Use of a split dura for revascularization of ischemic hemispheres in moyamoya disease

Outcome prediction of pediatric moyamoya disease using midterm cerebral blood flow measured between staged anastomoses

PURPOSE

Cognitive outcomes of pediatric moyamoya disease are variable and difficult to predict on the basis of initial neurological signs and examinations. To determine the best early time point for outcome prediction, we retrospectively analyzed the correlation between cognitive outcomes and the cerebrovascular reserve capacity (CRC) measured before, between, and after staged bilateral anastomoses.

METHODS

Twenty-two patients aged 4-15 years were included in this study. CRC was measured before the first hemispheric surgery (preoperative CRC), 1 year after the first surgery (midterm CRC), and 1 year after the surgery on the other side (final CRC). The cognitive outcome was the Pediatric Cerebral Performance Category Scale (PCPCS) grade more than 2 years after the final surgery.

RESULTS

The 17 patients with favorable outcomes (PCPCS grades 1 or 2) showed a preoperative CRC of 4.9% ± 11.2%, which was not better than that of the five patients with unfavorable outcomes (grade 3; 0.3% ± 8.5%, p = 0.5). The 17 patients with favorable outcomes showed a midterm CRC of 23.8% ± 15.3%, which was significantly better than that of the five patients with unfavorable outcomes (-2.5% ± 12.1%, p = 0.004). The difference was much more significant for the final CRC, which was 24.8% ± 13.1% in the patients with favorable outcomes and -11.3% ± 6.7% in those with unfavorable outcomes (p = 0.00004).

CONCLUSION

Cognitive outcomes were first clearly discriminated by the CRC after the first-side unilateral anastomosis, which is the optimal early timing for the prediction of individual prognosis.

Placement of Dermal Regeneration Template on Fibrotic Dura

We report the case of a male presenting with a large, fungating Marjolin ulcer over a prior craniectomy defect that had undergone several attempts at reconstruction. On presentation, he had a large area of exposed, fibrotic dura that ultimately required excision of the outer layer prior to placement of Integra (Integra LifeSciences, Plainsboro, NJ) and subsequent split-thickness skin grafting. Although there have been four other reports of dermal regeneration templates being used on exposed dura, this is the first case report of one being used on exposed dura that required dural preparation prior to placement. We discuss our rationale for this method of reconstruction, the histology of dermal regeneration template incorporation, and why this approach was necessary to allow for incorporation in this patient. 

Indirect revascularization with the dural inversion technique for pediatric moyamoya disease: 20-year experience

OBJECTIVENumerous surgical procedures facilitate revascularization of the ischemic brain in patients with moyamoya disease. Dural inversion is a technique in which flaps of dura mater centered around the middle meningeal artery are inverted, encouraging the formation of a rich collateral blood supply. This procedure has been used in combination with encephaloduroarteriosynangiosis for more than 20 years at the authors' institution for the treatment of pediatric moyamoya disease. The objective of this study was to describe the clinical and radiographic outcomes for a cohort of consecutive pediatric moyamoya patients undergoing dural inversion.METHODSClinical and radiographic data on patients who had undergone dural inversion in the period from 1997 to 2016 were reviewed. Univariate and multivariate logistic regression and Kaplan-Meier analyses were performed to assess the risk of postoperative stroke, functional outcome, and the angiographic degree of revascularization.RESULTSDural inversion was performed on 169 hemispheres in 102 patients. Median follow-up was 4.3 years. Six patients (3.6% of hemispheres) suffered postoperative ischemic or hemorrhagic stroke. Overall mortality was 1.0%. Good postoperative neurological status (modified Rankin Scale [mRS] score ≤ 2) was observed in 90 patients (88%); preoperative and postoperative mRS scores showed significant improvement (p < 0.001). Eighty-six percent of hemispheres had Matsushima grade A or B revascularization. Younger age was associated with postoperative stroke and poor functional outcome. Patients with secondary moyamoya syndrome had a significantly worse radiographic outcome. The cumulative 5-year Kaplan-Meier risk for stroke was 6.4%.CONCLUSIONSDural inversion is a useful technique of cerebral revascularization in pediatric moyamoya disease. A 20-year experience demonstrates the safety and efficacy of this technique with a relatively low rate of postoperative stroke, good functional outcomes, and favorable angiographic results.

Complementary Relation Between Direct and Indirect Bypass in Progress of Collateral Circulation in Moyamoya Disease

BACKGROUND

One of the important aims of surgery for moyamoya disease is to establish indirect revascularization. The purpose of this study was to assess the progress of the middle meningeal artery (MMA) after our novel preservation method and to evaluate the relation between direct and indirect bypass in the chronic stage.

