Arterial injuries in the head and neck can present immediately or can remain indolent for some time. The two major mechanisms of arterial injury are blunt and penetrating trauma. Both may cause:

• extravasation
• thrombosis/occlusion
• pseudoaneurysm formation

Fig 1: 43 year old male presenting from rehabilitation facility 6 months after motor vehicle collision with fever and fluctuant right temporal mass. Found to be a superficial temporal artery pseudoaneurysm with Yin-yang sign seen on colour Doppler ultrasound. [CT Angiogram with MIP reconstructions and Spectral Doppler Ultrasound].

• dissection
• intramural haematoma
• arterial transection

Vertebral injuries most commonly lead to arterial occlusion whereas penetrating trauma more often causes arterial transections. Later, arteriovenous fistula formation may be seen.Investigation with multislice computed tomography (CT) angiography is preferred due to speed of acquisition and high spatial resolution. This provides superior sensitivity in the detection of vascular insults. Magnetic resonance imaging (MRI) is a useful adjunct in the detection of adverse arterial vascular events. Magnetic resonance angiography (MRA) shows high specificity for intramural haematoma and can be used for problem solving but is limited by artifacts:

• Acute/hyperacute artifacts
• Feathering artifacts
• Inflow artifacts

Digital subtraction angiography (DSA) remains the gold standard for evaluation but is primarily reserved for treatment purposes.

The Biffl classification system is used to grade blunt arterial injuries to provide prognostic implications for potential stroke following trauma.  Injuries produce cerebral ischaemia by exposing thrombogenic subendothelial collagen due to intimal disruption. The Biffl classification can be applied to either CT angiography or DSA. Stenosis is determined by comparing the injured segment to the nearest normal part of the vessel proximally.

• Grade I: minimal luminal irregularity or intramural haematoma/dissection with <25% luminal narrowing

Fig 2: (Biffl Grade I Injury) Left C1 lateral mass fracture with mild luminal narrowing and irregularity of the V3 segment of the left vertebral artery [CT Angiography].

Fig 3: (Biffl Grade I Injury) Left internal carotid artery dissection and intramural haematoma with <25% luminal narrowing [CT Angiography].

Fig 4: (Biffl Grade I Injury) Acute fracture of the left temporal bone involving the petrous apex and crossing the internal auditory canal and posterior wall of the carotid canal [CT Temporal Bones | Left]. Dissection and intramural haematoma with <25% luminal narrowing of the left petrous/distal cervical segments of the left internal carotid artery [CT Angiography | Right].

• Grade II: dissection or intramural haematoma with >25% luminal narrowing, intraluminal thrombus, or raised intimal flap

Fig 5: (Biffl Grade II Injury) Patient fell from horse. Left internal carotid artery dissection and intramural haematoma with >25% narrowing [MR Angiography and CT Angiography].

Fig 6: Corresponding to Figure 5, a large left middle cerebral artery territory stroke resulting from the Biffl Grade II Injury [CT Perfusion Imaging, Color maps showing of Cerebral Blood Flow in pink and Tmax in green].

Fig 7: (Biffl Grade II Injury) Patient involved in motor vehicle collision. Perched left C6-C7 facet with bilateral long segment internal carotid artery dissection and intramural haematoma with >25% narrowing [From left to right: CT angiography, CT angiography, MR angiography, CT 3-D Reconstruction].

Fig 8: (Biffl Grade II Injury) Patient struck by vehicle while riding bicycle. Hangman's fracture of C2 with distal left vertebral artery dissection and intramural haematoma with >25% narrowing [CT Angiography].

Fig 9: (Biffl Grade II Injury) Bilateral internal cerebral artery dissections and intramural haematomas with >25% narrowing [MR Angiography]. Hyperflexion injury at C5-C6 level with anterior translation [CT Non-contrast | MRI Non-contrast].

Fig 10: (Biffl Grade II Injury) Gun shot victim with minimal intimal injury of the left common carotid artery and intraluminal thrombus [CT Angiography].

Fig 11: (Biffl Grade II Injury) Gun shot victim with comminuted fracture of the left facet and left common carotid artery dissection and intraluminal thrombus [CT Angiography].

Fig 12: (Biffl Grade II Injury) Motor vehicle collision. Right supraclinoid internal carotid artery dissection. Extensive facial fractures with bilateral LeFort I-II-III and NOE fractures as well as skull base fractures involving the middle and anterior cranial fossa [CT Angiography | 3D CT Reconstrustion].

• Grade III: pseudoaneurysm

Fig 13: (Biffl Grade III Injury) Gun shot victim. Highly comminuted fractures of the lateral masses and vertebral bodies of C5-C6 with left common carotid artery aneurysm with intraluminal dissection flap and thrombus. [CT Angiography].

