Novel Bypass Surgery for Moyamoya Disease Using Pericranial Flap: Its Impacts on Cerebral Hemodynamics and Long-term Outcome

Moyamoya disease and moyamoya syndrome in Ireland: patient demographics, mode of presentation and outcomes of EC-IC bypass surgery

BACKGROUND

There are no previously published reports regarding the epidemiology and characteristics of moyamoya disease or syndrome in Ireland.

AIMS

To examine patient demographics, mode of presentation and the outcomes of extracranial-intracranial bypass surgery in the treatment of moyamoya disease and syndrome in Ireland.

METHODS

All patients with moyamoya disease and syndrome referred to the National Neurosurgical Centre during January 2012-January 2019 were identified through a prospective database. Demographics, clinical presentation, radiological findings, surgical procedures, postoperative complications and any strokes during follow-up were recorded.

RESULTS

Twenty-one patients were identified. Sixteen underwent surgery. Median age at diagnosis was 19 years. Fifteen were female. Mode of presentation was ischaemic stroke in nine, haemodynamic TIAs in eight, haemorrhage in three and incidental in one. Sixteen patients had Moyamoya disease, whereas five patients had moyamoya syndrome. Surgery was performed on 19 hemispheres in 16 patients. The surgical procedures consisted of ten direct (STA-MCA) bypasses, five indirect bypasses and four multiple burr holes. Postoperative complications included ischaemic stroke in one patient and subdural haematoma in one patient. The median follow-up period in the surgical group was 52 months; there was one new stroke during this period. Two patients required further revascularisation following recurrent TIAs. One patient died during follow-up secondary to tumour progression associated with neurofibromatosis type 1.

CONCLUSIONS

Moyamoya is rare but occurs in Caucasians in Ireland. It most commonly presents with ischaemic symptoms. Surgical intervention in the form of direct and indirect bypass is an effective treatment in the majority of cases.

Clinical and Radiological Features of Childhood Onset Adult Moyamoya Disease: Implication for Hemorrhagic Stroke

Some of the pediatric moyamoya patients spend their childhood without diagnosed as moyamoya disease (MMD) because of their mild ischemic attacks and emerge again with ischemic or hemorrhagic stroke in their adulthood. This study was aimed to clarify the clinical characteristics of adult moyamoya patients with childhood onset and elucidate the impact of long disease period on their clinical features. Present study included 116 untreated hemispheres of 69 adult patients with MMD. They were divided into two groups: childhood onset group (26 hemispheres of 14 patients) and adult onset group (90 hemispheres of 55 patients). Clinical features were compared between the two groups. The incidence of hemorrhagic stroke was significantly higher in childhood onset group (P = 0.0091). Lenticulostriate and choroidal channels were more developed in childhood onset group (P = 0.044 and P <0.001, respectively). Vault moyamoya was more frequently observed in childhood onset group (P <0.001). The development of surgical collaterals through indirect bypass was more marked in childhood onset group (P = 0.0019). Multivariate analysis revealed that childhood onset and developed choroidal channels were significantly associated with the occurrence of hemorrhagic stroke (OR 4.31 [95% CI 1.21-15.4], P = 0.025 and OR 6.78 [95% CI 1.78-25.8], P = 0.0050, respectively). This study clearly shows that adult moyamoya patients with childhood onset have more developed spontaneous collaterals, which may, in turn, highly causes hemorrhagic stroke. Adult moyamoya patients with "childhood onset" should be recognized as a novel and important concept when elucidating the underlying mechanisms of hemorrhagic stroke in MMD.

Large Craniotomy Increases the Risk of Minor Perioperative Complications in Revascularization Surgery for Moyamoya Disease

OBJECTIVE

Larger craniotomy is expected to increase blood flow over a wider range after indirect revascularization. However, the optimal size of craniotomy has not been established. In this study perioperative complications in revascularization surgery for moyamoya disease are evaluated, focusing on craniotomy size.

METHODS

We retrospectively analyzed 87 hemispheres in 65 patients with moyamoya disease who had undergone revascularization surgery. Areas and types of craniotomy were classified as 1-piece craniotomy in the middle cerebral artery (MCA) territory (1-piece group) in 54 hemispheres (mean area of craniotomy, 40.6 ± 13.5 cm²); 2-piece craniotomy in the MCA territory with anterior cerebral artery (ACA) territory (2-piece group) in 16 hemispheres (mean area of craniotomy, 55.4 ± 12.0 cm²); and 1-piece craniotomy in both MCA and ACA territories (large group) in 17 hemispheres (mean area of craniotomy, 84.2 ± 11.0 cm²). Perioperative complication rates in each craniotomy group were analyzed.

RESULTS

Perioperative complications occurred in 45 hemispheres (52%). Transient, moderate, and severe complications occurred in 38 hemispheres, 3 hemispheres, and 4 hemispheres, respectively. Complication rates in the 1-piece, 2-piece, and large groups were 41%, 63%, and 76%, respectively. Large craniotomy was associated with a significantly higher frequency of complications (P = 0.01). However, no significant difference was found among groups when limiting analysis to moderate and severe complications. Multivariate analysis showed large craniotomy as the only factor independently related to complications (odds ratio, 2.93; 95% confidence interval, 1.08-7.92; P = 0.034).

CONCLUSIONS

Large craniotomy is associated with more frequent perioperative complications, especially transient symptoms.

Strategy and effect of repeat bypass surgery for anterior/posterior circulation in refractory moyamoya disease

OBJECTIVE

In this study the authors aimed to describe clinical features, surgical techniques, and long-term outcomes of repeat bypass surgery required for a certain subset of patients with moyamoya disease.

METHODS

The authors retrospectively reviewed a total of 22 repeat bypass surgeries for 20 patients (age range 1-69 years) performed during the last 20 years at their institutions. The patients were classified into 2 groups. Group A included 10 patients who underwent repeat bypass surgery for anterior circulation due to insufficient revascularization on the ipsilateral side. Group B included 10 patients who underwent repeat bypass surgery for posterior circulation due to the involvement of the posterior cerebral artery (PCA) after successful initial surgery for anterior circulation.

RESULTS

Preoperative symptoms included headache in 3 patients, transient ischemic attack in 10, cerebral infarction in 3, and intracranial hemorrhage in 4 patients. Intervals between the initial bypass surgery and repeat bypass surgery were 0.3-30 years (median 3 years). In group A, superficial temporal artery to middle cerebral artery (MCA) anastomosis and indirect bypass were performed on 7 hemispheres. Only indirect bypass was performed on 3 hemispheres because of the lack of suitable donor or recipient arteries. In group B, occipital artery (OA) to PCA anastomosis and indirect bypass were conducted on 4 hemispheres, and OA-MCA anastomosis and indirect bypass on 1 hemisphere. Only indirect bypass was conducted on 7 hemispheres because of the lack of suitable recipient arteries. All 22 repeat bypass surgeries were successfully conducted. During follow-up periods (median 4 years), none of the patients suffered repeat stroke except 1 patient who died of recurrent intracerebral hemorrhage 3 years after repeat bypass surgery for anterior circulation.

CONCLUSIONS

Repeat bypass surgery was feasible and effective to reduce further incidence of headache attack, transient ischemic attack, and ischemic/hemorrhagic stroke in moyamoya disease patients. Through precise radiological analysis, surgical procedures should be planned to yield maximal therapeutic effects.

