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INTRODUCTION
Aneurysmal subarachnoid haemorrhage (SAH) remains a devastating condition, with a 30-day mortality of approximately 45% and survival morbidity of 50%. The size, location, and morphology of intracranial aneurysms (IAs) are considered the best predictors for future aneurysm rupture. Geographic region is also an important determinant in the natural history of intracranial aneurysms [1,2].
Intracranial aneurysms are abnormal dilations of cerebral arteries that can lead to devastating consequences if ruptured. Understanding the morphological characteristics, size, and location of ruptured intracranial aneurysms is crucial for effective management and treatment strategies [3]. Subarachnoid hemorrhage resulting from aneurysm rupture is associated with high mortality and morbidity rates, with 45% mortality in the first year and 64% disability among survivors [3].
Identifying risk factors for aneurysm rupture is essential for clinical decision-making and treatment planning. Previous studies have identified several morphological parameters associated with aneurysm rupture, including size, aspect ratio, size ratio, height-width ratio, and flow angle [4]. The International Study of Unruptured Intracranial Aneurysms (ISUIA) found that aneurysm size and location are significant predictors of hemorrhage risk. For example, the annual rupture risk was 0.05% for asymptomatic aneurysms <10 mm in size, while aneurysms measuring 7–12 mm had a rupture risk of 0.52% [1,3]. However, the critical size for rupture remains a controversial topic, with studies reporting varying thresholds [5].
The location of ruptured aneurysms also varies, with the anterior communicating artery (ACOM), internal carotid artery (ICA), and middle cerebral artery (MCA) being common sites [6]. Studies have reported that ruptured aneurysms are more frequently found in the ACOM [4].
Endovascular treatment has emerged as a viable alternative to surgical clipping for managing ruptured intracranial aneurysms. The International Subarachnoid Aneurysm Trial (ISAT) highlighted a significant shift toward endovascular treatment, including techniques such as coiling, stent-assisted coiling, and flow diversion, tailored to different aneurysm morphologies and locations [7].
This retrospective study aims to better understand the size, site, and morphological correlation of ruptured intracranial aneurysms and the outcomes of endovascular treatment in one of the largest institutions in Central India. By analyzing these factors in this geographic region, this study seeks to contribute valuable insights into the management of ruptured aneurysms.
Aims and objectives
The present study aimed to identify high-risk characteristics of intracranial aneurysms in this demographic population with the intention of timely treatment. The study had the following objectives:
1. To study the angiographic features (size, location, morphology) of ruptured intracranial aneurysms.
2. To study the demographic characteristics and risk factors of ruptured intracranial aneurysms in this geographic area.
3. To assess the outcome of symptomatic ruptured cerebral aneurysm cases treated with endovascular treatment.
MATERIALS AND METHODS
This retrospective cohort study analyzed 102 patients with ruptured intracranial aneurysms treated at a tertiary care teaching hospital in Central India between December 2021 and November 2024. Patients were identified through a registry, with inclusion criteria comprising confirmed aneurysmal subarachnoid hemorrhage via computed tomography angiography or digital subtraction angiography, complete clinical and radiological data, and receipt of endovascular or surgical intervention. Exclusion criteria included traumatic or mycotic aneurysms and incomplete follow-up data. Demographic, clinical, and radiological variables—including age, sex, comorbidities (hypertension, diabetes, dyslipidemia, substance addiction), aneurysm characteristics (size, location, neck width), Hunt & Hess (H&H) grade at admission, treatment modality (coiling, stent-assisted coiling, flow diversion), and functional outcome (modified Rankin Scale [mRS] at admission and discharge)—were extracted from electronic medical records. Statistical analysis was performed using SPSS (IBM Corp., Armonk, NY, USA), with descriptive statistics summarizing baseline characteristics. Comparative analyses included chi-square/Fisher’s exact tests for categorical variables and t-tests/Mann-Whitney U tests for continuous variables. Multivariate logistic regression, adjusted for age, sex, comorbidities, aneurysm features, and H&H grade, identified independent predictors of poor outcome (mRS 3–6), with significance set at p<0.05. The study received institutional review board approval (IRB No. AAPG76B) with a waiver for informed consent due to retrospective anonymized data analysis. Limitations included potential selection bias from the retrospective design, single-center generalizability constraints, and lack of long-term outcome assessment due to loss of follow-up. This methodology facilitated a comprehensive evaluation of factors influencing clinical outcomes in ruptured intracranial aneurysm management.
