The role of surgical disconnection for posterior fossa pial arteriovenous fistulas and dural fistulas with pial supply: an illustrative case series.

BACKGROUND: Pial arteriovenous fistulas (pAVFs) are rare vascular malformations characterized by high-flow arteriovenous shunting involving a cortical arterial supply directly connecting to venous drainage without an intermediate nidus. Dural arteriovenous fistulas (dAVFs) can infrequently involve additional pial feeders which can introduce higher flow shunting and increase the associated treatment risk. In the posterior fossa, arteriovenous fistula (AVF) angioarchitecture tends to be particularly complex, involving either multiple arterial feeders-sometimes from both dural and pial origins-or small caliber vessels that are difficult to catheterize and tend to be intimately involved with functionally critical brainstem or upper cervical cord structures. Given their rarity, published experience on microsurgical or endovascular treatment strategies for posterior fossa pAVFs and dAVFs with pial supply remains limited. METHODS: Retrospective chart review from 2019-2023 at a high-volume center identified six adult patients with posterior fossa pAVFs that were unable to be fully treated endovascularly and required microsurgical disconnection. These cases are individually presented with a technical emphasis and supported by comprehensive angiographic and intraoperative images. RESULTS: One vermian (Case 1), three cerebellopontine angle (Cases 2-4) and two craniovertebral junction (Cases 5-6) posterior fossa pAVFs or dAVFs with pial supply are presented. Three cases involved mixed dural and pial arterial supply (Cases 1, 4, and 6), and one case involved a concomitant microAVM (Case 2). Endovascular embolization was attempted in four cases (Cases 1-4): The small caliber and tortuosity of the main arterial feeder prevented catheterization in two cases (Cases 1 and 3). Partial embolization was achieved in Cases 2 and 4. In Cases 5 and 6, involvement of the lateral spinal artery or anterior spinal artery created a prohibitive risk for endovascular embolization, and surgical clip ligation was pursued as primary management. In all cases, microsurgical disconnection resulted in complete fistula obliteration without evidence of recurrence on follow-up imaging (mean follow-up 27.1 months). Two patients experienced persistent post-treatment sensory deficits without significant functional limitation. CONCLUSIONS: This illustrative case series highlights the technical difficulties and anatomical limitations of endovascular management for posterior fossa pAVFs and dAVFs with pial supply and emphasizes the relative safety and utility of microsurgical disconnection in this context. A combined approach involving partial preoperative embolization-when the angioarchitecture is permissive-can potentially decrease surgical morbidity. Larger studies are warranted to better define the role for multimodal intervention and to assess associated long-term AVF obliteration rates in the setting of pial arterial involvement.

Impact of Cerebral Revascularization on Pial Collateral Flow in Patients With Unilateral Moyamoya Disease Using Quantitative Magnetic Resonance Angiography.

BACKGROUND AND OBJECTIVES: Moyamoya disease (MMD) is a chronic steno-occlusive disease of the intracranial circulation that depends on neoangiogenesis of collateral vessels to maintain cerebral perfusion and is primarily managed with cerebral revascularization surgery. A quantitative assessment of preoperative and postoperative collateral flow using quantitative magnetic resonance angiography with noninvasive optimal vessel analysis (NOVA) was used to illustrate the impact of revascularization on cerebral flow distribution. METHODS: A retrospective review of patients with unilateral MMD who underwent direct, indirect, or combined direct/indirect cerebral revascularization surgery was conducted between 2011 and 2020. Using NOVA, flow was measured at the anterior cerebral artery (ACA), ACA distal to the anterior communicating artery (A2), middle cerebral artery (MCA), posterior cerebral artery (PCA), and PCA distal to the posterior communicating artery (P2). Pial flow (A2 + P2) and collateral flow (ipsilateral [A2 + P2])-(contralateral [A2 + P2]) were measured and compared before and after revascularization surgery. Total hemispheric flow (MCA + A2 + P2) with the addition of the bypass graft flow postoperatively was likewise measured. RESULTS: Thirty-four patients with unilateral MMD underwent cerebral revascularization. Median collateral flow significantly decreased from 68 to 39.5 mL/min ( P = .007) after bypass. Hemispheres with maintained measurable bypass signal on postoperative NOVA demonstrated significant reduction in median collateral flow after bypass ( P = .002). Median total hemispheric flow significantly increased from 227 mL/min to 247 mL/min ( P = .007) after bypass. Only one patient suffered an ipsilateral ischemic stroke, and no patients suffered a hemorrhage during follow-up. CONCLUSION: NOVA measurements demonstrate a reduction in pial collateral flow and an increase in total hemispheric flow after bypass for MMD, likely representing a decrease in leptomeningeal collateral stress on the distal ACA and PCA territories. Further studies with these measures in larger cohorts may elucidate a role for NOVA in predicting the risk of ischemic and hemorrhagic events in MMD.

