Using postoperative remodeling of donor arteries on MR angiography to predict the development of surgical collaterals in moyamoya disease

Stroke and Disease Progression During Long-Term Follow-Up of Patients with Moyamoya Disease Older Than 50 Years

OBJECTIVE

The long-term prognosis of elderly patients with moyamoya disease (MMD) is not fully understood and needs to be elucidated.

METHODS

MMD patients who first visited our institute between 1999 and 2019, were ≥ 50 years of age, and were followed for ≥1 year were retrospectively included. Follow-up data such as stroke and disease progression on magnetic resonance angiography (MRA) were collected from medical records. The surgical outcomes of ischemic patients treated with indirect revascularization were assessed.

RESULTS

Of the 60 patients included (mean (standard deviation) = 57.0 (5.5) years, 38 females), 9 patients initially received indirect revascularization, 3 patients received direct revascularization, and 49 patients were treated conservatively. During the 57.4 (53.7) month follow-up, the symptomatic stroke rate (person-year %) was 2.79%, and MRA progression was 3.14%. Symptomatic patients had a greater rate of symptomatic stroke than asymptomatic patients did (1.46%-5.74% vs. 0.94%, P = 0.15), while MRA progression was more common in asymptomatic patients (0%-3.83% vs. 5.64%, P = 0.22). Among the 14 hemispheres of 11 patients who underwent indirect revascularization, 13/14 (92.9%) demonstrated good neovascularization and no ischemic stroke occurred after surgery.

CONCLUSIONS

In elderly patients with MMD, MRA progression was not uncommon, especially in asymptomatic patients. Symptomatic patients exhibited a high symptomatic stroke rate, and indirect revascularization seems to be effective at reducing future ischemic stroke in ischemic patients with misery perfusion. Because follow-up events were not uncommon, lifelong follow-up seems necessary for elderly MMD patients, as well as for younger patients.

Predictive value of the hemispheric magnetic resonance angiography score on the development of indirect pial synangiosis after combined revascularization surgery for adult moyamoya disease

PURPOSE

It is difficult to precisely predict indirect bypass development in the context of combined bypass procedures in moyamoya disease (MMD). We aimed to investigate the predictive value of magnetic resonance angiography (MRA) signal intensity in the peripheral portion of the major cerebral arteries for indirect bypass development in adult patients with MMD.

METHODS

We studied 93 hemispheres from 62 adult patients who underwent combined direct and indirect revascularization between 2005 and 2019 and genetic analysis for RNF213 p.R4810K. The signal intensity of the peripheral portion of the major intracranial arteries during preoperative MRA was graded as a hemispheric MRA score (0-3 in the middle cerebral artery and 0-2 in the anterior cerebral and posterior cerebral arteries, with a high score representing low visibility) according to each vessel's visibility. Postoperative bypass development was qualitatively evaluated using MRA, and we evaluated the correlation between preoperative factors, including the hemispheric MRA score and bypass development, using univariate and multivariate analyses.

RESULTS

A good indirect bypass was observed in 70% of the hemispheres. Hemispheric MRA scores were significantly higher in hemispheres with good indirect bypass development than in those with poor indirect bypass development (median: 3 vs. 1; p < 0.0001). Multiple logistic regression analysis revealed hemispheric MRA score as an independent predictor of good indirect bypass development (odds ratio, 2.1; 95% confidence interval, 1.3-3.6; p < 0.01). The low hemispheric MRA score (< 2) and wild-type RNF213 predicted poor indirect bypass development with a specificity of 0.92.

CONCLUSION

Hemispheric MRA score was a predictive factor for indirect bypass development in adult patients who underwent a combined bypass procedure for MMD. Predicting poor indirect bypass development may lead to future tailored bypass surgeries for MMD.

