis, and management of BCVIs. This study reports the outcomes of one institution’s experience with a standardized BCVI protocol for trauma patients where a CTA is included in a standard initial imaging assessment for all patients with suspected BCVIs. Most of grade III and IV injuries remained unchanged on follow-up CTA. Improvement and healing were the main patterns of change for Grade I and II injuries. However, all cases that progressed to a higher grade were originally of grade I and II and the most frequent consequence was progression to grade III of the ICA.