METHODS

A total of 24 hemispheric sides of 19 patients with moyamoya disease were included in this study. Craniotomy was performed with preservation of the MMA during the procedure, then direct bypass was carried out. The relationship between anatomic variations of the MMA and success rate of preserving the MMA during craniotomy was noted. The alteration of the MMA and superficial temporal artery (STA) diameters was then evaluated using magnetic resonance imaging, and the correlation between the MMA and the STA in the chronic stage was examined.

RESULTS

In total, the MMA was preserved during craniotomy in 20 hemispheric sides (83.3%). During the 3-year follow-up period, the MMA and STA diameters were significantly increased. At 3 years after surgery, the alteration of the MMA diameter was significantly more marked in pediatric cases than in adult cases, and MMA diameter was moderately but significantly negatively correlated with STA diameter.

CONCLUSIONS

In moyamoya disease, the MMA could be developed as a pathway for indirect revascularization even after simple preservation, especially in pediatric patients. The progress of the MMA and the STA occurs through their synergistic interaction, and the balance might be decided based on their complementary relations in the chronic stage.

Foramen spinosum and middle meningeal artery in moyamoya disease: Preliminary results of a pilot study

OBJECT

This study investigated whether the size of the middle cranial fossa foramina reflects the severity of moyamoya disease (MMD).

METHODS

It compared 20 adult patients managed without surgical revascularization with 2 age- and sex-matched controls. MR angiography scores were assigned by the severity of occlusive changes of the internal carotid artery, the middle cerebral artery, the anterior and the posterior cerebral arteries and the signals of the distal branches of these arteries. These scores were stratified into MR angiography grades (Houkin's grade: 1-4). The relationships between the Houkin's grade and the size of the foramen spinosum (FS), foramen ovale, carotid canal and middle meningeal artery (MMA) were evaluated.

RESULTS

Simple regression analysis showed the correlation between the Houkin's grade and the bilateral FS (right, r = 0.56, p = 0.010; left, r = 0.46, p = 0.044) and MMA (right, r = 0.89, p = 0.0050; left, r = 0.47, p = 0.036). It also showed the correlation between the FS and MMA (right, r = 0.53, p = 0.018; left, r = 0.55, p = 0.013). There were no significant differences between the Houkin's grade, the size of the carotid canal and the foramen ovale.

CONCLUSIONS

The larger FS and MMA on brain CT, which might be performed for patients suspected of intracranial lesions, could aid the diagnosis of MMD.

Selective and superselective angiography of pediatric moyamoya disease angioarchitecture: the anterior circulation

The angioarchitecture of the so-called moyamoya vessels in children has not been explicitly analyzed. We aimed to investigate the precise anatomy of the vascular anastomotic networks in patients with childhood moyamoya disease. Six children diagnosed with moyamoya disease for the first time underwent an angiographic investigation with selective and superselective injections. We recorded the arterial branches feeding the moyamoya anastomotic networks, their connections and the recipient vessels. Depending on the level of the steno-occlusive lesion, the feeding vessels included the medial striate arteries, the perforators of the choroidal segment of the carotid, the uncal artery, the medial and lateral branches of the intraventricular segment of the anterior choroidal artery, perforators of the communicating segment, the superior hypophyseal arteries, the prechiasmal branches of the ophthalmic artery, the ethmoidal arteries and the dural branches of the cavernous carotid. Through connections, which are described, the recipient vessels were the lateral striate arteries and the middle cerebral, the medial striate arteries and the anterior cerebral, medullary arteries around the ventricular system, anterior temporal branches of the middle cerebral, orbitofrontal and frontopolar branches of the anterior cerebral, as well as other cortical branches of the anterior and middle cerebral territories. The use of high quality selective and superselective angiography enabled us to clearly demonstrate for the first time aspects of the microangiographic anatomy of the moyamoya anastomotic network previously only vaguely or incompletely described.

Selective and superselective angiography of pediatric moyamoya disease angioarchitecture in the posterior circulation

The anastomotic network of the posterior circulation in children with moyamoya disease has not been analyzed. We aimed to investigate the angiographic anatomy of this unique vascular network in patients with childhood moyamoya disease. Selective and superselective injections of the posterior circulation were performed in six children with newly diagnosed moyamoya disease. The arterial branches feeding the moyamoya anastomotic network, their connections and the recipient vessels were demonstrated. Depending on the level of the steno-occlusive lesion, the feeding vessels were the thalamoperforators, the posterior choroidals, the splenic artery, parietoccipital artery, other cortical posterior cerebral artery (PCA) branches, the dural branch of the PCA, the premamillary artery and other posterior communicating artery perforators. Through connections, which are described, the recipient vessels were the striate and medullary arteries, other thalamic arteries with or without medullary extensions, the pericallosal artery, medial parietoccipital cortical branches of the PCA and the anterior choroidal artery. High quality selective and superselective angiography helped in demonstrating the angiographic anatomy of the moyamoya posterior anastomotic network previously either vaguely or incompletely described, as well as connections within the posterior circulation but also its relevance as a collateral to the anterior circulation.