Association of Genetic Variants with Postoperative Donor Artery Development in Moyamoya Disease: RNF213 and Other Moyamoya Angiopathy-Related Gene Analysis

Robust postoperative bypass development is a characteristic of moyamoya disease (MMD); however, genetic factors mediating this phenomenon remain incompletely understood. Therefore, we aimed to elucidate the relationship between postoperative donor artery development and genetic variants. We retrospectively enrolled 63 patients (79 hemispheres) who underwent combined revascularization surgery. Postoperative development of the superficial temporal artery (STA), middle meningeal artery, and deep temporal artery (DTA) was assessed using the caliber-change ratio determined from magnetic resonance angiography measurements. We analyzed RNF213 and 36 other moyamoya angiopathy-related genes by whole-exome sequencing and extracted rare or damaging variants. Thirty-five participants carried RNF213 p.Arg4810Lys (all heterozygotes), whereas 5 had RNF213 rare variants (RVs). p.Arg4810Lys was significantly associated with postoperative DTA development, while age at surgery, hypertension, and hyperlipidemia were inversely associated. Multiple regression analysis revealed that age and p.Arg4810Lys held statistical significance (P = 0.044, coefficient - 0.015, 95% confidence interval (CI) - 0.029 to 0.000 and P = 0.001, coefficient 0.670, 95% CI 0.269 to 1.072, respectively). Those with RNF213 RV without p.Arg4810Lys exhibited a significant trend toward poor DTA development (P = 0.001). Hypertension demonstrated a significant positive association with STA development, which remained significant even after multiple regression analysis (P = 0.001, coefficient 0.303, 95% CI 0.123 to 0.482). Following Bonferroni correction for multiple comparisons, targeted analyses of RNF213 and 36 moyamoya angiopathy-related genes showed a significant association of only RNF213 p.Arg4810Lys with favorable DTA development (P = 0.001). A comprehensive analysis of RNF213, considering both p.Arg4810Lys and RVs, may provide a clearer prediction of postoperative DTA development.

Impact of RNF213 c.14576G>A Variant on the Development of Direct and Indirect Revascularization in Pediatric Moyamoya Disease

BACKGROUND

Superficial temporal artery (direct) and encephalomyosynangiosis (indirect) revascularization may develop after combined bypass surgery in pediatric patients with moyamoya disease (MMD). However, arterial development varies widely among patients, and the underlying mechanisms remain unknown.

OBJECTIVES

We evaluated the relationship between the development of donor arteries after bypass surgery in pediatric patients with MMD and the MMD-susceptibility gene variant c.14576G>A of ring finger protein (RNF) 213.

METHODS

The data of pediatric patients with MMD (age <16 years at the time of surgery) treated with combined bypass surgery between September 2013 and April 2019 were consecutively analyzed. Quantitative measurements of the superficial temporal artery (STA), deep temporal artery (DTA), and middle meningeal artery (MMA) diameters with magnetic resonance angiography (MRA) source imaging were performed preoperatively and at 6-12 months postoperatively. The postoperative caliber change ratios (CCRs) were calculated. The relationship between CCRs and RNF213 c.14576G>A status was examined.

RESULTS

Forty-eight hemispheres from 28 pediatric patients with MMD were examined. Three hemispheres belonged to patients with the AA genotype; 33 to patients with the AG genotype (AA/AG group); and 12 to patients with the GG genotype (GG group; wild type). The CCRs for the DTA were significantly higher in patients with RNF213 variant (AA/AG group; 2.5 ± 0.1) than in the GG group (2.0 ± 0.2) (p = 0.03), whereas the CCRs for the STA were significantly higher in the GG (1.6 ± 0.1) than in the AA/AG group (1.3 ± 0.6) (p = 0.02). There was no significant difference in the CCRs for the MMA and basilar artery between the groups. Other factors, including sex, age, and MRA grading, were not associated with the development of specific bypass development.

CONCLUSIONS

The extent of collateral development associated with direct or indirect bypass was found to differ between the genotypes of the RNF213 c.14576G>A associated with pediatric MMD. This genetic variant correlates with the development of the disease and affects revascularization after bypass surgery in pediatric patients with MMD.

Pediatric moyamoya disease associated with ipsilateral internal carotid artery agenesis: illustrative case

BACKGROUND

Although most cases of internal carotid artery (ICA) agenesis are clinically silent due to a well-developed collateral pathway, some cases may develop ischemic symptoms when they are associated with other occlusive cerebrovascular disorders. The authors describe herein the first case with ICA agenesis that developed ischemic attack because of coincidence with moyamoya disease.

