Occipital Artery to Middle Cerebral Artery Direct Bypass: A Salvage Revascularization Technique for Ischemic Moyamoya Disease

OBJECTIVE

The main treatment for moyamoya disease (MMD) is revascularization surgery. Most bypasses use the superficial temporal artery (STA) as the donor vessel. However, even if the STA-middle cerebral artery (MCA) bypass is functioning, the affected hemisphere can continue to be symptomatically malperfused. We sought to assess the efficacy of salvage direct revascularization surgery using the occipital artery (OA) as a donor vessel in patients with ischemic MMD who experience continued cerebral malperfusion despite previous successful STA-MCA bypass.

METHODS

We retrospectively analyzed the cerebrovascular databases of 2 surgeons and described patients in whom the OA was used as the donor vessel for direct revascularization.

RESULTS

Seven patients were included (5 women). Previous STA-MCA bypasses were direct (n = 2), indirect (n = 3), or combined/multiple (n = 2). The mean (SD) interval between STA-MCA and OA-MCA procedures was 29.2 (13.1) months. Despite an intact STA-MCA bypass in all 7 cases, all 7 patients had recurrent symptoms and demonstrated residual impaired cerebral perfusion. All 7 patients underwent successful OA-MCA direct revascularization. Follow-up perfusion imaging was obtained for 6 of 7 patients. All 6 of these patients demonstrated improved cerebral blood flow to the revascularized hemispheres. All 7 patients demonstrated clinical improvement.

CONCLUSIONS

Patients with ischemic MMD who have continued symptoms and cerebral malperfusion despite previous successful STA-MCA bypass present a challenging clinical scenario. Our series highlights the potential utility of the OA-MCA direct bypass as a salvage therapy for these patients.

Occipital artery: Anatomical variations and neurosurgical applications

Background

The occipital artery (OA) is a branch of the external carotid artery. It gives rise to several cutaneous, muscular, and meningeal branches to supply different anatomical areas. The implication of OA in the neurosurgical field is well-established in the literature. Our aim in this study is to draw a complete picture of the anatomical variations and neurosurgical applications of the OA.

Methods

A literature review was conducted in Google Scholar and PubMed to review the studies discussing OA, its anatomical variation, and neurosurgical applications.

Results

We identified 29 articles that discuss the anatomical variations and neurosurgical applications of the OA. Certain variables are used to describe the surgical anatomy of OA. We also discussed certain applications of OA and its importance in neurosurgical bypass, embolization, and aneurysms.

Conclusion

Comprehending the anatomy of the OA is crucial for neurosurgeons to safely and effectively perform procedures such as bypass and embolization. In addition, knowledge of the anatomical variations of the OA can help surgeons anticipate potential challenges and tailor their approach accordingly.

Risk factors and a novel cerebral infarction extent scoring system for postoperative cerebral ischemia in patients with ischemic Moyamoya disease

Postoperative cerebral ischemic complication is the most common complication of revascularization surgery for patients with moyamoya disease (MMD). This retrospective study was conducted on 63 patients with ischemic MMD. Postoperative ischemia occurred in 15 of the 70 revascularization operations performed for patients after surgical revascularization, translating to an incidence of 21.4%. Univariate analysis revealed that onset infarction (p = 0.015), posterior cerebral artery involvement (p = 0.039), strict perioperative management (p = 0.001), interval time between transient ischemic attack (TIA) or infarction presentation and operation (p = 0.002) and preoperatively cerebral infarction extent score (CIES) (p = 0.002) were significantly associated with postoperative cerebral ischemia. Multivariate analysis revealed that strict perioperative management (OR = 0.163; p = 0.047), and preoperatively CIES (OR = 1.505; p = 0.006) were independently associated with postoperative cerebral ischemia-related complications. After comprehensive improvement of perioperative management protocol, the incidence of symptomatic infarction declined to 7.4% (4 out of 54). Analysis of the area under the receiver operating characteristic curve (AUROC) indicated CIES was a predictor for both postoperative ischemia and high follow-up modified Rankin Scale scores. In summary, strict perioperative management and CIES were identified as independent risk factors for postoperative ischemic complications in ischemic MMD, demonstrating that comprehensive and individualized perioperative management improve postoperative outcomes in patients with MMD. Furthermore, application of CIES to evaluate pre-existing cerebral infarction can improve the management of patients.

