Partially thrombosed anterior communicating artery aneurysm mimicking a suprasellar tumor: Microsurgical reconstruction after aneurysmotomy and ultrasonic thrombectomy

Abstract

Background:

Partially thrombosed intracranial aneurysms are uncommon lesions that may mimic intracranial neoplasms because of their heterogeneous radiological appearance and mass effect. When associated with broad-neck morphology and incorporation of adjacent vessels, treatment may require complex microsurgical reconstruction.

Case Description:

A 69-year-old woman with hypertension and type 2 diabetes mellitus underwent investigation after a mild traumatic brain injury. Initial computed tomography (CT) demonstrated a suprasellar lesion suggestive of a neoplastic process. CT angiography and digital subtraction angiography subsequently revealed a partially thrombosed anterior communicating artery aneurysm measuring 19 × 10 mm with a 6.6-mm neck and incorporation of the right A2 segment into the aneurysm neck. The patient underwent elective microsurgical treatment through a right fronto-orbital approach. Following temporary vascular control, aneurysmotomy and ultrasonic thrombectomy using the Clarity^® system were performed. Definitive reconstruction required sequential placement of eight permanent clips while preserving both A2 segments. Intraoperative fluorescein angiography confirmed adequate vessel patency. The patient remained neurologically intact, with a modified Rankin Scale score of 0 at 90-day follow-up.

Conclusion:

Partially thrombosed anterior communicating artery aneurysms may mimic suprasellar tumors and represent an important diagnostic challenge. In selected cases with branch incorporation, broad-neck morphology, and significant thrombotic burden, microsurgical reconstruction remains a safe and effective treatment strategy. Aneurysmotomy combined with ultrasonic thrombectomy facilitates visualization of the true aneurysm neck and may assist complex clip reconstruction.

INTRODUCTION

Intracranial aneurysms affect approximately 2–5% of the general population, and anterior communicating artery (AComA) aneurysms represent one of the most common aneurysm locations within the anterior circulation. Although most lesions exhibit a typical saccular morphology, partially thrombosed aneurysms constitute a distinct subgroup characterized by the coexistence of a patent lumen and organized intraluminal thrombus. This particular configuration may lead to progressive aneurysm enlargement, distortion of local anatomy, and mass effect on adjacent neurovascular structures.[1,2,4]

Partial thrombosis frequently produces atypical radiological findings. Depending on the amount and distribution of thrombotic material, these aneurysms may resemble skull base tumors, particularly lesions arising in the sellar and suprasellar regions. Consequently, pituitary adenomas, craniopharyngiomas, meningiomas, Rathke’s cleft cysts, and other neoplasms are often included in the differential diagnosis.[5,8,13]

Treatment of partially thrombosed aneurysms remains challenging because these lesions commonly exhibit broad-neck morphology, branch incorporation, calcification, and irregular luminal anatomy. Although endovascular techniques have evolved considerably, microsurgical treatment continues to play a critical role in selected cases, particularly when direct reconstruction of the parent vessels is required.[2,4]

We present a case of a partially thrombosed AComA aneurysm initially interpreted as a suprasellar tumor and successfully treated through aneurysmotomy, ultrasonic thrombectomy using the Clarity^® system, and complex microsurgical reconstruction requiring eight permanent clips.

CASE REPORT

A 69-year-old woman with a medical history of hypertension and type 2 diabetes mellitus underwent evaluation after a mild traumatic brain injury caused by a fall from bed during sleep. There was no loss of consciousness, seizure activity, focal neurological deficit, or evidence of intracranial hemorrhage.

A noncontrast computed tomography (CT) scan demonstrated a rounded suprasellar lesion that was initially interpreted as a possible neoplastic process [Figure 1a]. Subsequent CT angiography (CTA) immediately revealed the vascular nature of the lesion and suggested the diagnosis of a partially thrombosed aneurysm [Figure 1b-d]. Magnetic resonance imaging (MRI) was not obtained before treatment because CTA established the vascular diagnosis and digital subtraction angiography (DSA) was subsequently performed for definitive anatomical characterization and operative planning.