Surgical outcomes for moyamoya angiopathy at barrow neurological institute with comparison of adult indirect encephaloduroarteriosynangiosis bypass, adult direct superficial temporal artery-to-middle cerebral artery bypass, and pediatric bypass: 154 revascularization surgeries in 140 affected hemispheres

BACKGROUND

Untreated, moyamoya angiopathy is a progressive vaso-occlusive process that can lead to ischemic or hemorrhagic stroke.

OBJECTIVE

To review 1 institution's surgical experience with both direct and indirect bypass (encephaloduroarteriosynangiosis) in adult and pediatric groups.

METHODS

A retrospective review was conducted of a consecutive series of patients treated for moyamoya angiopathy between 1995 and 2009.

RESULTS

Thirty-nine adult patients underwent indirect bypass as their initial therapy; 29 adult patients underwent direct bypass. Twenty-four pediatric patients included 20 indirect bypasses and 4 direct bypasses. Overall, 140 hemispheres were treated; 48 patients received revascularization of both hemispheres. There were 14 additional revascularization procedures (10% per hemisphere) performed over a site of continued hypoperfusion postoperatively. Fourteen postoperative ischemic strokes occurred during the entire follow-up (10% per hemisphere), and the Kaplan-Meier analysis was not significantly different between groups (P = .59). Four grafts (9.09%) had failed at radiographic follow-up of the 44 direct bypasses performed. Before the initial surgery, the modified Rankin Scale score was 1.58 ± 0.93, 1.48 ± 0.74, and 1.8 ± 1.1 in the pediatric, adult direct, and adult indirect groups (P = .39). At last follow-up, it was 1.29 ± 1.31, 1.09 ± 0.90, and 1.94 ± 1.51 (P = .04) in the pediatric, adult direct, and adult indirect groups.

CONCLUSION

This series demonstrates that both direct and indirect bypasses can be equally effective in preventing stroke. However, in adult patients, direct bypass patients had significantly greater improvement in symptoms, as seen in modified Rankin Scale scores. Pediatric patients, despite undergoing predominantly indirect bypasses, fared roughly the same as the adults in the direct bypass group.

Application of the chick embryo chorioallantoic membrane in neurosurgery disease

The chick embryo chorioallantoic membrane (CAM) is a highly vascularized extraembryonic membrane. Because of its ease of accessibility, extensive vascularization and immunodeficient environment, the CAM has been broadly used in the oncology, biology, pharmacy, and tissue regeneration research. The present review summarizes the application of the CAM in neurosurgery disease research. We focused on the use of the CAM as an assay for the research of glioma, vascular anomalies, Moyamoya Disease, and the blood-brain barrier.

History of the development of surgical treatments for moyamoya disease

Many surgical treatments for moyamoya disease have been developed over the past 40 years. The optimum treatment for ischemic-type moyamoya disease is almost established. The first surgical treatment for the disease was the superficial temporal artery to middle carotid artery (STA-MCA) anastomosis. The discovery of spontaneous collateral formation following the STA-MCA anastomosis surgery led to the development of various indirect bypass procedures. Collateral formation and clinical outcomes from direct and indirect procedures have been compared to assess the merits and limitations of each technique. Experience and a greater understanding of the surgical effects of moyamoya disease have led to the development of surgical procedures combining various direct and indirect bypass techniques for optimal restoration of perfusion. This review of the historical development and efficacy of each procedure will aid surgeons in selecting the most appropriate surgical procedure for patients of different ages with different symptoms and disease severities.

Meningeal management for optimal revascularization from middle meningeal artery

Numerous surgical techniques have been developed and refined for the treatment of moyamoya disease. Among the indirect techniques of revascularization, encephaloduroarteriosynangiosis has been recognized as effective in promoting revascularization and reversing symptomatology. Neovascularization occurs between the donor artery, either the superficial temporal artery or the occipital artery, and the underlying ischemic cortex. Additionally, the middle meningeal artery and its dural branches have also been shown to contribute to collateral blood supply. In this report the authors describe an integrated management of the meninges for optimal revascularization. They emphasize the importance of recognizing the 3 major layers of the dura and describe a technique of dural splitting at the locus minoris resistentiae between the dura mater's vascular (middle) layer and internal median layer. Applying the dura's vascular layer to the surface of the brain after opening of the arachnoid is designed to optimize dural-pial synangiosis related to middle meningeal artery branches.

