Ameliorative Effects of Combined Revascularization Surgery on Abnormal Collateral Channels in Moyamoya Disease

Intraoperative Superficial Temporal Artery-middle Cerebral Artery Bypass Failure during Combined Bypass Surgery in Children with Moyamoya Disease

Pediatric patients with moyamoya disease frequently show rapid progression with a high risk of stroke. Indirect revascularization is widely accepted as a surgical treatment for pediatric moyamoya disease, but it does not augment cerebral blood flow immediately, which leaves patients at risk for stroke peri-operatively. This delay in flow augmentation may make adding direct bypass the better option. This study documents our cases of direct bypass failure that underwent indirect bypass supplemented with superficial temporal artery-middle cerebral artery bypass to evaluate the adverse effects of direct bypass failure. A retrospective review of all surgeries for pediatric moyamoya disease after introducing intraoperative indocyanine green videoangiography to confirm direct bypass patency identified 78 surgical hemispheres. Direct bypass failure was defined as failure to confirm blood flow from the superficial temporal artery to the middle cerebral artery on indocyanine green videoangiography. The occurrence of ischemic complications was evaluated by magnetic resonance imaging. During the period, postoperative ischemic complications were seen in 3 surgical hemispheres (3.8%) and one contralateral hemisphere (1.3%). One case in which hyperventilation was difficult to control postoperatively developed extensive cerebral infarction. Direct bypass failure was seen in 3 patients (3.8%), none of whom had additional cerebral infarction on magnetic resonance imaging. The results of this study indicate that failure of direct bypass surgery does not necessarily lead to cerebral infarction. Based on these results, surgeons can safely attempt to add a direct bypass to an indirect bypass, with special attention to perioperative patient management.

Moyamoya Periventricular Choroidal Collateral Registry-A Multicenter Cohort Study of Moyamoya Disease with Choroidal Anastomosis: Study Protocol

Recent cohort studies on hemorrhagic and asymptomatic moyamoya disease have revealed that choroidal anastomosis, a type of fragile periventricular collateral pathway (periventricular anastomosis) typical of the disease, is an independent predictor of hemorrhagic stroke. However, treatment strategies for less-symptomatic nonhemorrhagic patients with choroidal anastomosis remain unclear. The Moyamoya Periventricular Choroidal Collateral (P-ChoC) Registry is an ongoing multicentered observational study that will test the hypothesis that extracranial-intracranial bypass prevents de novo hemorrhagic stroke in less symptomatic, nonhemorrhagic patients with choroidal anastomosis and may thus contribute to improving the prognosis of moyamoya disease. In this study, we report the study protocol of the moyamoya P-ChoC Registry and review the literature on choroidal anastomosis as a fragile collateral pathway.

Post-Surgical Cognitive Outcomes of Moyamoya Disease: A Systematic Review

BACKGROUND

Moyamoya disease (MMD) is an occlusive arteriopathy leading to stroke. Progressive if left untreated, revascularization surgery has become the mainstay of treatment. Although clinical and radiographic outcomes of MMD after intervention are well-characterized, cognitive outcomes in pediatric patients remain unclear. We aimed to examine postoperative cognitive outcomes in children with MMD, examine factors associated with cognitive changes after intervention, and define the effect of revascularization surgery on cognitive outcomes.

METHODS

A systematic review was conducted following PRISMA guidelines searching PubMed, Embase, and Scopus databases. Articles met inclusion criteria if they studied pediatric patients undergoing revascularization surgery for MMD and examined cognitive outcomes either qualitatively or quantitatively. All data extracted from included articles was examined descriptively.

RESULTS

Of 1091 resultant articles, 12 articles containing 446 patients were included. Surgery was associated with maintained or improved full scale intellectual quotient (IQ), performance IQ, perceptual IQ, memory quotient and verbal memory. However, 70% of patients had impaired cognitive function, with associated poor school performance. Improvements in cognition were associated with increased cerebral blood flow, particularly to the middle cerebral artery, due to the development of collaterals. Female sex, shorter duration from symptom onset to surgery, and surgery after age 7 were predictive of cognitive improvement. Completed ischemic stroke prior to surgery was associated with poorer cognitive outcomes.

CONCLUSIONS

Although children with MMD have improved cognitive outcomes following revascularization overall, a distinct subset experience cognitive impairment. Consideration of patient-specific and treatment-related factors is important to enable proper risk stratification and inform management approaches.

Pediatric Moyamoya Biomarkers: Narrowing the Knowledge Gap

Moyamoya is a progressive cerebrovascular disorder that leads to stenosis of the arteries in the distal internal carotid, proximal middle cerebral and proximal anterior cerebral arteries of the circle of Willis. Typically a network of collaterals form to bypass the stenosis and maintain cerebral blood flow. As moyamoya progresses it affects the anterior circulation more commonly than posterior circulation, and cerebral blood flow becomes increasingly reliant on external carotid supply. Children with moyamoya are at increased risk for ischemic symptoms including stroke and transient ischemic attacks (TIA). In addition, cognitive decline may occur over time, even in the absence of clinical stroke. Standard of care for stroke prevention in children with symptomatic moyamoya is revascularization surgery. Treatment of children with asymptomatic moyamoya with revascularization surgery however remains more controversial. Therefore, biomarkers are needed to assist with not only diagnosis but also with determining ischemic risk and identifying best surgical candidates. In this review we will discuss the current knowledge as well as gaps in research in relation to pediatric moyamoya biomarkers including neurologic presentation, cognitive, neuroimaging, genetic and biologic biomarkers of disease severity and ischemic risk.

Larger Posterior Revascularization Associated with Reduction of Choroidal Anastomosis in Moyamoya Disease: A Quantitative Angiographic Analysis

BACKGROUND AND PURPOSE

Choroidal anastomosis, a hemorrhage-prone periventricular collateral manifestation in Moyamoya disease, outflows to the cortex posterior to the central sulcus. The objective of the present study was to test whether the angiographic extent of revascularization posterior to the central sulcus contributes to the postoperative reduction of choroidal anastomosis.

MATERIALS AND METHODS

This retrospective cohort study included choroidal anastomosis-positive hemispheres before direct bypass surgery. The postoperative reduction of choroidal anastomosis was determined by a consensus of 2 raters according to the previous research. An imaging software automatically traced the angiographic revascularization area, which was subsequently divided into anterior and posterior parts by an anatomic line corresponding to the central sulcus. Each area was quantitatively measured as a percentage relative to the whole supratentorial area.

RESULTS

Postoperative reduction of choroidal anastomosis was achieved in 68 (85.0%) of the 80 included hemispheres. The revascularization area posterior to the central sulcus was significantly larger in the hemispheres with reduction than in those with no reduction (mean, 15.2% [SD, 7.1%] versus 4.2% [SD, 3.4%], P < .001), whereas no significant difference was observed in the revascularization area anterior to the central sulcus. Multivariate analysis revealed that the revascularization area posterior to the central sulcus was the only significant factor associated with reduction (OR, 1.57; 95% CI, 1.21-2.03, for every 1% increase).

CONCLUSIONS

The results suggest that a larger revascularization posterior to the central sulcus is associated with postoperative reduction of choroidal anastomosis regardless of the extent of anterior revascularization. It might facilitate optimal selection of the revascularization site for preventing hemorrhage.