Fig 14: (Biffl Grade III Injury) Proximal left common carotid artery pseudoaneurysm with mediastinal hematoma in the prevascular region. [CT Angiography].

Fig 15: (Biffl Grade III Injury) Continued from Figure 14, Proximal left common carotid artery pseudoaneurysm with mediastinal hematoma. [CT Angiography | 3D CT Reconstruction]

Fig 16: (Biffl Grade III Injury) Left internal carotid artery pseudoaneurysm with bilateral occipital condyle grade III fractures. [CT Angiography | CT Non-contrast]

Fig 17: (Biffl Grade III Injury) Enlargement of right cavernous internal carotid artery pseudoaneurysm. Exam on left was 12 days prior to the middle and right images. [CT Angiography].

• Grade IV: occlusion

Fig 18: (Biffl Grade III and IV) Stab victim. Subcutaneous gas is seen in the posterior occipital region with occlusion of the left V2 segment. [CT Angiography]. Pseudoaneurysm involving the left V3 segment [Digital subtraction angiography].

Fig 19: (Biffl Grade III and IV) Continued from Figure 18. Multiple foci of infarcts seen in the posterior circulation after left vertebral artery injury [MRI Diffusion weighted imaging].

Fig 20: (Biffl Grade IV) Acute fracture involving the anterolateral border of the left carotid canal with complete occlusion of the left internal carotid artery [CT Angiography | Left]. (Biffl Grade III) Reconstitution of the supraclinoid internal carotid artery with small pseudoaneurysm at the junction of the cavernous and supraclinoid segments [CT Angiography | Right].

Fig 21: (Biffl Grade IV) Occlusion of the right vertebral artery V2 segment [MR Angiography]. Hyperextension ligamentous injury pattern at C3-C4 with prevertebral hematoma extending from C2-C5 [MRI Cervical Spine]. Acute spinous process fractures involving the C7 and T11 vertebrae [CT Non-contrast Cervical Spine]. Extension teardrop fractures involving C2 and C4 [CT Non-contrast Cervical Spine].

Fig 22: (Biffl Grade IV) Traumatic dislocation of C3-C4 with perched right facet and fracture of the left inferior and superior articular processes of C3 and C4 [CT Non-contrast Neck | Left two images]. Acute flexion-distraction injury with acute cord compression and associated cord edema from C3-C5 levels [MRI Cervical Spine]. Complete occlusion of the left vertebral artery V2 segment [CT Angiography | Right].

• Grade V: transection with free extravasation (arteriovenous fistulas also included)

Fig 23: (Biffl Grade V) Gun shot victim. Highly comminuted fractures involving the C5-C6 right lateral masses and vertebral bodies with ballistic fragments. Active extravasation is seen from the right vertebral artery V2 segment [CT Angiography].

Fig 24: (Biffl Grade V) Continued from Figure 23. Two months after prior. Multiple serpiginous engorged vessels surrounding and connecting to the right vertebral artery compatible with arteriovenous fistula [CT Angiography].

Fig 25: (Biffl Grade V) Continued from Figure 24. Selective angiography of the right subclavian artery demonstrates a right sided arteriovenous fistula involving the right vertebral artery [Digital Subtraction Angiography].

Fig 26: (Biffle Grade V) Stabbing victim. Traumatic multilobulated pseudoaneurysm of the right common carotid artery with active extravasation. [From left to right: CT 3D Reconstruction | CT Angiography | CT Angiography]

Treatment with systemic anticoagulation is used for surgically inaccessible injuries and no contraindications. Unfractionated heparin with partial thromboplastin time at 40-50 seconds is used. Patients with relative contraindications, including pelvic fractures or solid organ injury, are given antiplatelets subcutaneous heparin or low molecular weight heparin.

Grade II and III lesions rarely resolve without endovascular treatment .Embolisation is used to stop active extravasation or occlude pseudoaneurysm lumens. Coils and gelfoam are primarily used with the difference being whether temporary or permanent occlusion is desired. Coil embolisation in the carotid or vertebral system is recommended to be performed under flow-controlled conditions due to the risk of distal emboli.

N-butyl cyanoacrylate (NBCA) is used to obliterate bleeding vessels by polymerising upon contact with ionic solutions. It’s main advantages are speed of preparation, no reliance on the body’s natural clotting cascade, and selectivity.Stenting is used when vessel patency must be maintained.

Baloon expandable stents and self expanding stents may be used in the head and neck. They may be bare metal or covered. Pseudoaneurysms (Grade III) can be treated by stenting across with or without embolisation coils placed into the pseudoaneurysm. Long term antiplatelet therapy is needed to prevent in-stent stenosis/thrombosis.

Most cerebrovascular injuries change within 30 days and rarely change after 90 days. Therefore, follow-up imaging is unlikely to be useful after 90 day period.