OBSERVATIONS

A 3-year-old girl was admitted to the authors’ hospital due to sudden onset of right arm weakness followed by clonic convulsion. Skull computed tomography could not identify the carotid canal on the left side. Simultaneously, magnetic resonance (MR) imaging and MR angiography demonstrated the luminal stenosis and outer diameter reduction of the carotid fork and posterior cerebral artery on the left side. She was diagnosed with unilateral moyamoya disease associated with ipsilateral ICA agenesis. She successfully underwent combined bypass surgery on the left side and has been free from any cerebrovascular events during a follow-up period of 6 months.

LESSONS

When patients with ICA agenesis develop ischemic symptoms, careful investigation of the cause and appropriate care, including surgical treatment, are required.

Changes in cerebral blood flow in the postoperative chronic phase after combined cerebral revascularization for moyamoya disease with ischaemic onset

The purpose of this study was to examine the effects of combined revascularization for ischaemic-onset moyamoya disease (MMD) on cerebral haemodynamics by comparing cerebral blood flow (CBF) during the postoperative chronic phase with preoperative CBF. A retrospective cohort of 24 MMD patients (representing 31 surgeries) who received single photon emission computed tomography (SPECT) before and more than 6 months after surgery was investigated. The CBF value of each vascular territory was extracted from SPECT data, and the value relative to the ipsilateral cerebellar value (relative CBF, or RCBF) was calculated. The correlation between the revascularization effect and the proportional change in RCBF before and after surgery (calculated as post-RCBF/pre-RCBF ("post/pre-RCBF")) was analysed. Furthermore, the relationships between changes in neurological symptoms and post/pre-RCBF were investigated. Preoperative and postoperative mean RCBF values were 0.92 ± 0.15 and 0.96 ± 0.13 (p = 0.619) in the anterior cerebral artery territory, 0.99 ± 0.17 and 1.01 ± 0.17 (p = 0.598) in the middle cerebral artery territory and 1.15 ± 0.22 and 1.14 ± 0.19 (p = 0.062) in the posterior cerebral artery territory, respectively. No significant correlation was found between the revascularization score and post/pre-RCBF. The revascularization score and post/pre-RCBF were not significant predictors of worsening neurological symptoms postoperatively. No significant change in RCBF was observed in any vascular territory in the chronic phase after revascularization. Combined revascularization may assist in the redirection of blood flow from the internal to the external carotid system and contribute to CBF maintenance.

＜Editors' Choice＞ Indocyanine green emission timing of the recipient artery in revascularization surgery for moyamoya disease

In superficial temporal artery to middle cerebral artery anastomosis with indirect revascularization for patients with moyamoya disease, the optimal method for selecting the most appropriate cortical artery for the recipient in anastomosis has not been established. We investigated the relationship between the fluorescence emission timing of the recipient artery in the preanastomosis indocyanine green videoangiography and operative outcomes. This retrospective study included 51 surgical revascularization procedures for 39 moyamoya disease patients. The enrolled surgical procedures were classified into three groups based on the fluorescence emission timing of the recipient artery in preanastomosis indocyanine green videoangiography: the EARLIEST, the INTERMEDIATE, and the LATEST. Clinical characteristics and operative outcomes were also collected. The occurrence of white thrombus at the anastomosis site and symptomatic hyperperfusion showed significant differences between the groups classified by the fluorescence emission timing of the recipient artery in preanastomosis indocyanine green videoangiography (white thrombus, p = 0.001; symptomatic hyperperfusion, p = 0.026). The development of white thrombi was significantly higher in the LATEST group, and all symptomatic hyperperfusion was observed in the EARLIEST group. These results indicated that the LATEST group had a significantly higher risk for developing white thrombus, and the EARLIEST group was prone to occur symptomatic hyperperfusion. Selecting the recipient artery based on evaluating the fluorescence emission timing in preanastomosis indocyanine green videoangiography may be useful in reducing perioperative complications.

Imaging methods for surgical revascularization in patients with moyamoya disease: an updated review

Neuroimaging is crucial in moyamoya disease (MMD) for neurosurgeons, during pre-surgical planning and intraoperative navigation not only to maximize the success rate of surgery, but also to minimize postsurgical neurological deficits in patients. This is a review of recent literatures which updates the clinical use of imaging methods in the morphological and hemodynamic assessment of surgical revascularization in patients with MMD. We aimed to assist surgeons in assessing the status of moyamoya vessels, selecting bypass arteries, and monitoring postoperative cerebral perfusion through the latest imaging technology.

