was similar between groups. A systematic review published in 2005 identified 55 studies with data for 1156 children (mainly from Japan) who had surgical revascularization for moyamoya [2]. Most patients were treated with indirect surgical techniques or a combination of direct and indirect methods. The perioperative stroke rate was 4.4 percent. Over a mean postoperative follow- up of 58 months, symptomatic benefit, defined as complete disappearance or reduction in symptomatic cerebral ischemia, was reported in 1003 children (87 percent). In detail, outcomes were asymptomatic, improved, unchanged, or worse in 51, 36, 11, and 3 percent of patients, respectively. Longer-term outcomes in children also appear to be favorable. In a series from the United States of 143 children with symptomatic moyamoya who were treated with pial synangiosis, perioperative stroke occurred in 11 (8 percent) [55]. Among 126 patients followed for more than one year, late-onset stroke occurred in four (3 percent). In 46 patients who were followed for more than five years, late-onset stroke occurred in two patients (4 percent). Complications of surgery Perioperative stroke Peri- and postoperative stroke is a major complication of surgical revascularization for moyamoya. Ischemic stroke may occur due to baseline impairment of cerebral blood flow and perioperative hypoperfusion or thrombosis. Improved cerebral blood flow with surgery may also expose patients to the risk of postoperative intracerebral hemorrhage or edema from hyperperfusion. Additionally, other sites of intracranial hemorrhage, including subdural hematoma, may occur following revascularization. Efforts to maintain optimal cerebral perfusion during the perioperative period are important to minimize the risk of complications. Relative hypoperfusion can occur as a result of competing blood flow from the preexisting collateral circulation and the new anastomosis in the setting of impaired cerebral autoregulation [56]. In a single-center series of 1250 pediatric and adult revascularizations performed from 1991 to 2014, the 30- day postoperative rate of major stroke was 6.8 percent [57]. In a meta-analysis of eight studies with over 1600 adult patients with moyamoya disease who had surgery, independent risk factors for postoperative stroke were operative ischemic events, posterior cerebral artery involvement, and diabetes [58]. https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 12/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Maintaining normocapnia is recommended during and after perioperative period to prevent ischemic complications. Both hypercapnia and hypocapnia can alter the regional cerebral blood flow through the mechanisms of vasoconstriction and steal phenomenon via vasodilation [59]. Delayed transient neurologic deficits Delayed transient neurologic deficits can occur typically 12 to 24 hours after revascularization surgery. Symptoms may include aphasia, oro-bulbar apraxia, motor weakness, or sensory abnormalities. Imaging shows no evidence of ischemic stroke, hemorrhage, or edema in these cases, and the symptoms usually resolve within several days to weeks. While the pathophysiology of this syndrome is uncertain, it may be due to either hyperperfusion or hypoperfusion [56,60,61]. Hyperperfusion syndrome Cerebral hyperperfusion syndrome may occur after surgical revascularization due to abrupt changes in perfusion to the ischemic hemisphere [5,62,63]. Changes in cerebral autoregulation induced by chronic cerebral hemodynamic insufficiency lead to compensatory vasodilation of cerebral vessels. After revascularization, blood flow is restored to a normal or elevated perfusion pressure within the previously hypoperfused hemisphere. The chronically dilated cerebral vessels are unable to vasoconstrict quickly enough to protect the capillary bed because of impaired cerebral blood flow autoregulation. Breakthrough perfusion pressure then causes the clinical manifestations that may include headache, seizures, focal neurologic deficits, cerebral edema, and rarely intracerebral hemorrhage. The reported incidence of clinically symptomatic cerebral hyperperfusion syndrome following bypass surgery for moyamoya disease ranges from 15 to 47 percent [62,64-66]. In a 2020 meta-analysis that included 2225 patients from 27 cohort studies, the incidence of postoperative hyperperfusion for adults was 20 percent but only 4 percent for children [63]. In nearly all cases, complete resolution occurs over several days to weeks. However, some patients with hyperperfusion syndrome can have persistent deficits when associated with intracerebral hemorrhage. Prophylactic postoperative blood pressure control may prevent or ameliorate symptomatic cerebral hyperperfusion. In a cohort of 108 adults with moyamoya, immediate postoperative blood pressure control to a target systolic blood pressure