16.2.1 Casel

A 46-year-old right-handed female with no past medical history presented to the emergency department with acute onset aphasia and right hemibody numbness. Over the prior month, she had intermittent blurry vision including the day of presentation.

Past medical history: No history of trauma.

Past surgical history: Noncontributory.

Social history: No history of tobacco or drug use.

Family history: No history of familial stroke or connective tissue disorders.

Examination: The patient was alert and following commands appropriately. She was unable to answer the questions due to word-finding difficulty and dysarthria. Visual field testing demonstrated right lower quadrantanopia. There was no pronator drift or lower extremity weakness. Right-sided touch was diminished. The National Institutes of Health Stroke Scale (NIHSS) score was 8.

Computed tomography angiography (CTA) of the brain revealed no evidence of hemorrhage or intracranial arterial thrombus, or dissection. CTA of the neck showed near occlusive luminal narrowing, 1.5 cm in length, consistent with the “string sign” of a dissection in the cervical segment of the left internal carotid artery (ICA) proximal to the skull base (Fig. 16.1).

CT perfusion revealed prolonged time-to-peak (TTP) and mean transit time (MTT) with preserved cerebral blood volume (CBV), indicating at-risk perfusion, of the entire left hemisphere (Fig. 16.2).

Magnetic resonance imaging (MRI) demonstrated punctate foci of subacute infarction in the left hemisphere deep white matter.

Hospital course: The patient was admitted to the neurosci-ence ICU and administered an Aspirin bolus. During the course of hospital day (HD) 1, neurological examination fluctuated with intermittent global aphasia and mild right pronator drift and full-dose heparin drip was initiated. These fluctuations persisted on HD 2. The decision was made to proceed with urgent carotid artery stent placement, and the patient was loaded with clopidogrel.

Under monitored anesthesia care with conscious sedation, the patient underwent diagnostic angiography followed by left ICA stenting and angioplasty. Left ICA angiography confirmed near-occlusive dissection with delayed intracranial ICA flow (Fig. 16.3a). Given the high degree of stenosis, luminal irregularity, and lack of atherosclerotic plaque, a .017 microcatheter/ .014 microwire combination was used to navigate the dissection. We elected not to use distal embolic protection as, with the high degree of stenosis and the lack of atherosclerotic disease, we prefer the greater ability to torque and steer the .014 microwire compared to the wire of a distal protection device. Microcatheter angiography was also performed to confirm that the catheter remained in the true lumen. Carotid artery stent placement was performed with poststent balloon angioplasty to improve stent expansion (Fig. 16.3b,c). Post-angioplasty angiography demonstrated excellent filling of the left ICA and distal branches.

Postoperatively, systolic blood pressure (SBP) was maintained less than 140 to avoid reperfusion injury and the heparin drip was weaned. The patient’s examination improved dramatically, and she was discharged home on HD 5 with mild aphasia (NIHSS score 1). She was maintained on dual antiplatelet therapy. At 3-month follow-up, she had returned to her neurologic baseline.

Case 1 review: Spontaneous carotid artery dissection

Spontaneous cervical artery dissection (SCAD) is a leading cause of stroke in patients less than 40 years of age. It occurs at an annual incidence of 3 per 1,00,000 for the ICA and 1 per 1,00,000 for the vertebral artery (VA). ¹ Fisher et al provided one of the early descriptions of SCAD including definition of the “string sign,” distal pouch formation (i.e., pseudoaneurysm), and occlusion. ² SCAD arise from a tear in one or more of the three arterial layers (i.e., tunica intima, media, and adventitia). Tears allow blood to enter the arterial wall and create an intramural hematoma, that is, false lumen. ³ Subintimal dissection can result in stenosis of the arterial lumen, and more extensive subadventitial dissection can create an aneurysmal dilation (commonly referred to as a pseudoaneurysm) that may also compromise the arterial lumen. ³ SCAD occurs in the absence of major trauma but can result from arteriopathies such as fibro-muscular dysplasia, Marfan syndrome, and Ehler-Danlos type IV. Comorbidities associated with SCAD include infection, radiation and cervical tumors, and repeated microtrauma including chiropractic cervical manipulation, coughing, and abrupt head turns. ^{3 , 4} Headache, neck pain, oculosympathetic palsy with miosis and ptosis, and lower cranial neuropathy as well as ischemic manifestations from hypoperfusion and thromboembolic phenomena are common presentations of SCAD. ^{3 , 5 , 6} ICA stenosis or occlusion is associated with a 0.3% annual risk of transient neurological deficit and 0.7% annual risk of stroke. ⁷ A prospective study of 970 patients with SCAD of the ICA (n = 668) and VA (n = 302) revealed that ischemic presentations were more common in the VA (84% vs. 70%, p< 0.001), but stroke severity was worse with ICA dissection (10 + /- 7.1 vs. 5 + /- 5.9, p < 0.001 ). ⁸ As well, VA dissections had more favorable outcomes at 3 months but also had more recurrent ischemic symptoms. ⁸ In a recent study of patients who present without ischemia, the absolute risk of stroke was 1.25% over the first 2 weeks with no significant increase in stroke over the subsequent 10 weeks. ⁹ Both antiplatelet and antithrombotic agents are used to treat SCADs to decrease the risk of stroke and have recently been shown to provide similar benefit in the Cervical Artery Dissection in Stroke Study (CADISS) trial. ^{10 , 11} The indications for endovascular intervention are uncertain with no randomized trials to demonstrate efficacy. ^{4 , 12 , 13 , 14 , 15}