Resection of Cervical Intradural Extramedullary Melanoma Metastasis with Pial Invasion: 2-Dimensional Operative Video.

Intradural extramedullary metastatic melanoma is a rare entity with only 13 other cases reported in the literature.1 Of these, only 3 have been described in the cervical spine.2-4 Metastatic melanoma to the brain has historically portended a grim prognosis; however, due to the paucity of reported intradural lesions, the clinical course, including surgical findings, is less well known. This video illustrates a case of a 59-year-old man with new left arm pain and numbness found to have cervical intradural extramedullary metastatic melanoma (Video 1). This video also demonstrates surgical principles and techniques for removal of a rare cervical intradural extramedullary melanoma metastasis using standard cervical laminectomy with intraoperative ultrasound for tumor localization. Considering its rarity, visualizing the intraoperative resection is important for surgeons who may potentially treat such pathology. Patient consented for the procedures and for publication of the video.

Effect of Durotomy versus Myelotomy on Tissue Sparing and Functional Outcome after Spinal Cord Injury.

Various surgical strategies have been developed to alleviate elevated intraspinal pressure (ISP) following acute traumatic spinal cord injury (tSCI). Surgical decompression of either the dural (durotomy) or the dural and pial (myelotomy) lining of the spinal cord has been proposed. However, a direct comparison of these two strategies is lacking. Here, we compare the histological and functional effects of durotomy alone and durotomy plus myelotomy in a rodent model of acute thoracic tSCI. Our results indicate that tSCI causes local tissue edema and significantly elevates ISP (7.4 ± 0.3 mmHg) compared with physiological ISP (1.7 ± 0.4 mmHg; p < 0.001). Both durotomy alone and durotomy plus myelotomy effectively mitigate elevated local ISP (p < 0.001). Histological examination at 10 weeks after tSCI revealed that durotomy plus myelotomy promoted spinal tissue sparing by 13.7% compared with durotomy alone, and by 25.9% compared with tSCI-only (p < 0.0001). Both types of decompression surgeries elicited a significant beneficial impact on gray matter sparing (p < 0.01). Impressively, durotomy plus myelotomy surgery increased preservation of motor neurons by 174.3% compared with tSCI-only (p < 0.05). Durotomy plus myelotomy surgery also significantly promoted recovery of hindlimb locomotor function in an open-field test (p < 0.001). Interestingly, only durotomy alone resulted in favorable recovery of bladder and Ladder Walk performance. Combined, our data suggest that durotomy plus myelotomy following acute tSCI facilitates tissue sparing and recovery of locomotor function. In the future, biomarkers identifying spinal cord injuries that can benefit from either durotomy alone or durotomy plus myelotomy need to be developed.

Clinical outcomes of epidural and intradural decompression for treatment of degenerative cervical myelopathy.

