Thirty-six patients were identified who met the inclusion criteria above . The average age of these patients was 59, and the range was 33-88. The average time of presentation after the SAH was 2 days (range, 0–7). The median Hunt Hess score was 2 (range, 1–5), and the median Fisher grade was 3 (range, 1–4) . Twenty-three patients were treated for aneurysms in the anterior circulation. The majority of these aneurysms were sidewall postclinoid ICA aneurysms (N = 16) and three patients were treated for aneurysms located in the anterior communicating complex. Four patients were treated for ruptured middle cerebral artery aneurysms. Only one patient was treated for an aneurysm of the vertebral artery. The remaining 12 patients had basilar apex aneurysms. Nearly all of the aneurysms treated had a dome-to-neck ratio less than 1.5 (N = 32, mean ratio 1.1, and range 0.8–1.47). The remaining four patients had a neck size greater than 4 mm. Nine patients underwent placement of ventriculostomy prior to embolization and antiplatelet therapy.
Patient characteristics and outcomes
Average timing of stent placement for embolization was 3.2 days after the initial hemorrhage (range, 1–7). There were two treatment failures in which a stent was placed, but the aneurysm was not coiled. One of these patients had complete thrombosis of the ICA (see later section). The other patient had an aneurysm which could not be accessed with a microcatheter after stent placement. Ten patients were treated in a staged fashion with initial placement of stent followed by coil embolization (N = 1) or initial subtotal embolization of dome followed by definitive stent embolization (N = 9, see Case #1). (All staged embolizations were completed during the acute phase of hospitalization.) The former patient had a distal thrombotic event after stent placement. Although the flow was partially re-established in this vessel using mechanical disruption of the thrombus, treatment of the aneurysm was postponed to minimize the risk of re-occlusion. This latter group includes a patient who initially failed balloon-assisted embolization. Thirteen patients underwent stent placement as a salvage procedure for complications associated with unassisted coiling of the ruptured aneurysm (see Case #2). (All salvage embolizations were completed in the same setting as unassisted embolization). The reason for salvage stenting included protrusion of the coil mass out of the neck of the aneurysm (N = 7), inability to obtain purchase within the aneurysm due to the small size or tortuosity of the parent vessel (N = 4), stagnant flow in a distal branch following embolization of an anterior communicating artery aneurysm (N = 1), and a combination of coil pack protrusion through the neck of the aneurysm and thrombus formation at the origin of distal vessels (N = 1) .
Figure 1 Illustrative case of a basilar tip aneurysm treated via staged embolization. (a) Digital subtraction angiography (DSA) showing a basilar tip aneurysm with a lobule extending from the dome. (b) DSA showing coil embolization of lobule as stage 1. (c) DSA (more ...)
Seventeen patients were pretreated with aspirin and clopidogrel prior to their procedure. There was no consensus about the timing of antiplatelet therapy; therefore, this varied depending on the case and the preference of the responsible practitioner. Ten of these patients were treated with a loading dose of clopidogrel (300 mg), an average of 8.5 h prior to deployment of the stent (range, 1–36 h). One patient began antiplatelet therapy (daily clopidogrel 75 mg and aspirin 81 mg) after initial embolization of the dome of the aneurysm and 4 days prior to definitive stent-assisted embolization. Five patients received an intraoperative loading dose of clopidogrel during the procedure. Fourteen patients were treated with antiplatelet therapy an average of 4.9 h after stent embolization of their aneurysm (range, 1–9). All but one patient received intravenous heparin during stent placement. The average dose of heparin was 5250 (range, 2000–8000).
The majority of patients had total or near total embolization of the aneurysm on postprocedural arteriography. Seven patients (30%) had a class 1 result (no residual filling of the aneurysm). Another seven patients (30%) had residual filling of neck (class 2 result). Seven patients (30%) also had residual filling of the dome of the aneurysm (class 3 result) although six of these had significant stagnation of contrast within the dome. Two (9%) aneurysms were left untreated in this series. One of these aneurysm cases involved thrombosis of the ICA as described below. The other aneurysm (carotid-ophthalmic) could not be accessed with a microcatheter through the interstices of the stent due to the tortuosity of the carotid siphon and the small height of the aneurysm (3 mm).
