This article reviews complications associated with the endovascular management of intracranial aneurysms, focusing on risk factors, avoidance, recognition, and management. Such complications can be devastating. Both neurologic and nonneurologic complications can occur. Several patient and procedure related parameters can increase the incidence of complications. Reduction of complication rates can be achieved by careful patient selection, meticulous planning and preparation for the procedure, anticipating potential complications, and preparing for their management. Tracking outcomes and a robust case conference can further enhance outcomes. Education of the care team and a collaborative environment can foster greater focus on avoidance of complications.
Key points
- •
It is crucial to recognize and understand the potential complications associated with endovascular treatment of intracranial aneurysms.
- •
Understanding the complications associated with endovascular treatment of intracranial aneurysms allows the health care provider to account for several measurements that could potentially avoid the complications and provide more efficiency in their treatment.
- •
Improved patient selection for endovascular treatment, meticulous planning and preparation of the procedure, anticipating potential complications and preparing for management, building databases that include patients’ outcomes assessment, and allowing peer rating and feedback on operative skill can all help to avoid complications.
- •
The importance of the operator’s expertise cannot be overemphasized in the prevention and successful management of these complications.
- •
Current advancements in simulation, 3-dimensional printing, and holography can potentially play a crucial role in training the novices in endovascular management of intracranial aneurysms and increasing the level of proficiency of the graduating physicians, thus decreasing the incidence of complications.
Introduction
Complications associated with the endovascular management of intracranial aneurysms can be devastating. Successful patient management requires vigilant avoidance, recognition, and management of complications. Both neurologic and nonneurologic complications can occur. Several patient-related and procedure-related parameters can increase the incidence of complications. Reduction of complication rates can be achieved by careful patient selection, meticulous planning and preparation for the procedure, anticipating potential complications, and preparing for their management. Tracking outcomes and a robust case conference for discussion of cases and complications can further enhance outcomes. Education of the care team and a collaborative environment can foster greater focus on complication avoidance. This article reviews complications associated with the endovascular management of intracranial aneurysms, focusing on risk factors, avoidance, recognition, and management.
Introduction
Complications associated with the endovascular management of intracranial aneurysms can be devastating. Successful patient management requires vigilant avoidance, recognition, and management of complications. Both neurologic and nonneurologic complications can occur. Several patient-related and procedure-related parameters can increase the incidence of complications. Reduction of complication rates can be achieved by careful patient selection, meticulous planning and preparation for the procedure, anticipating potential complications, and preparing for their management. Tracking outcomes and a robust case conference for discussion of cases and complications can further enhance outcomes. Education of the care team and a collaborative environment can foster greater focus on complication avoidance. This article reviews complications associated with the endovascular management of intracranial aneurysms, focusing on risk factors, avoidance, recognition, and management.
Risk factors
Patient-Related Risk Factors
Age
Using the National Inpatient Sample (NIS) database, Lawson and colleagues retrieved data on 14,050 patient admissions and concluded that endovascular procedures may confer greater risks than aneurysmal rupture in patients older than 80 years. On the other hand, patients younger than 70 years may have greater benefits from endovascular coiling. Similarly, Brinjikji and colleagues collected data from the NIS on patients undergoing clipping or coiling of unruptured intracranial aneurysms in the United States between 2001 and 2008 to assess the effect of age on clinical outcome. Their analysis showed that for both treatment groups, morbidity and mortality rates increased with age yet were more pronounced in the surgical group. Furthermore, the biggest difference in outcome was seen in the age group of 80 years and older, whereby morbidity reached 33.5% for clipping versus 9.8% for coiling ( P <.0001) and mortality reached 21.4% for clipping versus 2.4% for coiling ( P <.0001). On a more specific level, rising trends of morbidity and mortality with age were also seen in patients undergoing endovascular coiling, starting respectively from 3.5% and 0.6% in the age group younger than 50 years, to 0.5% and 4.0% in patients aged 50 to 64 years, to 0.8% and 6.9% in patients aged 65 to 79 years, and reaching 2.4% and 9.8% in those older than 80 years. Fifi and colleagues conducted a retrospective study to assess clinical predictors of complications in 3636 diagnostic catheter cerebral angiograms at a single center. Among predictors including patient age, sex, inpatient versus outpatient status, and indications for angiography, only age older than 65 years was significantly associated with development of complications. Patients in this age group were 4 times more likely (95% confidence interval 1.268–13.859) than younger patients to develop procedural complications. Similar findings were reported by Willinsky and colleagues, who evaluated prospectively a total of 2899 cerebral digital subtraction angiograms to determine risk factors for neurologic complications related to cerebral angiography. Patients aged 55 years and older were found to be significantly more prone than their younger counterparts to develop neurologic complications (1.8% vs 0.9%, respectively; P <.035). Although age seems an important risk factor to take into consideration, it may be difficult to determine a specific cutoff beyond which risks of endovascular procedures would significantly increase, as cutoff ages have been shown to vary among studies.
