The pathogeneses of both thoracic aortic aneurysm (TAA) and intracranial aneurysm (ICA) share common pathologic mediators. However, the prevalence of ICA in patients with TAA is not known. The present study investigated the prevalence of concurrent ICA to determine whether patients with TAA should be screened for ICA. The records of 212 patients with TAA and concurrent brain images (computed tomographic angiograms or magnetic resonance angiograms) were retrospectively analyzed. A bivariate statistical analysis (Fisher’s exact test) was used to compare the subgroups. We found that patients with TAA had a 9.0% prevalence of ICA (19 of 212 patients), ninefold greater than that in the general population. Also, the location of the TAA influenced the prevalence of ICA. The prevalence of ICA in patients with a descending TAA was significantly greater—33% (5 of 15 patients)—than the prevalence (7.1%) in patients (14 of 197 patients) with an ascending TAA (p = 0.006). Hypertension also increased the prevalence of concurrent ICA: 18 (11.8%) of 153 patients with hypertension and a TAA had concurrent ICA, but only 1 (1.7%) of 59 normotensive patients with a TAA had an ICA (p = 0.03). A history of cigarette smoking increased the risk of an ICA. Race, age, and gender did not significantly affect the prevalence of concurrent ICA. In conclusion, patients with a TAA are at increased risk of having an ICA. We suggest that patients with a TAA be screened for an ICA.
Understanding the prevalence of intracranial aneurysm (ICA) in the setting of concurrent thoracic aortic aneurysm (TAA) is important not just for long-term patient health, but also perioperatively. Empirical observations by our group have pointed to an increased risk of ICA rupture after surgical TAA repair (2 patients). Although aneurysm rupture rates can vary by aneurysm size and underlying defects, subarachnoid hemorrhage secondary to ICA rupture has been associated with substantial morbidity and mortality: 40% of hospitalized patients die within 1 month and >30% of survivors have persistent neurologic deficits. In contrast, the rate of adverse outcomes after treatment of unruptured ICA has been as low as 1%. Measures such as strict postoperative blood pressure control can also be taken in the setting of a known ICA to reduce the risk of rupture. Therefore, early identification of an ICA in the TAA patient population is likely to confer significant benefits. The present study investigated the incidence of ICA concurrent with TAA, and, therefore, whether patients presenting with TAAs should be considered for evaluation for the presence of ICAs.
Methods
We retrospectively reviewed patient records from 1997 to 2009 in a large TAA database to identify patients with TAA who also had available high-quality intracranial images by either computed tomographic angiography or magnetic resonance angiography. We identified 212 such patients of approximately 1,560 patients who had undergone TAA repair during that period. The cerebral imaging scans had been ordered either as a preoperative screening test by our thoracic aortic team or before evaluation for TAA repair as screening for neurologic (e.g., headache, neck pain) or oncologic reasons. The patients who had not undergone preoperative cerebral imaging had not been screened for a variety of reasons, including emergent circumstances, poor compliance, inability to travel, and cost or lack of insurance coverage. Forty-five patients (21%) had undergone brain scans in the past for largely nonspecific neurologic symptoms unrelated to the aneurysm (e.g., dizziness, weakness, headache in 37 patients) or for oncologic screening (4 patients). In addition, 1 patient had a history of cerebrovascular accident, 1 patient had a history of transient ischemic attack, and 1 patient had a history of mental status changes. Four patients also had a known ICA. These 52 patients (25%) comprised the nonprospective group. The remaining 160 patients (75%), which we termed the prospective group, had undergone cerebral computed tomographic angiography before thoracic aortic surgery for the purposes of the present study. All brain images were reviewed by a neuroradiologist for the present study.
Of the 212 patients, 141 were men (67%) and 71 were women (33%). The patient age range was 18 to 92 years (mean 62). The patients were divided into an ascending or descending TAA group according to the most clinically significant portion of the aneurysmal aorta; arch aneurysms were classified with the portion of the aorta to which they were most closely related anatomically. Thus, 197 patients (93%) were in the ascending TAA group and 15 (7%) were in the descending TAA group. The prevalence of ICA in the general population was identified through review of published studies, from thousands of autopsies and angiographies, and served as our comparison population. Statistical comparison of the ICA-positive and ICA-negative patients groups in the various categories was done using Fisher’s exact test (available from: www.langsrud.com/fisher.htm ), with significance defined at the 0.05 level.
The Yale University Human Investigation Committee (No. 0509000633) approved the study protocol.
Results
Of the 212 patients with TAA, 19 (9.0%) had a concurrent ICA ( Table 1 ). Of the 160 patients in the prospective patient group, 10 (6.3%) had a concurrent ICA. The ICAs ranged from 1.0 to 11.0 mm (mean 3.7, SD 2.6). Figure 1 shows a representative example.
| Age | Gender | TAA | ICA | Modality | HTN | Smoker | Race |
|---|---|---|---|---|---|---|---|
| 36 | Male | Des | ACA | MRA | + | 0 | African-American |
| 56 | Female | Asc | Left SCICA | CTA | + | + (quit) | European-American |
| 57 | Female | Asc | Left MCA | CTA | + | + | African-American |
| 59 | Male | Des | MCA | CTA | + | 0 | European-American |
| 61 | Male | Asc | Basilar artery | CTA | + | + | European-American |
| 64 | Male | Asc | Left vertebral artery | CTA | 0 | + | European-American |
| 64 | Female | Asc | Left cavernous internal carotid artery | CTA | + | + | European-American |
| 66 | Female | Des | Left internal carotid artery | MRA | + | + | African-American |
| 67 | Male | Asc | Left internal carotid artery | CTA | + | + | European-American |
| 67 | Male | Asc | Left internal carotid artery | CTA | + | + | European-American |
| 68 | Female | Asc | Right cavernous internal carotid artery | CTA | + | + | European-American |
| 71 | Male | Asc | Right anterior cerebral artery | MRA | + | 0 | European-American |
| 75 | Male | Asc | Right internal carotid artery | CTA | + | 0 | European-American |
| 77 | Female | Asc | Left internal carotid artery | CTA | + | + | European-American |
| 77 | Female | Asc | Left SCICA | CTA | + | 0 | European-American |
| 79 | Male | Des | Right internal carotid artery | MRA | + | + | European-American |
| 81 | Male | Des | basilar | MRA | + | + | European-American |
| 82 | Male | Asc | ACA | CTA | + | 0 | European-American |
| 86 | Female | Asc | Right MCA | CTA | + | + | European-American |
Of the 9 patients with concurrent ICA from the nonprospective group, 5 had undergone cerebral imaging because of nonspecific symptoms of headache or neck pain, and the aneurysm had been an incidental finding. Of the remaining 4 patients, 2 had undergone aneurysm clipping in the past, 1 had the ICA discovered after it had ruptured, and 1 was screened because of a family history of ICA.
The results of the statistical comparison of the ICA-positive and ICA-negative patient groups in the various categories were as follows ( Figure 2 ).
