Ronald P. Benitez

Endovascular occlusion of wide-necked aneurysms with a new intracranial microstent (Neuroform) and detachable coils.

OBJECTIVE:The long-term durability of the endovascular occlusion of cerebral aneurysms is one of the major factors limiting the more widespread use of this technique. Long-term occlusion of wide-necked aneurysms has improved with new assistive devices that seem to improve aneurysm occlusion while protecting the parent vessel. We report the use of a new intracranial stent—the Neuroform microstent—in the treatment of patients with wide-necked cerebral aneurysms. METHODS:Patients identified as harboring wide-necked intracranial aneurysms were evaluated for stent-assisted coiling. After appropriate anticoagulation was performed, depending on whether the aneurysm was ruptured or unruptured, the Neuroform stent was delivered across the neck of the aneurysm and deployed with a coil pusher. After stent placement, standard coil occlusion of the aneurysm was achieved in the majority of cases. RESULTS:Fifty-six patients were identified as having wide-necked intracranial aneurysms suitable for stent-assisted coiling. A total of 49 aneurysms in 48 patients were treated with this procedure. In eight cases, stent deployment failed. Forty-one of the aneurysms were initially stented, followed by coil placement. Six aneurysms were stented only, and one aneurysm was initially coiled, followed by stent placement. There were five deaths (8.9%), one of which occurred secondary to a stroke after the procedure (1.8%). Four patients (7%) experienced thromboembolic events, three of which were considered to have been secondary to the procedure (5.3%). In addition, there were two femoral pseudoaneurysms. The overall complication rate was 10.7%. Five patients were available for follow-up angiographic evaluation, and their cases are discussed. CONCLUSION:Intracranial stenting may overcome important technical limitations in current endovascular therapy by improving the occlusion of wide-necked aneurysms while protecting the parent vessel.

Therapeutic Modalities for the Management of Cerebral Vasospasm: Timing of Endovascular Options

OBJECTIVES To determine if a window of time could be defined during which angioplasty would be most effective in reversing neurological decline and ultimately improving outcome. METHODS Of a group of 466 patients, 93 underwent endovascular management of clinical vasospasm that was medically refractory. Eighty-four of the 93 patients were available for follow-up for at least 6 months. All patients underwent mechanical angioplasty using compliant microballoon systems and, if distal spasm was present, the administration of papaverine. RESULTS Fifty-one patients underwent endovascular management within a 2-hour window, and 33 patients underwent treatment more than 2 hours after the development of their symptoms. Compared with the group treated more than 2 hours after neurological decline (P < 0.01; chi2 = 8.02), the group that underwent endovascular management within a 2-hour window after the development of symptoms demonstrated sustained clinical improvement. CONCLUSION When a patient develops symptomatic vasospasm and is unresponsive to traditional measures of critical care management, angioplasty may be effective in improving the patients neurological status if this procedure is performed as early as possible. The results indicate that a 2-hour window may exist for restoration of blood flow to ultimately improve the patients outcome.

Fractionated stereotactic radiotherapy for the treatment of large arteriovenous malformations with or without previous partial embolization.

OBJECTIVE Despite the success of stereotactic radiosurgery, large inoperable arteriovenous malformations (AVMs) of 14 cm3 or more have remained largely refractory to stereotactic radiosurgery, with much lower obliteration rates. We review treatment of large AVMs either previously untreated or partially obliterated by embolization with fractionated stereotactic radiotherapy (FSR) regimens using a dedicated linear accelerator (LINAC). METHODS Before treatment, all patients were discussed at a multidisciplinary radiosurgery board and found to be suitable for FSR. All patients were evaluated for pre-embolization. Those who had feeding pedicles amenable to glue embolization were treated. LINAC technique involved acquisition of a stereotactic angiogram in a relocatable frame that was also used for head localization during treatment. The FSR technique involved the use of six 7-Gy fractions delivered on alternate days over a 2-week period, and this was subsequently dropped to 5-Gy fractions after late complications in one of seven patients treated with 7-Gy fractions. Treatments were based exclusively on digitized biplanar stereotactic angiographic data. We used a Varian 600SR LINAC (Varian Medical Systems, Inc., Palo Alto, CA) and XKnife treatment planning software (Radionics, Inc., Burlington, MA). In most cases, one isocenter was used, and conformality was established by non-coplanar arc beam shaping and differential beam weighting. RESULTS Thirty patients with large AVMs were treated between January 1995 and August 1998. Seven patients were treated with 42-Gy/7-Gy fractions, with one patient lost to follow-up and the remaining six with previous partial embolization. Twenty-three patients were treated with 30-Gy/5-Gy fractions, with two patients lost to follow-up and three who died as a result of unrelated causes. Of 18 evaluable patients, 8 had previous partial embolization. MeanAVM volumes at FSR treatment were 23.8 and 14.5 cm3, respectively, for the 42-Gy/7-Gy fraction and 30-Gy/5-Gy fraction groups. After embolization, 18 patients still had AVM niduses of 14 cm3 or more: 6 in the 7-Gy cohort and 12 in the 5-Gy cohort. For patients with at least 5-year follow-up, angiographically documented AVM obliteration rates were 83%for the 42-Gy/7-Gy fraction group, with a mean latency of 108 weeks (5 of 6 evaluable patients), and 22% for the 30-Gy/5-Gy fraction group, with an average latency of 191 weeks (4 of 18 evaluable patients) (P = 0.018). For AVMs that remained at 14 cm3 or more after embolization (5 of 6 patients), the obliteration rate remained 80% (4 of 5 patients) for the 7-Gy cohort and dropped to 9% for the 5-Gy cohort. A cumulative hazard plot revealed a 7.2-fold greater likelihood of obliteration with the 42-Gy/7-Gy fraction protocol (P = 0.0001), which increased to a 17-fold greater likelihood for postembolization AVMs of 14 cm3 or more (P = 0.003). CONCLUSION FSR achieves obliteration for AVMs at a threshold dose, including large residual niduses after embolization. With significant treatment-related morbidities, further investigation warrants a need for better three-dimensional target definition with higher dose conformality.