This case demonstrates the presentation of a patient with recurrent transient symptoms followed by cerebral ischemia from SCAD resulting in near occlusion of the left cervical ICA. Initial therapy with aspirin for SCAD is supported by Class lib recommendation, Level B-Randomized evidence in the 2018 Guidelines for Management of Acute Ischemic Stroke, which is reviewed in a subsequent section. ¹⁵ Despite medical therapy, the patient had a worsening neurological examination and severe perfusion deficit on CT with the entire left hemisphere at risk of stroke from the high-grade dissection. The decision to proceed with EVT is supported by multiple retrospective studies demonstrating effectiveness in patients who have failed medical management. ^{16 , 17 , 18 , 19 , 20} EVT is supported by Class lib recommendation, Level C-Limited Data evidence in the 2018 Guidelines, which state that “consideration of EVT should be reserved for patients with definite recurrent cerebral ischemic events despite medical therapy.” ¹⁵

16.2.2 Case 2

A 19-year-old male was in an automobile struck by a semitrailer truck at high speed and was brought to an outside institution after stabilization at the scene. His traumatic injuries included pulmonary contusions, liver and splenic lacerations, and right radial/femur/ankle fractures. Initial CT brain imaging was negative. The orthopaedic injuries were stabilized. On HD 2, the patient developed left upper extremity weakness. CT head revealed multiple hypodensities in the right hemisphere confirmed by MRI (Fig. 16.4a, b). MRA revealed distal cervical ICA dissection with pseudoaneurysm formation (Fig. 16.4c). The patient was subsequently transferred to a tertiary center for a higher level of care.

On examination upon arrival, the patient was intubated but obeying commands off sedation. The right upper extremity was casted and right lower extremity was in an immobilizer. He was able to follow simple commands on the left but weaker than on the right. CTA with perfusion on arrival confirmed the right distal cervical ICA pseudoaneurysm and identified a left distal cervical ICA dissection with mild luminal narrowing with intact perfusion of both hemispheres except areas of reduced blood volume associated with prior thromboembolic events. Full-dose heparin drip was initiated after embolization of the splenic and hepatic lacerations and stabilization of hematocrit. We recommended cerebral angiography to determine the severity and type of the dissections and assess blood flow and collateral circulation. Angiography on HD 2 confirmed the dissections and demonstrated delayed right hemispheric flow through the right ICA but adequate collateral flow from the left ICA and vertebrobasilar system (Fig. 16.5). The right cervical ICA dissection had 50 to 60% luminal narrowing and endovascular intervention was not performed due to the risk of dual antiplatelet therapy with multiple traumatic injuries and adequate cerebrovascular reserve.