Additional Revascularization Using Multiple Burr Holes for PCA Involvement in Moyamoya Disease

In specific cases of moyamoya disease (MMD), posterior cerebral artery (PCA) stenosis can develop after treatment of the anterior circulation and require additional revascularization. Here, we report two cases that underwent additional posterior indirect revascularization with multiple burr holes for PCA involvement after bilateral revascularization treatment of the anterior circulation. They presented with transient ischemic attack even after bilateral superficial temporal artery-middle cerebral artery bypass, and magnetic resonance angiography (MRA) showed that PCA stenosis had worsened. Indirect revascularization with multiple burr holes using Benz-marked skin incisions was performed. After surgery, the symptoms improved without perioperative complications, and cerebral angiography showed collateral circulation via the burr hole. Indirect revascularization for MMD is often combined with direct revascularization, and there are only a few reports on the use of multiple burr hole surgery alone. In addition, there are few reports of posterior circulation, despite the emphasis on the importance of PCA involvement in MMD. Indirect revascularization with multiple burr holes alone can be performed in multiple areas and applied to patients who cannot undergo direct revascularization using the occipital artery. The procedure is simple and less invasive than traditional direct revascularization procedures. Therefore, it can be effective, especially in pediatric cases of MMD with PCA involvement.

Specific clinical features and one-stage revascularization surgery for moyamoya disease with severe cerebral ischemia in the territory of posterior cerebral artery

BACKGROUND

There are no reports describing the surgical procedure for moyamoya disease (MMD) patients with severe cerebral ischemia in the territory of the posterior cerebral artery (PCA) at initial presentation. In this study, therefore, we describe their clinical and radiological features and clinical results of one-stage revascularization surgery for both anterior and posterior circulation.

METHODS

This study included 6 MMD patients who had severe cerebral ischemia in the PCA territory and underwent one-stage revascularization surgery for both anterior and posterior circulation. Of these, one patient underwent it on both sides. Their clinical and radiological data were precisely analyzed. Compared with usual procedure, craniotomy was extended towards the temporo-parietal area more widely. The parietal branch of superficial temporal artery (STA) was anastomosed to the angular or posterior temporal artery, while the frontal branch was anastomosed to the frontal branch of MCA. Ultimate indirect bypass was added. Their clinical and radiological outcomes were evaluated.

RESULTS

Their neurological symptoms included visual and speech disturbance as well as numbness of the extremities. Cerebral infarct was distributed in the posterior temporal, parietal, and/or occipital lobe. Cerebral hemodynamics and metabolism were also impaired in the same regions. These findings were completely different from those in MMD patients without PCA lesion. Postoperative course was uneventful, and none of them recurred stroke during a mean follow-up period of 10.5 years. Surgical collaterals widely provided blood flow to the entire hemispheres, including the occipital lobe. Cerebral hemodynamics and metabolism markedly improved after surgery.

CONCLUSION

One-stage revascularization surgery for both anterior and posterior circulation is feasible and effective to prevent future stroke in MMD patients with severe cerebral ischemia in the PCA territory at initial presentation.

Occipital artery to middle cerebral artery bypass in pediatric moyamoya disease: rescue therapy after failed revascularization

OBJECTIVE

Patients with pediatric moyamoya disease (PMMD) showing recurrent symptoms or decreased cerebral blood flow after initial revascularization therapy may require additional revascularization to improve their clinical condition. The authors evaluated the clinical and hemodynamic benefits of an occipital artery (OA)-middle cerebral artery (MCA) bypass for patients with PMMD who have undergone an initial revascularization procedure.