Cerebrovascular risk factors
Cerebrovascular risk factors have been implicated in increasing the risk of neurologic complications following cerebral angiography. Of these, stroke and transient ischemic attacks (TIAs) have been shown to increase the rate of complications the most. Cloft and colleagues conducted a meta-analysis to assess patients who presented with subarachnoid hemorrhage, cerebral arteriovenous malformation, and aneurysms. The risk of transient and permanent neurologic complications was found to be greater in the presence of TIAs and strokes (3.7%) than in patients with subarachnoid hemorrhage (1.8%) or aneurysms/arteriovenous malformations (0.3%).
Cardiovascular risk factors
The presence of cardiovascular risk factors such as elevated blood pressure, diabetes, and heart failure also has an impact on the risk of procedural complications. A systolic blood pressure of more than 160 mm Hg appears to be significantly associated with the risk of complications. In their prospective study, Earnest and colleagues found an increased risk of local (small hematomas) and neurologic complications with the presence of systolic blood pressure greater than 160 mm Hg. Similar findings were also reported by Willinsky and colleagues, who noted a 2.3% risk of complications in patients with a history of cardiovascular disease. Diabetes was found to increase the risk of neurologic complications between 24 and 72 hours following cerebral angiography procedures.
Renal and hydration status
Although contrast-induced nephropathy (CIN) is a well-known complication of angiography with severe consequences, its incidence has decreased remarkably since the advent of nonionic contrast media. In the absence of other causes of renal damage, CIN can be defined as a decline in renal function with more than 25% increase in serum creatinine levels within 24 hours following exposure to contrast agents. The risk of CIN tends to increase with the presence of comorbidities such as diabetes and heart failure, in addition to a state of hydration before endovascular procedures. Earnest and colleagues found that elevated serum creatinine levels and overall poor preprocedural renal status were associated with a higher risk of neurologic complications. With a significant amount of information on CIN now available in the cardiac literature with a reported average complication risk of 14% in patients undergoing diagnostic procedures for coronary intervention, there is wide consensus that patient hydration is an effective way to prevent the development of CIN. However, there is controversy regarding adjuvant empiric steps such as the use of N -acetylcysteine (NAC) or sodium bicarbonate. Some studies of coronary angiography reported benefit with the administration of NAC even after the use of moderate and high doses of contrast agent. By contrast, other studies reported no benefit from the use of NAC compared with normal saline alone. This finding has also been confirmed recently by the Acetylcysteine for Contrast-Induced Nephropathy Trial (ACT), which showed no advantage of NAC in preventing CIN in patients undergoing vascular or coronary angiography. As for sodium bicarbonate, there exists even more controversy regarding its usefulness as a renoprotective agent. In a retrospective study conducted at the Mayo Clinic involving 7977 patients, findings show that administration of sodium bicarbonate may have harmful effects in comparison with saline.
Procedural-Related Risk Factors
Type of contrast agent
Several studies have compared ionic and nonionic contrasts in endovascular interventions, with varying results in relation to the rate of complications. In a prospectively reviewed series of 230 arch and carotid arteriograms that used ionic contrast agents in 98 patients and nonionic contrast agents in 132 patients, McIvor and colleagues found no significant difference in neurologic outcome. On the other hand, Skalpe evaluated neurologic complications of 1509 cerebral angiograms that used ionic contrast agent in a comparison with 1000 angiograms that used nonionic contrast. He found higher complication rates with ionic agents (2%) than with nonionic agents (1.3%). Whereas some studies have linked the use of ionic agents in angiography to an increased risk of renal damage and cerebrovascular complications, with respect to nonionic contrast agents the evidence may be controversial.