OBJECTIVE: This study was performed to examine the clinical outcomes of epidural and intradural decompression for degenerative cervical myelopathy. METHODS: The data for 13 patients who underwent epidural and intradural decompression for treatment of degenerative cervical myelopathy (study group) and 20 patients who underwent only cervical laminoplasty, fusion, and epidural decompression (historical control group) were retrospectively reviewed. The preoperative and postoperative neurological status was evaluated using the Japanese Orthopaedic Association (JOA) score. RESULTS: All patients' neurological symptoms were significantly improved at the final follow-up. In the study group, the patients' mean preoperative JOA score was 8.07 ± 1.80, and the final score improved by 70.88% ± 21.18%. The blood loss and operation time were significantly greater in the study group than control group. The recovery time was shorter in the study group than control group. The improvement rate was not significantly different between the two groups. CONCLUSIONS: A pia mater incision with separation of the arachnoid adhesion can significantly improve the cerebrospinal fluid flow and spinal blood flow in degenerative cervical myelopathy. Arachnoid adhesion can lead to intradural spinal scar compression. The surgical intervention described herein can achieve satisfactory neurological outcomes and shorten the recovery time.

Surgical Disconnection of a Residual Pediatric Pial Arterio-Venous Fistula Following Partial Embolization: A Case Study.

BACKGROUND: Pial arteriovenous fistulas (AVFs) are rare intracranial vascular lesions consisting of 1 or more feeder arteries connecting directly to a venous system without a nidus, in the subpial space. Because of the high-flow system, they are commonly associated with a large varix. They are thought to represent between 1.6% and 7.3% of all pediatric arteriovenous malformations (AVMs). Morbidity and mortality is high in this condition and surgical or endovascular treatment options are usually considered. There have been limited reports on the clinical features, treatment options, and outcomes of pial AVMs due to its rarity. We present a case study of a pediatric patient in our institution and her clinical course, focusing on her presenting clinical features and management. CASE DESCRIPTION: A 1-year-old girl presents with progressively prominent and dilated facial veins and no other features suggestive of pial AVF. She was diagnosed with pial AVF with two feeder arteries and a large varix on imaging. Embolization was undertaken 3 times before successful surgical disconnection was done. Genetic testing for associated syndromes were all negative. CONCLUSIONS: Prominence of facial veins could be 1 of the more uncommon presenting features of pial AVFs. Genetic testing should always be considered in the pediatric population diagnosed with AVFs because of their association to various syndromes. Despite endovascular embolization being considered the less invasive choice, decision on mode of treatment should be a multifactorial decision.

How I do it: dorsolateral approach for ventrolateral intramedullary cavernoma.

BACKGROUND: For small and lateral lesions, in order to avoid postoperative sequelae related to dorso-median myelotomy, we propose to describe the use of a ventrolateral approach for intramedullary lesions. METHOD: Performing this approach entails that the denticulate ligament is cut from its dural attachment and retracted. Rotation of the spinal cord must be achieved with great caution and under electrophysiological monitoring. After pia mater incision, hydrodissection is useful to gently dissect the cavernoma and promote a cleavage plane. CONCLUSION: In the case of lateral intramedullary lesions, using this approach maximized the absence of postoperative deficit.

Pial Arteriovenous Fistula with Multiple Venous Aneurysms Resembling a Vein of Galen Aneurysmal Malformation; Case Report and Review of Literature.

BACKGROUND: Pial arteriovenous fistulas are abnormal vascular connections between arteries and the cranial venous system on the surface of the brain in the pia mater. In contrast to vein of Galen aneurysmal malformations, they lack a true vascular nidus and may only indirectly involve the vein of Galen. CASE DESCRIPTION: An 18-month-old boy was referred to us with a history of seizures, drowsiness, bulging cephalic veins, and cranial nerves palsy identified as vein of Galen aneurysmal malformation according to initial magnetic resonance imaging. Digital subtraction angiography showed a vertebrobasilar junction pial high-flow fistula between the basilar artery and anterior pontomesencephalic vein, causing retrograde flow, dilation, and tortuosity of the lateral and posterior mesencephalic vein as well as the vein of Galen. Endovascular treatment, including coil embolization of fistula site, was done successfully without complication resulting in recovery from previous symptoms and signs. CONCLUSIONS: If cerebral venous dilations are encountered, one must keep in mind that the location of the fistula may not be in close proximity to the dilated veins, especially when there is a suspicion for vein of Galen aneurysmal malformation. Other pathologies, such as pial arteriovenous fistula, in a region away from the site of the vein of Galen must be considered.