METHODS

The authors retrospectively identified 9 patients with PMMD who had undergone OA-MCA bypass between March 2013 and December 2017, and who had received a previous superficial temporal artery-MCA bypass. The following clinical data were collected: initial revascularization procedure, symptoms (presence or recurrence), pre- and postoperative cerebral blood flow and cerebrovascular reactivity (CVR) changes, posterior cerebral artery (PCA) stenosis, PCA-related and nonrelated symptoms, and latest follow-up.

RESULTS

Preoperatively, all patients (n = 9) suffered non-PCA-related recurrent symptoms, and 4 had PCA-related symptoms. At 1-year follow-up, all patients with PCA-related symptoms showed complete recovery. Additionally, 8 (89%) patients with non-PCA symptoms experienced improvement. Only 1 (11%) patient showed no improvement after the surgical procedure. The mean pre- and postoperative CVR values of the MCA territory were 14.8% and 31.3%, respectively, whereas the respective mean CVR values of the PCA territory were 22.8% and 40.0%.

CONCLUSIONS

The OA-MCA bypass is an effective rescue therapy to improve the clinical condition and hemodynamic changes caused by PMMD in patients who experience recurrent symptoms after initial revascularization.

Current Surgical Options for Moyamoya Disease

Moyamoya disease (MMD) is a cerebrovascular disease of unknown etiology characterized by stenotic and occlusive arterial changes of the anterior circulation, with subsequent proliferative development of arterial collateralization. In spite of there being limited understanding of the clear etiology of MMD, surgical revascularization for MMD is considered the standard treatment to prevent further stroke. While the use of surgical revascularization to prevent future hemorrhagic stroke in MMD is still controversial, it is considered effective in the case of ischemic stroke. This article presents a review of the current surgical management of MMD based on an analysis of the most recent data from peer-reviewed articles and opinion based on personal experience with surgical revascularization in the treatment of MMD.

Neuroendoscope-Assisted Aneurysm Trapping for Ruptured Intraventricular Aneurysms in Moyamoya Disease Patients

BACKGROUND

Intracranial hematomas associated with abnormal collateral vessels are observed in certain populations of adult patients with moyamoya disease (MMD). Of these, intraventricular hematomas resulting from rupture of intraventricular aneurysms, which are formed along an abnormal peripheral choroidal artery, are sometimes detected and could be severe. No appropriate treatment option for these ruptured aneurysms has been well established to date. Therefore in this report, we describe the case of an MMD patient with an intraventricular hematoma resulting from a ruptured intraventricular aneurysm arising along the abnormal collateral vessels near the lateral ventricular wall, which was successfully treated using a neuroendoscope.

CASE DESCRIPTION

A 53-year-old female with MMD presented with an intraventricular hematoma. The patient had already undergone bilateral, combined direct/indirect cerebral revascularization surgery 3 years prior. Digital subtraction angiography revealed an aneurysm along the abnormal collateral choroidal artery near the posterior horn of the left lateral ventricle. A neuroendoscopic technique was applied to approach and treat the aneurysm; this was performed successfully by trapping using aneurysm clips without intraoperative or postoperative complications.

CONCLUSIONS

Neuroendoscopic aneurysm trapping using aneurysm clips is a treatment option for an intraventricular aneurysm that causes an intraventricular hematoma in patients with MMD. This technique is minimally invasive and offers good visibility of the surgical field.

Combined structural and diffusion tensor imaging detection of ischemic injury in moyamoya disease: relation to disease advancement and cerebral hypoperfusion

OBJECTIVE

The microstructural integrity of gray and white matter is decreased in adult moyamoya disease, suggesting covert ischemic injury as a mechanism of cognitive dysfunction. Establishing a microstructural brain imaging marker is critical for monitoring cognitive outcomes following surgical interventions. The authors of the present study determined the pathophysiological basis of altered microstructural brain injury in relation to advanced arterial occlusion, cerebral hypoperfusion, and cognitive function.