Natural history and progression factors of unilateral moyamoya disease in pediatric patients

PURPOSE

Thirty-four pediatric age patients with unilateral moyamoya disease (MMD) were reviewed to analyze the natural history and the predictive factors for progression to bilateral MMD.

METHODS

Forty out of 259 MMD patients cared for between January 2000 and June 2008 in the Severance Hospital had unilateral lesion. These patients were followed for a mean of 32.3 months for their symptoms and imaging studies. Thirty-four out of 40 patients were included in this study. Magnetic resonance angiography (MRA) and magnetic resonance perfusion (MR perfusion) images were taken for all patients for initial diagnosis and repeated at 6 months from the initial diagnosis and then at yearly basis. Clinical manifestations, the results of imaging studies, outcome of the indirect revascularization procedure, and the progression of the lesion were reviewed in this study.

RESULTS

Of these 34 patients, contralateral progression was identified in 20 patients (58.8%). Fourteen (70%) out of the 20 patients presented with anterior cerebral artery abnormalities at diagnosis progressed to bilateral disease as well as did 5 (83%) out of 6 patients with middle cerebral artery lesions at the initial examination. Among the 34 patients, six exhibited familial history of MMD and all of them progressed to bilateral disease (100%, p < 0.005).

CONCLUSION

Careful and long-term follow-up would be essential to evaluate the hemodynamic status and progression to bilateral disease in unilateral MMD patients to make prompt decision for a surgical revascularization.

Indirect revascularization techniques for treating moyamoya disease

There have been many indirect revascularization techniques described by surgeons for the treatment of moyamoya disease. These surgical procedures are typically used more commonly in pediatric, than in adults', cases. Some of the techniques include: cervical sympathectomy, omental transplantation, multiple burr holes, encephalo-myo-synangiosis (EMS), encephalo-arterio-synangiosis (EAS), encephalo-duro-synangiosis (EDS), encephalo-myo-arterio-synangiosis (EMAS), encephalo-duro-arterio-synangiosis (EDAS), encephalo-duro-arterio-myo-synangiosis (EDAMS), encephalo-duro-galeo (periosteal)-synangiosis (EDGS), and combinations of all the above. This chapter will detail the technical aspects of many of these procedures and some of the reported clinical outcomes.

Relative contributions of the middle meningeal artery and superficial temporal artery in revascularization surgery for moyamoya syndrome in children: the results of superselective angiography

OBJECT

The authors used postoperative superselective angiography to assess the relative contributions of the middle meningeal artery (MMA) and the superficial temporal artery (STA) to revascularization following surgery for moyamoya syndrome in children.

METHODS

Using the neurosurgical database at the Hospital for Sick Children, the authors reviewed the clinical and pre- and postoperative angiographic records obtained in patients with moyamoya syndrome undergoing superselective angiography. Patients were 16 years of age or younger and were undergoing revascularization surgery for moyamoya syndrome during the study period. Lateral internal carotid artery, external carotid artery, STA, and MMA angiograms were analyzed in the late arterial phase to assess the relative contributions of the STA and MMA to overall revascularization as determined by the external carotid artery injection.

RESULTS

The total moyamoya surgical revascularization experience at the Hospital for Sick Children over a 12-year period (May 1996-December 2008) comprised 33 patients (20 girls and 13 boys) undergoing a total of 50 craniotomies. A decision was made in 2001 to perform superselective angiography postoperatively in patients with moyamoya syndrome. Superselective angiography was identified to have been performed postoperatively in 12 patients and 18 treated hemispheres, and it demonstrated that the MMA contributed more significantly than the STA in 11 (61%) of the 18 hemispheres. Seven patients were Asian, 3 patients had neurofibromatosis Type 1, 1 had Down syndrome, and 2 had no apparent risk factors (1 patient was Asian and had neurofibromatosis Type 1). Stroke had occurred in 58% of patients and transient ischemic attacks in 50% prior to surgery. Within the first 30 days of surgery, there were 2 episodes of stroke (11.7% per surgically treated hemisphere and 18.2% per patient). Seventy-eight percent of hemispheres surgically treated exhibited excellent revascularization (Matsushima Grade A) on follow-up angiography, and there were no strokes documented in any patients more than 1 month after surgery, in a long-term follow-up of mean 4.1 years.

CONCLUSIONS

The contributions of the MMA to revascularization after pial synangiosis for moyamoya syndrome are significant and may frequently exceed the contribution of the STA when surgery is performed with preservation of dural vasculature and dural inversion.