Six patients (17%) experienced thrombotic events associated with stent embolization of the ruptured aneurysm. Two patients had nonocclusive thrombus formation at the neck of the aneurysm. One of these was treated with intra-arterial abciximab (2 mg) and intravenous abciximab (0.25 mg/kg) resulting in partial resolution on follow-up arteriography. The other was treated with intravenous abciximab (0.25 mg/kg) with complete resolution on follow-up arteriography. One patient was found to have a nonocclusive embolus distal to the aneurysm with some evidence of migration. This was treated with an intravenous bolus of heparin (2000 units) resulting in complete resolution. Two patients had evidence of complete carotid occlusion. One of these patients was treated with abciximab (2 mg intra-arterial, 0.25 mg/kg intravenous bolus followed by infusion) resulting in partial recanalization and distal flow. The other patient was not treated with abciximab because the aneurysm was not secured and there was excellent collateral blood supply across the anterior communicating artery. One patient had complete occlusion of the posterior cerebral artery (PCA) after placement of a stent across the neck of the aneurysm. Although flow was re-established by passing the microcatheter through the stent, the distal PCA remained occluded. Abciximab was not administered because the aneurysm was not secured.
The prevalence of thrombotic events increased based on the timing of administration of antiplatelet (P = 0.043). Six percent of patients pretreated with clopidogrel experienced a thrombotic event and 20% of patients treated with clopidogrel during the procedure experienced a thrombotic event. The prevalence of thrombotic events in patients who received clopidogrel after the procedure was 29%.
There was no evidence of intraprocedural rupture during treatment of any patient. Two patients had thromboembolic complications not associated with stenting. One of these is a patient who underwent placement of a Y-stent as a salvage procedure for thrombus at the neck of the aneurysm after coiling. The thrombus resolved after deployment of the two stents without any use of abciximab. In addition, there was no evidence of distal embolus. The other patient had evidence of thrombus formation at the neck of an anterior communicating artery aneurysm, which was coiled after stent-assisted embolization of an ICA aneurysm. This patient also received IV abciximab bolus (0.25 mg/kg) with interval resolution of the thrombus on follow-up arteriography .
Figure 2 Illustrative case of a basilar tip aneurysm requiring salvage stent placement following unassisted embolization complicated by coil migrations and thrombus formation. (a) DSA of basilar tip aneurysm prior to embolization. (b) DSA of initial unassisted (more ...)
Of the six patients described above who had intraprocedural stent-related thrombotic complication, three patients had evidence of ischemia after the procedure. Two of these patients had complete occlusion of the ICA and one had complete occlusion of the PCA. The patient who was treated with abciximab with partial recanalization had mild-to-moderate contralateral hemiparesis postoperatively. The patient's hemiparesis improved during the hospital course until the patient suffered a contralateral intraparenchymal hemorrhage 10 days after the procedure. Angiography at this time did not reveal any evidence of thromboembolism. The second patient had good evidence of collateral circulation from the contralateral ICA. Postoperatively, the patient had evidence of a watershed infarct on CT but was neurologically intact. Another two patients, who had no evidence of intraprocedural thromboembolism, had small areas of diffusion restriction on postoperative MRI, which were of no neurological consequence. Only one patient had evidence of severe SAH-related vasospasm resulting in a hemispheric stroke.
The median GOS for patients at the time of discharge was 5, and 28 patients (78%) had a GOS of 4 or better. Average number of days in the hospital was 16 days (range, 9–37) and average number of days in ICU was 12 days (range, 4–29). Seven patients had a GOS of 2 or less. Two of these patients presented with a Hunt Hess grade 5 SAH and failed to make a neurological improvement during their hospital course. A third patient who initially presented with a Hunt Hess grade 4 SAH suffered a severe hemispheric stroke related to vasospasm. All patients who suffered intraprocedural thromboembolic complications had a GOS of 4 or better at discharge with the exception of the patient described above who suffered an intraparenchymal hemorrhage contralateral to the side of the treated aneurysm. A total of 12 ventriculostomy procedures (including placement of ventriculoperitoneal shunts) were completed in nine patients while they were treated with aspirin and clopidogrel. All patients received preprocedural platelet infusion and no patients suffered any hemorrhagic or thromboembolic complications. Routine CT scans were not completed after removal of drains; therefore, subclinical hemorrhages may not have been identified.
Follow-up angiographic data were available for 21 patients . Mean time to follow-up was 4.8 months (range, 2.5–9). Ten patients (48%) had no evidence of residual aneurysm and four patients (19%) had a residual neck measuring less than 3 mm and required no further embolization. Five (24%) patients had residual filling of the neck of the aneurysm measuring greater than 3 mm. All of these patients underwent successful re-embolization. Two patients (10%) had recanalization of the dome of the aneurysm and also underwent re-embolization.
Treatment efficacy and recurrence