Development of bilateral dural arteriovenous fistulae following pial synangiosis for moyamoya syndrome: case report.

Moyamoya syndrome predisposes patients to ischemic or hemorrhagic stroke due to progressive narrowing of intracranial vessels with subsequent small-vessel collateralization. Dural arteriovenous fistulae (DAVFs) are most commonly noted after venous sinus or cortical vein thrombosis and are believed to be primarily due to venous hypertension and elevated sinus pressures, although there is no known association with moyamoya syndrome, or with surgical treatment for moyamoya disease (MMD). The authors present the case of a 14-year-old girl with Down syndrome treated using pial synangiosis for MMD who subsequently was noted to have bilateral DAVFs. This case provides a new perspective on the origins and underlying pathophysiology of both moyamoya syndrome and DAVFs, and also serves to highlight the importance of monitoring the moyamoya population closely for de novo cerebrovascular changes after revascularization procedures.

Dural and Pial Arteriovenous Fistulas Connected to the Same Drainer in the Middle Cranial Fossa: A Case Report.

BACKGROUND: Dural arteriovenous fistulas (AVFs) in the middle cranial fossa are rare. Pial AVFs are similarly rare but differ from dural AVFs in that they derive their arterial supply from pial or cortical arterial vessels and do not lie within the intradural region. We report an extremely rare case of dural and pial AVF connected to the same drainer in the middle cranial fossa. CASE DESCRIPTION: In a 58-year-old man with a subcortical hemorrhage in the right temporal lobe, digital subtraction angiography showed a dural AVF in the middle cranial fossa fed by the middle meningeal artery (MMA) and draining into the sphenopetrosal vein. A combination with a small pial AVF connected to the same sphenopetrosal vein was suspected. Open surgery was performed to directly observe the shunt points. Transarterial indocyanine green (ICG) angiography using the MMA via the superficial temporal artery on a skin flap was performed to repeatedly and distinctly evaluate the dural shunt points and to prevent cerebral thromboembolism. Although the dural supply was completely disconnected, the sphenopetrosal vein remained arterialized. ICG angiography revealed pial AVF, which was fed by the cortical arteries draining into the same drainer. The pial supply was completely disconnected, and disappearance of the dural and pial AVF was confirmed. CONCLUSIONS: We report an extremely rare case of dural and pial AVF connected to the same drainer in the middle cranial fossa. To our knowledge, this is the first such case report described in the literature.

Clipping of a Pediatric Pial Arteriovenous Fistula Located at Basilar Artery Tip Using a Hybrid Trapping-Evacuation Technique.

BACKGROUND: Intracranial pial arteriovenous fistulas (PAVFs) are rare cerebrovascular lesions with high mortality rates. We report a rare case of pediatric PAVF at the basilar artery tip and its treatment with surgical clipping aided by a trapping-evacuation technique in a hybrid operating room. CASE DESCRIPTION: An 18-month-old boy was admitted with hypoevolutism and 4-month history of weakness in the left extremities. Magnetic resonance imaging showed a giant aneurysm-like malformation in the area of midbrain and pons. Angiography showed a high-flow PAVF fed by the basilar artery and bilateral P1 segments of the posterior cerebral artery, with deep draining veins into the transverse sinus and straight sinus. Given the intrinsic characteristics of the lesion, such as deep location, giant fistula and varix, and multiple feeding arteries, clipping of PAVF was performed in a hybrid operating room aided by a trapping-evacuation technique to clearly identify and block the shunting point. CONCLUSIONS: The successful obliteration of the lesion is reported. In addition, a brief review of literature comparing endovascular embolization, surgical disconnection, and hybrid technique for treatment of PAVF is included.

Surgical Revascularization for Children with Moyamoya Disease: A New Modification to the Pial Synangiosis.