METHODS

The authors examined 58 patients without apparent brain lesions and 30 healthy controls by using structural MRI, as well as diffusion tensor imaging (DTI). Arterial occlusion in each hemisphere was classified as early or advanced stage based on MRA and posterior cerebral artery (PCA) involvement. Regional cerebral blood flow (rCBF) was measured with N-isopropyl-p-[123I]-iodoamphetamine SPECT. Furthermore, cognitive performance was examined using the Wechsler Adult Intelligence Scale, Third Edition and the Trail Making Test (TMT). Both voxel- and region of interest-based analyses were performed for groupwise comparisons, as well as correlation analysis, using parameters such as cognitive test scores; gray matter volume; fractional anisotropy (FA) of association fiber tracts, including the inferior frontooccipital fasciculus (IFOF) and superior longitudinal fasciculus (SLF); PCA involvement; and rCBF.

RESULTS

Compared to the early stages, advanced stages of arterial occlusion in the left hemisphere were associated with a lower Performance IQ (p = 0.031), decreased anterior cingulate volumes (p = 0.0001, uncorrected), and lower FA in the IFOF, cingulum, and forceps major (all p < 0.01, all uncorrected). There was no significant difference in rCBF between the early and the advanced stage. In patients with an advanced stage, PCA involvement was correlated with a significantly lower Full Scale IQ (p = 0.036), cingulate volume (p < 0.01, uncorrected), and FA of the left SLF (p = 0.0002, uncorrected) compared to those with an intact PCA. The rCBF was positively correlated with FA of the SLF, IFOF, and forceps major (r > 0.34, p < 0.05). Global gray matter volumes were moderately correlated with TMT part A (r = 0.40, p = 0.003). FA values in the left SLF were moderately associated with processing speed (r = 0.40, p = 0.002).

CONCLUSIONS

Although hemodynamic compensation may mask cerebral ischemia in advanced stages of adult moyamoya disease, the disease progression is detrimental to gray and white matter microstructure as well as cognition. In particular, additional PCA involvement in advanced disease stages may impair key neural substrates such as the cingulum and SLF. Thus, combined structural MRI and DTI are potentially useful for tracking the neural integrity of key neural substrates associated with cognitive function and detecting subtle anatomical changes associated with persistent ischemia, as well as disease progression.

Late (5-20 years) outcomes after STA-MCA anastomosis and encephalo-duro-myo-arterio-pericranial synangiosis in patients with moyamoya disease

OBJECTIVE

Surgical revascularization is known to reduce the incidence of further ischemic and hemorrhagic events in patients with moyamoya disease, but the majority of previous studies report only short-term (< 5 years) outcomes. Therefore, in this study the authors aimed to evaluate late (5-20 years) outcomes of moyamoya patients after superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect bypass (encephalo-duro-myo-arterio-pericranial synangiosis [EDMAPS]).

METHODS

Cumulative incidences of late morbidity/mortality and disease progression were evaluated among 93 patients who underwent STA-MCA anastomosis and EDMAPS. All of the patients were prospectively followed up for longer than 5 years postsurgery (10.5 ± 4.4 years). There were 35 pediatric and 58 adult patients. Initial presentation included transient ischemic attack/ischemic stroke in 80 patients and hemorrhagic stroke in 10 patients, and 3 patients were asymptomatic. Surgery was performed in a total of 141 hemispheres. Follow-up MRI/MRA was performed within a 6- or 12-month interval during the follow-up periods.

RESULTS

During the follow-up periods, 92/93 patients were free from any stroke or death, but 1 patient had a recurrence of hemorrhagic stroke (0.10% per patient-year). Disease progression occurred in the territory of the contralateral carotid or posterior cerebral artery (PCA) in 19 hemispheres of 15 patients (1.5% per patient-year). The interval between initial surgery and disease progression varied widely, from 0.5 to 15 years. Repeat bypass surgery for the anterior and posterior circulation resolved ischemic attacks in all 10 patients.