Crossed cerebellar diaschisis as an indicator of severe cerebral hyperperfusion after direct bypass for moyamoya disease

Cerebral hyperperfusion (HP) complicates the postoperative course of patients with moyamoya disease (MMD) after direct revascularization surgery. Crossed cerebellar diaschisis (CCD) has been considered to be rarely associated with HP after revascularization surgery. This study aimed to describe the clinical features and factors associated with CCD secondary to cerebral HP after revascularization surgery for MMD. We analyzed 150 consecutive hemispheres including 101 in adults and 49 in pediatric patients who underwent combined direct and indirect bypass for MMD. Using single-photon emission computed tomography (SPECT), serial cerebral blood flow (CBF) was measured immediately after the surgery and on postoperative days 2 and 7. Pre- and postoperative voxel-based analysis of SPECT findings was performed to compare the changes in regional CBF. Multivariate logistic regression analysis was performed to test the effect of multiple variables on CCD. Asymptomatic and symptomatic HP was observed in 41.3% (62/150) and 16.7% (25/150) of the operated hemispheres, respectively. CCD was observed in 18.4% (16/87) of these hemispheres with radiological HP. Multivariate analysis revealed that the occurrence of CCD was significantly associated with symptomatic HP (p = 0.0015). Voxel-based analysis showed that the CBF increase in the operated frontal cortex, and the CBF reduction in the contralateral cerebellar hemisphere on day 7 were significantly larger in symptomatic HP than in asymptomatic HP (median 11.3% vs 7.5%; - 6.0% vs - 1.7%, respectively). CCD secondary to postoperative HP is more common than anticipated in MMD. CCD could potentially be used as an indicator of severe postoperative HP in patients with MMD.

[Modern trends in diagnosis and surgical treatment of moyamoya disease]

This review is devoted to moyamoya disease. It is a rare chronic steno-occlusive cerebrovascular disease. However, moyamoya disease is increasingly diagnosed by neurosurgeons in our country. Unlike atherosclerotic lesions of cerebral arteries, pathogenesis and course of this disease are much more complex and variable. Therefore, specialists often have certain difficulties in diagnosis, management and treatment of these patients. To date, a large number of surgical interventions have been proposed for the treatment of moyamoya disease. Revascularization approaches include direct procedures (extra-intracranial microanastomoses), indirect methods (synangioses) and combined revascularization. The purpose of the review is to systematize current literature data on the pathogenesis, diagnosis, clinical patterns and surgical treatment of patients with moyamoya disease. results Outcomes of surgical revascularization and the role of its various components in combined approach are under particular attention.

Association of cognitive function with cerebral blood flow in children with moyamoya disease

OBJECTIVE

The cognitive effects of main cerebral artery occlusive lesions are unclear in children with moyamoya disease (MMD). The authors aimed to investigate cognitive function in the presurgical phase of pediatric patients with MMD with no apparent brain lesions.

METHODS

In this prospective, observational, single-center study, 21 children (mean age 10 ± 3.0 years, range 5-14 years) diagnosed with MMD at Hokkaido University Hospital between 2012 and 2018 were enrolled. A cross-sectional evaluation of intellectual ability was performed using the Wechsler Intelligence Scale for Children-Fourth Edition at the initial diagnosis. rCBF was measured using [123I] N-isopropyl p-iodoamphetamine/SPECT. The associations among clinical factors, disease severity, regional cerebral blood flow (rCBF), and intelligence test scores were also examined.

RESULTS

The mean full-scale intelligence quotient (FIQ) was 101.8 ± 12.5 (range 76-125) in children with no apparent brain lesions. A significant difference in the intelligence scale index score was observed, most frequently (42.9%) between working memory index (WMI) and verbal comprehension index (VCI; VCI - WMI > 11 points). Regional CBF was significantly reduced both in the left and right medial frontal cortices (left: 61.3 ± 5.3 ml/100 g/min, right 65.3 ± 5.3 ml/100 g/min; p < 0.001) compared to the cerebellum (77.8 ± 6.8 ml/100 g/min). There was a significant association of rCBF in the left dorsolateral prefrontal cortex (DLPFC) with FIQ (r = 0.46, p = 0.034), perceptual reasoning index (PRI; r = 0.44, p = 0.045), and processing speed index (PSI; r = 0.44, p = 0.045). There was an association between rCBF of the left medial frontal cortex and PSI (r = 0.49, p = 0.026). Age of onset, family history, ischemic symptoms, and angiographic severity were not associated with poor cognitive performance.

CONCLUSIONS

Although average intellectual ability was not reduced in children with MMD, the association of reduced rCBF in the left DLPFC and medial frontal cortex with FIQ, PRI, and PSI suggests mild cognitive dysfunction due to cerebral hypoperfusion.

Ischemic sequelae and other vascular diseases

Although pediatric stroke is associated with higher survival rates compared with adult stroke, a substantial body of evidence indicates significant neuropsychologic morbidity in pediatric stroke survivors. Neuroplasticity does not guarantee good outcome in children. The general trends observed in the literature are reviewed as is the profile observed in common causes of pediatric stroke: congenital heart disease, moyamoya disease, and sickle cell disease. The neuropsychologic profile of pediatric stroke patients is heterogeneous due to the multiplicity of associated causes. Stroke in early infancy and large strokes are associated with cognitive impairment while more limited disorders, such as phasic deficit, are observed in childhood stroke. Executive dysfunction is common in pediatric stroke, but social interaction skills are usually preserved. Congenital heart disease and sickle cell disease are associated with global neuropsychologic dysfunction while cognition is usually preserved in moyamoya. Executive dysregulation is instead more frequently reported in this population. Further study of maladaptive processes after pediatric stroke will allow identification of predictors of functional and neuropsychologic outcomes and permit personalization of care.

Surgical outcomes for pediatric moyamoya: a systematic review and meta-analysis

OBJECTIVE

The optimal revascularization for pediatric moyamoya for reducing the incidence of future stroke events remains to be determined.

METHODS

The authors conducted a search of PubMed, MEDLINE, Embase, and Web of Science electronic databases from inception until January 2019. The primary endpoint was the presence of a future ischemic stroke event. Secondary endpoints were angiographic outcomes as measured by postoperative Matsushima grade and clinical symptom persistence. Patients who underwent either direct or combined direct/indirect revascularization were classified into the direct cohort. Data from each study on presence of postoperative stroke events were used to generate standardized mean differences and 95% confidence intervals, which were combined using inverse variance-weighted averages of standardized mean differences in a random effects model.

RESULTS

Twenty-nine studies met the inclusion criteria for analysis, comprising 2258 patients (1011 males, mean age 8.3 ± 1.8 years) who were followed up clinically for an average of 71.4 ± 51.3 months. One hundred fifty-four patients underwent direct bypass alone, 680 patients underwent either direct or combined direct/indirect revascularization procedures, while 1424 patients underwent indirect bypass alone. The frequencies of future stroke events in patients undergoing direct bypass alone, combined bypass, or indirect bypass alone were 1 per 190.3 patient-years, 1 per 108.9 patient-years, and 1 per 61.1 patient-years, respectively, in each cohort. The estimated stroke rates were 9.0% with indirect revascularization, 4.5% with direct revascularization alone, and 6.0% with combined revascularization. A forest plot did not reveal any significant differences in the incidence of future stroke events or angiographic outcomes following direct-only, combined, or indirect-only revascularization.

CONCLUSIONS

Direct, indirect, and combined indirect/direct bypass techniques are all effective revascularization options for pediatric moyamoya disease. A relative paucity of granular studies-and inherent surgical selection bias-limits direct comparison between interventions. Suitably designed prospective cohort studies may be useful in identifying patients likely to receive benefit from specific procedures.