Carotid ultrasonography predicts collateral development following combined direct and indirect revascularization surgery in adult ischemic Moyamoya disease

OBJECTIVE

The relationship between carotid ultrasonographic parameters and postoperative collateral development in adult ischemic moyamoya disease (MMD) patients who received combined direct and indirect revascularization surgery remains unclear. Herein, we investigated the postoperative changes in carotid ultrasonographic parameters in patients with adult ischemic MMD.

METHODS

We studied 28 adult ischemic MMD patients (31 hemispheres) who underwent combined revascularization surgery. Patients underwent preoperative and postoperative (within 14 days and 3, 12, and 24 months after surgery) magnetic resonance imaging and carotid ultrasonography. We defined the hemisphere in which all signal intensities of the superficial temporal, middle meningeal, and deep temporal arteries were increased compared with that before surgery on magnetic resonance angiography as well-developed collateral establishment.

RESULTS

Patients with good collateral establishment on MRA at 2-year after surgery had a lower external carotid artery (ECA) pulsatility index (PI) (P = 0.0413) and ECA/internal carotid artery (ICA) pulsatility index (PI) ratio (P = 0.0427) at 3-month post-operation. At 3-month post-operation, a cut-off ECA PI of 1.416 (sensitivity 40.0 %, specificity 92.3 %, area under the curve 0.7282, likelihood ratio 5.20, P = 0.0404) and ECA/ICA PI ratio of 0.8768 (sensitivity 50.0 %, specificity 92.31 %, area under the curve 0.7308, likelihood ratio 6.50, P = 0.0415) provided reliable values for good prediction of collateral development at 2 years after revascularization.

CONCLUSION

ECA/ICA PI ratio and ECA PI at 3-month after surgery can be one of the indicators for predicting future well-developed neovascularization on MRA and better outcome in patients with adult ischemic MMD who received combined direct and indirect revascularization surgery.

Vessel-selective 4D MRA based on ASL might potentially show better performance than 3D TOF MRA for treatment evaluation in patients with intra-extracranial bypass surgery: a prospective study

OBJECTIVES

To compare bypass patency and intracranial collaterals from the external carotid artery (ECA) by four-dimensional MR angiography (MRA) based on super-selective pseudo-continuous arterial spin labeling (pCASL) combined with the keyhole and view-sharing techniques (4D-sPACK) versus three-dimensional time-of-flight (3D TOF) MRA in patients with extra-intracranial revascularization.

METHODS

The MR data of 45 patients administered bypass surgery were collected. The image quality of 4D-sPACK was evaluated using a 4-point grading system according to whether the diagnosis of intracranial collaterals was affected. Anastomosis patency and intracranial collateral visualization from ECA were assessed by two radiologists on 4D-sPACK and 3D TOF MRA, with digital subtraction angiography (DSA) findings as reference. Intracranial collateral assessment employed another 4-point grading system according to the number of vessels shown. Interobserver agreement was assessed with the weighted kappa statistic.

RESULTS

Fifty hemispheres in 43 patients were included. The image quality of 4D-sPACK was good in 47 (47/50, 94.0%) hemispheres. 4D-sPACK had a higher sensitivity than 3D TOF MRA (97.73% vs 79.55%) for visualizing anastomoses. There were significant differences between 4D-sPACK (scores, 3.22 ± 1.15) and 3D TOF MRA (scores, 1.80 ± 0.67) in the visualization of intracranial collaterals from ECA (p < 0.001). The interobserver agreement was substantial for intracranial collateral assessment (κ_4D-sPACK = 0.788; κ_{3D TOF MRA} = 0.800) and almost perfect for bypass patency (κ_4D-sPACK = 0.912; κ_{3D TOF MRA} = 0.816; κ_DSA = 0.811).

CONCLUSION

This pilot study shows that, 4D-sPACK has a better performance than 3D TOF MRA in treatment evaluation of patients after bypass surgery, and has high consistency with DSA.

KEY POINTS

• 4D-sPACK is a non-contrast-enhanced dynamic MRA method for the visualization of intracranial vessels. • 4D-sPACK has higher specificity for the diagnosis of anastomosis occlusion. • 4D-sPACK is better than 3D TOF MRA in the visualization of intracranial collaterals in patients after bypass surgery.