of <130 mmHg was associated a lower risk of hyperperfusion complications than expectant management (25 versus 7 percent) [67]. Hyperperfusion syndrome is discussed in greater detail separately. (See "Complications of carotid endarterectomy", section on 'Hyperperfusion syndrome'.) https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 13/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Other complications Infection and surgical site bleeding are other uncommon complications of moyamoya surgery [5]. MANAGEMENT OF COMPLICATIONS OF MOYAMOYA Patients may present with complications due to moyamoya vasculopathy, including ischemic stroke or intracerebral hemorrhage. Management of the presenting complication involves minimizing the risk of further brain injury associated with cerebral stenosis from moyamoya. Transient ischemic attack and ischemic stroke For children and adults with moyamoya and ischemic stroke, acute treatment is mainly supportive, directed toward minimizing ischemic injury, reducing cerebral edema, and controlling secondary complications such as seizures [68]. Acute treatment measures During hospitalization for acute stroke or surgery, specific management issues should be addressed to minimize ischemic injury, especially in children with moyamoya [5]: Precautions to minimize hyperventilation Hyperventilation occurring with pain, excitement, or crying can lower the carbon dioxide levels in the blood and induce or worsen cerebral ischemia by causing vasoconstriction [5,69]. Strategies to provide a comfortable and calm setting and control pain are recommended. Pain control may help reduce the risk of hyperventilation and also reduce the risk of stroke and the length of hospitalization [70]. Specific methods include appropriate periprocedural sedation, painless wound-handling techniques (eg, Steri-Strip closure, use of paraffin gauze, avoidance of adhesive tapes), and protocolized pain management. Maintaining euvolemia Oral and intravenous fluids should be given to reduce the risk of cerebral ischemia from hypotension and hypovolemia [55,69]. Intravenous hydration with isotonic fluids may be administered at 1.25 to 1.5 times the normal maintenance rate [1,70]. Other experts keep blood pressure slightly elevated in the acute setting [70]. However, cerebral hyperperfusion syndrome may occur with significant elevations in blood pressure; blood pressure treatment may be helpful to prevent this complication. Thrombolysis The safety of intravenous thrombolytic therapy for acute ischemic stroke in moyamoya patients has not been established. Its use may be considered on an individual basis for selected patients with disabling stroke symptoms and no history of https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 14/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate brain hemorrhage after discussing risks and benefits. Because of the risk of hemorrhage in areas of extensive moyamoya collateral vessels, many experts are reluctant to use thrombolytic therapy to treat acute ischemic stroke in patients with moyamoya [71]. Secondary preventive therapy Antiplatelet medications are typically prescribed for patients with ischemic stroke due to moyamoya. Antithrombotic therapy is discussed in greater detail separately. (See 'Management of antithrombotic medications' above.) Patients with moyamoya may have hypertension, and treatment is indicated to reduce the risk of future ischemic and hemorrhagic complications. However, hypotension and hypovolemia should be avoided to minimize the risk of ischemia. Additional details on the general approach to the evaluation and management of acute ischemic stroke is reviewed separately. (See "Ischemic stroke in children: Clinical presentation, evaluation, and diagnosis" and "Initial assessment and management of acute stroke".) Intracranial hemorrhage The treatment of acute intracranial hemorrhage is similar for patients with or without moyamoya. Ventricular drainage and/or hematoma removal may be required for some patients with intracerebral hemorrhage. Vascular repair of ruptured aneurysm may be required for patients presenting with subarachnoid hemorrhage. The acute treatment of forms of intracranial hemorrhage are presented separately. (See "Spontaneous intracerebral hemorrhage: Acute treatment and prognosis" and "Aneurysmal subarachnoid hemorrhage: Treatment and prognosis" and "Subdural hematoma in adults: Management and prognosis".) Other complications Patients with moyamoya may also present with other neurologic symptoms such as seizures and headaches. Other neurologic presentations are uncommon. (See "Moyamoya disease and moyamoya syndrome: Etiology, clinical features, and diagnosis", section on 'Clinical presentations'.) Neuroimaging evaluation should be performed to assess for evidence of associated cerebral ischemia. In some cases, neurologic symptoms such as