Evaluation of 99mTC-ECD SPECT/CT brain Imaging with NeuroGam analysis in Moyamoya disease after surgical revascularization

To evaluate the clinical value of NeuroGam software in assessing the brain foci perfusion changes by TC-ECD single photon emission computed tomography/computed tomography (SPECT/CT) brain imaging in patients with Moyamoya Disease (MMD).Seventy-two patients with MMD who underwent superficial temporal artery-middle cerebral artery (STA-MCA) bypass combined with encephalo-duro-myo-synangiosis (EDMS) surgical revascularization were included. Baseline and follow-up TC-ECD SPECT/CT brain scans were performed on all patients at least twice before and after operation. Pre- and post-SPECT dicom images were reoriented into Talairach space using NeuroGam Software package. Additional visual analysis was performed. Differences mean pixel value between pre- and post- operation brain perfusion were assessed with paired t test and McNemar test.Significant differences in the number of hypoperfusion foci were found between visual assessment and NeuroGam aided assessment. More hypoperfusion foci were found by NeuroGam software aided assessment in the frontal, parietal, temporal, occipital lobe, thalamus, basal ganglia and cerebellum before and after surgery (P < .0001). According to NeuroGam software assessment, the perfusion of frontal, parietal, temporal lobe, anterior and middle cerebral regions on the operative side significantly improved before and after surgery (t = -3.734, t = -3.935, t = -5.099, t = -4.006, t = -5.170, all P < .001). However, no significant differences were found in the occipital lobe (t = -1.962, P = .054), thalamus (t = 1.362, P = .177), basal ganglia (t = -2.394, P = .019), and cerebellum (t = 1.383, P = .171) before and after surgery.The NeuroGam software provides a quantitative approach for monitoring surgical effect of MMD in a variable time (3-12 months after surgery). It could discover the perfusion changes that are neglected in conventional visual assessment.

The Targeted Bypass Strategy for Preventing Hemorrhage in Moyamoya Disease: Technical Note

Although direct bypass is effective at preventing intracranial hemorrhage in moyamoya disease, the optimal strategy for achieving this purpose has rarely been addressed. The tailored targeting bypass strategy is a novel technical modification of direct bypass focused on hemorrhage prevention. The strategy is based on the promising theory of periventricular anastomosis, which explains the mechanism of hemorrhage in moyamoya disease. The strategy is defined as the use of multi-imaging modalities to predetermine in a tailored manner a target vessel at the point at which the medullary artery directly extends from the periventricular anastomosis of interest. Direct bypass with a wide craniotomy was performed on 13 hemispheres in eight patients according to this strategy. Marked shrinkage of the periventricular anastomosis of interest was observed in all but one hemisphere after surgery, and no new hemorrhages have occurred as of this writing. The present case series illustrates the technical aspects and preliminary results of the tailored targeting bypass strategy, an approach that might expand the potential of direct bypass in preventing hemorrhage.

Long-Term Outcomes of Indirect Bypass for 629 Children With Moyamoya Disease: Longitudinal and Cross-Sectional Analysis

Background and Purpose- In pediatric moyamoya disease, there are few reports on the efficacy of surgical intervention for stroke prevention. We evaluated the long-term outcomes of indirect bypass surgery on a relatively large number of children with moyamoya disease in a single center. Methods- From August 1988 to December 2012, 772 children underwent indirect bypass surgery. This study included 629 patients who were followed up for >5 years, excluding patients with moyamoya syndrome. The mean clinical follow-up duration was 12 years (range, 5-29 years). Cross-sectional analysis was performed based on either Karnofsky Performance Scale or Lansky Play Performance Scale to evaluate overall clinical outcomes and factors associated with unfavorable outcomes. To analyze the longitudinal effect of surgery, the annual risk of symptomatic infarction or hemorrhage on the operated hemisphere after indirect bypass surgery was calculated with a person-year method, and the event-free survival rate was evaluated using the Kaplan-Meier method. Results- The overall clinical outcome was favorable in 95% of the patients. The annual risks of symptomatic infarction and hemorrhage on the operated hemispheres were 0.08% and 0.04%, respectively. Furthermore, the 10-year event-free survival rates for symptomatic infarction and hemorrhage were 99.2% and 99.8%. Conclusions- Indirect bypass surgery could provide satisfactory long-term improvement in overall clinical outcome and prevention of recurrent stroke in children with moyamoya disease.

Predictors and clinical features of transient neurological events after combined bypass revascularization for moyamoya disease

OBJECTIVE

Transient neurological events (TNEs) are frequently observed after revascularization surgery for moyamoya disease (MMD). However, clinical features and pathophysiology of TNEs in MMD are still unclear. This study was aimed to clarify the incidence and time course of TNEs and to determine the independent predictors of TNEs in MMD.

PATIENTS AND METHODS

A total of 195 hemispheres in 171 consecutive patients with MMD who had undergone combined direct and indirect bypass surgery were analyzed. Preoperative clinical characteristics and radiographic features were recorded. The incidence and clinical feature of postoperative TNEs were evaluated. Multivariate logistic regression analyses were performed to identify the risk factors for postoperative TNEs. Outcomes were compared between patients who had TNEs with those without TNEs at the time of discharge.

RESULTS

Postoperative TNEs were detected in 40 (20.5%) of 195 operated hemispheres, including 17 (42.5%) aphasia, 9 numbness of the extremities (22.5%), 6 seizures (15%), 5 motor weakness (12.5%), 4 dysarthria (10%) and 6 others (15%). The incidence of TNEs was significantly higher in adult patients than in pediatric ones. Multivariate analysis revealed that female, left-sided surgery and the presence of the edematous lesion was an independent predictor of TNEs after surgery in MMD (OR, 3.0; 95% CI, 1.1-8.2; P = 0.03, OR, 2.9; 95% CI, 1.2-7.0; P = 0.02 and OR, 17.4; 95% CI, 5.7-53.0; P < 0.01, respectively). DSA stage (OR 0.05, 95% CI 0.0-0.5, p = 0.005; OR 0.08, 95% CI 0.0-0.4, p = 0.008), PCA involvement (OR 2.75, 95% CI 1.0-7.4, p = 0.046), left-sided surgery (OR 2.73, 95% CI 1.2-6.5, p = 0.022) and edematous lesion (OR 21.2, 95% CI 7.6-59.7, <0.001) were significantly associated with TNE severity. Compared with patients without postoperative TNEs, no significant differences in mRS score between the two groups were detected.

CONCLUSIONS

Female, left-sided surgery and edematous lesion were independent risk factors for postoperative TNEs; the left-sided surgery and edematous lesion were also independently associated with the severity of TNE. Although patients with postoperative TNEs had worse neurological status during the perioperative period, postoperative TNEs had no associations with worse mRS score at the time of discharge.

Surgery for Moyamoya Disease in Children

Moyamoya disease is a chronic progressive cerebrovascular occlusive disease of the terminal portion of the internal carotid arteries associated with an acquired abnormal vascular network at the base of the brain, often leading to ischemic or hemorrhagic stroke. Moyamoya disease is a relatively common cause of pediatric stroke with a specific racial and well-identified clinical and imaging phenotype. Moyamoya disease is more prevalent in East Asian countries compared with other geographic regions with a higher incidence of familial cases and clinically more aggressive form. Moyamoya disease is one of the few causes of stroke that is amenable to effective surgical revascularization treatment. There are various surgical options available for revascularization, including the direct, indirect, or combined bypass techniques, each with variable responses. However, due to the heterogeneity of the diseases, different clinical course, geographical variables associated with the disease, and availability of a wide variety of surgical revascularization procedures, optimal selection of a surgical candidate and the surgical technique becomes challenging, particularly in the pediatric population. This brief review presents pertinent literature of clinical options for the diagnosis and surgical treatment of moyamoya disease in children.

Sternocleidomastoid Encephalomyosynangiosis for Treatment-Resistant Moyamoya Disease

BACKGROUND AND IMPORTANCE

Refractory ischemic symptoms in moyamoya disease are a challenging problem, particularly in situations in which multiple direct and indirect revascularization techniques have already been employed. In addition, revascularization of the parietal lobes is difficult, as this area is a watershed between the middle cerebral artery and posterior cerebral artery distributions.