Intradural arteriosynangiosis in pediatric moyamoya disease: modified technique of encephalo-duro-arterio-synangiosis with reduced operative damage to already growing revascularization

OBJECTIVE

Various operative procedures have been described for the treatment of pediatric moyamoya disease. However, the majority of invasive or radical procedures proposed have focused primarily on revascularization and few have discussed to maximizing preservation of the already growing neovascular network.

METHODS

This present procedure describes the supratemporal artery is anastomosed to the inner layer of the dura mater and surrounded by the outer layer as a sandwich with a blunt procedure of dural layer separation.

RESULTS

This technique efficiently established an anastomotic connection between the supratemporal artery and the cortical brain, and the dura mater postoperatively with maximally preserving the existing vascular network.

CONCLUSION

IDAS, the modified surgical technique of EDAS, shall be benefit in preserving the already developed collateral circulation, and underlying structure over the brain cortex as much as possible, which is important particularly in pediatric moyamoya patients.

Indications for one-stage extensive indirect vascular reconstructive surgery for pediatric moyamoya disease: 4 case reports

BACKGROUND

Many modified surgical techniques for moyamoya disease have been developed, and each of which has some advantages and disadvantages. We report the indication for one-stage extensive indirect vascular reconstructive surgery that is our original technique for pediatric moyamoya disease.

CASE DESCRIPTION

Case 1 was a 3-year-old boy who had TIAs involving the bilateral extremities and provoked by intense crying. Case 2 was a 5-year-old girl who had TIAs involving the right extremities and provoked by intense crying. Case 3 was an 8-year-old girl who had frequent TIAs involving the bilateral extremities. Case 4 was a 3-year-old boy who had mild tetraplegia due to bilateral cerebral infarction. In all cases but case 4, preoperative investigations demonstrated same-stage moyamoya disease. In case 4, preoperative investigations demonstrated different-stage moyamoya disease in which acute progression of bilateral major arterial stenosis occurred. Hence, all patients underwent one-stage extensive indirect vascular reconstructive surgery of the bilateral cerebral hemispheres. Postoperative investigations revealed the development of rich neovascularization, disappearance of clinical symptoms in all cases.

CONCLUSIONS

We recommend one-stage extensive indirect vascular reconstructive surgery for pediatric moyamoya disease, particularly for patients younger than 5 years, when preoperative investigations reveal a same-stage case or bilateral acute progressive case.

Expression of vascular endothelial growth factor in dura mater of patients with moyamoya disease

Vascular endothelial growth factor (VEGF) has been found to be involved in vasculogenesis in different intracranial lesions. We investigated meningeal cellularity and VEGF expression in dura mater of patients with and without moyamoya disease. Nine dural specimens from nine cerebral hemispheres of seven patients with moyamoya disease and four control dural specimens from four non-moyamoya patients were collected during surgery and investigated. Dural specimens were immunohistochemically stained with VEGF antibody, and then meningeal cellularity and VEGF expression in dural tissue were analyzed. The mean+/-standard error (SE) of total number of meningeal cells (meningeal cellularity) in dural tissue was 21.5+/-3.0 in the moyamoya disease patients, whereas it was 2.7+/-0.7 in control patients. The mean+/-SE of VEGF expression was 51.1+/-4.9% in the moyamoya disease patients, whereas it was 13.8+/-5.9% in control patients. The meningeal cellularity and VEGF expression were statistically significantly higher in the moyamoya group in comparison to control group (p<0.0001). Meningeal cellularity and VEGF expression are significantly increased in dura mater of the patients with moyamoya disease.

Modified encephaloduroarteriosynangiosis with bifrontal encephalogaleoperiosteal synangiosis for the treatment of pediatric moyamoya disease. Technical note

The authors describe a modified technique of encephaloduroarteriosynangiosis (EDAS) with bifrontal encephalogaleoperiosteal synangiosis (EGPS) and present the preliminary results of the procedure. Between January 2004 and June 2005 the authors performed modified EDAS with bifrontal EGPS in 17 patients with moyamoya disease. Surgical results were evaluated in terms of clinical outcomes, changes visible on neuroimages, extent of revascularization noted on angiograms, and hemodynamic changes demonstrated on single-photon emission computed tomography (SPECT) scans. The follow-up period ranged from 6 to 21 months (mean 11.5 months). The overall clinical outcomes were excellent or good in 15 patients (88.2%) and poor in two (11.8%). The overall morbidity rate was 5.9% (one of 17 patients). Based on changes in the anterior cerebral artery (ACA) and middle cerebral artery (MCA) territories after surgery, as shown on SPECT scans following administration of acetazolamide, 14 patients (82.4%) exhibited an improved vascular reserve capacity in both the ACA and MCA territories. It is the authors' opinion that wide covering of the cortex is necessary for sufficient revascularization. In the present study they demonstrate that modified EDAS with bifrontal EGPS is a safe and efficient surgical approach that covers not only the MCA territory but also the ACA territory.