Figure 1:

Preoperative imaging studies. (a) Noncontrast computed tomography demonstrating a rounded suprasellar lesion initially interpreted as a possible neoplasm. (b) Computed tomography angiography revealing the vascular nature of the lesion. (c) Three-dimensional angiographic reconstruction providing an overview of the partially thrombosed anterior communicating artery aneurysm, including its broad-neck morphology and anteroinferior projection. (d) Magnified three-dimensional reconstruction emphasizing the aneurysm neck and incorporation of the right A2 segment into the aneurysm complex.

The patient reported only nonspecific chronic headaches and denied previous episodes suggestive of aneurysmal rupture. Neurological examination was normal, with no motor, sensory, visual, cognitive, or language deficits. Her Karnofsky Performance Status score was 100.

DSA demonstrated a complex partially thrombosed anterior communicating artery aneurysm measuring approximately 19 × 10 mm, with a 6.6-mm neck and an anteroinferior projection. Three-dimensional rotational angiography revealed direct incorporation of the right A2 segment into the aneurysm neck, representing a major technical challenge for treatment [Figure 2a-c].

Figure 2:

Digital subtraction angiography. (a) Lateral projection demonstrating the partially thrombosed anterior communicating artery aneurysm. (b) Anteroposterior projection. (c) Oblique projection showing aneurysm morphology, neck configuration, and relationship with the distal anterior cerebral arteries.

The lesion exhibited a broad neck, a significant thrombosed component, and intimate involvement of the right distal anterior cerebral artery. After multidisciplinary discussion, microsurgical treatment was considered more appropriate than endovascular reconstruction because of the unfavorable anatomy and the need for direct vessel preservation.

The patient and her family were informed about the surgical risks, benefits, and available treatment alternatives. Written informed consent was obtained, and elective microsurgical treatment was scheduled.

Surgical technique

The patient was positioned supine with the head secured in a three-pin fixation system, slightly extended and rotated contralaterally to optimize exposure of the anterior skull base and anterior communicating artery complex [Figure 3a]. A right fronto-orbital craniotomy was performed through a standard skull base approach [Figure 3b and c].

Figure 3:

Surgical positioning and skull base exposure. (a) Patient positioning with head fixation in a three-pin system before surgery. (b) Right fronto-orbital craniotomy. (c) Operative view after dural opening demonstrating exposure of the frontal lobe and basal cisterns.

After dural opening, extensive cerebrospinal fluid drainage was achieved through opening of the basal cisterns, allowing satisfactory brain relaxation. Microsurgical dissection exposed the bilateral optic nerves, optic chiasm, bilateral A1 and A2 segments, anterior communicating artery complex, and the aneurysm itself.

Circumferential aneurysm dissection demonstrated direct incorporation of the right A2 segment into the aneurysm neck, confirming the complexity anticipated during preoperative imaging studies. Adequate proximal and distal vascular control was obtained through temporary clipping of the left internal carotid artery and bilateral A1 and A2 segments [Figure 4]. Temporary occlusion was applied intermittently, with an estimated cumulative occlusion time of approximately 10–15 min. The duration of each individual temporary clip application was not prospectively recorded.

Figure 4:

Microsurgical dissection and vascular control. Exposure of the aneurysm before aneurysmectomy and thrombectomy.

Following temporary vascular occlusion, aneurysmotomy was performed under high magnification. Opening of the aneurysm sac exposed a large organized intraluminal thrombus occupying a substantial portion of the lesion [Figure 5a]. A formal volumetric percentage of thrombus burden was not calculated preoperatively, and the thrombotic material was not characterized histopathologically. Therefore, the thrombus is described according to its intraoperative macroscopic appearance as organized and extensive.

Figure 5:

Aneurysmotomy and ultrasonic thrombectomy. (a) Aneurysmotomy demonstrating the organized intraluminal thrombus occupying a substantial portion of the aneurysm sac. (b) Ultrasonic thrombectomy performed using the Clarity^® system. (c) Final clip configuration after microsurgical reconstruction using eight permanent clips while preserving both A2 segments.

Progressive thrombus removal was performed using the Clarity^® ultrasonic aspirator system. Ultrasonic thrombectomy allowed internal decompression of the aneurysm and progressive visualization of the true aneurysm neck, facilitating identification of adjacent vascular structures and the incorporated right A2 segment [Figure 5b].