CLINICAL PRESENTATION

This is the case of a 50-yr-old woman with hemibody sensorimotor deficits, who had previously undergone bilateral arterial bypass and temporalis myosynangiosis. A method for indirect surgical cerebral revascularization is described, utilizing a rotated and tunneled sternocleidomastoid flap. The perfused muscle is approximated to the cortical surface, with adjacent sulci dissected to expose the underlying vasculature. After sternocleidomastoid encephalomyosynangiosis, the patient experienced symptomatic improvement, along with the appearance of new pial collateral vasculature on diagnostic cerebral angiography. Pre- and postoperative dynamic perfusion computed tomography with acetazolamide challenge demonstrate an increase in cerebral blood flow and decrease in mean transit time, as well as improved cerebrovascular reserve.

CONCLUSION

Sternocleidomastoid encephalomyosynangiosis using a tunneled muscle flap is a useful method for revascularization of the parietal and occipital lobes, particularly for refractory moyamoya in cases where a variety of other options have been exhausted.

Modified encephalo-duro-periosteal-synangiosis (EDPS) for the revascularization of anterior cerebral artery territory in moyamoya disease: A single-center experience

OBJECTIVES

Anterior cerebral artery (ACA) territory, a crucial area of intellectual development in children, is frequently involved in the progress of moyamoya disease (MMD). However, revascularization surgeries for this area are not as established as surgeries for middle cerebral artery (MCA) territory. This study aimed to describe our experience and study the effect of revascularizing ACA territory with periocranium and dural leaflets, which is referred to as 'encephalo-duro-periosteal-synangiosis (EDPS)'.

PATIENTS AND METHOD

Fourteen hemispheres of 9 MMD patients who had undergone EDPS from November 2015 till July 2017 in our hospital were retrospectively included. Clinical characteristics and procedure-related information were recorded. Cerebral perfusion was evaluated by computed tomography perfusion (CTP). Absolute and relative (r) CTP parameters of ROIs in ACA territory at the level of centrum semiovale and middle basal ganglia were calculated. Preoperative and postoperative parameters were compared.

RESULTS

All EDPS procedures were technically successful with no postoperative complications. The mean operating time was 75.00 ± 22.53 min per hemisphere. Postoperative absolute cerebral blood flow (CBF), rCBF were significantly increased and absolute time to peak (TTP), rTTP, absolute mean transit time (MTT) were significantly reduced in ACA territory at centrum semiovale level (P = 0.002, 0.045, 0.007, 0.005 and 0.039 respectively). Improved outcomes were achieved in five patients, stabilization in three and one patient had deterioration out of intracerebral hemorrhage during follow-up.

CONCLUSION

EDPS is a simple but effective technique to revascularize ACA territory for MMD. EDPS significantly improved cerebral blood perfusion of frontal lobe in the majority of patients without increasing procedure-related risks.

Epidemiology, diagnosis and treatment of moyamoya disease

Moyamoya disease (MMD) is a type of chronic cerebrovascular occlusion disease, which frequently occurs in East Asian populations, including pediatric and adult patients, and may lead to ischemic or hemorrhagic stroke, headache, epilepsy or transient ischemic attack. To date, the underlying mechanisms of MMD have remained to be fully elucidated, but certain studies have indicated that genetic factors may be an important component of its development. Cerebral angiography is the best approach for diagnosing MMD. However, with technological advances, non-invasive techniques are increasingly used to accurately evaluate MMD. MMD is commonly treated via surgery, and an increasing number of patients are benefitting from the intra- and extra-cranial revascularization. The present article provides a comprehensive review of MMD on the basis of previous research.

Combined (direct and indirect) revascularization in adult patients with moyamoya disease

The study objective is to analyze the results of combined (direct and indirect) brain revascularization in adult patients with moyamoya disease. 

Materials and methods. From February 2015 to August 2016, 12 operations were performed on 12 hemispheres in 7 patients (2 men, 5 women) with moyamoya disease. Six patients had bilateral disease, 1 – unilateral. The age of patients ranged from 25 to 60 year old, the average – 41 year old. Multislice computed tomography (MSCT) perfusion imaging of the brain with a stress test was made in every patient, MSCT angiography of the extraand intracranial arteries was perfomed. Stages of the disease were determined according to the Suzuki–Takaku classification: stage III was revealed in 5 patients, stage IV – in 2. To evaluate the clinical course of the disease the Matsushima classification was used: type VI – in 2 cases, type III – in 2, type IV – in 1, type V – in 1. In 1 case, the pathological vascular network of 1 hemisphere was detected by accident. Extracranial-intracranial (EC–IC) bypass and encephaloduromyosynangiosis (EDMS) was used in 3 cases; a double-barreled EC–IC bypass and EDMS – in 3; a double-barreled EC–IC bypass and encephaloduroperiosteomyosynangiosis – in 1; EC–IC bypass and encephaloduroarteriomyosynangiosis (EDAMS) – in 3. In 1 case was perfomed EC–IC bypass and encephaloduroperiosteosynangiosis. Only indirect revascularization was performed in 1 case – EDAMS. We assessed the neurological status in the follow-up period (5–11 months); MSCT angiography and MSCT perfusion imaging of the brain were performed. 

Results. All patients in follow-up period demonstrated the increase of cerebrovascular reserve according to MSCT perfusion imaging of the brain with stress tests. Stroke, epilepsy, surgical complications were not detected in the postoperative period. In 1 case, the left-hand monoparesis regressed.

Conclusion. The combined (direct and indirect) revascularization may be effective in adult patients with moyamoya disease. To obtain more objective conclusions it is necessary to analyze the long-term results of interventions.

Novel Indirect Revascularization Technique with Preservation of Temporal Muscle Function for Moyamoya Disease Encephalo-Duro-Fascio-Arterio-Pericranial-Synangiosis: A Case Series and Technical Note

BACKGROUND

Direct and/or indirect bypass surgery is the established approach for preventing stroke in patients with moyamoya disease. However, conventional indirect revascularization, including encephalo-myo-synangiosis, has some disadvantages associated with the mass effect of the temporal muscle under the bone flap and postsurgical depression in the temporal region. We devised a novel indirect revascularization method, using only the temporal fascia, to address the aforementioned disadvantages.

METHODS

A skin incision was performed along the superficial temporal artery. The temporal fascia was cut such that the base of the fascia flap was on the posterior side. The fascia and temporal muscles were dissected separately. After turning over the fascia, the muscle was cut such that the base of the muscle flap was on the anterior side. Craniotomy, direct bypass, and encephalo-duro-synangiosis were performed conventionally. Only the temporal fascia was used for indirect revascularization and duraplasty. The muscle was replaced in the anatomically correct position after replacing the bone flap.

RESULTS

We performed the aforementioned surgery on 18 (13 women and 5 men) consecutive patients (21 cerebral hemispheres) enrolled between 2012 and 2016. The average age was 28.7 years. The mean follow-up period was 31.6 months. In 17 patients (94%), the symptoms and cerebral blood flow improved. Digital subtraction angiography showed satisfactory angiogenesis from the temporal fascia. Depression in the temporal region and atrophy of the temporal muscle were negligible.

CONCLUSIONS

This surgical technique provides good clinical and cosmetic outcomes. It may also be one of the good surgical treatments available for symptomatic moyamoya disease.

Postoperative Intracerebral Hemorrhage After Combined Revascularization Surgery in Moyamoya Disease: Profiles and Clinical Associations

OBJECTIVE

In combined revascularization surgery for patients with moyamoya disease, intracerebral hemorrhage (ICH) during the postoperative acute phase is a rarely observed but severe complication. Its clinical features remain unclear because of its low incidence rate. The aim of this study was to clarify the clinical characteristics of immediate postoperative ICH.