Prevention of carotid angioplasty-induced bradycardia and hypotension with temporary venous pacemakers.

OBJECTIVECarotid angioplasty with stent placement is becoming an established treatment modality for patients with high-risk carotid stenosis. Unlike carotid endarterectomy, angioplasty causes direct mechanical dilation of the stenotic carotid artery and bulb. Stimulation of the sinus baroreceptors induces a reflexive response that consists of increased parasympathetic discharge and inhibition of sympathetic tone, which results in bradycardia and subsequent cardiogenic hypotension. METHODSAt a single institution, the experience with 43 patients treated from November 1994 to January 2000 with 47 angioplasty and stent procedures for occlusive carotid artery disease was retrospectively reviewed. Prophylactic temporary venous pacemakers were used to prevent hypotension from possible angioplasty-induced bradycardia. Pacemakers were set to capture a heart rate decrease below 60 beats per minute. Variables analyzed included demographics, etiology of disease, side of the lesion, the presence of symptoms, history of coronary artery disease, percent stenosis, type of stent used, number of dilations, pressure of dilation, and angioplasty balloon diameter. RESULTSTen patients were excluded because pacemakers were not used during their angioplasty procedures, and these included three emergencies and a lesion that was unrelated anatomically to the carotid sinus (petrous carotid). The remaining 37 procedures were performed in 33 patients with a mean age of 67 years, and consisted of 17 men, 16 women, 20 right and 17 left-sided lesions. The pacemakers maintained a cardiac rhythm in 23 (62%) of the 37 procedures and in no case did the pacemaker fail to respond when activated. Recurrent (56%; 10 of 18), radiation-induced (78%; 7 of 9), and medically refractory carotid stenosis (67%; 6 of 9) required intraprocedural pacing. Two patients with recurrent stenosis became hypotensive despite the aid of the pacing device but were not symptomatic. Seventy-nine percent (15 of 19) of symptomatic lesions and 57% (8 of 14) of nonsymptomatic lesions required pacing, which was statistically significant (P = 0.049). No patient experienced an operative morbidity or mortality as a consequence of the temporary pacing devices. CONCLUSIONAngioplasty-induced bradycardia is a common condition, and it is more prevalent in radiation-induced stenosis and with symptomatic lesions. Temporary venous demand pacing is a safe procedure and may prevent life-threatening, baroreceptor-induced hypotension.

Assessment of acutely unsuccessful attempts at detachable coiling in intracranial aneurysms.