Power Doppler imaging in detection of surgically induced indirect neoangiogenesis in adult moyamoya disease

Object. Moyamoya is a rare, chronic disease that leads to the progressive narrowing and/or occlusion of the distal internal carotid and proximal cerebral arteries. Chronic cerebral ischemia ensues due to insufficient collateral blood supply. One potential treatment consists of the restoration of regional cerebral blood flow by direct or indirect revascularization surgery. The extent of neovascularization, especially in indirect procedures such as encephalomyosynangiosis (EMS), is currently evaluated with conventional angiography. Because this method is invasive and carries some risks, the authors investigated power Doppler imaging as an alternative noninvasive bedside procedure that can be used to assess surgically induced indirect revascularization in adult patients with moyamoya disease.

Methods. Twelve symptomatic patients with adult moyamoya disease (seven women and five men, mean age 38 ± 17 years) underwent combined (direct and indirect) revascularization. They were then examined using conventional angiography and power Doppler imaging to assess the extent of revascularization within 120 days postsurgery. According to the number of intracranial vessels demonstrating opacification on conventional angiography and power Doppler imaging studies, EMS was graded as follows: 1, absent (0 vessels); 2, moderate (one—four vessels); and 3, extensive (> four vessels) for both methods. Examiners were blinded to the classification results for the procedure that they did not grade.

All 24 hemispheres were examined. The visual grading of EMS revealed a highly significant agreement between conventional angiography and power Doppler imaging (Spearman rank coefficient, r = 0.92; p < 0.001) and there was 100% agreement of patency of the bypass between the direct and indirect methods.

Conclusions. The authors found excellent agreement between the two methods. Therefore, power Doppler imaging is a valid noninvasive alternative to carotid artery angiography in evaluating direct and indirect revascularization.

Surgical management of moyamoya syndrome

Moyamoya syndrome, a vasculopathy characterized by chronic progressive stenosis at the apices of the intracranial internal carotid arteries, is an increasingly recognized entity which is associated with cerebral ischemia. Diagnosis is made on the basis of clinical and radiographic findings, including a characteristic stenosis of the internal carotid arteries in conjunction with abundant collateral vessel development. Adult moyamoya patients often present with hemorrhage, leading to rapid diagnosis. In contrast, children usually present with transient ischemic attacks or strokes, which may prove more difficult to diagnose because of patient's inadequate verbal and other skills, leading to delayed recognition of the underlying moyamoya. The progression of disease can be slow, with rare, intermittent events, or it can be fulminant, with rapid neurologic decline. However, regardless of the course, it is apparent that moyamoya syndrome, both in terms of arteriopathy and clinical symptoms, inevitably progresses in untreated patients. Surgery is generally recommended for the treatment of patients with recurrent or progressive cerebral ischemic events and associated reduced cerebral perfusion reserve. Many different operative techniques have been described, all with the main goal of preventing further ischemic injury by increasing collateral blood flow to hypoperfused areas of the cortex, using the external carotid circulation as a donor supply. This article discusses the various treatment approaches, with an emphasis on the use of pial synangiosis, a method of indirect revascularization. The use of pial synangiosis is a safe, effective, and durable method of cerebral revascularization in moyamoya syndrome and should be considered as a primary treatment for moyamoya, especially in the pediatric population.

Revascularisation surgery for paediatric moyamoya: a review of the literature

INTRODUCTION AND AIMS

The role of and optimal surgical revascularisation technique for paediatric moyamoya syndrome (MMS) are controversial. In this literature review our primary aim was to evaluate the evidence base for the efficacy of surgical revascularisation for the treatment of paediatric MMS. Secondary aims were to estimate the rate of peri-operative complications and to ascertain whether direct or indirect revascularisation techniques resulted in differences in clinical or radiological outcomes.

METHODS

Papers describing surgical revascularisation and its outcome in the treatment of children with MMS were identified from the OVID Medline database (1966-2004). Only papers in English were reviewed. Data were abstracted using a standardised form.

RESULTS

Fifty-seven studies, including data on 1,448 patients, were reviewed. Most were Japanese; 10% were from Western institutions. Indications for revascularisation were described in <15% of studies and varied between centres. Indirect procedures were most commonly performed (alone in 73% of cases, combined with direct procedures in 23%). The rates of peri-operative stroke and reversible ischaemic events were 4.4 and 6.1% respectively. Out of 1,156 (87%) patients, 1,003 derived symptomatic benefit from surgical revascularisation (complete disappearance or reduction in symptomatic cerebral ischaemia), with no significant difference between the indirect and direct/combined groups. Data on developmental and functional outcomes were limited and of uncertain significance as they were not related to pre-operative status. Good collateral formation was significantly more frequent in the direct/combined group than in the indirect group (chi(2), p<0.001).