METHODS

The frequency, onset timing, and hematoma location of patients who demonstrated immediate postoperative ICH were investigated in 201 consecutive surgeries performed in 134 patients. Associations between immediate postoperative ICH and demographics, clinical presentation type, perioperative blood pressure (BP), and neuroimaging data were analyzed.

RESULTS

Postoperative ICH was observed in 6 cases (2.99%; mean age, 46.0 ± 7.6 years). The onset timing of ICH was within 24 hours after surgery in most patients (83.3%). Hematomas were located at the subcortical lesion beneath the anastomosed cortex (n = 5) and caudate head (n = 1). Three cases (50.0%) required hematoma evacuation. A higher age at surgery was associated with postoperative ICH (P = 0.046). In adult cases (132 surgeries, 65.7%), hemorrhagic presentation at onset (P = 0.0027) and an increase in BP from pre- to postoperative stage (systolic BP increase: P = 0.0058, diastolic BP increase: P = 0.0274) were significantly associated with postoperative ICH.

CONCLUSIONS

The results suggest that older patients, with hemorrhagic presentation and greater postoperative BP increase, should be carefully managed to avoid postoperative ICH. Immediate hematoma evacuation may be effective in preventing devastating outcomes after postoperative ICH.

Encephaloduroarteriosynangiosis for pediatric moyamoya disease: long-term follow-up of 100 cases at a single center

OBJECTIVE The object of this study was to summarize the long-term effect of encephaloduroarteriosynangiosis (EDAS) for the treatment of pediatric moyamoya disease (MMD) and to investigate factors influencing the clinical outcomes of EDAS. METHODS Clinical features, angiographic findings, and clinical outcomes were analyzed among MMD patients younger than 18 years who had been treated with EDAS between 2002 and 2007 at the authors' institution. The Kaplan-Meier method was used to estimate stroke risk after EDAS. Predictors of neurological outcome were assessed. RESULTS One hundred fifteen patients were identified. The mean age at symptom onset was 7.3 ± 4.0 years. The incidence of familial MMD was 11.3%. The female/male ratio was 1:1.16. A total of 232 EDAS procedures were performed, and the incidence of postoperative complications was 3%. Postoperative digital subtraction angiography was performed in 54% of the patients, and about 80% of the hemispheres showed good or excellent results. Neovascularization showed significant correlations with delay time (from symptom onset to first operation), Suzuki stage, and preoperative stroke (all p < 0.05). Clinical follow-up was available in 100 patients with a mean follow-up of 124.4 ± 10.5 months. Ten-year cumulative survival was 96.5% after surgery, and the risk of stroke was 0.33%/person-year. An independent life with no significant disability was reported by 92% of the patients. A good outcome correlated with a low Suzuki stage (p = 0.001). Older children and those without preoperative stroke had better clinical outcomes (p < 0.05). CONCLUSIONS On the basis of long-term follow-up data, the authors concluded that EDAS is a safe and effective treatment for pediatric MMD, can reduce the risk of subsequent neurological events, and can improve quality of life. The risk of ischemia-related complications was higher in younger patients, and older children showed better outcomes. Compensation was greater with more prominent cerebral ischemia. The long-term clinical outcome largely depended on the presence and extent of preoperative stroke.

Berlin Grading System Can Stratify the Onset and Predict Perioperative Complications in Adult Moyamoya Disease

BACKGROUND

The grading system for moyamoya disease is not established.

OBJECTIVE

To assess the usefulness of a recently proposed grading system for stratifying the clinical severity and predicting postoperative morbidity in adult moyamoya disease.

METHODS

We investigated 176 hemispheres from 89 adult patients who were diagnosed with moyamoya disease in Japan. Their data were analyzed using the Berlin grading system with minor modifications. After summarizing the numerical values for digital subtraction angiography (1-3 points), magnetic resonance imaging (0-1 points), and single-photon emission computed tomography (0-2 points), 3 grades of moyamoya disease were defined: mild (grade I) = 1 to 2 points, moderate (grade II) = 3 to 4 points, and severe (grade III) = 5 to 6 points. In total, 82 of 161 hemispheres underwent superficial temporal artery to middle cerebral artery anastomosis and indirect synangiosis. Postoperative neurological morbidity was included within 30 d after surgery.

RESULTS

Preoperative examinations categorized 87 hemispheres as grade I, 39 as grade II, and 50 as grade III. There was a significant correlation between the Berlin grading system and clinical severity (P < .001). Perioperative complications occurred in 12 of 82 (14.6%) hemispheres, including transient ischemic attack in 3 hemispheres, ischemic stroke in 4 hemispheres, symptomatic hyperperfusion in 4 hemispheres, and intracerebral hemorrhage in 1 hemisphere. The Berlin grading system was related to their occurrence (P < .001).

CONCLUSION

The Berlin grading system facilitates the stratification of clinical severity and predicting postoperative neurological morbidity in adult moyamoya disease, thereby suggesting its general usage in clinical practice.

Posterior cerebral artery stenosis and posterior circulation revascularization surgery in pediatric patients with moyamoya disease

OBJECTIVE Some pediatric patients with moyamoya disease (MMD) present with posterior cerebral artery (PCA) stenosis before and after anterior circulation revascularization surgery and require posterior circulation revascularization surgery. This study evaluated the factors associated with PCA stenosis and assessed the efficacy of posterior circulation revascularization surgery, including occipital artery (OA)-PCA bypass, in pediatric patients with MMD. METHODS The presence of PCA stenosis before and after anterior circulation revascularization surgery and its clinical characteristics were investigated in 62 pediatric patients (< 16 years of age) with MMD. RESULTS Twenty-three pediatric patients (37%) with MMD presented with PCA stenosis at the time of the initial diagnosis. A strong correlation between the presence of infarction and PCA stenosis before anterior revascularization was observed (p < 0.001). In addition, progressive PCA stenosis was observed in 12 patients (19.4%) after anterior revascularization. The presence of infarction and a younger age at the time of initial diagnosis were risk factors for progressive PCA stenosis after anterior revascularization (p < 0.001 and p = 0.002, respectively). Posterior circulation revascularization surgery, including OA-PCA bypass, was performed in 9 of the 12 patients with progressive PCA stenosis, all of whom showed symptomatic and/or radiological improvement. CONCLUSIONS PCA stenosis is an important clinical factor related to poor prognosis in pediatric MMD. One should be aware of the possibility of progressive PCA stenosis during the postoperative follow-up period and consider performing posterior circulation revascularization surgery.

Late Cerebrovascular Events and Social Outcome after Adolescence: Long-term Outcome of Pediatric Moyamoya Disease

In this article, the authors review the literature related to long-term outcome of pediatric moyamoya disease, focusing on late cerebrovascular events and social outcome of pediatric patients once they reach adulthood. Late-onset de novo hemorrhage is rare but more serious than recurrence of ischemic stroke. Long-term follow-up data on Asian populations suggest that the incidence of de novo hemorrhage might increase at age 20 or later, even more than 10 years after bypass surgery. Social adaptation difficulty, possibly related to cognitive impairment caused by frontal ischemia, continues in 10-20% of patients after they reach adulthood, even if no significant disability is present in daily life. A treatment strategy aimed at improving long-term outcome and careful follow-up might be required.

Spatial distribution of flow and oxygenation in the cerebral venous drainage system

PURPOSE

To investigate the venous oxygenation and flow in the brain, and determine how they might change under challenged states.