Definitions
Aneurysms were categorized based on size as small (<5 mm), medium (5–10 mm), large (10–25 mm), or giant (>25 mm) [8], and the neck of aneurysms was classified as narrow (<4 mm) or wide (>4 mm).
The aneurysms were further classified into types such as saccular, fusiform, blister, dissecting, pseudoaneurysm, or dysplastic.
Saccular aneurysm ‒ Intracranial aneurysms with a characteristic rounded shape.
Fusiform ‒ Dilated intracranial aneurysms involving the entire circumference of an arterial segment and without a neck.
Blister aneurysm ‒ Small thin-walled intracranial aneurysms arising at a non-branch point of a vessel with a broad base.
Dissecting aneurysm ‒ Saccular or fusiform aneurysm associated with narrowing of the parent vessel, giving what has been described as the “pearl and string” appearance.
Pseudoaneurysm ‒ It is the product of damaging the vessel wall, resulting in an encapsulated hematoma in communication with the ruptured artery.
Dysplastic aneurysm ‒ Bizarre-looking aneurysm arising from a diseased vessel.
Morphological features such as single lobe, bilobed, multilobulated, or the presence of a pseudo sac (daughter dome) were also recorded.
Single lobe ‒ Aneurysm with a single sac showing a uniform wall.
Bilobed ‒ Aneurysm with two separate outpouchings sharing a common wall and neck.
Multilobulated ‒ Aneurysm with ≧3 separate outpouchings sharing a common wall and neck.
Pseudo sac (Daughter dome) ‒ Local protrusion of a weak area of the aneurysm wall arising from the dome of the aneurysm lobe.
Location of the aneurysms was categorized based on the ISUIA classification into seven locations: cavernous carotid artery, internal carotid artery, anterior communicating artery, middle cerebral artery, posterior communicating artery, vertebrobasilar or posterior cerebral artery, and basilar tip.
Information on aneurysm multiplicity and classification as sidewall or bifurcation aneurysms was also documented.
Clinical grading scales, including the Fisher and Hunt & Hess scales, were used as reported in the records to evaluate the severity of SAH. Functional outcomes were assessed using the mRS at admission and discharge. Outcomes were categorized as “good” (mRS 0–2) or “poor” (mRS 3–6).
Statistical analysis
The data were entered into Microsoft Excel 2010 and analyzed statistically. Descriptive statistics were used to calculate proportions and percentages for quantitative and categorical variables. The epidemiological and clinical characteristics of the sample were summarized using descriptive statistical methods.
RESULTS
Our analysis of 102 patients with ruptured intracranial aneurysms revealed a female predominance (62.8% vs 37.3% male; p=0.010) with peak incidence in the 51-60 year age group (35.3%, Table 1). Hypertension was the most prevalent comorbidity (44.1%, p=0.003), followed by diabetes (32.4%) and substance addiction (25.5%). Medium/large aneurysms (≥5 mm) were associated with older age (57.8±12.1 vs 53.2±10.5 years; p=0.028) and higher hypertension prevalence (46.3% vs 34.5%; p=0.049, Table 2).
Anterior circulation aneurysms predominated (88.4%, Table 3), most commonly at the anterior communicating artery (27.7%). Posterior circulation aneurysms, though less frequent (11.6%), had significantly worse outcomes (69.2% poor mRS vs 31.3% anterior; p=0.007, Table 4). Unassisted coiling was the primary intervention (68.6%), with stent-assisted coiling preferred for wide-neck aneurysms (63.6% vs 35.7%; p=0.019, Table 2, Figs. 1-4).
Multivariate analysis identified Hunt & Hess grade ≥3 (aOR=3.1, 95% CI 1.4-6.9; p=0.005) and posterior location (aOR=2.8, 95% CI 1.1-7.2; p=0.032) as independent predictors of poor outcomes (Table 4). Despite 83.3% presenting with poor initial status (mRS 3-6), 68.6% achieved good outcomes post-treatment (Table 4), particularly notable given 77.5% had moderate-severe Hunt & Hess grades (3-5, p<0.001, Table 4, Figs. 5-6).
DISCUSSION
The present study, “Morphological Characteristics, Size, Location of Ruptured Intracranial Aneurysms & Endovascular Treatment in Central India – A Retrospective Study,” provides valuable insights into the demographic, anatomical, and morphological characteristics, size, location, and clinical profiles of patients with ruptured intracranial aneurysms and the outcomes of endovascular treatments [9]. These findings align with and diverge from previous studies by Froelich et al. [3] and Lai et al. [7], offering a region-specific perspective while corroborating broader trends in aneurysm characteristics and treatment outcomes [9].
