This is a presentation on piped revascularization as a novel surgical technique for treatment of anterior cerebral territory ischemia and pediatric Moyamoya, a case series with long-term clinical and radiographic follow-up. The authors have nothing to disclose. Moyamoya disease is an idiopathic cerebrovascular arteriopathy characterized by progressive stenoclusive changes of the internal cerebral arteries and their branches, the anterior and the middle cerebral arteries, with the resulting parenchymal ischemia. In general, the MCA territory is frequently affected either alone or with the ACA territory, however, isolated ACA territory ischemia and pediatric Moyamoya is relatively rare. It's well known that surgical revascularization is the fundamental treatment modality for Moyamoya, and this study aims to evaluate a novel variant of surgical revascularization in the ACA territory for pediatric patients. We've conducted a retrospective review of the medical records of all pediatric patients with Moyamoya who presented at our institute from July 2009 through July 2019 to identify pediatric Moyamoya patients with ACA territory ischemia who were treated with piped revascularization. Only patients who were under 18 years of age were included. A thorough review of the medical records of identified cohort was conducted, and the following data were collected and analyzed. Patient demographics, associated medical conditions, clinical presentation, radiographic findings, surgical indications, postoperative complications, clinical and radiographic outcome. Our standard technique for revascularization is PL syngiosis, however, if no adequate vessel is available in the surgical field for syngiosis or direct bypass, we opt for piped revascularization, which is a hybrid approach incorporating several principles derived from our institution and others, building on the principle of PL syngiosis, but unique in using pericranium and dura as the primary vascular supply and employing a larger craniotomy with arachnoid dissection to provide robust full territory revascularization in all ages without the attendant risk of more complex procedures. The patient is positioned supine and the head is placed in a neutral position on a gel donut. Skin incision is marked over the brain region intended for revascularization. After opening the skin, the plane between the gallia and the pericranium is carefully dissected, and a wide pericranial flap is prepared with a broad-based inferior pedicle. A craniotomy flap is then created with an enlarged, unique, dashed-sign burr hole fashioned at the base of the flap to allow tunneling of the pericranial flap later on in the procedure. The dura is opened in a still-laid fashion, and the arachnoid is opened in as many spots as possible to maximize the exposure of the cortical surface with a vascularized pericranial flap. The flap is then laid in direct contact over the brain, affixed to the pia with a 10-0 nylon sutures, the dura leaflets are placed back on the brain without suturing, the bone flap is replaced, and then the incision is closed. Our search yielded a total of 446 operations performed on 290 pediatric Moyamoya patients from July 2009 through July 2019. Moyamoya was affecting the ACA territory in 21 patients with a total of 25 operations. The average age of patients was 9.4 years, and there was female preponderance in the cohort. Almost one-third of patients showed syndromic associations, however, there were no familiar cases. There were no complications in the postoperative period, including strokes, hemorrhage, seizures, or mortalities. Only one patient had superficial wound infection, which was treated successfully. Long-term follow-up data was available for 18 out of 21 patients, and the average follow-up period was 24.9 months. Evidence of radiographic engraftment was present in more than 90% of hemispheres. No new strokes were evident on MRI on long-term follow-up, despite radiographic progression of the disease. This is a case of a 5-year-old male patient with no past medical history, who presented with a series of transient ischemic attacks for a few years that have been accelerating in their tempo and intensity over several months prior to presentation. Most of his TIAs were bilateral, more on the left side, and they were more involving weakness of the arms more than the legs. Brain MRI and MRA was consistent with bilateral moyamoya, and this is an axial T2 image at the level of the basal cisterns and at the level of the basal ganglia, showing extensive proliferation of the lenticular striate vessels and multiple void signals of moyamoya collaterals. FLAIR sequence demonstrated extensive IV sign. The patient underwent bilateral PL-synangiosis with uneventful postoperative course. His TIA symptoms dramatically improved. However, 6 months later, TIAs recurred with involvement of both lower extremities. Brain MRI and MRA was obtained, which showed significant bilateral engraftment at the synangiosis site, and digital subtraction and geography with external carotid injections demonstrated brisk flow through the synangiosis bilaterally, consistent with Matsushima grade A, with no transduriculaterals at the ACA territory. Injections of the bilateral ICAs showed severe anterior cerebral artery disease, so the decision was to perform bilateral pipe revascularization of the ACA territories, and the procedure was uneventful with no postoperative complications. Follow-up cerebral angiogram at 1 year was still showing Matsushima grade A at the previous synangiosis site and brisk flow at the pipe revascularization sites, and noticed the hypertrophied arterial feeders supplying the ACA territory. In comparing this to the preoperative angiogram, the significant difference in the flow to the ACA territory can be appreciated. At 5 year follow-up visit, the patient was asymptomatic with no TIAs since surgery, and MRI at 5 year follow-up was showing significant reduction in disappearance of IV sign. The ACA territory is frequently involved as Moyamoya arteriopathy progresses. We describe here a variant of surgical technique that can be helpful in dislocation, which is pipe revascularization, incorporating methods used by our group and others, and we have tried to be very transparent in acknowledging the contribution of previous efforts in providing various components of this strategy. Our goal in putting a name to it is to better codify the approach so that surgeons have a very specific technique to choose from when weighing treatment options. Surgical treatment of ACA territory can be challenging, whether with a direct bypass which provides immediate augmentation of blood flow, but often untenable in pediatrics due to delicacy and small caliber of vessels, or with indirect revascularization techniques including multiple birth holes, which have limited efficacy outside of infancy, due to the thickness of the skull in older children, precluding robust engross of collaterals through long, narrow, bony corridors, and because of the technical difficulty of opening the door in arachnoid in older children through a birth hole, which is time-consuming when performed in multiple birth holes, and even larger craniotomies, they are limited by graft choices including omentum, gallia, and percranium. The use of these grafts for indirect revascularization has been previously reported, but its application for treatment for ACA territory ischemia is still limited, and the long-term outcome in a large pediatric case series has not been well studied. So the question is, are there alternative methods in children? Taken together, these data suggest that there is a continued need for additional methods to treat ACA disease in pediatric Moyamoya. Pipe revascularization technique is a hybrid approach incorporating several principles derived from our program and others. Versatility is the main advantage of this technique, as it can be used directly over the ischemic brain region in need for revascularization without being limited by the course of a donor vessel. This technique is safe, simple, less time-consuming, and reliable in terms of outcome. Evidence of radiographic engraftment was present in more than 90% of hemispheres, indicating that during percranium can supply a rich collateral network which persisted over the long-term on serial imaging. Pipe revascularization provided protection from future TIAs and strokes, as non-used strokes were evident on long-term follow-up MRI in all patients, despite ongoing evidence of worsening primary arteriopathy. All patients with preoperative TIAs became symptom-free. None of the patients had worsening of the preoperative ischemic symptoms. To sum up, surgical management of ACA-territory ischemia in pediatric Moyamoya patients is challenging. The use of durin-percranium for indirect revascularization provides robust vascularized graft with great flexibility in location and high potential for engraftment, which may obviate the need for more complex and higher-risk operations. Long-term follow-up demonstrates that pipe revascularization provides durable and long-term radiographic and clinical protection from stroke in pediatric Moyamoya patients. Based on the results of the current study, pipe revascularization technique can be considered an additional tool to the armamentarium of indirect revascularization procedures in select cases of Moyamoya in pediatric populations.

piped revascularization

anterior cerebral territory ischemia

pediatric Moyamoya

surgical technique

cerebrovascular arteriopathy