MATERIALS AND METHODS

Eight healthy human subjects (24-37 years) were studied. T2 -relaxation under spin tagging (TRUST) magnetic resonance imaging (MRI) and phase-contrast MRI were performed to measure venous oxygenation and venous blood flow, respectively, in the superior sagittal sinus (SSS), the straight sinus (SS), and the internal jugular veins (IJVs). Venous oxygenation was assessed at room air (0.03%CO2 , 21%O2 ) and under hyperoxia (O%CO2 , 95%O2 , and 5%N2 ) conditions. Venous blood flow was assessed at room air and under hypercapnia (5%CO2 , 21%O2 , and 74%N2 ) conditions. Whole-brain blood flow was also measured at the four feeding arteries of the brain using phase-contrast MRI. The changes in venous oxygenation and blood flow from room air to hyperoxia or hypercapnia conditions were tested using paired t-tests.

RESULTS

Venous oxygenation in the SSS, the SS, and the IJVs was 61 ± 4%, 64 ± 4%, and 62 ± 4%, respectively, at room air, and increased to 70 ± 3% (P < 0.01 compared to room air), 71 ± 5% (P = 0.59), and 68 ± 5% (P < 0.05) under hyperoxic condition. The SSS, SS, and IJV drained 46 ± 9%, 16 ± 4%, and 79 ± 1% of whole-brain blood flow, respectively, and this flow distribution did not change under hypercapnic condition (P > 0.5).

CONCLUSION

The results found in this study provide insight into the venous oxygenation and venous flow distribution and its heterogeneity among different venous structures.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1091-1098.

Adolescents with moyamoya disease: clinical features, surgical treatment and long-term outcomes

BACKGROUND

This study aimed to elucidate the clinical features, surgical treatment and long-term outcomes of adolescent patients with moyamoya disease.

METHODS

We reviewed consecutive patients with moyamoya vasculopathy who were admitted to our hospital from 2009 to 2015 to identify adolescent patients with moyamoya disease. Clinical features, surgical treatment and long-term outcomes were analyzed. Follow-up was performed by face-to-face or structured telephone interviews. Outcome measures were future stroke events. We performed univariate and multivariate time-to-event analyses to identify risk factors associated with future stroke events.

RESULTS

A total of 95 adolescent patients with moyamoya disease (age at onset, 13.1 ± 2.3 years) were included in this study. During follow-up, 12 patients (12.6%) had stroke events. We found that the patients who underwent direct/combined bypass had a significantly lower risk of future strokes [hazard ratio (HR), 0.16; 95% confidence interval (CI), 0.03-0.74; P = 0.019] compared to patients who underwent indirect bypass.

CONCLUSIONS

Our results demonstrate that direct/combined bypass can be more effective in preventing future strokes than indirect bypass in adolescent patients with moyamoya disease.

Moyamoya Disease Emerged with Corpus Callosum Hemorrhage: A 3D Computer Graphic Analysis

The authors present a rare case of moyamoya disease emerged with corpus callosum hemorrhage. A 31-year-old woman suddenly complained of severe headache followed by consciousness disturbance. Radiological examinations revealed the bleeding in the splenium of corpus callosum, which was associated with intraventricular hemorrhage. On cerebral angiography, the carotid fork was severely stenotic on both sides, and a marked dilatation was observed in the anterior/posterior choroidal arteries and posterior pericallosal artery as well as the lenticulostriate arteries. Therefore, she was diagnosed as moyamoya disease. She successfully underwent superficial temporal artery to middle cerebral artery (STA–MCA) anastomosis and indirect bypass on both sides. Postoperative course was uneventful. Follow-up cerebral angiography performed 4 months after surgery showed well-developed surgical collaterals via the external carotid system and a marked decrease of the dilated moyamoya vessels. She has been free from any cerebrovascular events for 36 months after surgery. Radiological findings strongly suggest that splenial bleeding occurred due to the rupture of the dilated abnormal collateral vessels that originate from the medial posterior choroidal artery and penetrate the corpus callosum in this case. Three-dimensional computer graphic analysis was useful to determine the complex collateral circulation in moyamoya disease.

Long-term effect of surgical revascularization on silent microbleeds in adult moyamoya disease: A case report

BACKGROUND

Recent development of magnetic resonance (MR) imaging has shown that silent microbleeds can be observed in a certain subgroup of adult patients with moyamoya disease. The patients with microbleeds are at higher risk for hemorrhagic stroke. However, the beneficial effects of surgical revascularization have not been established in asymptomatic patients with moyamoya disease. The authors present a case that underwent surgical revascularization for asymptomatic moyamoya disease because the number of silent microbleeds increases on serial MR examinations.

CASE DESCRIPTION

A 61-year-old female was referred to our hospital because of nonspecific headache. T2-weighted MR imaging revealed silent microbleeds in the corpus callosum. She was diagnosed as moyamoya disease on cerebral angiography. She was conservatively followed up, however, de novo microbleeds developed in the right temporal and frontal lobes on follow-up MR imaging 6 months later. Superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass were performed on the right side to prevent hemorrhagic stroke. Postoperative course was uneventful. Follow-up cerebral angiography performed 10 months after surgery showed a marked development of surgical collateral through both direct and indirect bypass and the diminishment of moyamoya vessels. For the last 7 years after surgery, she is free from any cerebrovascular events, and serial MR examinations revealed no further development of de novo microbleeds.

CONCLUSIONS

Surgical revascularization may be useful to reduce the moyamoya vessels and prevent cerebrovascular events in a certain subgroup of patients with asymptomatic moyamoya disease, although its universal benefits on asymptomatic moyamoya disease have not been established yet.

Indocyanine green visualization of middle meningeal artery before craniotomy during surgical revascularization for moyamoya disease

BACKGROUND

The middle meningeal artery (MMA) is well known to function as an important collateral channel to the territory of the anterior cerebral artery in moyamoya disease. This study was aimed to evaluate whether indocyanine green (ICG) videoangiography could visualize the anterior branch of the MMA before craniotomy during surgical revascularization for moyamoya disease.

METHODS

This study included 19 patients who developed TIA, ischemic stroke or hemorrhagic stroke due to moyamoya disease. Plain CT scan and three-dimensional time-of-flight MR angiography were performed in all patients before surgery. All of them underwent superficial temporal artery to middle temporal artery anastomosis and indirect bypass on 27 sides in total.

RESULTS

ICG videoangiography could clearly visualize the anterior branch of the MMA in 10 (37%) of 27 sides. The patients with a "visible" MMA are significantly younger than those without. Radiological analysis revealed that ICG videoangiography could visualize it through the cranium when the diameter of the MMA is >1.3 mm and the sphenoid bone thickness over the MMA is <3.0 mm. The MMA could be preserved during craniotomy in all "visible" MMAs, but not in 4 (23.5%) of 17 "invisible" MMAs. The results strongly suggest that ICG videoangiography can visualize the anterior branch of the MMA before craniotomy in about one-third of patients with a large-diameter MMA (>1.3 mm) and thin sphenoid bone (<3.0 mm).

CONCLUSION

ICG videoangiography is a safe and valuable technique to preserve the anterior branch of the MMA during craniotomy for moyamoya disease.

Synergistic Interactions Between Direct and Indirect Bypasses in Combined Procedures: The Significance of Indirect Bypasses in Moyamoya Disease

BACKGROUND: Whether additional indirect bypasses effectively contribute to revascularization in combined procedures remains unclear in patients with moyamoya disease.

OBJECTIVE: To evaluate the longitudinal changes associated with combined procedures while following up pediatric and adult patients long term and to assess whether any other clinical factors or hemodynamic parameters affected these changes to determine an optimal surgical strategy.

METHODS: We studied 58 hemispheres in 43 adults and 39 hemispheres in 26 children who underwent combined revascularization for moyamoya disease. To evaluate bypass development, we assessed the sizes of the superficial temporal artery and middle meningeal artery using magnetic resonance angiography. Multivariate analysis determined the effects of multiple variables on bypass development.

