Article Text
Abstract
Introduction The management of unruptured intracranial aneurysms in the elderly remains controversial. Treatment risks are thought to be higher in this group. Large series assessing endovascular treatment of unruptured intracranial aneurysms in the elderly are lacking. Our single center endovascular experience in treating unruptured intracranial aneurysms in the elderly is presented.
Methods 77 patients, 70 years or older, were referred to the endovascular neurosurgery service for treatment of an unruptured intracranial aneurysm between February 2000 and May 2008. Hospital records, operative reports, angiograms and radiology reports were reviewed and analyzed retrospectively.
Results 99 aneurysms were treated in 77 patients in 102 procedures. Mean patient age was 75±4 years, and the average aneurysm size was 11±7 mm. Adjuvant techniques were used in 66% of cases. Endovascular procedures included coiling alone (32%), balloon assisted coiling (19%), stent assisted coiling (37%), balloon assisted stent and coiling (8%), stent only (1%) and glue (2%). The permanent morbidity and mortality rates were 1% and 3%, respectively. Four adverse events were attributed to the patient's age. Posterior circulation aneurysms were associated with more adverse events (41%) than anterior circulation aneurysms (14%). Endovascular treatments using adjuvant techniques were associated with a higher complication rate than coiling alone.
Conclusions With only a 4% permanent rate of neurological morbidity and mortality, endovascular treatment of unruptured aneurysms can be performed safely in the elderly. Age should not be the limiting factor when considering endovascular therapy.
- Aneurysm
- Coil
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Developed nations are experiencing an unprecedented growth in their elderly populations. Thanks to the modernization of both society and medical care, life expectancy in the USA has nearly doubled over the past century. A 65-year-old person can now anticipate an additional 17 years of life and an 80-year-old an additional 8 years. The optimal management of patients with unruptured aneurysms remains undefined, especially with regard to the elderly population. The presence of symptoms from an unruptured aneurysm is believed to increase the risk of subsequent bleeding and has traditionally been considered a valid indication for treatment. It is generally accepted that asymptomatic unruptured aneurysms are less prone to bleeding than their symptomatic counterparts, and the natural history of asymptomatic unruptured aneurysms has been the focus of considerable discussion.
The decision making process for the optimal treatment strategy for an elderly patient with an asymptomatic unruptured aneurysm represents a vexing medical challenge. The decision to treat or to observe an unruptured aneurysm in the elderly population requires an honest assessment of the treatment related risks, a careful estimation of the involved individual's life expectancy and a precise knowledge of the natural history of the disease process. Such information will assist practicing neurosurgeons in counseling elderly patients and their families on whether to treat an aneurysm. Unfortunately, the literature contains only limited data about the feasibility of endovascular treatment in elderly patients with unruptured cerebral aneurysms. We present our single center endovascular experience in treating unruptured intracranial aneurysms in the elderly.
Materials and methods
Clinical material
A prospectively collected database of patients referred to the endovascular neurosurgery service was reviewed. All patients aged 70 years and older who were treated for unruptured intracranial aneurysms by the endovascular neurosurgery service at the Barrow Neurological Institute between January 2000 and April 2008 were identified. January 2000 was chosen as the initial date because that was the first entry into the electronic database. Hospital records, operative reports, office charts and radiologic reports were reviewed to identify perioperative complications that occurred during the 30 day postoperative period. Aneurysms that were treated for a recurrence during the study period were counted as a second aneurysm treatment.
Embolization procedure
All procedures were performed with the patient under general anesthesia on a biplane angiographic unit with somatosensory evoked monitoring and electroencephalography. Brainstem auditory evoked responses were monitored during embolization of posterior circulation aneurysms. Most of the procedures were performed via a femoral artery approach; three were performed via brachial access. Percutaneous femoral artery catheterization was used to achieve access in all patients. Patients were heparinized to maintain activated clotting times between 200 and 300 s. Standard coaxial techniques were used. Guide catheters were navigated into the appropriate parent vessel. Microcatheters were advanced into the selective branches and then into the lumen of the aneurysm. Patients undergoing stent assisted coiling were placed on aspirin and clopidogrel at least 3 days before the procedure.
