Abstract

Background: The ultrasonic surgical aspirator is widely used in intracranial tumor resection as this instrument is considered safe. The advantage of an ultrasonic surgical aspirator is that it does not damage vessels or nerves close to the tumor. Therefore, limited information exists regarding intraoperative arterial injury by the ultrasonic surgical aspirator.

Case Description: We report two cases. The first case was a 30-year-old woman who underwent surgery for a recurrent craniopharyngioma, and the second was a 50-year-old man who underwent surgery for a meningioma. A craniopharyngioma encased the basilar artery in the former case, and the superior cerebellar artery was encased by a meningioma in the latter. An ultrasonic surgical aspirator was used to resect the tumors in two cases. During surgery, the arteries involved in the tumors were unintentionally injured using an ultrasonic surgical aspirator. Intraoperative hemostasis was achieved for the bleeding from the injured arteries. However, postoperative digital cerebral angiography revealed pseudoaneurysms in the injured arteries. A subarachnoid hemorrhage occurred in the first case. The pseudoaneurysms were managed using endovascular embolization.

Conclusion: Intraoperative arterial injury can occur with the application of an ultrasonic surgical aspirator. Neurosurgeons should be cautious when using ultrasonic surgical aspirators to avoid damaging the arteries involved with the tumor.

Keywords: Brain tumor, Complication, Endovascular embolization, Pseudoaneurysm, Ultrasonic aspirator

INTRODUCTION

Central nervous system tumors, including malignant tumors, account for approximately 1% of all invasive neoplasms.[ 4 ] To manage patients with central nervous system tumors, tumor resection is essential for the pathological diagnosis and resolution of symptoms. However, during tumor resection, attention should be paid to avoid damaging the important vessels and nerves close to the tumors. Therefore, surgical instruments have been developed to achieve safe and less invasive operations in patients with central nervous system tumors.

The ultrasonic surgical aspirator is a surgical instrument that was first applied in the neurosurgical field in 1978.[ 1 ] The vibrating tip of this surgical instrument has specific tissue selectivity, which can avoid damage to vessels close to the tumors.[ 7 ] Due to this advantage, ultrasonic surgical aspirators have been widely used in liver, kidney, and femoral artery surgeries.[ 3 , 5 , 8 ] As ultrasonic surgical aspirators are relatively safe, little has been described in terms of intraoperative complications related to their application. To the best of our knowledge, intraoperative arterial injury resulting in pseudoaneurysm formation using an ultrasonic surgical aspirator has not yet been reported.

Here, we report two cases of arterial injury induced by an ultrasonic surgical aspirator, indicating the possibility of rare intraoperative complications.

CASE PRESENTATION

Case 1

A 30-year-old woman was admitted to our hospital. The patient had a past episode of recurrent and refractory craniopharyngioma for which she underwent tumor removal surgery, radiotherapy, and chemotherapy. As the growth of the residual craniopharyngioma resulted in incontinence and aggravated the recent memory disturbances, direct salvage surgery was planned. Neurological examination on admission revealed incontinence, aggravated memory disturbances, and total blindness. Preoperative magnetic resonance imaging revealed that the tumor extended near the brainstem and involved the basilar artery [ Figure 1a and b ]. No vascular lesions were observed on magnetic resonance angiography [ Figure 1c ]. An ultrasonic surgical aspirator was used to resect the tumor during the direct surgery. The basilar artery was unexpectedly damaged intraoperatively using an ultrasonic surgical aspirator. The bleeding point of the basilar artery was coated with oxycellulose and fibrin glue, and hemostasis was successfully achieved. However, postoperative computed tomography angiography revealed a pseudoaneurysm of the basilar artery, which had progressively enlarged [ Figure 1d - f ]. The pseudoaneurysm ruptured, resulting in a subarachnoid hemorrhage 14 days after direct surgery [ Figure 1g ]. Emergent intraventricular drainage was performed to control intracranial pressure. The ruptured pseudoaneurysm was successfully embolized with microcoils and three intracranial stents in two sessions [ Figure 2a - d ]. After endovascular embolization, no ischemic lesions were confirmed on follow-up magnetic resonance images [ Figure 2e ]. Preoperative neurological deficits, such as incontinence and recent memory disturbances, did not change. The subarachnoid hemorrhage did not result in any other sequelae. The patient was discharged 54 days after the second endovascular embolization procedure. Her modified Rankin scale score at discharge was 3.