CONCLUSIONS

The study results indicate that STA-MCA anastomosis and EDMAPS would be the best choice to prevent further ischemic and hemorrhagic stroke for longer than 10 years on the basis of the demonstrated widespread improvement in cerebral hemodynamics in both the MCA and ACA territories in the study patients. However, after 10 years postsurgery regular follow-up is essential to detect disease progression in the territory of the contralateral carotid artery and PCA and prevent late cerebrovascular events.

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

OBJECTIVE

The calibers of donor arteries can change dynamically after bypass surgery in patients with moyamoya disease (MMD). The present study aimed to evaluate the cutoffs of caliber changes in donor arteries associated with good surgical revascularization and to assess the impact of clinical factors potentially related to bypass development.

METHODS

The authors studied 71 hemispheres of 30 adults and 16 children with MMD who underwent combined direct and indirect revascularization. They quantitatively measured the calibers of the superficial temporal artery (STA), deep temporal artery (DTA), and middle meningeal artery (MMA) with MR angiography (MRA) source images and calculated the postoperative caliber change ratios (CCRs) to assess direct and indirect bypass development. These values were compared with the findings of digital subtraction angiography, in which revascularization areas were categorized into 3 groups (poor, good, and excellent).

RESULTS

In both adult and pediatric hemispheres, the median STA and DTA CCRs were higher in better-revascularization groups (p < 0.05), while MMA CCRs were not significantly different among the groups. Receiver operating characteristic analysis revealed that the cutoff STA CCRs of > 1.1 and > 1.3 were associated with good direct revascularization in adult and pediatric hemispheres, respectively. Cutoff DTA CCRs of > 1.6 and > 1.2 were associated with good indirect revascularization in adult and pediatric hemispheres, respectively. Considering these cutoff values, STA and DTA CCRs showed high median values, irrespective of age, severity of cerebrovascular reserve, disease stage, and disease-onset type.

CONCLUSIONS

Caliber changes in STAs and DTAs can be easily measured using MRA, and they could be indicators of direct and indirect bypass development. The dual development of a direct and indirect bypass was most frequently observed in the context of a combined bypass procedure in both adults and children with MMD.

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.

Clinical importance of the occipital artery in vascular lesions: A review of the literature

The occipital artery (OA) is a critical artery in vascular lesions. However, a comprehensive review of the importance of the OA is currently lacking. In this study, we used the PubMed database to perform a review of the literature on the OA to increase our understanding of its role in vascular lesions. We also provided our typical cases to illustrate the importance of the OA. The OA has several variations. For example, it may arise from the internal carotid artery or anastomose with the vertebral artery. Therefore, the OA may provide a crucial collateral vascular supply source and should be preserved in these cases. The OA is a good donor artery. Consequently, it is used in extra- to intracranial bypasses for moyamoya disease (MMD) or aneurysms. The OA can be involved in dural arteriovenous fistula (DAVF) and is a feasible artery for the embolisation of DAVF. True aneurysms and pseudoaneurysms can occur in the OA; surgical resection and embolisation are the effective treatment approaches. Direct high-flow AVF can occur in the OA; embolisation treatment is a good option in such cases. The OA can also be involved in MMD and brain arteriovenous malformation (AVM) by forming transdural collaterals. For a patient in the prone position, if occipital and suboccipital craniotomies are performed, the OA can also be used for intraoperative angiography. In brief, the OA is a very important artery in vascular lesions.

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.