The patient was maintained on heparin drip and followed with daily transcranial Doppler ultrasonography with micro-embolic monitoring of bilateral middle cerebral artery (MCA) territories (TCDe). Microembolic signals (MES, 9 per hour) were detected on HD 3, and daily aspirin was started after a loading dose due to ongoing emboli from the dissection. Over the next several days, MES were intermittently detected but declining in number in the right MCA and the patient remained neurologically stable after extubation on HD 4. Once MES were absent for 3 consecutive days and the patient was neurologically unchanged, repeat CTA was performed which demonstrated stable appearance of the dissections. Therapeutic heparin was discontinued and aspirin was continued with no evidence of MES. After a prolonged hospitalization and repair of other injuries, he was discharged home on HD 25. At 3 months, the patient returned to clinic continuing to rehab from his orthopaedic injuries but otherwise neurologically intact. CTA head and neck demonstrated stable appearance of the bilateral ICA dissections, and the patient was maintained on aspirin monotherapy.

Case 2 review: Blunt cerebrovascular injury

BCVI is a type of traumatic cervical arterial dissection. The incidence of BCVI has increased over the past two decades with improved CTA screening protocols for asymptomatic patients with traumatic presentations and is present in 0.5 to 1.0% of admissions for trauma. ^{21 , 22 , 23} CTA as opposed to diagnostic cerebral angiography and MRA is generally used for screening patients presenting with trauma because it is less invasive than angiography, part of overall trauma screening with CT and quicker than MRA. ^{24 , 25 , 26 , 27 , 28} Typical screening protocols for BCVI include patients with cervical soft tissue hematoma, carotid bruit, cerebral infarction, Horner syndrome, lateralizing neurological deficit, intracranial hemorrhage, and transient ischemic attack (TIA) as well as high-energy trauma resulting in LeFort fractures and cervical spine fractures. ^{24 , 25}

BCVI involves the ICA more commonly than the VA (62% vs. 38% cases). ^{22 , 29} The most commonly used BCVI grading scale is the Denver (also known as the BifTl) criteria, which has five grades of decreasing incidence and increasing stroke risk (<10% for Grade I and 100% for Grade V). ^{22 , 24 , 29} Grade I (54% of BCVI) is luminal irregularity or dissection with < 25% luminal narrowing; Grade II (20%) is dissection or intramural hematoma with > 25% luminal narrowing; Grade III (13%) involves any dissection with pseudoaneurysm formation; Grade IV (10%) is traumatic occlusion; and Grade V (3%) is transection with free extravasation. ²⁹

Treatment of BCVI typically involves antiplatelet or anticoagulant medication. There have not been direct randomized trials comparing antiplatelet or anticoagulation for stroke prevention, but in retrospective analysis, antiplatelet and anticoagulant agents have similar effectiveness in preventing stroke and injury healing rates. ³⁰ Low-dose heparin (i.e., PTT 40-50 s) is the typical anticoagulant used during the acute phase with aspirin or other antiplatelet agents reserved for patients with contraindications to anticoagulation or for long-term therapy. TCDe has been used to help monitor and guide medical therapy with the presence of continued emboli requiring additional antiplatelet or anticoagulant agents or potentially EVT. ^{31 , 32 , 33 , 34} Serial imaging with CTA or angiography can be used to monitor low-grade lesions due to risk of progression and pseudoaneurysm development (8% risk with Grade I and 43% with Grade II at 7-10 postinjury); however, more recent studies have questioned the utility of early follow-up injury, especially for high-grade injuries. ^{29 , 35} Endovascular stenting or arterial sacrifice may be warranted for patients with progressive stenosis, enlarging pseudoaneurysms, persistent microemboli, and progressive neurological deficits despite adequate medical therapy. ^{24 , 29 , 31 , 36 , 37 , 38} Routine EVT for low-grade lesions has not been shown to provide additional benefit compared to anticoagulant therapy. ³⁹ However, EVT reserved for symptomatic patients and major dissections may reduce the risk of stroke. ³⁸ Grade V injury (transection) warrants immediate endovascular intervention, either arterial sacrifice or covered stenting or open surgical repair/sacrifice due to acute and active arterial extravasation.

This case demonstrates the presentation of a patient with multiple traumatic injuries who sustained a stroke from a right cervical ICA Grade III BCVl and also sustained a left cervical ICA Grade I BCVl. Initial therapy with heparin drip with plan to transition to aspirin therapy in the absence of a contraindication is supported by Level B-Non Randomized evidence and recommended by trauma surgery guidelines. ^{24 , 40} Medical therapy was tailored based on TCDe and aspirin was initiated when emboli were present, which may signify that therapy with heparin alone was insufficient. Early repeat imaging was also used to monitor response to therapy and progression of the dissections, which is also supported by guidelines for BCVl. ^{24 , 40}