Results
Ninety aneurysms were identified in 77 patients (20 men, 57 women, mean age 75±4 years, age range 70–90 years) (table 1). Seventy aneurysms were located in the anterior circulation and 20 were in the posterior circulation. Mean aneurysm size was 11 ±7 mm. Fifty-six aneurysms (62%) were asymptomatic at the time of presentation. Thirty-four patients (38%) were symptomatic. Clinical symptoms included headaches for 12 aneurysms (13%); transient ischemic attack or stroke for seven (8%); cranial nerve deficits for six (7%); and neurological deficits from mass effect such as confusion, ataxia and hemiparesis for nine (10%).
Size and location of aneurysms
Of the 90 aneurysms treated, nine required a second treatment for a recurrence. Altogether, 99 aneurysms were treated (table 2). Thirty aneurysms were smaller than 7 mm. Forty-two aneurysms undergoing endovascular therapy were 7–12 mm. Twenty aneurysms ranged between 13 and 24 mm. Seven aneurysms were giant, measuring more than 25 mm (table 2). The mean size of aneurysms in the anterior circulation was 9.4±5.5 mm. These aneurysms were located on the posterior communicating artery (n=25), anterior cerebral artery (n=15), paraclinoid internal carotid artery (n=11), cavernous carotid (n=10), ophthalmic artery (n=7), internal carotid artery bifurcation (n=5) and middle cerebral artery (n=3). Aneurysms in the posterior circulation were significantly larger than those in the anterior circulation (mean 14.5±8.5 mm; p<0.05) and involved the basilar apex (n=8), posterior inferior cerebellar artery (n=4), superior cerebellar artery (n=4), vertebral artery (n=4) and posterior cerebral artery (n=3).
Endovascular procedures
Altogether, 102 endovascular procedures were completed for the treatment of unruptured cerebral aneurysms: 98 embolization procedures, three stents as part of a staged procedure and one stent alone (table 3). One aneurysm was treated with a superficial temporal artery-to-middle cerebral artery bypass followed by coil occlusion. Two patients each had two distinct aneurysms embolized during the same endovascular procedure. Ninety procedures, not including the staged stenting, were performed in aneurysms that were newly diagnosed, and nine were performed for aneurysm recurrences.
Coil embolization was used as a standalone treatment for 32 aneurysms: 26 (34%) aneurysms in the anterior circulation and six (26%) aneurysms in the posterior circulation. Adjuvant techniques were used to assist with coil embolization in 65 cases: 49 in the anterior circulation and 16 in the posterior circulation (table 3). Forty-six aneurysms were treated with or planned for stent assisted coiling: 42 during the same procedure and three as part of staged procedures. One aneurysm was planned for staged stent assisted coiling and was treated only with stenting. Six aneurysms were treated with balloon remodeling and stent assisted coiling. Nineteen aneurysms were treated with balloon remodeling without a stent. Sixty-four per cent of the anterior circulation aneurysms were treated with stenting (n=27), balloon remodeling (n=16) or balloon assisted stent coiling (n=6). Seventy per cent of posterior circulation aneurysms required stenting (n=11), balloon remodeling (n=3) or balloon assisted stent coiling (n=2) of adjuvant techniques. Two aneurysms, one in the anterior circulation and one in the posterior circulation, were embolized with n-butyl cyanoacrylate (n-BCA) glue.
Complications
The permanent morbidity and mortality rates were 1% and 3%, respectively. Four adverse events were identified as due to patient age: a 75-year-old patient suffered a myocardial infarction; a 71-year-old patient who walked with a cane developed deep venous thrombosis; a 73-year-old patient who lived alone was readmitted 1 week after the procedure for dehydration; and a 73-year-old patient developed a vertebral artery dissection during the treatment of a 5 mm left posterior cerebral artery aneurysm.