Volume of injected contrast agent
The volume of injected contrast agent appears to be related to an increased risk of procedural complications. Dion and colleagues found that using high volumes of contrast agent increased the risk of neurologic events in the first 24 hours ( P = .03) and between 24 and 72 hours ( P = .001) following cerebral angiography procedures. There was also an increased risk of nonneurologic events, especially wound hematomas of less than 5 cm in diameter ( P <.00001).
Time of the procedure
An increase in procedural time has been associated with an increased risk of complications and overall patient clinical outcome in a wide range of surgical specialties. Mani and Eisenberg assessed the procedural time of 4795 consecutive cerebral angiograms and reported a high complication rate when the time of procedure surpassed 80 minutes ( P <.01). Similar conclusions were also drawn by Heiserman and colleagues, who analyzed 1000 cerebral angiograms. Nevertheless, many investigators consider fluoroscopy time to be an important measure of procedural difficulty. In their study, Willinsky and colleagues found that the rate of neurologic complications increased significantly after 10 minutes of fluoroscopy time.
Catheter exchange
Frequent catheter exchange and manipulation during endovascular procedures may reflect the difficulty of the case at hand (tortuous vasculature) or even the inexperience of the operator, and several studies have reported higher rates of neurologic complications with increased number of catheters used. Dion and colleagues noted an increasing trend of neurologic complications in the first 24 hours following cerebral angiography when 3 or more catheters were used ( P = .08). Nonneurologic complications, especially small wound hematomas, also increased significantly in relation to the number of catheters used ( P <.00001). Even more than 24 hours following the procedure, frequent catheter use was associated with higher rates of neurologic complications and was found to be a prognostic indicator for patients’ neurologic outcome, irrespective of their diagnosis or complexity of the lesions.
Operator experience
Whereas some studies did not show an association between operator experience and the rate of neurologic complications, many others have demonstrated higher complication rates with inexperienced hands. Mani and colleagues retrospectively analyzed 5000 cerebral angiograms and found an increased rate of procedural complications in training hospitals in comparison with nontraining hospitals (3.9% vs 0.9%), but the rate of permanent complications was similar in both groups (0.1%). On the other hand, Willinsky and colleagues compared procedures done by faculty members and those by fellows alone but did not find a difference in the rate of neurologic complications, although this rate seemed to increase when the procedures were jointly performed by faculty members and fellows. However, in many of these instances the patient had been older with a worse disease history.
Technique
A complete review of aneurysm coiling techniques is beyond the scope of this article, but it is worth mentioning some nuances of aneurysm coiling as they relate to complication avoidance. Femoral-access complications can be minimized by careful attention to anatomic landmarks and thoughtful use of fluoroscopy to avoid traumatic placement of a sheath. Radial access should be considered in selected cases if femoral access is not feasible or is considered high risk. Guide-catheter placement in the target cervical vessel should be done carefully to avoid complications. Newer guide catheters have dramatically enhanced the stability and safety of such catheters. Three-dimensional angiography has proved to be a useful tool to optimize working views and the understanding of what can be highly complex anatomy. Microcatheter placement in the target aneurysm should be approached with caution and high-magnification road-map fluoroscopy. Sizing of the coils and their choice should be methodical, and the placement of every loop should be carefully monitored. It is important to avoid placing very small coils at the neck, which are not interwoven into the coil matrix, to avoid distal embolization. When a stent is needed the authors typically jail the catheter in the aneurysm first. Though not necessary, the authors have found that this technique avoids the need to traverse a newly paced stent, which can be difficult occasionally. Knowing when to stop adding coils is as much art as it is individual. Although complete aneurysm occlusion is ideal, leaving a neck remnant may be a good tradeoff in favor of safety. Staging may be needed in complex scenarios. Final angiography should carefully rule out dissections and thromboembolic complications. Closure of the access site should be meticulous to avoid hemorrhagic and ischemic complications. Because of the potential for aneurysm recurrence after coiling, a clear follow-up plan must be in place and carefully explained to the patient.