seizures or movement disorders may be attributed to moyamoya in patients without clinical or radiographic ischemia. The decision to pursue surgery for these symptomatic patients should be individualized, based on severity of symptoms, effectiveness of medical therapy, and patient preferences after clinical and imaging evaluation. (See 'Identify patients with an indication for surgical referral' above and 'Follow-up surveillance' above.) https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 15/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Symptomatic management of these conditions is typically the same for patients with or without moyamoya. (See "Evaluation and management of the first seizure in adults" and "Seizures and epilepsy in children: Initial treatment and monitoring" and "Evaluation of headache in adults" and "Headache in children: Approach to evaluation and general management strategies".) PROGNOSIS The natural history of moyamoya tends to be progressive in children and adults [72-74]. In studies with long-term follow-up of untreated patients, progressive neurologic deficits and poor outcome were reported in 50 to 66 percent [75-77]. Radiographic progression within five years of diagnosis was reported in 36 percent of a cohort of children with moyamoya [78]. The vascular pathology usually worsens with extensive intracranial large artery occlusion and collateral circulation. Patients often suffer cognitive and neurologic decline due to repeated ischemic stroke or hemorrhage [74]. However, the rate and extent of progression varies substantially between populations. Moyamoya may have a more rapid progression and a worse prognosis in younger rather than in older children, as evidenced by a single-center observational study of 204 patients from Korea who had surgical treatment for moyamoya [54]. Ischemic stroke was more frequent at initial presentation in children 6 years old compared with children >6 years old, as were subsequent preoperative infarctions. The median interval between the onset of symptoms and preoperative infarction was three months (range 1 to 14). The rate of favorable clinical outcomes was significantly lower in children less than three years old compared with those who were three to six or older than six years, mainly because of preoperative infarctions. SOCIETY GUIDELINE LINKS Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Stroke in adults" and "Society guideline links: Stroke in children".) SUMMARY AND RECOMMENDATIONS Identify patients with an indication for surgical referral For patients with symptomatic moyamoya as well as those with impaired resting blood flow or hypoperfusion on neuroimaging, we suggest surgical revascularization ( algorithm 1) (Grade 2C). Antiplatelet management with follow-up surveillance imaging is continued for https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 16/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate other patients who are asymptomatic and have preserved cerebral blood flow. (See 'Identify patients with an indication for surgical referral' above.) Antithrombotic therapy Antiplatelets For patients with asymptomatic or symptomatic ischemic-type moyamoya, we suggest long-term aspirin for children (2 to 5 mg/kg daily) and adults (50 to 100 mg daily) rather than no therapy (Grade 2C). Cilostazol may be used as an alternative. (See 'Management of antithrombotic medications' above.) For most patients who present with hemorrhagic-type moyamoya, we avoid antiplatelet therapy acutely and during recovery. We typically start antiplatelet therapy postoperatively for patients with ischemic or hemorrhagic moyamoya who undergo surgical revascularization. Anticoagulation Long-term anticoagulation is generally contraindicated for patients with moyamoya. (See 'Management of antithrombotic medications' above.) Follow-up surveillance Patients with moyamoya who are not referred for surgical revascularization should undergo serial surveillance testing to evaluate for evidence of disease progression ( algorithm 1). (See 'Follow-up surveillance' above.) Clinical examination We monitor patients with periodic clinical examinations to assess for the development of symptoms or neurologic examination findings attributable to vascular stenosis in moyamoya including transient episodes of weakness that may be provoked by crying, laughing, or hyperventilating. (See 'Clinical examination' above.) Neuroimaging We perform surveillance imaging studies for patients with moyamoya because progressive changes in stenosis or impairment of cerebral perfusion may precede clinical symptoms. The timing of imaging studies varies by the severity of baseline and subsequent surveillance imaging findings. (See 'Neuroimaging' above.) Patients who develop symptoms or progression on imaging are typically referred for surgical revascularization. Surgical management Surgery for