Thromboembolic events, transient ischemic attack, stroke and hemorrhage were the most common causes of adverse events and represented eight of the 21 complications (see table 4 online, and tables 5 and 6). One patient had a permanent neurological deficit. At their follow-up examination, four patients were at their neurological baseline. One patient suffered a fatal subarachnoid hemorrhage and two patients died from strokes despite thrombolysis. Adverse events at the site of vascular access were the second most frequent complication; four patients had either a hematoma or thrombus. Other complications included a seizure, parotiditis, perforated colon, hematuria and hemorrhage from the endotracheal tube in one patient each.
Complications appeared to be related more to the method of treatment than to patient age. Coiling alone, the safest treatment modality in the series, was associated with a 6% complication rate (two of 32 cases) (table 6). One patient experienced an asymptomatic vessel dissection, and one had a thromboembolic event that resulted in a permanent neurological deficit. The use of adjuvant techniques was associated with higher complication rates than coiling alone. Of the 21 patients undergoing stenting or balloon remodeling, 19 had adverse events. When all complications were considered, stent assisted coiling was associated with a 27% complication rate, balloon assisted coiling with a 26% complication rate and balloon assisted stenting with a 38% complication rate.
Of the 65 patients that required adjuvant techniques with coiling, seven (11%) experienced a complication that was directly associated with the use of a stent or balloon: six thromboembolic events and one fatal subarachnoid hemorrhage (table 6). Balloon remodeling and stent assisted coiling were both associated with an 11% thromboembolic event rate. Two patients had thromboembolic events after balloon assisted coiling but neither resulted in a permanent neurological deficit. Four patients had thromboembolic complications after stenting: two patients had no permanent sequelae and two patients died. Of the 46 patients who underwent stenting, two died from thromboembolic complications and one from subarachnoid hemorrhage.
When assessed by anatomical location, posterior circulation aneurysms were associated with a higher adverse event rate (41%) than those in the anterior circulation (14%). Eleven interventions for aneurysms in the anterior circulation were associated with adverse procedural events: nine were transient, one was permanent and one patient died. Ten interventions for posterior circulation aneurysms were associated with complications, eight of which were transient. Two patients died after interventions in the posterior circulation. One patient with a 22 mm basilar apex aneurysm developed basilar thrombosis and stroke. The other patient, who had a 35 mm vertebrobasilar aneurysm, suffered a fatal subarachnoid hemorrhage 3 days after stenting.
Discussion
In the eighth decade of life, the incidence of subarachnoid hemorrhage is 40–78 per 100 000 per year.1 2 Whether endovascular therapy should be performed according to an age related category is often questioned. Unfortunately, the literature contains limited data about the feasibility of endovascular treatment in elderly patients with cerebral aneurysms. Studies on the use of endovascular therapies for carotid stenosis in elderly patients have revealed a higher risk for this subgroup of patients. Data on carotid artery stenting among elderly patients are modest; however, the Stent Protected Angioplasty versus Carotid Endarterectomy (SPACE) study reported a higher risk for patients older than 70 years.3 The lead-in phase for Carotid Revascularization Endarterectomy versus Stenting Trials (CREST) reported 749 carotid stent patients. The 30 day stroke and death rate was 12.1% in octogenarians which was significantly higher than that for patients aged 70–79 years (5.3%), 60–69 years (1.3%) and <60 years (1.7%).4 Chastain and colleagues5 reported a 30 day stroke, myocardial infarction and death rate of 25% among 24 octogenarians compared with 8.2% for 158 patients aged <80 years. A higher incidence of atherosclerotic diseases and tortuous vessels may explain the procedural complications in respect to thromboembolic events and therapy failure.