Figure 1:

Radiological characteristics before endovascular embolization of the pseudoaneurysm (case 1). (a-b) Gadolinium-enhanced T1-weighted magnetic resonance images showing the basilar artery (white arrowhead) involved in the tumor (a: sagittal image and b: axial image).(c) Magnetic resonance angiography reveals no apparent vascular lesions .(d-f) A pseudoaneurysm (white arrow) in the basilar artery increased chronologically on computed tomography angiography (d: the following day, e: 5 days, and f: 13 days after tumor removal).(g) Subarachnoid and intraventricular hemorrhages occur due to the ruptured pseudoaneurysms.

Figure 2:

Radiological characteristics during and after endovascular embolization of the pseudoaneurysm (case 1). (a-d) The pseudoaneurysm (white arrow) in the basilar artery is embolized using microcoils via the stent-assisted technique. After embolization, no flow into the pseudoaneurysm was observed (white arrowhead) (a and b: intraoperative angiography before embolization; c and d: after embolization). (e) Postoperative magnetic resonance imaging showing no ischemic complications.

Case 2

A 50-year-old man was referred for the surgical removal of an incidentally diagnosed tumor. Although the tumor was asymptomatic, it compressed the brainstem [ Figure 3a - c ]. The tumor encased the left superior cerebellar artery and received a rich blood supply. No aneurysms were identified preoperatively [ Figure 3d and e ]. The tumor was resected using the retrosigmoid approach, and unexpected arterial bleeding occurred during the procedure. This resulted from the injury to the superior cerebellar artery by the ultrasonic surgical aspirator used for tumor debulking. Bleeding was controlled using oxidized cellulose and fibrinogen adhesives. After hemostasis, the tumor was removed. Subsequently, the patient was moved to an angiography suite for evaluation of the injured superior cerebellar artery. Left vertebral angiography revealed a pseudoaneurysm in the superior cerebral artery [ Figure 4a and b ]. Parent artery occlusion was performed to embolize the pseudoaneurysm [ Figure 4c ]. Postoperative infarction was confirmed in the sacrificed superior cerebellar artery region [ Figure 4d ]. The histopathological diagnosis was an angiomatous meningioma. The patient underwent rehabilitation for truncal ataxia and dysarthria. Follow-up digital cerebral angiography showed the resolution of the embolized pseudoaneurysm. Ambulation disturbance and truncal ataxia appeared due to embolization of the superior cerebellar artery. The patient was discharged on postoperative day 14. The patient’s modified Rankin scale score at discharge was 1.

Figure 3:

Radiological characteristics before endovascular embolization of the pseudoaneurysm (case 2). (a-c) Gadolinium-enhanced T1-weighted magnetic resonance images showing involvement of the superior cerebellar artery (white arrowhead) by the tumor. The left posterior cerebral artery is compressed by the tumor (white arrow) (a: axial image, b: coronal image, and c: sagittal image). (d-e) Left vertebral angiography showing that the pathway of the left posterior cerebral artery (white arrow) is shifted by the tumor. The vascular-rich tumor is fed by the superior cerebellar artery (white arrowhead) (d: arterial phase; e: capillary phase). AP: anterior-posterior projection; Lat: lateral projection.

Figure 4:

Radiological characteristics during and after endovascular embolization of the pseudoaneurysm (case 2). (a) Left vertebral angiography shows a pseudoaneurysm (white arrowhead) in the left superior cerebellar artery (black arrowhead).The posterior cerebral artery (black arrow) is intact.(b) Three-dimensional reconstructed maximum intensity projection images also revealed a pseudoaneurysm (white arrowhead).(c) Parent artery occlusion, including the pseudoaneurysm (dagger), was performed using microcoils (white arrow).The posterior cerebral artery (black arrow) remained intact.(d) Postoperative magnetic resonance image showing cerebellar infarction due to the sacrificed superior cerebellar artery.