CONCLUSIONS

Data from the medical literature suggest that surgical revascularisation is a safe intervention for paediatric MMS and most treated patients derive some symptomatic benefit. However, paucity of data on selection criteria and more global outcome measures means that the impact of surgical revascularisation on natural history remains uncertain. Direct and/or combined procedures provide better revascularisation, but this is not associated with differences in symptomatic outcome. International standardisation of the clinical approach to the treatment of paediatric MMS is urgently needed to critically evaluate the optimal indications for and timing of surgical revascularisation.

Surgical approaches to vascular anomalies of the child's brain

The population of pediatric patients with cerebrovascular disease presents a unique set of challenges to the neurosurgeon. The wide scope of pathology, including arteriovenous malformations, cavernous malformations and moyamoya disease, coupled with marked advances in diagnosis and treatment of these conditions over the past several years has resulted in a proliferation of the literature related to this subject. The present review provides an overview of current methods of surgical treatment for pediatric cerebrovascular diseases, focusing on indications and use of recent refinements of pre-existing surgical approaches, and newly evolved operative techniques developed to treat these entities.

Non-anastomotic bypass surgery for childhood moyamoya disease using dural pedicle insertion over the brain surface combined with encephalogaleomyosynangiosis

BACKGROUND

Anastomotic bypass surgery for childhood moyamoya disease provides more rapid improvement of blood circulation than indirect non-anastomotic bypass surgery, but there are several problems, such as the technical difficulty of the operation, the extended period of anesthesia, and temporary occlusion of blood flow in the vessels of the brain surface.

METHODS

We describe a new non-anastomotic bypass procedure using dural pedicle insertion over the brain surface combined with encephalogaleomyosynangiosis and preservation of the superficial temporal artery (STA). We treated nine patients with childhood moyamoya disease admitted to our institution from 1989 through 1994. The operative field was determined based on the ischemic site identified by preoperative neuroimaging methods. Our procedure was performed in a total of 15 hemispheres, and the patients have been followed up for 5 months to 5 years after operation.

RESULTS

Cerebral angiography, cerebral blood flow measurements, and clinical symptoms and signs were improved at the operation site in all patients. Because the STA and the superficial portion of the temporal muscle attached to the skin flap were preserved, the skin at the operation site was not depressed and no necrosis, infection, or alopecia developed.

CONCLUSION

Childhood moyamoya disease is progressive, so repeated bypass surgery may be required. Therefore, non-anastomotic bypass surgery is better for the first operation because the STA is preserved. The present procedure using temporal muscle, galea, and dura can be extended over a wider brain surface than the operative field, and is suitable for establishing collateral circulation in the frontal lobe. Blood flow in the skin flap is maintained, so the cosmetic result is satisfactory.

Multiple combined indirect procedure for the surgical treatment of children with moyamoya disease. A comparison with single indirect anastomosis with direct anastomosis

Considering three different bypass procedures now in use, (single indirect nonanastomotic bypass procedure, multiple combined indirect (MCI) nonanastomotic procedure and direct anastomosis), the authors attempted to identify the most appropriate bypass procedure for treating ischemic-type moyamoya disease in children.

The authors performed three procedures (the original encephaloduroarteriosynangiosis [EDAS] alone, the frontotemporoparietal combined indirect bypass procedure, and the superficial temporal artery-middle cerebral artery [STA-MCA] anastomosis with encephalomyosynangiosis [EMS]) on 72 hemispheres in 50 patients with pediatric moyamoya disease. Analyses were then performed to compare postoperative collateral vessel formation found on angiograms, complications, and clinical improvements. Postoperative collateral formations were observed in more than two-thirds of the MCA distribution after the EDAS alone, the MCI procedure, and the direct anastomosis in 44%, 52%, and 74% of the surgically treated hemispheres, respectively. In addition, frontal encephalomyoarteriosynangiosis of the MCI bypass procedure formed collateral vessels of the anterior cerebral artery distribution in 94% of the treated hemispheres. Postoperatively, clinical symptoms resolved in 56%, 63%, and 74% of the treated sides 1 year after EDAS alone, MCI procedure, and the direct anastomosis, respectively. One patient suffered a minor stroke after EDAS alone, two patients developed epidural hematomas after the MCI procedure, and one patient suffered a major stroke and one patient a minor stroke after undergoing direct anastomosis.