OBJECTIVE: To summarize therapeutic efficacy of modified pial synangiosis in children with moyamoya disease and our experience with this method. METHODS: A retrospective study was conducted to analyze clinical efficacy of modified pial synangiosis in children with moyamoya disease who were treated between October 2002 and August 2015 at our center. Clinical characteristics of these rare cases were summarized, and surgical efficacy was assessed based on long-term follow-up results. RESULTS: We employed modified pial synangiosis to treat 10 children with moyamoya disease; 18 modified pial synangiosis procedures were performed. The study included 2 boys and 8 girls (mean age at disease onset, 6.5 years ± 2.6). According to preoperative digital subtraction angiography, Suzuki grade III was noted in 80% (16/20) of hemispheres, and Suzuki grade II was noted in the remaining hemispheres (4/20). Mean follow-up period was 63.4 months ± 36.0. During the follow-up period, 2 cases of transient ischemic attack were reported. The remaining patients had no evidence of cerebral ischemia, seizures, or cerebral hemorrhage. Postoperative assessments based on Matsushima classification scores showed that patients with grade A revascularization accounted for 66.7% (12/18) of treated hemispheres, patients with grade B accounted for 27.8% (5/18), and patients with grade C accounted for 5.6% (1/18). CONCLUSIONS: Our clinical findings provide data on efficacy and safety of modified pial synangiosis, but analysis of more cases is necessary to draw solid conclusions. A randomized controlled study is required to verify improved surgical efficacy of modified pial synangiosis.

Pial Arteriovenous Fistula: A Brief Review and Report of 14 Surgically Treated Cases.

OBJECTIVE: The authors report their successful experience of treating 14 cases of pial arteriovenous fistula (PAVF) by direct surgery. METHODS: During the period January 2010 to April 2017, 14 patients with PAVF were treated by surgery. Only those patients were selected who had a single arterial feeding channel. There were 9 male patients and 5 female patients, and their ages ranged from 5 to 53 years (average, 19 years). Ten patients were younger than 20 years of age. Five patients presented clinical and radiologic features that suggested hemorrhage from the PAVF. Ten patients had seizures. Two patients had hemispheric symptoms or neurologic deficits at the time of presentation. In 12 patients, there were no gross neurologic deficits. The diagnosis was made on the basis of digital subtraction angiography in all patients and computed tomographic angiography in 8 patients. Angiography revealed that the PAVFs in 8 patients were supplied by the middle cerebral artery, in 5 patients by the anterior cerebral artery, and in 1 patient by branches of the basilar artery. Surgical procedures involved identification of the site of fistula, obliteration of the feeding artery, and resection of the entire venous varix. RESULTS: The PAVF was successfully excluded from circulation in all patients. There were no neurologic deficits related to the surgical procedure. CONCLUSIONS: Direct surgical resection of the entire PAVF is a safe, effective, and probably curative method of treatment.

Multiple subpial transections and magnetic resonance imaging.

INTRODUCTION: Multiple subpial transection (MST) has been applied to the treatment of refractory epilepsy when epileptogenic zone involves eloquent areas since 1989. However, there is a lack of data evaluating the effect of this surgical technique on the cortex as measured by Magnetic Resonance Imaging (MRI). PATIENTS AND METHODS: Ten consecutive patients (3F/7M, average age: 18.5 years) were operated on using radiating MST (average: 39; min: 19, max: 61) alone (n=3) or associated with another technique (n=7). Seven patients underwent a post-operative 3.0T MRI while 3 had a 1.5T MRI. Three patients had an early post-operative MRI and 7 a late MRI, among which 3 previously had an intraoperative MRI. RESULTS: The MR sequences that allowed the best assessment of MST-induced changes were T2 and T2*. The traces of MST are more visible on late MRI. These discrete non-complicated stigmas of MST were observed in all 10 studied patients: on the intraoperative MRI they are seen as micro-hemorrhagic spots (hypo-T2), on the early postoperative MRI as a discreet and limited cortical edema whether associated or not with micro-hemorrhagic spots and on the late MRI as liquid micro-cavities (hyper-T2) surrounded with a fine border of hemosiderin. CONCLUSIONS: MST-induced cerebral lesions are best visualized in T2-sequences, mainly on the late postoperatively MRIs. On all the MRI examinations in this study, the MST are only associated with limited modifications of the treated cortical regions.

