Pediatric nonsaccular intracranial aneurysms can cause symptoms, such as headaches, mass effect, focal neurologic deficits, and seizures, and can even cause subarachnoid hemorrhage or stroke; in severe cases, this can endanger the child's life (1, 2). Although this disease is rare, it can be challenging for both neurosurgeons and neurointerventionists. These lesions generally have a dissecting or fusiform morphology, a large or giant size, and rapid disease progression (2, 3). With the advancement of interventional techniques and imaging technology, endovascular therapy has become one of the main methods for treating aneurysms (4–7). The pipeline embolization device (PED; Medtronic Neurovascular; Irvine, California, USA) is a flow diverter used for the endovascular treatment of intracranial aneurysms. Previous case reports and case series have shown that PEDs may provide a paradigm shift in the treatment of intracanal aneurysms in pediatric patients (8–10). However, these studies did not individually describe the treatment outcomes of nonsaccular aneurysm patients treated with PEDs.

In this study, we retrospectively collected patient demographics, aneurysm characteristics, procedural details, and clinical and angiographic outcomes of pediatric patients with nonsaccular aneurysms treated with PEDs, to evaluate the safety and efficacy of PEDs for their management.

Pediatric nonsaccular intracranial aneurysms are rare but challenging lesions. These aneurysms typically manifest with fusiform or dissecting morphology, causing a range of neurological symptoms that can be life-threatening (1–3). In recent years, PEDs have gained popularity for the treatment of intracranial aneurysms. Previous studies have indicated that PEDs can be used to treat pediatric intracranial aneurysms (8–10, 12, 13). However, there is minimal evidence on PED safety and efficacy in pediatric nonsaccular aneurysm patients. In this study, we retrospectively examined 16 pediatric patients with 16 nonsaccular aneurysms treated with PEDs. The complication rate was found to be 25%. Finally, 93.75% of the patients achieved favorable outcomes and 93.33% achieved complete occlusion without any neurologic deficits. These findings suggest that PEDs are a safe and effective treatment method for pediatric nonsaccular aneurysms.

Mass effect is a complex complication of PED treatment for intracranial aneurysms. This complication often occurs in large or giant aneurysms, especially those in the posterior circulation, which are adjacent to important brainstem structures and cranial nerves (14, 15). PEDs can effectively reduce blood flow through the aneurysm and promote thrombus formation, allowing neointimal hyperplasia over their surface to reconstruct the parent artery and heal the aneurysm. The literature suggests that during the acute stage of intra-aneurysm thrombosis, aneurysm volume increases, leading to or exacerbating the mass effect. However, as time passes after PED implantation, the aneurysm shrinks in size, and the mass effect diminishes or disappears (16–19). The previous study indicates that usage of corticosteroids could reduce the occurrence of mass effect in adults, which might also be applicable in children (20). In this study, our findings were similar to those reported in previous studies. Two patients developed a mass effect after PED implantation; the aneurysms in both patients were large vertebrobasilar artery aneurysms adjacent to the brainstem and important cranial nerve nuclei. One patient died of respiratory and circulatory failure secondary to mass effect, at 3 days post-procedure. Another patient experienced dysphagia after recovering from anesthesia at 2 days post-procedure, and owing to the mass effect, and a gastric tube was inserted. The patient recovered 55 days after the procedure without any neurological complications. In clinical practice, we found that strict blood pressure control, careful nursing, and timely treatment of mass effect can prevent the occurrence of mass effects or reduce associated outcomes, including disability and death.

It is generally complicated and difficult to manage recurrent aneurysms after coiling, stenting, stent-assisted coiling, and surgical clipping. The application of PEDs in treating these aneurysms leads to favorable outcomes, with high complete occlusion rates and low complication rates (21–25). However, little evidence exists on the safety and effectiveness of PED treatment for recurrent pediatric aneurysms. This study included two pediatric patients with recurrent aneurysms. One patient had a recurrent aneurysm located at the C4 segment of the left internal carotid artery, which had previously undergone Willis covered stent placement. We successfully treated the aneurysm with a single PED implantation, and imaging follow-up 7 months later demonstrated complete aneurysm occlusion. Another patient had a recurrent aneurysm located at the M1 segment of the middle cerebral artery that had undergone two treatments previously: endovascular coiling and surgical clipping. The patient was treated with PED implantation without adjunctive coils, and follow-up imaging showed complete occlusion of the aneurysm 3 months after the operation. None of the patients had neurological complications. Our results suggest that PEDs are a potentially effective method for the treatment of recurrent aneurysms in pediatric patients.

Previous studies have confirmed that the use of specific doses of dual antiplatelet therapy in adults can reduce thromboembolic complications after PED placement (26–28). However, there are few studies on antiplatelet regimens after PED placement in pediatric patients. Therefore, the pediatric antiplatelet therapy remains controversial. A randomized controlled trial on heart disease in children aged 0–24 months demonstrated that administration of 0.2 mg/kg clopidogrel per day achieves a platelet inhibition level comparable to taking 75 mg per day in adults (29). Another comparative study suggested age-specific differences in agonist-simulated platelet reactivity in children compared to that in adults and highlighted the need for age-specific reference ranges for platelet function in children (30). These studies suggest differences between the use of antiplatelet drugs in children and adults. In a previous study on the use of flow diverters to treat pediatric cerebrovascular diseases, the authors administered different doses of aspirin and clopidogrel depending on whether the patients weighed more than 45 kg and achieved favorable clinical outcomes (31). In this study, the dosage of antiplatelet drugs was determined by considering the previous literature, the experience of neurointerventionists, and the specific situation of the patients. The included patients of our study were generally older, with the youngest patient being 4 years old and the rest being over 5 years old. To prevent thromboembolic complications, we administered an adult dose of aspirin and clopidogrel for patients older than 5 years. Considering the young age and low body weight, we halved both doses for the 4-year-old patients to prevent the occurrence of potential hemorrhage. In our study, a 10-year-old male patient experienced major ischemic stroke 2 months after the operation; the patient recovered 9 days after conservative treatment without any neurological complications. In summary, the dosage of using antiplatelet drugs in pediatric patients treated with flow diverters requires further investigation. Subsequent studies with larger case numbers are needed to explore the optimal antiplatelet therapy regimen.

This study has several limitations. First, this was a retrospective study with a relatively small sample size and a short follow-up duration. Due to the small sample size, we could not explore factors influencing the complications and embolization outcomes. Additionally, as the youngest patient in our study was 4 years old, we were unable to determine the safety and effectiveness of PED treatment for these aneurysms in children younger than 4 years.

In this cohort, we achieved a high rate of complete aneurysm occlusion and favorable clinical follow-up outcomes. These findings suggest that the use of PED to treat pediatric nonsaccular aneurysms is safe and effective.

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding authors.

Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

JH and FL collected and analyzed the data and drafted and revised the paper. YuxZ monitored data collection and analyzed the data. YupZ and SL revised the paper and gave final approval of the version to be submitted. HZ, YC, and CM monitored data collection. LL revised the paper critically and gave final approval of the version to be submitted. CJ and ZJ concepted and designed the article, revised the paper critically, and gave final approval of the version to be submitted. All authors contributed to the article and approved the submitted version.