The direct anastomosis procedure was found to result in the best postoperative collateral vessel formation and clinical improvement. However, the single and multiple combined indirect nonanastomotic bypass procedures were found to be safer than direct anastomosis. Furthermore, the frontotemporoparietal combined indirect bypass procedure caused the formation of collateral circulation not only in the MCA but also in the ACA distribution. Based on analysis of these findings, the authors recommend the MCI procedure as the appropriate surgical procedure in the treatment of children with moyamoya disease, although the best treatment is the STA-MCA anastomosis with EMS when feasible.

Clinical features of moyamoya disease in the United States

BACKGROUND AND PURPOSE

We report the clinical features and longitudinal outcome of the largest cohort of patients with moyamoya disease described from a single institution in the western hemisphere. Moyamoya disease in Asia usually presents with ischemic stroke in children and intracranial hemorrhage in adults.

METHODS

Our study population included all patients with moyamoya disease evaluated at a university hospital in Houston, Texas from 1985 through 1995 (n = 35). We used Kaplan-Meier methods to estimate individual and hemispheric stroke risk by treatment status (medical versus surgical). Predictors of neurological outcome were assessed.

RESULTS

The ethnic background of our patients was representative of the general population in Texas. The mean age at diagnosis was 32 years (range, 6 to 59 years). Ischemic stroke or transient ischemic attack was the predominant initial symptom in both adults and children. Of the 6 patients with intracranial hemorrhage, 5 had an intraventricular site of hemorrhage. The crude stroke recurrence rate was 10.3% per year in 116 patient-years of follow-up. Twenty patients underwent surgical revascularization, the most common procedure being encephaloduroarteriosynangiosis. The 5-year risk of ipsilateral stroke after synangiosis was 15%, compared with 20% for medical treatment and 22% overall for surgery.

CONCLUSIONS

Our observations indicate that moyamoya disease may have a different clinical expression in the United States than in Asia, and may demonstrate a trend toward a lower stroke recurrence rate and better functional outcome after synangiosis.

Surgical techniques and the results of a fronto-temporo-parietal combined indirect bypass procedure for children with moyamoya disease: a comparison with the results of encephalo-duro-arterio-synangiosis alone

We recently treated children with Moyamoya disease using a fronto-temporo-parietal combined indirect bypass procedure. Three different indirect bypass procedures (frontal EMAS, EDAS, EMS) were simultaneously carried out at three different sites. We thus treated 16 sides in 12 pediatric patients with Moyamoya disease using this method. Both the collateral formation and the improvement in the clinical symptoms were evaluated postoperatively. These results were then compared with those of the patients treated by EDAS alone. The postoperative collateral formation was more extensively seen in the patients treated with the combined bypass procedure than in those treated by EDAS alone. The improvement in ischemic symptoms was also better in the patients treated by the combined indirect bypass procedure. We therefore conclude that the combined indirect bypass procedure is more effective than EDAS alone.

Revascularization with split duro-encephalo-synangiosis in the pediatric moyamoya disease--surgical result and clinical outcome

Dural arteries are potential donor arteries for cortical revascularization. In this report, a technique of indirect anastomosis using a split dura is presented. At surgery, the dura near the branches of the middle meningeal artery was split into outer and inner layers, and the split surface of the outer layer was attached to the cortical surface (split duro-encephalo-synangiosis; split DES). This procedure, combined with standard encephalo-duro-arterio-synangiosis, was applied to 25 hemispheres in 18 patients with pediatric Moyamoya disease (mean age, 6 years). Postoperative superselective angiograms demonstrated effective cortical revascularization through the dural arteries in addition to the supply from the scalp arteries. All the patients were symptom free by 1.5 years after surgery. Postoperative reversible ischemic neurological deficit and infarction were seen in three (12%) and one (4%), respectively. The follow-up period ranged from 1 to 12 years (mean, 6.5 years). Thirteen of 16 (81%) patients led normal lives and three were mildly handicapped due to mental retardation that existed preoperatively. The split DES is a useful technique to extend the area of revascularization of ischemic hemispheres in Moyamoya disease.

Dural inversion procedure for moyamoya disease. Technical note

A variety of surgical procedures have been proposed for the treatment of moyamoya disease, but few have used the potential of the middle meningeal artery to any great extent. During the period of spontaneous collateral formation, patients with this disease are at risk for the development of transient ischemic attacks and strokes. Surgical treatments aimed at increasing collateral flow to the brain from the external carotid system have included both direct and indirect anastomotic methods. In this report, the authors describe a technique that used the middle meningeal artery circulation as a source of collateral blood supply by inverting dural flaps that are located on a large meningeal vessel, allowing the richly vascularized outer dural surface to contact a large surface area of the ischemic cortex. An extensive degree of revascularization was observed.