RESULTS: Indirect bypass (middle meningeal artery) development occurred in 95% and 78% of the pediatric and adult hemispheres, respectively. Of these, dual development of direct and indirect bypasses occurred in 54% of the pediatric hemispheres and in 47% of the adult hemispheres. Reciprocal superficial temporal artery regression occurred in 28% of the hemispheres during the transition from the postoperative acute phase to the chronic phase during indirect bypass development. Good indirect bypass development was associated with adult hemispheres at Suzuki stage 4 or greater (odds ratio, 7.4; 95% confidence interval, 1.4-39.4; P = .02). Disease onset type and preoperative hemodynamic parameters were not considered predictors for the development of surgical revascularization.

CONCLUSION: Simultaneous direct and indirect bypass development was most frequently observed, regardless of patient age and hemodynamic status. Applying indirect bypass as an adjunct to direct bypass could maximize revascularization in adults and children.

Direct versus indirect revascularization procedures for moyamoya disease: a comparative effectiveness study

OBJECTIVE Moyamoya disease (MMD) is a chronic cerebrovascular disease that can lead to devastating neurological outcomes. Surgical intervention is the definitive treatment, with direct, indirect, and combined revascularization procedures currently employed by surgeons. The optimal surgical approach, however, remains unclear. In this decision analysis, the authors compared the effectiveness of revascularization procedures in both adult and pediatric patients with MMD. METHODS A comprehensive literature search was performed for studies of MMD. Using complication and success rates from the literature, the authors constructed a decision analysis model for treatment using a direct and indirect revascularization technique. Utility values for the various outcomes and complications were extracted from the literature examining preferences in similar clinical conditions. Sensitivity analysis was performed. RESULTS A structured literature search yielded 33 studies involving 4197 cases. Cases were divided into adult and pediatric populations. These were further subdivided into 3 different treatment groups: indirect, direct, and combined revascularization procedures. In the pediatric population at 5- and 10-year follow-up, there was no significant difference between indirect and combination procedures, but both were superior to direct revascularization. In adults at 4-year follow-up, indirect was superior to direct revascularization. CONCLUSIONS In the absence of factors that dictate a specific approach, the present decision analysis suggests that direct revascularization procedures are inferior in terms of quality-adjusted life years in both adults at 4 years and children at 5 and 10 years postoperatively, respectively. These findings were statistically significant (p < 0.001 in all cases), suggesting that indirect and combination procedures may offer optimal results at long-term follow-up.

Direct Anastomosis Using Occipital Artery for Additional Revascularization in Moyamoya Disease After Combined Superficial Temporal Artery–Middle Cerebral Artery and Indirect Bypass

BACKGROUND: The posterior cerebral artery (PCA) is involved in approximately 30% of moyamoya disease (MMD) cases. However, there have been insufficient reports describing revascularization techniques in the posterior portion of the brain, particularly of direct anastomosis.

OBJECTIVE: To perform a technical assessment in patients with MMD who underwent either occipital artery (OA)–PCA bypass or OA–middle cerebral artery (MCA) bypass.

METHODS: A total of 428 revascularization procedures in 368 patients were retrospectively assessed by reviewing clinical charts and radiological data.

RESULTS: Ten patients (3.5%) were treated with direct bypass after the anterior revascularization with a median interval of 30 months (range, 5 months-16 years). Seven patients were &lt; 18 years of age (average age, 17.5 ± 15.6 years). Preoperative symptoms included transient motor deficits involving the lower extremities (n = 5), visual disturbances (n = 6), and cerebral infarctions (n = 6). A favorable outcome (modified Rankin Scale score &lt; 3) was achieved in 9 of these 10 patients. Direct anastomosis was performed in 3 hemispheres with an OA-MCA bypass and in 8 hemispheres with an OA-PCA bypass. Patency of the direct bypass was confirmed on angiogram in 7 of 7 patients who underwent conventional angiogram performed within 1 year after the surgery. None of the 10 patients demonstrated cerebral infarctions after the posterior revascularization.

CONCLUSION: In MMD, symptomatic PCA regression after anterior revascularization was found predominantly in children and young adults. Direct anastomosis in the posterior portion of the brain can be successfully achieved and is effective in preventing ischemic events.

Edaravone Reduces Hyperperfusion-Related Neurological Deficits in Adult Moyamoya Disease

Background and Purpose—

Postoperative hyperperfusion-related transient neurological deficits (TNDs) are frequently observed in adult patients with moyamoya disease who undergo direct bypass procedures. The present study evaluated the effect of the free radical scavenger edaravone on postoperative hyperperfusion in adult moyamoya disease.

Methods—

This study included 92 hemispheres in 72 adult patients who underwent direct bypass for moyamoya disease. Serial measurements of cerebral blood flow were conducted immediately after surgery and on postoperative days 2 and 7. In 40 hemispheres for 36 patients, edaravone (60 mg/d) was administered from the day of surgery to postsurgical day 7. The incidence of postoperative hyperperfusion and associated TNDs were compared with a control group that included 52 hemispheres in 36 patients.

Results—

Radiological hyperperfusion was observed in 28 of 40 (70.0%) and 39 of 52 (75.0%) hemispheres in the edaravone and control groups, respectively ( P =0.30). Hyperperfusion-related TND incidences were significantly lower in the edaravone group compared with the control group (12.5% versus 32.7%; P =0.024). Multivariate analysis demonstrated that edaravone administration ( P =0.009) and left-sided surgery ( P =0.037) were significantly correlated with hyperperfusion-related TNDs (odds ratios, 0.3 and 4.2, respectively).

Conclusions—

Perioperative administration of edaravone reduced the incidence of hyperperfusion-related TNDs after direct bypass procedures in adult patients with moyamoya disease.

Moyamoya Disease: Treatment and Outcomes

Although the pathogenesis of moyamoya disease (MMD) has not been fully elucidated, the effectiveness of surgical revascularization in preventing stroke has been addressed by many studies. The main mechanism of surgical revascularization is augmenting the intracranial blood flow using an external carotid system by either direct bypass or pial synangiosis. This can improve resting cerebral blood flow as well as vascular reserve capacity. For direct revascularization, the superficial temporal artery is used as the donor artery in most cases, although the occipital artery may be used in limited cases. Usually, the cortical branch of the middle cerebral artery is selected as the recipient of direct anastomosis. As for indirect revascularization, various techniques using different kinds of connective tissues have been introduced. In some cases, reinforcing the anterior cerebral artery and the posterior cerebral artery territories can be considered. The effectiveness of surgical revascularization for preventing ischemic stroke had been generally accepted by many studies. However, for preventing hemorrhagic stroke, new evidence has been added by a recent randomized controlled trial. The incidence of peri-operative complications such as stroke and hyperperfusion syndrome seems to be high due to the nature of the disease and technical demands for treatment. Preventing and adequately managing these complications are essential for ensuring the benefits of surgery.

Stroke prevention by direct revascularization for patients with adult-onset moyamoya disease presenting with ischemia

OBJECT Moyamoya disease (MMD) is a progressive disease that can cause recurrent stroke. The authors undertook this retrospective case-control study with a large sample size in an attempt to assess the efficacy of direct or combined revascularization surgery for ischemia in adults with MMD. METHODS The authors investigated cases involving patients with moyamoya disease presenting with ischemia who visited Seoul National University Bundang Hospital and Seoul National University Hospital between 2000 and 2014. Among 441 eligible patients, 301 underwent revascularization surgery and 140 were treated conservatively. Variables evaluated included age at diagnosis, sex, surgical record, Suzuki stage, and occurrence of stroke. Patients were stratified into 2 groups based on whether or not they had undergone revascularization surgery. Actuarial 1-, 5-, and 10-year stroke rates were calculated using the life table method. Risk factor analysis for 5-year stroke occurrence was conducted with multivariate regression. RESULTS Of the 441 patients, 301 had been surgically treated (revascularization group) and 140 had not (control group). The mean follow-up durations were 45 and 77 months, respectively. The actuarial 10-year cumulative incidence rate for any kind of stroke was significantly lower in the revascularization group (9.4%) than in the control group (19.6%) (p = 0.041); the relative risk reduction (RRR) was also superior (52.0%) in the revascularization group, and the number needed to treat was 10. The 10-year rate of ischemic stroke was greater (13.3%) in the control group than in the revascularization group (3.9%) (p = 0.019). The RRR for ischemic stroke in the revascularization group was 70.7%, and the number needed to treat was 11. However, the actuarial 1- and 5-year rates of ischemic stroke did not significantly differently between the groups. Overall, revascularization surgery was shown to be an independent protective factor, as revealed by multivariate analysis. CONCLUSIONS Direct or combined revascularization for patients with adult-onset moyamoya disease presenting with ischemia can prevent further stroke.