Complications
Thromboembolic
Despite their low risk of occurrence, clinically relevant ischemic events associated with endovascular treatments of intracranial abnormalities can be serious. In diagnostic cerebral angiography, the rate of permanent neurologic deficits is estimated to be 0.14% to 0.50%. Moreover, with the emergence of diffusion-weighted magnetic resonance imaging (DW-MRI) techniques, clinically silent ischemic events appear to be associated with cerebral angiographic procedures in 10% to 40% of cases. In a study that included 72 patients who underwent DW-MRI before and after cerebral angiographic procedures, Park and colleagues reported 1 to 23 lesions in 37 patients. Most of these lesions were smaller than 5 mm and lacunar in nature. Interestingly these lesions occurred in vessels that were not directly related to the endovascular treatment, and were lodged mostly in the cerebral cortical border zone area and the cerebellar hemispheres rather than deep perforating arterial territories. Although clinically silent, these “soft” infarcts have the potential to cause neurocognitive impairments. The microemboli occurring during endovascular treatment of aneurysms can be either gaseous or thrombotic. Air emboli can appear when drawing the syringe quickly after contrast injection, during catheter flushing, and when exchanging guide wires. Thrombotic emboli can be dislodged from intravascular plaques while manipulating the catheter, or can propagate from a thrombus originating at the catheter tip. In an attempt to decrease the incidence of thromboembolic complications, Bendszus and colleagues conducted a prospective study in which they performed 150 cerebral angiography procedures randomized to 50 procedures using either a conventional angiographic technique, systemic heparin treatment throughout the procedure, or air filters between the catheter and both the contrast-medium syringe and catheter flushing. DW-MRI performed before and after the procedure revealed 18 lesions in 11 patients in the control group, and 4 lesions in 3 patients in each of the heparin and air-filter groups. The study concluded that air filters and heparin reduce the incidence of silent strokes ( P = .002) and have the potential to lower clinically overt ischemic events.
Thromboembolic Complications Associated with Treatment of Endovascular Aneurysms
Thromboembolic events resulting from endovascular coiling of cerebral aneurysms is estimated to be 8.2%. There are several potential mechanisms: coil migration into the vessel lumen and distal migration, dislodgment of a preexisting intra-aneurysmal thrombus, thrombus formation in the aneurysmal remnant after incomplete obliteration of the aneurysm, and endothelial injury. Most of these events occur preoperatively; therefore, although heparin is not routinely administered in diagnostic cerebral angiography, it is recommended to administer early anticoagulation during endovascular coiling of unruptured intracranial aneurysms. Several studies have advocated the additional use of heparin postoperatively in unruptured aneurysms to further decrease the incidence of thromboembolic events, although this can be challenging for ruptured aneurysms. In a meta-analysis, Qureshi and colleagues advocated that the postoperative administration of heparin is beneficial only in cases of coil migration and the presence of cerebral ischemia. Exact guidelines for ruptured aneurysm coiling are lacking. An option could be to administer half the dose of heparin at the beginning of the procedure and the other half after the first coil is secured in the aneurysm.
There is evidence from coronary angiography and coronary endovascular interventions that antiplatelet therapy before intervention has the potential to decrease the risk of thromboembolic complications. Aspirin and/or clopidogrel administration may therefore form an integral component for prevention of thromboembolic complications in endovascular management of intracranial aneurysms. The general trend is to administer aspirin and clopidogrel simultaneously in aneurysmal coiling, especially when a stent might be needed. In a retrospective study, Hwang and colleagues reviewed 328 aneurysms treated with elective coil embolization by microcatheter technique. The investigators compared 3 groups of patients: group 1 (95 cases) received no antiplatelet therapy, group 2 (61 cases) received either aspirin or clopidogrel, and group 3 (172 cases) received both aspirin and clopidogrel. There was no significant difference in the thromboembolic rate in the group that received antiplatelet therapy compared with the group that did not receive antiplatelet therapy (1.8% without antiplatelet, 2.2% with antiplatelet; P = 1.00) in the cases where the aneurysms were simple and noncomplex. However, in the cases of complex aneurysm configuration that necessitated the use of multiple catheters, there was a significant reduction in the rate of thromboembolic events in patients who received antiplatelet therapy compared with those who did not (12.8% no antiplatelet vs 2.1% with antiplatelet; P = .023). Overall, there was an 85.2% reduction in thromboembolic events. Furthermore, there was no increase in hemorrhagic complications in unruptured aneurysms with antiplatelet therapy ( P = .171). The investigators concluded that complex aneurysmal configuration should prompt the use of antiplatelets (aspirin 100 mg/d and clopidogrel 75 mg/d for at least 5 days before coiling) to reduce the risk of thromboembolic events. The results of this study are in accord with those of other studies that demonstrated the importance of antiplatelet administration before endovascular coiling of intracranial aneurysms to decrease the risk of procedure-related thromboembolic events. Heparin administration after endovascular access at the beginning of a case to achieve activated coagulation time of 250 to 300 seconds is common practice. In general it is likely preferable to avoid antiplatelets in most patients presenting with ruptured intracranial aneurysms, as they can increase the risk of hemorrhage.