Endovascular treatment of unruptured aneurysms in the elderly
The optimal management of patients with unruptured aneurysms remains undefined, especially with regard to the elderly population. Studies on the treatment of aneurysms in the elderly find that the outcome in elderly patients is not associated with age but with the clinical grade of the aneurysm. Conservative treatment of ruptured aneurysms in elderly patients is known to be associated with poor outcomes.6 The International Study of Unruptured Intracranial Aneurysms (ISUIA) analysis found that patient age was an important factor in overall surgical outcome, with a substantial increase in risk for those 50 years and older, and even more so after 60–70 years.7 Conversely, endovascular morbidity and mortality seem to be less dependent on a patient's age, suggesting that this approach offers advantages for older patients.7 The individual life expectancy and the risk for aneurysmal rupture have to be estimated before a decision about therapy is made. The Massachusetts General Hospital published their experience with 129 aneurysms in patients older than 70 years: it included 51 unruptured aneurysms in 40 patients.8 Similar to our cohort, 80% of the aneurysms were in the anterior circulation and 7% were giant aneurysms. Unlike our series, the majority of patients (78%) were treated with open surgery whereas the remainder were treated solely with endovascular therapy or with a combination of surgery and endovascular techniques (13% and 5%, respectively).8 One patient in the unruptured cohort died. No information was reported on the use of stenting or balloon remodeling.8
In a smaller series, Moret and colleagues treated 63 elderly patients with aneurysms, 22 of which were unruptured.9 As in other series, most (84%) were in the anterior circulation and 53% were between 13 and 24 mm. Of the 22 unruptured aneurysms, 15 (65%) were located in the cavernous sinus. Treatment was primarily via coil embolization: 11% were treated with balloon remodeling and 4% were treated with stent assisted coiling. Parent vessel occlusion was used in 13% of the cases, primarily for large or giant aneurysms. Based on review of the entire cohort, 91% (20 of 22) of the patients with unruptured aneurysms achieved excellent outcomes (modified Rankin Scale score, 0–1). Two patients (9%) with unruptured aneurysms suffered fatal events.9
More recently, Gizewski and colleagues10 reported their experience in patients older than 65 years. There were 85 ruptured and 23 unruptured aneurysms. Therefore, conclusions must be drawn carefully. Complete occlusion of the aneurysm was achieved in 74% of patients. Technical difficulties occurred in 4% of cases. Complications included four (17%) thrombotic events in patients with unruptured aneurysms and five (6%) in those with acute subarachnoid hemorrhage. None of the patients with unruptured aneurysms sustained permanent neurologic symptoms, and overall outcomes for the 23 unruptured aneurysms were good.
Most of what can be concluded is based on extrapolation of data from studies that included both ruptured and unruptured aneurysms. Our series of 93 aneurysms in 80 patients represents the largest single center study on the endovascular treatment of unruptured aneurysms in the elderly.
Complications associated with stenting and balloon remodeling
Since the introduction of aneurysm coiling in the early 1990s, numerous devices and strategies have evolved to facilitate the treatment of large and complex aneurysms. These have included the development of coils with complex, three-dimensional shapes; the application of balloons to ‘remodel’ wide necked aneurysms11–13; and finally, the implementation of intravascular stents to ‘reconstruct’ the parent vessel giving rise to an aneurysm.14–21 These devices facilitate the embolization of aneurysms that would not otherwise be amenable to endovascular therapy.
The balloon assisted or neck remodeling technique11–13 was the first adjunctive technique intended to overcome the limitations of the conventional coiling in the treatment of wide necked and geometrically difficult aneurysms.22 23 Malek and colleagues24 reported balloon assisted coiling in 22 unruptured aneurysms. They had three (13.6%) technical complications and two (9%) cases of distal emboli.24 Nelson and Levy12 treated 22 patients and reported thromboembolic complications in 18%. Only one patient (4.5%) experienced a permanent neurological deficit. More recently, Sluzewski et al treated 71 patients with balloon assisted coiling. Their rate of procedure related complications leading to death or dependency was significantly higher in the balloon assisted coiling cases (14.1%) compared with those undergoing coiling alone (3%).13 We found that balloon assisted coiling, when all events were included, was associated with a 26% complication rate and an 11% thromboembolic rate. None of these patients experienced permanent neurological deficits.