Radial Artery Grafts as Rescue Strategy for Patients with Moyamoya Disease for Whom Conventional Revascularization Failed

BACKGROUND

Failure of direct revascularization with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass for Moyamoya disease (MMD) is comparatively rare. However, for those cases where a bypass fails to prevent further ischemic attacks, safe and efficient rescue strategies are needed. We present our experience with radial artery grafts for secondary revascularization of MMD.

METHODS

Between April 2007 and April 2014, we have performed STA-MCA bypass in 182 patients diagnosed with Moyamoya vasculopathy. Four patients with typical MMD who had an unsuccessful STA-MCA bypass required additional revascularization because they remained symptomatic. Digital subtraction angiography revealed delayed STA graft failure in these patients, who continued to have transient ischemic attacks after the initial surgery. Cerebral blood flow studies confirmed persistent impairment of cerebrovascular reserve capacity. As an escape strategy, we performed radial artery graft bypass surgery from the external carotid artery to the M2 or M3 portion of the MCA.

RESULTS

The median duration between the 2 surgeries was 10 months. The mean follow-up period after rescue revascularization was 8.5 ± 3.3 months. Revascularization with the radial artery graft was successful in all cases without perioperative complications. Postoperatively, none of the patients experienced further cerebrovascular events. After 3 months, digital subtraction angiography revealed patent radial artery grafts and adequate revascularization in 3 patients; 1 patient presented with bypass graft failure but had developed transdural collateral vessels contributing to the filling of the cerebral vasculature.

CONCLUSIONS

Rescue bypass with a radial artery graft provides a useful function. Although delayed graft failure may occur, this procedure is successful if the patients remain symptom free with the development of collateral flow.

A novel application of four-dimensional magnetic resonance angiography using an arterial spin labeling technique for noninvasive diagnosis of Moyamoya disease

BACKGROUND

Noncontrast-enhanced time-resolved four-dimensional magnetic resonance angiography using an arterial spin labeling technique (ASL-4D MRA) is emerging as a next generation angiography for the management of neurovascular diseases. This study evaluated the feasibility of ASL-4D MRA for the diagnosis of Moyamoya disease (MMD) and MMD staging by using digital subtraction angiography (DSA) and time-of-flight MRA (TOF MRA) as current standards.

METHODS

Eleven consecutive non-operated patients who underwent DSA for the diagnosis of MMD were recruited. Two independent observers evaluated the three tests. The data were analyzed for inter-observer and inter-modality agreements on MMD stage. Nine of 22 hemispheres underwent surgical revascularization and ASL-4D MRA was repeated postoperatively.

RESULTS

Time-resolved inflow of blood through the cerebral vessels, including moyamoya vessels, was visualized in all the 22 non-operated hemispheres. MMD stages assessed by DSA and ASL-4D MRA were completely matched in 18 hemispheres, with a significant positive correlation between these modalities (r=0.93, P<0.001). Inter-observer agreement with ASL-4D MRA (κ=0.91±0.04, P<0.001) and inter-modality agreement between ASL-4D MRA and DSA (κ=0.93±0.04, P<0.001) were both excellent. MMD stages assessed by ASL-4D MRA have also a significant positive correlation with those assessed by TOF MRA (r=0.68, P=0.004). Repeated ASL-4D MRA clearly demonstrated the bypassed arteries and changes in the dynamic flow patterns of cerebral arteries in all the nine hemispheres after surgical revascularization. Of these, postoperative focal hyperperfusion was detected by single photon emission tomography in 7 hemispheres. In five of the seven hemispheres (71%) with postoperative hyperperfusion, ASL-4D MRA demonstrated focal hyperintense signals in the bypassed arteries, although TOF MRA did not.

CONCLUSIONS

Noninvasive ASL-4D MRA is feasible for the diagnosis of MMD staging. This next generation angiography may be useful for monitoring disease evolution and treatment response in cerebral arteries after revascularization surgery in MMD.

Ischemic stroke in pediatric moyamoya disease associated with immune thrombocytopenia--a case report

CASE REPORT

A 10-year-old boy developed refractory bleeding and was diagnosed with immune thrombocytopenia (ITP). He was treated with steroids and intravenous immunoglobulin (IVIG). Five months later, however, he developed right homonymous hemianopsia, sensory aphasia, agraphia, and agnosia. MR imaging demonstrated multiple cerebral infarction in the bilateral cerebral hemispheres, and MR angiography revealed severe stenosis of the bilateral internal carotid arteries. He was diagnosed with moyamoya disease and successfully underwent surgical revascularization on both sides under IVIG therapy. However, multiple cerebral infarcts developed in the bilateral cerebral hemispheres 10 days after the second surgical revascularization when platelet counts were within normal limits. Furthermore, chronic subdural hematoma gradually increased in size after each surgery, which required burr hole surgery to resolve increased intracranial pressure, when platelet counts decreased to less than 10 × 10(9)/L.

CONCLUSION

This is the first report presenting a case with moyamoya disease coincident with ITP. Critical managements would be essential to reduce perioperative complications, because ITP is known to provoke both hemorrhagic and ischemic events through multiple mechanisms.

"STA-MCA bypass with encephalo-duro-myo-synangiosis combined with bifrontal encephalo-duro-periosteal-synangiosis" as a one-staged revascularization strategy for pediatric moyamoya vasculopathy

PURPOSE

Moyamoya vasculopathy progressively compromises cerebral blood flow resulting in chronic hypoperfusion. The middle cerebral artery (MCA) territory and the bifrontal areas are the regions most frequently affected. Although most techniques aim to only revascularize the MCA territory, augmentation of blood flow of the bifrontal areas is of importance in the pediatric moyamoya population since these regions play an important role in cognition, intellectual development, and in lower extremity and sphincter function. We recently described a one-staged surgical procedure combining revascularization of three regions, the MCA territory unilaterally and the frontal areas bilaterally. The purpose of this article is to report our surgical experience in eight children and to emphasize the rational for bifrontal revascularization.

METHODS

We report a case series consisting of eight children where the following surgical strategy was applied: (1) a direct superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass with encephalo-duro-myo-synangiosis (EDMS) for unilateral MCA revascularization; in combination with (2) a bifrontal encephalo-duro-periosteal-synangiosis (EDPS) for bifrontal revascularization. Patients' characteristics and 30-day follow-up data are reported.

RESULTS

The patient group consisted of six girls and two boys (mean age 10.0, range 4.2-17.5 years): six children presented with moyamoya disease, two with moyamoya syndrome. We performed a one-staged revascularization of one MCA territory and both frontal areas in all patients. No significant complications occurred. Two patients experienced postoperative focal seizures, successfully treated with anti-epileptic medication.

CONCLUSIONS

The single-staged STA-MCA bypass with EDMS combined with bifrontal EDPS allowed revascularization of three regions (the MCA territory unilaterally and the frontal areas bilaterally) and may serve as an alternative and safe treatment option for pediatric moyamoya patients.