Moyamoya Disease in an 18-Month-Old Female Caucasian Complicated by Cerebral Hyperperfusion Syndrome Following Indirect Revascularization.

BACKGROUND Cerebral hyperperfusion syndrome is a rare complication of indirect revascularization due to moyamoya disease, but has not been reported previously in the pediatric population. We present a case of an 18-month-old girl with moyamoya disease that was treated with bilateral pial synangiosis and had complications consistent with cerebral hyperperfusion syndrome. This case report discusses the pathophysiological mechanisms involved in cerebral hyperperfusion in moyamoya syndrome. CASE REPORT An 18-month-old female Caucasian presented with seizures and weakness of the left side. Angiography confirmed bilateral cerebral moyamoya disease that was worse on the right side. Indirect revascularization with pial synangiosis was first performed on the right side to allow for healing. Five months later, pial synangiosis was then performed on the left side. Postoperatively, the patient experienced increased intracranial pressure (ICP), suggesting cerebral hyperperfusion syndrome. She was treated with a repeat lumbar puncture, a lumbar drain, and a lumbar shunt. CONCLUSIONS This report demonstrates a case of cerebral hyperperfusion syndrome as a complication of moyamoya disease in a pediatric patient. Although the patient progressed well after placement of a lumbar shunt, this case demonstrates the occurrence of cerebral hyperperfusion syndrome as a complication of revascularization in pediatric patients and highlights the need for further research in this area.

Navigation-guided clipping of a de novo aneurysm associated with superficial temporal artery-middle cerebral artery bypass combined with indirect pial synangiosis in a patient with moyamoya disease.

De novo aneurysms associated with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass are an extremely rare complication of direct revascularization surgery for moyamoya disease (MMD). The basic pathology of MMD includes fragility of the intracranial arterial wall characterized by medial layer thinness and waving of the internal elastic lamina. However, the incidence of newly formed aneurysms at the site of anastomosis currently remains unknown. Among 317 consecutive direct/indirect combined revascularization surgeries performed for MMD, we encountered a 52-year-old woman manifesting a de novo aneurysm adjacent to the site of anastomosis 11 years after successful STA-MCA bypass with encephalo-duro-myo-synangiosis (EDMS). Although the patient remained asymptomatic, the aneurysm gradually increased in diameter to more than 6 mm with the formation of a daughter sac, and a computational fluid dynamic study revealed low wall shear stress at the aneurysm dome. The patient underwent microsurgical clipping of the aneurysm using a neuro-navigation system that permitted the minimally invasive dissection of the temporal muscle flap used for EDMS at the site of the aneurysm without affecting pial synangiosis. The aneurysm was successfully occluded using a titanium clip without complications. The postoperative course was uneventful, and the patient was discharged without neurological deficits. De novo aneurysms associated with STA-MCA bypass for MMD may be safely treated with microsurgical clipping, even in cases initially managed by a combined revascularization procedure that includes complex pial synangiosis. We recommend the application of the neuro-navigation system for the maximum preservation of pial synangiosis during this procedure.

Hydrocephalus in a patient with an unruptured pial arteriovenous fistula: hydrodynamic considerations, endovascular treatment, and clinical course.

Intracranial pial arteriovenous fistulas, also known as nongalenic fistulas, are rare vascular malformations affecting predominantly the pediatric population. Hydrocephalus is an unusual presentation in which the exact pathophysiology is not fully understood. The aim of treatment in these cases is occlusion of the fistula prior to considering ventricular shunting. Here, the authors describe the hydrodynamic considerations of the paravascular pathway and the resolution of hydrocephalus with endovascular treatment of the fistula.