After complete decompression, definitive reconstruction was initiated. Because of the broad-neck morphology, complex three-dimensional anatomy, and incorporation of the right A2 segment, sequential clip reconstruction was required. Eight permanent clips were progressively applied to remodel the aneurysm neck while preserving both distal anterior cerebral arteries and the surrounding perforating vessels [Figure 5c].

Following removal of the temporary clips, vascular patency was assessed using intraoperative fluorescein angiography. Adequate flow was confirmed in both A2 segments and adjacent vessels, with complete exclusion of the aneurysm from the circulation [Figure 6a].

Figure 6:

Intraoperative vascular assessment and postoperative results. (a) Intraoperative fluorescein angiography confirming patency of the reconstructed vessels and preservation of distal circulation. (b) Postoperative three-dimensional vascular reconstruction demonstrating complete aneurysm exclusion. (c) Postoperative computed tomography showing expected surgical changes without hemorrhagic or ischemic complications.

Postoperative course

The postoperative period was uneventful except for transient bilateral periorbital edema related to the fronto-orbital approach. No new neurological deficits were observed.

Three-dimensional postoperative vascular imaging confirmed complete aneurysm exclusion and preservation of the anterior communicating artery complex and distal anterior cerebral circulation [Figure 6b]. No residual aneurysm filling was identified.

Postoperative CT demonstrated expected surgical changes without evidence of hemorrhage, infarction, hydrocephalus, or other procedure-related complications [Figure 6c].

The patient was discharged home neurologically intact. At the 90-day follow-up evaluation, she remained fully independent, without motor, sensory, visual, language, or cognitive deficits. Functional outcome was excellent, corresponding to a modified Rankin Scale score of 0.

DISCUSSION

Partially thrombosed intracranial aneurysms constitute a distinct subgroup of aneurysmal lesions characterized by the coexistence of a patent lumen and an organized thrombotic component. Unlike conventional saccular aneurysms, these lesions frequently demonstrate progressive enlargement, mass effect, distortion of local anatomy, and complex neck morphology, making both diagnosis and treatment particularly challenging.[2]

One of the most remarkable aspects of the present case was the initial radiological interpretation as a suprasellar tumor. The differential diagnosis of lesions located in the sellar and suprasellar regions commonly includes pituitary adenomas, craniopharyngiomas, meningiomas, Rathke’s cleft cysts, hypothalamic tumors, and other skull base neoplasms.[5,8,13] When thrombosis is present, aneurysms may demonstrate heterogeneous density on CT and heterogeneous signal characteristics on MRI, closely resembling neoplastic lesions. Several reports have described thrombosed anterior communicating artery aneurysms initially mistaken for tumors, emphasizing the importance of vascular imaging in the evaluation of atypical suprasellar masses.[5,8,13]

In the present patient, the lesion was initially identified during evaluation for mild head trauma and was interpreted on noncontrast CT as a possible neoplasm. Only after CTA and DSA was the correct diagnosis established. This finding reinforces the need to consider vascular lesions in the differential diagnosis of atypical sellar and suprasellar masses and highlights the value of vascular imaging whenever uncertainty exists.

Treatment selection represented another major challenge. Endovascular techniques have expanded considerably over the past two decades and currently represent the preferred treatment for many intracranial aneurysms. However, partially thrombosed aneurysms remain difficult lesions for endovascular reconstruction because they frequently exhibit broad-neck morphology, irregular residual lumen, branch incorporation, and substantial thrombotic burden.[2] Furthermore, endovascular treatment does not directly address the thrombosed component responsible for mass effect and anatomical distortion.

The most important anatomical feature influencing treatment strategy in this case was the direct incorporation of the right A2 segment into the aneurysm neck. Preservation of this vessel was mandatory to avoid ischemic injury within the distal anterior cerebral artery territory. Direct microsurgical visualization allowed complete assessment of the aneurysm anatomy, identification of incorporated branches, and precise reconstruction of the vascular complex.[4]

The incorporation of a distal anterior cerebral artery branch into the aneurysm neck is a well-recognized factor favoring microsurgical treatment. In such situations, direct exposure permits safe preservation of critical vessels while enabling tailored clip reconstruction according to the individual aneurysm morphology.