OBJECTIVE Guglielmi detachable coiling (GDC) has quickly become the most common endovascular method for the treatment of intracranial aneurysms. Although several published case series describe various authors’ successful experiences or complications, few have elaborated on failed attempts. We examined our experience with GDC, and we analyzed all failed attempts at coiling. METHODS Patients who underwent endovascular procedures from September 1995 through July 1999 were identified using endovascular case logs and billing records. Patient charts were then reviewed retrospectively for failed attempts at GDC. A treatment failure was defined as an inability to place coils into an aneurysm, a GDC procedure-related complication resulting in death, or an acute rehemorrhage from a coiled aneurysm that indicated a failure of coils to prevent rerupture. Thromboembolic events and other nonfatal sources of morbidity that did not preclude coiling of the aneurysm were analyzed only to the extent that they prevented successful coiling of the aneurysm. RESULTS From September 1995 to June 1999, 241 patients underwent GDC embolizations or attempts. In these patients, 35 procedures were unsuccessful, including 7 deaths from intraoperative or postoperative aneurysmal rerupture. Sixteen aneurysms could not be microcatheterized, nine of which were anterior communicating artery aneurysms. Coils from 13 wide-necked aneurysms (average fundus-to-neck ratio, <2) prolapsed into the parent vessel. Three procedures were abandoned when the aneurysms were found to have normal branches filling from the dome, and three additional procedures were abandoned for technical reasons. Five deaths resulted from intraoperative aneurysm rupture, and two patients died postoperatively from rerupture. CONCLUSION The number of successful coiling procedures has increased with experience and improved technology. The procedure still involves risks, however, primarily for patients with subarachnoid hemorrhage.

Feasibility and limitations of endovascular coil embolization of anterior communicating artery aneurysms: morphological considerations.

OBJECTIVE The purpose of this study is to analyze anterior communicating artery (AComA) aneurysm morphology and its relationship to the limitations and feasibility of endovascular coil embolization. METHODS One hundred twenty-three patients were treated with endovascular coil embolization for AComA aneurysms. Aneurysm morphology was classified into six categories according to the projection of the aneurysm (anterior, posterior/superior, or inferior) and neck size (< 4 mm or >or= 4 mm). The following categories were used: Class A1, anterior projection and neck of aneurysm less than 4 mm; Class A2, anterior projection and neck of aneurysm 4 mm or more; Class B1, posterior (superior) projection and neck of aneurysm less than 4 mm; Class B2, posterior (superior) projection and neck of aneurysm 4 mm or more; Class C1, inferior projection and neck of aneurysm less than 4 mm; and Class C2, inferior projection and neck of aneurysm 4 mm or more. Endovascular procedures were categorized as either successful or unsuccessful according to specific criteria. In addition, patients were followed for recanalization. Clinical follow-up data was obtained at discharge and after 6 months and was classified according to the Glasgow Outcome Scale. RESULTS Complete or near complete aneurysm occlusion was observed in 108 (88%) patients, partial embolization was performed in three (2.4%) patients, and embolization was attempted in 12 (9.7%) patients. Successful embolization for AComA aneurysms was performed in 86 out of 123 (70%) patients or 77.5% (86 out of 111 patients) of those patients in whom embolization was possible. Statistical analysis demonstrated that anterior projecting aneurysms were more likely to be successfully coiled than either inferior or posterior/superior directed AComA aneurysms. In addition, inferiorly projecting AComA aneurysms and wide-neck aneurysms had a significantly higher rate of recanalization. CONCLUSION Endovascular coil embolization of AComA aneurysms shows good outcome in our study. Despite advanced modern techniques, there are limitations in the endovascular approach to AComA aneurysms. Consideration of aneurysm morphology may be used to guide approaches in the treatment of AComA aneurysms.

Surgically treated aneurysms previously coiled: Lessons learned. Commentaries

OBJECTIVEIntravascular coil embolization of cerebral aneurysms has proved to be a safe and effective treatment in certain patient groups; however, this treatment is relatively new, and the long-term outcomes are unknown. One of the known complications is refilling of the aneurysm dome, which is seen in follow-up studies. This patient population poses unique technical difficulties for the neurosurgeon. We present a series of 18 patients who underwent surgery for residual aneurysms after coil remobilization. METHODSDuring a 5-year period, we performed surgery in 18 patients who had previously undergone coil embolization for their aneurysms. Of these aneurysms, four were in the anterior communicating artery, five were in the posterior communicating artery, three were in the internal carotid artery, three were in the posteroinferior cerebellar artery, and three were in the middle cerebral artery. One patient presented with rupture, one presented with acute IIIrd cranial nerve palsy, and the rest of the aneurysms were found on routine follow-up angiograms. Fifteen aneurysms were clipped, and in three patients, they were wrapped because the clip could not be placed adequately. RESULTSThere were no major complications in any of the patients, and all had uneventful recoveries. The presence of coils in the aneurysm dome and/or neck made clipping and exposure of the aneurysm neck difficult, resulting in incomplete neck obliteration in three patients. CONCLUSIONOperative clipping after previous coil embolization in aneurysms poses a unique problem for neurosurgeons. With the increasing use of coil embolization, this patient population will undoubtedly increase. The neurosurgeon should be aware of the difficulties and pitfalls encountered in these patients.