Intraoperative Rupture or Rerupture
Intraoperative aneurysmal rupture or rerupture can be devastating complications in the endovascular treatment of intracranial aneurysms. Aneurysmal rupture and rerupture can manifest with either frank extravasation of the contrast from the aneurysmal dome or sluggishness of flow, and should be suspected whenever there is abrupt change in vital signs and/or an increase in intracranial pressure (ICP). Pierot and colleagues conducted a prospective study involving 739 unruptured intracranial aneurysms treated selectively by coils alone (50.4%), balloon remodeling (37.3%), or stenting (7.8%). The investigators reported an intraprocedural risk of aneurysmal rupture in 2.6% of the cases, with 27.8% permanent clinical consequences and a 16.7% mortality rate. Intraoperative aneurysmal rerupture occurs in 3% to 5% of ruptured cases, and is associated with very high mortality rate ranging from 30% to 100%. The presence of intraprocedural aneurysmal rupture or rerupture should prompt immediate management and control. Inflating a balloon at or proximal to the neck can allow control while further packing of the aneurysm is achieved. Placement of an external ventricular drain should be considered once the aneurysm bleeding has been controlled. Under select circumstances, the patient may need to be taken to the operating room to undergo an emergent craniotomy to evacuate a hematoma and clip the ruptured aneurysm. Craniotomy may be needed to manage ICP.
Vascular Dissections
Iatrogenic vascular dissections are uncommon complications of neuroendovascular procedures with a mostly benign course, occurring at rates ranging from 0.14% to 0.4%. The clinical manifestation of an arterial dissection varies based on the vessel involved and the occlusive nature of the dissection. Most of the nonocclusive dissections can undergo resolution, especially when a patient’s initial manifestations do not involve ischemic symptoms. Several studies have reported that iatrogenic arterial dissection can occur more frequently during interventional procedures in comparison with diagnostic cerebral angiography alone. However, Cloft and colleagues reviewed 2437 diagnostic cerebral angiography cases and 675 endovascular interventional procedures, and reported 12 cases of arterial dissection (focal, <3 cm) in total, divided into 0.3% in the diagnostic cerebral angiograms and 0.7% in the neurointerventional procedures, with no statistical significance in the difference between the 2 groups ( P >.1). The investigators reported that none of the patients who had dissections developed ischemic symptoms, although one was noted later to have a small asymptomatic infarction in the region fed by the dissecting artery. Nine of these patients showed improvement of arterial lumen compromise on follow-up angiography after medical treatment, and the remaining 3 had conditions that remained unchanged. Two patients developed pseudoaneurysms that remained asymptomatic after a 9-month follow-up period. It was noted that most dissections occurred at the time of contrast-material injections, which can damage the arterial lumen when the jet flowing from the catheter tip hits the arterial wall. Furthermore, arterial luminal damage can occur during the manipulation of the catheter and guide wire. The investigators concluded that arterial dissections may be prevented by paying particular attention to the angiogram during test injections. Moreover, the operator can minimally retract the catheter after the tip is in position to dissipate the remaining tension and avoid its erosion over the intima. The authors recommend treatment with systemic heparinization followed by bridging to warfarin or switching to antiplatelet therapy. Surgery and other interventional procedures should be used as a last resort when medical therapy fails and ischemic symptoms progress.
