Endovascular embolectomy of acute basilar artery occlusion

Case report.

The patient was a healthy 31-year-old Asian man without previous illness. He was struck on his face with head twisting sideways during a football game. He was dazed and had brief episodes of confusion. His neurologic examination and CT of the head at a local hospital were reported as normal. A few hours later, he developed “seizure-like activity” and was sent to a trauma center for further evaluation. On arrival, he was noted to have dysarthria and right-sided weakness. A repeat CT showed a hyperdense basilar artery on two consecutive 5-mm cut images, indicative of acute basilar artery embolism. He soon became incoherent and unresponsive with marked vertical nystagmus. Neither systemic anticoagulation nor IV thrombolytic therapy was initiated because of a preliminary report of possible subarachnoid hemorrhage. After intubation for airway protection, he was emergently transferred to the University of California, San Francisco 4 hours after symptom onset. Family consent was obtained for endovascular therapy after full discussion of the benefit and risks of such therapy under an approved Food and Drug Administration (FDA) protocol for use of an experimental clot-retrieval device for acute cerebrovascular emboli. After an IV bolus of 2,000 U heparin, diagnostic angiography of the right vertebral artery demonstrated complete occlusion with an abrupt cutoff at the midcervical portion of the vertebral artery at C₄-C₅ (figure 1, A and B). The obstruction was gently traversed with a UCSF-2 catheter over a Bentson guidewire (Cook Incorporated, Bloomington, IN), and an injection of contrast medium confirmed the patency of the distal right vertebral artery above the dissection site. IV abciximab was initiated with a bolus injection of 0.25 mg/kg followed by an infusion of 0.125 μg/kg/min for 12 hours. A 6- × 40-mm Magic Wall Stent (Boston Scientific, Natick, MA) was then placed across the area of the dissection site with excellent restoration of blood flow (figure 1, C and D) at approximately 6 hours after symptom onset. Angiography of the now patent right vertebral artery demonstrated a large embolus in the distal basilar artery occluding both superior cerebellar arteries (SCAs) and the right posterior cerebral artery (PCA) (figure 2A). An initial attempt at embolectomy was made with the Neuronet (Guidant Corporation, Santa Clara, CA) to capture the embolus in the distal basilar artery but was unsuccessful. The Concentric Retriever (Concentric Medical, Mountain View, CA) was then used for clot removal. The device was advanced through a 7-French guide catheter in the right vertebral artery, and the tip was placed in the right PCA across the embolus over an Agility 0.014-inch microguidewire (Cordis Neurovascular, Miami, Florida) (figure 2B). The clot was captured with the helical coils of the device (figure 2C) and pulled back into the 7-French guide catheter. It was then removed in toto from the guide catheter through the femoral artery sheath at 7 hours after stroke onset. The embolus recovered from embolectomy measured 5 × 25 mm (figure 2D). Follow-up angiography demonstrated complete recanalization of the basilar artery with full restoration of blood flow to both SCAs and the right PCA (figure 2E). The patient regained complete consciousness after the stent and embolectomy and was extubated with only mild residual nystagmus and left-sided dysmetria for a few hours. A follow-up brain MRI showed only a small infarction in the left cerebellum and no infarct in the brainstem (figure 3). The patient was discharged home with aspirin and clopidogrel 2 days after the procedure. Two months later, he complained of episodes of lightheadedness and was found to have a high-grade stenosis at the proximal segment within the stent in the right vertebral artery. The stenosis was managed with balloon angioplasty without complication. He has returned to work and remained neurologically intact 9 months after embolectomy.

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Figure 1. Diagnostic angiography of right vertebral artery showed complete occlusion with an abrupt cutoff at the midcervical portion of the vertebral artery at C₄-C₅ level (A, B). After mechanical recanalization and abciximab infusion, the right vertebral dissection was visualized (C) and stented (D).

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Figure 2. Angiography of the stented right vertebral artery demonstrated a large embolus occluding both superior cerebellar arteries (SCAs) and right posterior cerebral artery (PCA) (A). The clot was captured by the soft helical coils of the Concentric Retriever and removed in toto from the guide catheter through the femoral artery sheath (B, C). The embolus recovered measured 5 × 25 mm (D). Repeat angiography demonstrated complete recanalization of the distal basilar artery with full restoration of blood flow to both SCAs and the right PCA (E).

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Figure 3. Diffusion-weighted MRI at day 2 after embolectomy showed a small cerebellar infarction (A) and no infarct in the brainstem (B).

Discussion.

Until recently, anticoagulation with IV heparin was the therapy of choice for acute basilar artery occlusion based on anecdotal reports. However, in a retrospective study of 25 patients who had acute basilar artery occlusion requiring mechanical ventilation, the mortality rate was 88% despite anticoagulant therapy.3 Three patients survived with a locked-in syndrome without further neurologic improvement. Therefore, the therapy is of little benefit. Recently, thrombolytic agents, including urokinase, streptokinase, and tissue plasminogen activator (tPA), have been administered either IV or IA for acute basilar artery occlusion. Although recanalization rates have approached 44 to 83%, the mortality rate has remained 65 to 75% because of rethrombosis, hemorrhagic complications, and irreversibility of the stroke itself.2,5-7⇓⇓⇓ Of note, patients with distal basilar artery occlusion and adequate collateral circulation tended to have a lower mortality rate of approximately 50% with IA thrombolysis.6 However, the overall good outcome with no or mild deficit was only 20 to 25%.6,7⇓

Stenting of dissected extracranial arteries has been reported. However, mechanical removal of emboli from intracranial arteries has only been described in three case reports. Microsnares have been used to retrieve foreign bodies, such as detachable coils and catheter fragments, in the circulation. Such a device was first used successfully to retrieve an embolus from the middle cerebral artery in one patient with an acute stroke.8 Subsequently, there are two reports of successful retrieval of clots from the basilar artery using the snare and Neuronet.9,10⇓ In one of these reports, five patients with basilar artery occlusion underwent mechanical removal of an embolus using the Neuronet.9 The device failed to retrieve clots in the initial two patients but succeeded in the subsequent three patients with flow reversal by temporarily occluding the vertebral artery. In this report, we initially attempted embolectomy with the Neuronet but were unable to capture the embolus with this device. However, the embolus was successfully captured with the Concentric Retriever and pulled back into the guide catheter without using flow reversal as described.9 The patient recovered quickly without neurologic deficit and remains healthy 9 months after the procedure.

Compared with thrombolytic therapy, endovascular embolectomy theoretically has a lower risk of hemorrhagic complications and can be used in patients with contraindications for thrombolytic therapy. Per FDA-approved protocol, patients evaluated within 8 hours of symptom onset are eligible for the clinic trial of embolectomy. It must be noted that experienced neurointerventional specialists may currently perform this procedure at 25 investigational sites in the United States. Although large randomized controlled studies are required to evaluate the safety and effectiveness of various clot-retrieval devices, our report corroborates previous reports9,10⇓ and indicates that endovascular embolectomy may be a promising therapy for life-threatening basilar artery occlusion and other types of strokes.