DISCUSSION

Here, we described two cases in which tumor resection was performed using an ultrasonic surgical aspirator. In both cases, the tumors encased the intracranial arteries, and were unexpectedly injured using an ultrasonic surgical aspirator. These accidents require intraoperative hemostasis, resulting in pseudoaneurysm formation. Endovascular embolization resolved these pseudoaneurysms, although a subarachnoid hemorrhage occurred in one case. No similar intraoperative complications related to ultrasonic surgical aspirators have been previously reported.

The rare incidence of arterial injury induced by the application of ultrasonic surgical aspirators is attributed to their excellent tissue selectivity. Kudo et al. reported an intraoperative arterial injury using an ultrasonic surgical aspirator.[ 2 ] They applied an ultrasonic surgical aspirator in cases of cavernous hemangiomas. Intraoperative bleeding from the internal carotid artery occurs during tumor removal. They used four aneurysm clips to control bleeding. However, in their report, entrapment of the artery by the tumor on preoperative radiological images was not described.[ 2 ] In our cases, the arteries injured by the ultrasonic surgical aspirator were encased by tumors. This accident may have occurred due to the ambiguous margins between the arteries and tumors. Once a meningioma expands and invades the surrounding vessels and brain tissues, the vessels can be pathologically entrapped by the tumor.[ 6 ] The entrapment of the vessels can ambiguate the border between them and the tumor.[ 6 ] This condition can impede the tissue selectivity of the ultrasonic surgical aspirator. Although we did not examine the tissues pathologically in our cases, we speculate that adhesion between the arteries and tumors could have resulted in an unexpected intraoperative injury. Especially as the patient in case 1 underwent tumor removal surgery and radiation therapy, the adhesion between the normal tissue and the tumor might have been even stronger.

In managing intraoperative arterial injuries caused by the ultrasonic surgical aspirator, achieving complete hemostasis is an indispensable step. However, as observed in our cases, pseudoaneurysms can consequently form. Therefore, postoperative digital subtraction angiography should be performed. Because pseudoaneurysms are known for their high rate of rupture, direct surgery or endovascular embolization is also warranted to prevent rupture or re-rupture.

A subarachnoid hemorrhage occurred due to a gradually enlarging pseudoaneurysm, which was observed in the first case. In the first case, a pseudoaneurysm formed in the basilar artery. Therefore, the parent artery occlusion was not observed in this case. Stent-assisted coil embolization of the pseudoaneurysm was planned, and dual antiplatelet therapy was initiated. However, the pseudoaneurysm ruptured before endovascular embolization was performed. However, in the second case, because the pseudoaneurysm was located in the superior cerebellar artery, parent artery occlusion could be performed. Therefore, the pseudoaneurysm was embolized with parent artery occlusion soon after the tumor resection. Even if endovascular embolization cannot be performed soon after tumor surgery due to the pseudoaneurysmal location, patients should be frequently monitored using computed tomography or magnetic resonance angiography.

CONCLUSION

As observed in our cases, the intraoperative application of an ultrasonic surgical aspirator can result in iatrogenic pseudoaneurysms. In cases where intracranial arteries are involved in a tumor, neurosurgeons should be aware of this rare complication. Intraoperatively, caution should be exercised to avoid damaging the arteries involved in the tumor. Once intraoperative hemostasis is achieved, the injured arteries should be closely followed up by angiographic examinations.

Ethical approval

The research/study approved by the Institutional Review Board at Medical Research Institute KITANO HOSPITAL, PIIF Tazuke-kofukai, number P221000400, dated October 17, 2022.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent.

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.

Disclaimer

The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of the Journal or its management. The information contained in this article should not be considered to be medical advice; patients should consult their own physicians for advice as to their specific medical needs.

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