Puncture-Site Hematoma
Puncture-site hematomas are common complications of neuroendovascular procedures. Their occurrence is not linked to the arterial-site puncture and can follow radial, brachial, or femoral access. Kaufmann and colleagues reviewed retrospectively 19,826 patients who underwent diagnostic cerebral angiography and reported arterial site hematoma as the most common complication, occurring with an overall rate of 4.2%. In a prospective study on 1002 cerebral angiographic procedures, Dion and colleagues reported that hematoma was the most common complication, occurring in 6.9% of cases. Advanced age was a risk factor for hematoma formation, as 50% of patients with hematoma were older than 60 years. One-third of those patients who were older than 70 years necessitated fluid replacement or surgical repair of the hematoma. Other risk factors included contrast volume, the number of guide wires used, the use of 3 or more catheters, catheters with a caliber higher than 6.5F, hypertension, procedural duration of more than 60 minutes, and the presence of TIAs at presentation. In a prospective study of more than 1500 cerebral angiograms, Earnest and colleagues reported a 4.4% rate of hematoma formation that was associated with advanced age. Another study by Fifi and colleagues reviewed 3636 cerebral angiograms, and reported that access-site hematoma accounted for 50% of the complications and was noted in 0.15% of the cases.
Arterial closure devices (ACDs) can efficiently seal the arteriotomy site, and have been proved to be safe and effective even in patients on antiplatelet or anticoagulation therapy. In their multicenter study comparing 1162 patients who received ACDs with 1162 patients managed by manual compression, Allen and colleagues reported that major bleeding significantly decreased in patients treated with ACDs (2.4% vs 5.2%, P <.001). Furthermore, the use of ACDs significantly reduced both the formation of pseudoaneurysms (0.3% vs 1.1%, P = .028) and the duration of hospitalization (1.9 ± 1.9 vs 2.3 ± 5.3 days, P = .007). Despite many studies proving the efficacy of ACDs, a meta-analysis conducted by Das and colleagues, which included 24 studies and more than 3600 patients, demonstrated no statistically significant difference in complications when comparing ACDs with manual compressions but marginally fewer complications with the use of ACDs were noted (odds ratio 0.87, 95% confidence interval 0.52–1.58; P = .13). The investigators reported that many of the included studies had poor methodology, and emphasized the need for randomized controlled studies to further evaluate the usefulness of ACDs.
A thoughtful approach to patient care and technique can help reduce complications. There are 5 areas worth emphasizing: (1) patient selection, (2) meticulous planning and preparation, (3) anticipation of potential complications, (4) careful and meticulous technique, and (5) careful review of results.
- 1.
A complete knowledge and understanding of the natural history of intracranial aneurysms and their treatment options, a careful assessment of the patient’s risk factors, and a thorough evaluation of the patient in his or her bio-psycho-social background are the most important steps in preventing complications. Other alternatives should be carefully considered in each case (eg, open surgical treatment vs observation). Wide aneurysm neck size, poor dome to neck ratio, and difficult access can all increase risk.
- 2.
When the decision for endovascular treatment of the aneurysm is made, the patient’s medical condition should be reviewed and optimized.
- 3.
The physician should be aware and prepared for the worst-case scenario. Anticipating complications is one way to minimize them.
- 4.
Although not reviewed in this article, case volume and high-quality training have an impact on results and avoidance of complications. Meticulous attention to detail in the procedure is clearly important. Balancing efficiency with caution is an art that should be respected and embraced.
- 5.
Careful assessment of results can help minimize complications. Birkmeyer and colleagues conducted a study involving 20 bariatric surgeons who submitted videotapes of themselves while performing a laparoscopic gastric bypass. These videotapes were used by peer surgeons to evaluate the technical skills of the performing physicians on a scale of 1 to 5 (higher number indicating higher performance). Across the 20 bariatric surgeons, the scores ranged from 2.6 to 4.8, and in comparison with the top quartile the bottom quartile was shown to have higher complication rates (14.5% vs 5.2%, P <.001), higher mortality (0.26% vs 0.05%, P = .01), longer operations (137 minutes vs 98 minutes, P <.001), higher rates of reoperation (3.4% vs 1.6%, P = .01) and higher readmission rates (6.3% vs 2.7%, P <.001).
Related posts:
General Technical Considerations for the Endovascular Management of Cerebral Aneurysms
Endovascular Management of Cavernous and Paraclinoid Aneurysms
Cerebral Vasospasm
Vertebrobasilar Fusiform Aneurysms
Endovascular Management and Treatment of Acute Ischemic Stroke
Endovascular Management of Intracranial Atherosclerosis
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