The fronto-orbital approach provided excellent exposure of the anterior skull base and anterior communicating artery complex. Skull base approaches remain valuable for the treatment of complex aneurysms because they improve visualization of the aneurysm neck, adjacent perforators, and parent vessels while minimizing brain retraction.[4,7,12]

Following temporary vascular occlusion, aneurysmotomy revealed a large organized thrombus occupying a substantial portion of the aneurysm sac. Removal of the thrombotic component was essential not only for decompression but also for identification of the true aneurysm neck. Without thrombectomy, clip reconstruction would have been considerably more difficult because the thrombus distorted the aneurysm anatomy and obscured critical vascular relationships.

A distinctive technical aspect of this case was the use of ultrasonic thrombectomy with the Clarity^® system. Ultrasonic aspiration enabled progressive removal of the organized thrombus and internal decompression of the sac, improving visualization of the reconstruction plane. The use of ultrasonic aspiration for thrombectomy in complex thrombosed aneurysms is not unique to this report: prior surgical series and technical reports have described thrombectomy with clip reconstruction and ultrasonic aspiration in giant or partially thrombosed aneurysms.[3,6,10,11] Accordingly, the present case should be viewed as an application of an established microsurgical adjunct to a rare partially thrombosed AComA aneurysm mimicking a suprasellar tumor, rather than as a novel use of ultrasonic aspiration itself.

Another noteworthy feature was the requirement for eight permanent clips to achieve complete aneurysm exclusion. Complex aneurysms with branch incorporation frequently cannot be treated with a single clip. Sequential clip reconstruction permits progressive remodeling of the aneurysm neck while preserving parent arteries, incorporated branches, and perforating vessels.[4,7,12] In our patient, this strategy enabled complete aneurysm exclusion while maintaining patency of both A2 segments.

Intraoperative fluorescein angiography served as an important adjunct during reconstruction. Fluorescence-based techniques allow immediate assessment of vessel patency and aneurysm occlusion, increasing the safety of complex aneurysm surgery.[1,9] In the present case, fluorescein angiography confirmed adequate blood flow through all reconstructed vessels before surgical closure.

Reports of thrombosed AComA aneurysms presenting as suprasellar mass lesions remain uncommon.[5,8,13] The present case adds a detailed operative example in which aneurysmotomy, ultrasonic thrombus evacuation, and multi-clip reconstruction were required because of broad-neck morphology and right A2 incorporation.

The patient experienced a favorable postoperative course, remaining neurologically intact and functionally independent at 90-day follow-up. This short-term result supports the technical feasibility of microsurgical reconstruction in selected partially thrombosed aneurysms when branch incorporation and complex anatomy limit endovascular alternatives, but it does not establish long-term durability.

The principal limitations of this report are its single-case nature, the absence of MRI before treatment, the lack of a quantitative estimate or histopathologic characterization of the thrombotic burden, incomplete recording of the duration of each individual temporary-clip application, and the absence of long-term angiographic follow-up. Postoperative vascular imaging confirmed complete exclusion during the index hospitalization, but vascular imaging beyond the 90-day clinical follow-up was not available at the time of this revision. Follow-up vascular imaging is planned at approximately 6 months, although a definitive examination date has not yet been established. Long-term vascular surveillance remains warranted because durability cannot be inferred from short-term follow-up alone. Despite these limitations, the case illustrates diagnostic, anatomical, and technical considerations relevant to complex partially thrombosed AComA aneurysms.

CONCLUSION

Partially thrombosed anterior communicating artery aneurysms may mimic suprasellar tumors and should be considered in the differential diagnosis of atypical sellar and suprasellar lesions.

In selected cases with broad-neck morphology, substantial thrombotic burden, and incorporation of major arterial branches, microsurgical treatment may permit direct vascular reconstruction when endovascular options are anatomically unfavorable.

This case demonstrates the technical feasibility of aneurysmotomy, ultrasonic thrombectomy, intraoperative fluorescence angiography, and sequential clip reconstruction for a complex partially thrombosed AComA aneurysm, with preservation of the parent vessels and a favorable short-term clinical and radiological outcome. Larger series and extended angiographic follow-up are required before conclusions regarding safety or durability can be made.

Ethical approval:

Institutional Review Board approval is not required.

Declaration of patient consent:

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given consent for their images and other clinical information to be reported in the journal. The patient understands that the patient’s names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship:

Nil.

Conflicts of interest:

There are no conflicts of interest.

Use of artificial intelligence (AI)-assisted technology for manuscript preparation:

The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.

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