moyamoya involves one of several techniques using a craniotomy to permit connecting a branch of the external carotid artery to the ischemic hemisphere. (See 'Surgical revascularization' above.) https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 17/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Preoperative evaluation The selection of patients who may benefit from surgical revascularization is guided by a preoperative evaluation that includes clinical examination and imaging testing. (See 'Preoperative evaluation' above.) Techniques Direct revascularization refers to procedures where a branch of the external carotid artery is directly connected to a cortical artery within the ischemic hemisphere. Indirect revascularization refers to procedures where tissue perfused by a branch of the external carotid artery is applied to the surface of the ischemic hemisphere to encourage revascularization with underlying cortical vessels over time. (See 'Surgical techniques' above.) The use of specific revascularization procedures for moyamoya varies by institutional protocol and surgical training and experience. However, indirect revascularization is generally preferred in younger children because of the small size of donor and/or recipient vessels. (See 'Efficacy of surgery' above.) Management of complications of moyamoya For children and adults with moyamoya and acute stroke, acute treatment is mainly supportive, directed toward minimizing brain injury, limiting cerebral edema, and controlling secondary complications such as seizures. Efforts to minimize cerebral ischemic injury include avoiding or controlling hyperventilation, preventing pain or agitation, and avoiding hypovolemia. (See 'Management of complications of moyamoya' above.) Prognosis The natural history of moyamoya tends to be progressive. However, the rate and extent of progression varies substantially between populations. (See 'Prognosis' above.) Use of UpToDate is subject to the Terms of Use. 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Topic 1112 Version 31.0 https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 24/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate GRAPHICS Evaluation and management of moyamoya disease and moyamoya syndrome https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 25/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 26/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Moyamoya is generally regarded as a progressive cerebrovascular entity, but the extent and rate of progression varies among patients. Treatment for patients with impaired blood flow is surgical, but other patients with milder findings may be managed with conservative therapy and surveillance imaging. ICA: internal carotid artery; MCA: middle cerebral artery; MMD: moyamoya disease; MMS: moyamoya syndrome; TIA: transient ischemic attack; MRA: magnetic resonance angiography; CTA: computed tomography angiography; DSA: digital subtraction angiography; TCD: transcranial Doppler; CT: computed tomography; MRI: magnetic resonance imaging; PET: positron emission tomography; SPECT: single photon emission computed tomography. Moyamoya vasculopathy is most frequently bilateral but may be asymmetric or initially unilateral. Vascular changes may also be found infrequently in the posterior circulation (eg, posterior cerebral arteries). MMS may be caused by several underlying conditions. Refer to the UpToDate topic for additional details on associated conditions. Evaluations for clinical or imaging progression may be performed every 12 months for asymptomatic patients. Less frequent evaluations may be appropriate for adult patients who remain stable for at least three years. Refer to the UpToDate topic for additional details. Graphic 139077 Version 1.0 https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 27/28 7/6/23, 12:32 PM Moyamoya disease and moyamoya syndrome: Treatment and prognosis - UpToDate Contributor Disclosures Nijasri Charnnarong Suwanwela, MD No relevant financial relationship(s) with ineligible companies to disclose. Jos Biller, MD, FACP, FAAN, FAHA No relevant financial relationship(s) with ineligible companies to disclose. Douglas R Nordli, Jr, MD No relevant financial relationship(s) with ineligible companies to disclose. Richard P Goddeau, Jr, DO, FAHA No relevant financial relationship(s) with ineligible companies to disclose. Contributor disclosures are reviewed for conflicts of interest by the editorial group. When found, these are addressed by vetting through a multi-level review process, and through requirements for references to be provided to support the content. Appropriately referenced content is required of all authors and must conform to UpToDate standards of evidence. Conflict of interest policy https://www.uptodate.com/contents/moyamoya-disease-and-moyamoya-syndrome-treatment-and-prognosis/print 28/28