Epidemiology Incidence of vertebral artery injury (VAI) 0.5% of all trauma patients 70% of VAI in blunt trauma has associated cervical fracture 33%-39% of all cervical spine fractures 0.3% anterior cervical spine surgery 4.1-8.2% posterior cervical spine surgery (C1-2 transarticular screws) Etiology Pathophysiology blunt traumatic injury pathoanatomy highest injury risk at point of entry into C6 transverse foramen second highest risk at C1-2 articulation iatrogenic injury during elective surgery safe zone C1: avoid dissection cephalad to the C1 posterior arch > 1.5 cm lateral to midline C1 lateral mass screw should be placed in a 10 degrees medial and 22 degrees cephalad trajectory Anatomy 4 arterial segments V1 extraosseous origin at subclavian artery, anterior to C7 transverse process, to the entry point of C6 transverse foramen V2 within the transverse foramina of C6-C1 most traumatic injuries occur here high risk during drilling, tapping, insertion of lateral mass or pedicle screws V3 superior aspect of the arch of atlas to foramen magnum VA is vulnerable during lateral exposure and laminectomy of C1 high risk of C1-2 transarticular screws are directed caudally and laterally V4 intradural extension from foramen magnum to unite with contralateral vertebral artery forms the basilar artery most injuries from cervical trauma in V2 (foraminal segment) Anomalous anatomy reported prevalence of 2.7% in anterior cervical surgery transverse foramen may be medial to or within 1.5mm of the uncovertebral joint reported prevalence of 2.3-20% in the atlantoaxial region high-riding C2 foramen C2 pedicle erosion C2 lateral mass thinning Classification Biffl VAI Injury Grading Grade I Arteriographic appearance of vessel dissection/intraumural hematoma; <25% luminal stenosis Grade II Intraluminal thrombosis or raised intimal flap; dissection/intramural hematoma with >25% luminal stenosis Grade III Pseudoaneurysm Grade IV Vessel occlusion Grade V Vessel transection Presentation History consists of recent: cervical spine trauma C1 or C2 fractures subaxial facet fractures and dislocations elective surgery of the cervical spine or craniocervical junction Symptoms variable in presentation and time of onset vertebrobasilar insufficiency manifests with dizziness vertigo nausea diplopia blindness ataxia bilateral weakness oropharyngeal dysfunction Imaging Radiographs xrays of certain fracture patterns raise suspicion for VAI CT angiography (CTA) identification of local occlusion or extravasation sensitivity reported at 100% indications for the trauma patient (any single criteria is an indication) unexplained central or lateralizing neurologic deficit evidence of acute cerebral infarct on CT scan of head GCS <9 evidence of diffuse axonal injury facial fracture or Le Fort type-II or III fracture cervical spine fracture or subluxation C1, 2, 3 fracture Fracture extension into the transverse foramen VAI demonstrated in 20% cervical spinal cord injury hanging injuries major thoracic injury or first-rib fracture Magnetic resonance angiography (MRA) identification of local occlusions/stenosis sensitivity 93.9% indications cervical spine fractures with neurologic deficits attributable to damaged vertebral or basilar artery perfusion sensitivity and specificity Treatment Post-operative anticoagulation goal is to prevent thromboembolic sequelae of injury intravenous heparin acetylsalicylic acid (aspirin) indications first line of treatment modalities heparin, aspirin, clopidogrel, IV thrombolysis, glycoprotein IIb/IIIa antagonists (abciximab, eptifibatide, tirofiban) contraindications: major intracranial infarction intraspinal hematoma/arteriovenous fistula Operative reduction and stabilization as neccessitated by fracture pattern Surgical techniques to control hemorrhage (see Techniques) Immediate intra-operative angiography can assist intra-operative decision making Post-operative management following iatrogenic injury observation further intervention dictated by clinical course immediate post-operative angiography detects vascular complications confirms adequate collateral cerebral circulation allows embolization of fistulae or pseudoaneurysm Techniques Hemostatic tamponade utilization of topical hemostatic agents, bone wax if injured during C1-2 transarticular screw placement, can tamponade by screw insertion risks include: delayed hemorrhage fistula formation Microvascular repair allows restoration of normal blood flow minimizes risk of ischemic complications technically demanding Direction ligation consider intraoperative angiography first to evaluate collateral circulation risks certain morbities cerebellar infarction loss of flow via the posterior inferior cerebellar atery (PICA) isolated cranial nerve paresis hemiplegia IR-guided embolization Complications Complications may occur days to years following injury arteriovenous fistula late-onset hemorrhage pseudoaneurysm may be delayed presentation thrombosis with embolic incidents cerebral ischemia/Stroke persistent vertigo death Prognosis Impact of VAI difficult to predict Many patients initially asymptomatic some progress to cerebral ischemia or stroke with permanent neurologic deficit Variable symptomatology
QUESTIONS 1 of 4 1 2 3 4 Previous Next (SBQ18SP.23) During a C1-C2 posterior spinal fusion, while performing the dissection of posterior arch of C1 and pedicle of C2, the surgeon encounters rapid pulsatile arterial bleeding. The artery is tamponaded off,vascular surgery is consulted and an intra-operative angiogram is performed. Given adequate collateral flow, the injured artery is embolized. Post-operatively the patient's neurologic function is normal. Injury to this arterial structure could have best been avoided by minimizing dissection in which of the following areas? QID: 211355 Type & Select Correct Answer 1 Dorsolaterally along the C1-C2 facet, medial to the foramen transversarium 11% (219/1933) 2 Ventral along the medial border of the the pars of C2 3% (58/1933) 3 Cephalad to the posterior arch of C1 when > 1.5cm lateral to the midline 62% (1191/1933) 4 Caudal to the posterior arch of C1 when < 1.0cm lateral to the midline 10% (186/1933) 5 Cephalad to the posterior arch of C1 when < 1.0cm lateral to the midline 13% (250/1933) N/A Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (SBQ18SP.56) During the posterior exposure of the atlas arch in the cervical spine, excessive retraction of >2 cm past midline would cause injury to an anatomical structure. Which of the following statements is true about this structure? QID: 211718 Type & Select Correct Answer 1 Injury to this structure causes postoperative hoarseness 5% (90/1756) 2 The structure is a branch of the vagus nerve 4% (72/1756) 3 Injury to this structure causes weakness in forearm supination 1% (20/1756) 4 The structure typically originates from the subclavian artery and travels cephalad through the transverse foramen 81% (1427/1756) 5 The structure is a terminal branch of the common carotid artery 8% (140/1756) L 1 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (SBQ12SP.64) A 75-year old female presents to the ER after a motor vehicle collision where she was rear-ended. Her imaging studies are shown in Figures A through C. She undergoes posterior stabilization and instrumented fusion (PSIF) without complications. During surgery, C1 lateral mass screws are placed with a starting point directly beneath the medial edge of the posterior arch at the point where it joins the lateral mass. The screws are directed 10 degrees medial and 22 degrees cephalad in order to be: QID: 3762 FIGURES: A B C Type & Select Correct Answer 1 Inferior and medial to the vertebral artery 40% (668/1667) 2 Inferior and lateral to the vertebral artery 6% (92/1667) 3 Superior and medial to the vertebral artery 46% (765/1667) 4 Superior and lateral to the vertebral artery 7% (121/1667) 5 Superior and aligned in the coronal plane 1% (9/1667) L 5 Question Complexity C Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 1 Review Tested Concept Review Full Topic Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK
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