The use of self-expanding stents has revolutionized endovascular treatment of intracranial aneurysms with wide necks or poor dome-to-neck ratios.16 18 20 21 25 26 Stents provide a buttress for the coil mass to minimize the risk of coil herniation into the parent vessel, allowing increased packing density15 and possibly creating a flow diversion.17 27 The thrombogenicity of endovascular stents, however, represents an important limitation with respect to the treatment of aneurysms. In the current series, stent assisted coiling was associated with an 11% thromboembolic rate. Benitez et al observed an 8.9% mortality rate and a 7% thromboembolic event rate in patients undergoing stent assisted coiling.16 Lylyk et al19 reported one of the largest series using stents, although not specifically designed for use in the cerebral vasculature. They placed cerebrovascular stents in 111 patients with either occlusive atherosclerotic disease or aneurysms. Their overall mortality and morbidity rates were 6.3% and 10.9%, respectively19 More recently, Lylyk et al reported procedure related morbidity and mortality rates of 8.6% and 2.1%, respectively, associated with stent assisted coiling procedures.20 Biondi et al25 reported a small series of stent assisted coiling cases performed with the Neuroform stent. Their 4.8% rate of morbidity and 2.4% mortality rate were relatively low. Akpek and colleagues14 reported a 13% thromboembolic rate with stenting. Previous reports from our institution on stent assisted coiling found thromboembolic events in 9% of patients. All age groups were included and the mean age of patients was 58.6 years.18 26 More recently, the Enterprise Stent Multicenter Registry reported 143 attempted stent deployments.21 Morbid events occurred in 13 cases (9%), of which four were permanent (2.7%) and nine were temporary (6%).21 Temporary events were similar to what we observed and included access related events.21 In the entire Enterprise Registry, the permanent morbidity rate was 2.8% and the mortality rate was 2%.21
The thrombogenicity of microcatheter balloons and endovascular stents represents an important limitation with respect to the treatment of aneurysms. The utilization of stenting or balloon remodeling requires a rigorous pre-, peri- and postprocedural pharmacological regimen to help reduce thromboembolic events.17 18 21 As a result, dual antiplatelet regimens have been established. In our study, patients treated with adjuvant techniques had higher complication rates than those who underwent coiling alone. Bleeding complications at the arteriotomy site represent a relatively frequent problem in patients who undergo intracranial stenting. These complications are the sequelae of pretreatment with dual antiplatelet agents in conjunction with systemic anticoagulation during and after the procedure. In an attempt to reduce the incidence of complications in the groin area, we routinely use an arterial closure device at the conclusion of the procedure.17 18 Overall, our complication rates in this elderly cohort was well within the range of those reported previously and in the general endovascular population.28 29
Conclusion
Our permanent morbidity and mortality rate of only 4% supports the fact that elderly patients with unruptured aneurysms can safely undergo endovascular treatment with acceptable complication rates.7 8 10 30 The cumulative bleeding rate of an unruptured aneurysm is approximately 10.5% in 10 years after diagnosis.31 Therefore, even elderly patients have a relevant risk of hemorrhage within their expected life span. Moreover, additional risks such as the smoking status of the patients, a multiplicity of aneurysms and a family history of bleeding are relevant considerations for elderly patients just as they are for the average population.32
Endovascular treatment of unruptured aneurysms in the elderly remains controversial. Together with known risk factors for bleeding, the therapeutic procedure should be individually tailored for each patient. The use of adjuvant techniques is associated with a higher complication rate than coiling alone. However, these rates do not differ significantly in the elderly compared with overall published complication rates. Balloon assisted coiling should be considered if conventional coiling alone has failed and the anticipated surgical risks are too high. Based on our 4% combined morbidity and mortality rate and on other analyses,7 8 10 30 the conclusion can be drawn that no patient should be excluded from treatment of an unruptured aneurysm because of age.
References
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Footnotes
Competing interests None.
Ethics approval This study was conducted with the approval of the hospital's internal review board.
Provenance and peer review Not commissioned; not externally peer reviewed.
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