Occipital artery-anterior cerebral artery bypass with posterior auricular artery-middle cerebral artery bypass for stenosis of the internal carotid artery bifurcation

Superficial temporal artery (STA)-middle cerebral artery (MCA) bypass, and STA-anterior cerebral artery (ACA) bypass, are options for direct revascularisation of anterior circulation. However, some patients don't have a suitable STA to use as a donor, so an alternative procedure must be performed. A 59-year-old, right-handed man presented with dysphasia and right-sided hemiparesis due to a transient ischaemic attack. Imaging studies revealed severe stenosis of the left internal carotid artery bifurcation. Iodoamphetamine single photon emission computed tomography demonstrated reduced cerebrovascular reserve capacity in the left hemisphere. The patient was started on antiplatelet therapy, but the ischaemic attacks persisted after one month. Thus, revascularisation of the ACA and MCA territories was considered. Digital subtraction angiography revealed prominence in the left occipital artery (OA) and posterior auricular artery (PAA), while the left STA was hypoplastic, terminating at the squamous suture level. Therefore, anastomoses were performed between both the OA and ACA and the PAA and MCA. Revascularisation was successful, and the ischaemic attacks disappeared. OA-ACA bypass, together with PAA-MCA bypass, may be effective for wide cerebral revascularisation when the STA is not available.

Clinical importance of the superficial temporal artery in neurovascular diseases: A PRISMA-compliant systematic review

The superficial temporal artery (STA) plays a very important role in neurovascular diseases and procedures. However, until now, no comprehensive review of the role of STA in neurovascular diseases from a neurosurgical perspective has ever been published. To review research on the clinical importance of STA in neurovascular diseases, a literature search was performed using the PubMed database. Articles were screened for suitability and data relevance. This paper was organized following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. According to the literature, STA is one of the terminal branches of the external carotid artery and can give off scalp, muscle, and transosseous branches. STA-middle cerebral artery (MCA) bypass is very useful for intracranial ischemic diseases, including moyamoya disease, chronic ICA and MCA insufficiency, and even acute ischemic stroke. For intracranial complex aneurysms, STA bypass remains a major option that can serve as flow replacement bypass during aneurysmal trapping or insurance bypass during temporary parent artery occlusion. Occasionally, the STA can also be involved in dural AVFs (DAVFs) via to its transosseous branches. In addition, the STA can be used as an intraoperative angiography path and the path to provide endovascular treatments. Therefore, STA is a very important artery in neurovascular diseases.

Assessment of Single-Barrel Superficial Temporal Artery-Middle Cerebral Artery Bypass in Treatment for Adult Patients with Ischemic-Type Moyamoya Disease

BACKGROUND Moyamoya disease (MMD) is an idiopathic disease caused by progressive steno-occlusion of the distal internal carotid artery. Ideal surgical treatment for adult patients with ischemic-type MMD has not been achieved. The aim of this study was to evaluate the efficacy of single-barrel superficial temporal artery-middle cerebral artery (STA-MCA) bypass in treatment for adult patients with ischemic-type MMD by analyzing clinical and radiological data retrospectively. MATERIAL AND METHODS The present study included 37 patients with non-hemorrhagic MMD, including 21 women and 16 men (21~55 years old, mean age 38.1 years). The bypass surgery was performed on 56 sides in the 37 patients. The clinical charts, angiographic revascularization, and hemodynamic changes were reviewed at 6-60 months after surgery. RESULTS Among the 37 patients, the clinical symptoms and signs of 32 patients were improved or stabilized. Five patients had complications, including 2 cases of acute cerebral infarction, 1 case of epidural hematoma, and 1 case of transient speech disturbance, and 1 patient died. Follow-up computed tomography perfusion (CTP) revealed that cerebral blood flow (CBF) was markedly improved after surgery (P<0.05). Time to peek (TTP) and mean transit time (MTT) were significantly decreased after surgery (P<0.05). No significant change in cerebral blood volume (CBV) was found after surgery (P>0.05). Postoperative patency was clearly verified in 52 bypasses (92.8%) of 56 bypasses on follow-up DSA imaging. CONCLUSIONS Single-barrel STA-MCA bypass can be considered as an effective surgical treatment, which exhibits satisfactory clinical efficacy in ischemic-type MMD patients.

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.