Demographics and comorbidities
The study population comprised predominantly middle-aged to older adults, with the highest prevalence in the 51–60 years and 61–70 years age groups, accounting for 65.7% collectively. This is consistent with Lai et al.’s findings, where the mean age of presentation was 59 years. The female predominance in the current study (F:M ratio of 1.7:1) closely aligns with the 2:1 female-to-male ratio reported by Lai et al. [11]. Hypertension emerged as the most common comorbidity in both the present study (44.1%) and Lai et al.’s cohort, reaffirming its role as a critical risk factor for aneurysm rupture [11].
Aneurysm characteristics
The study revealed a strong predominance of anterior circulation aneurysms (88.4%), with the anterior communicating artery (ACOM) being the most common site (27.7%). This finding is consistent with both Froelich et al. [10] and Lai et al. [11] studies, which also reported the anterior circulation as the most common location for ruptured aneurysms. However, the current study showed a higher percentage of anterior circulation aneurysms compared to Lai et al. (88.4% vs 84.0%) [11].
Size: Small aneurysms (<5 mm) were the most prevalent (51.8%) in the current study. This is in contrast to the ISUIA study findings, where the risk of rupture is higher in the 7-12 mm aneurysm group. However, this aligns closely with Froelich et al.’s findings, where 49% of ruptured aneurysms were <5 mm. However, it differs slightly from Lai et al.’s study [11], which reported 64% of aneurysms ≤5 mm. This variation might be attributed to population differences or imaging techniques used.
Morphology: The majority of aneurysms were saccular (96.4%) and single-lobed (80.4%). This high prevalence of saccular aneurysms is consistent with general aneurysm literature, although the previous studies did not specifically report on aneurysm morphology.
Multiplicity
The current study found that 11.8% of patients had multiple aneurysms, which is lower than the 17% reported by Lai et al. [11]. This difference could be due to variations in genetic predisposition or environmental factors between the Indian and Chinese populations.
Endovascular treatment
Unassisted coiling was the predominant treatment method (68.6%), followed by stent-assisted coiling (21.6%). This reflects the current trend in endovascular treatment of ruptured aneurysms, favoring minimally invasive techniques. However, the previous studies did not provide detailed information on treatment methods, making direct comparisons difficult.
Clinical severity and outcomes
The study reported a high proportion of patients presenting with severe SAH, with 51% having a Modified Fisher Scale grade of 3. Similarly, on the Hunt and Hess Scale, moderate to severe grades (3-5) were common. Despite the severity of presentation, there was a significant improvement in functional outcomes at discharge, with 68.6% of patients achieving good outcomes (mRS 0-2). This improvement highlights the effectiveness of modern endovascular treatments in managing ruptured aneurysms.
This study from Central India provides valuable data on ruptured intracranial aneurysms, largely corroborating findings from previous international studies. The predominance of small, anterior circulation aneurysms, particularly in the ACOM, is consistent across studies. However, some variations in aneurysm size distribution and multiplicity were noted, which may reflect population-specific characteristics.
The study’s findings emphasize the importance of early detection and treatment of small aneurysms, as they constitute a significant proportion of ruptured cases. Additionally, the high prevalence of hypertension among patients underscores the need for aggressive management of cardiovascular risk factors.
Limitations
The study’s limitations include its retrospective design and potential selection bias. Being conducted at a single center in Central India limits the generalizability of findings. The sample size may not represent rare aneurysm characteristics, and the lack of long-term follow-up restricts insights into the durability and complications of treatments. Additionally, factors such as genetic predispositions, lifestyle, and advanced imaging techniques were not extensively analyzed. Future multicenter prospective studies with larger cohorts and long-term follow-ups are needed to address these limitations.
Future research should focus on understanding the genetic and environmental factors contributing to these population-specific differences in aneurysm characteristics. Furthermore, long-term follow-up studies are needed to assess the durability of endovascular treatments and identify factors associated with improved outcomes in patients with ruptured intracranial aneurysms.
CONCLUSIONS
In conclusion, this study provides valuable insights into the morphological characteristics, size, location, and endovascular management of ruptured intracranial aneurysms in Central India. Most aneurysms were located in the anterior circulation, predominantly in the anterior communicating artery, with small, saccular, and narrow-necked aneurysms being the most common. Females were more affected than males, with hypertension as the most prevalent comorbidity. Unassisted coiling was the primary treatment modality, showing significant improvement in functional outcomes post-intervention. Despite its limitations, the study highlights the importance of early detection, optimized treatment strategies, and the need for larger, multicenter studies to enhance understanding and management of intracranial aneurysms.
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