Steal phenomenon through the anterior communicating artery in Moyamoya disease

Contralateral improvement of cerebrovascular reactivity and TIA frequency after unilateral revascularization surgery in moyamoya vasculopathy

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Contralateral cerebrovascular reactivity may improve after unilateral surgery in moyamoya.

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TIA frequency from the contralateral hemisphere can decrease after unilateral moyamoya surgery.

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These findings support staged rather than direct bilateral surgery in moyamoya.

Objective

Moyamoya vasculopathy is a rare, often bilateral disease characterized by progressive stenosis and occlusion of the distal internal carotid artery, leading to a progressive deterioration of cerebrovascular reactivity (CVR) and increased risk of transient ischemic attacks (TIAs), infarction and hemorrhage. Surgical revascularization is a widely accepted symptomatic treatment, often performed bilaterally in one or two stages. To possibly further optimize treatment strategy, we investigated the effect of unilateral revascularization surgery on the CVR of, and TIA frequency originating from, the contralateral hemisphere.

Methods

From our database of 143 moyamoya vasculopathy patients we selected those with bilateral disease, who underwent hemodynamic imaging ([15O]H2O positron emission tomography (PET)-CT with acetazolamide challenge) before and 14 months (median) after unilateral revascularization. We evaluated CVR in three regions per hemisphere, and averaged these per hemisphere for statistical comparison. Conservatively treated patients were showed as a comparison group. To examine TIA frequency, we selected patients who presented with TIAs that (also) originated from the contralateral – not to be operated – hemisphere. We scored changes in CVR and TIA frequency of the ipsilateral and contralateral hemisphere over time.

Results

Seven surgical and seven conservative patients were included for CVR comparison. Of the 20 scored contralateral regions in the surgical group, 15 showed improved CVR after unilateral revascularization, while 5 remained stable. The averaged scores improved significantly for both hemispheres. In conservatively treated patients, however, only 3 of the 20 scored regions improved in the least-affected (contralateral) hemispheres, and 9 deteriorated. From the 6 patients with contralateral TIAs at presentation, 4 had a decreased TIA frequency originating from the contralateral hemisphere after unilateral surgery, while 2 patients remained stable.

Conclusion

Both CVR and TIA frequency in the contralateral hemisphere can improve after unilateral revascularization surgery in bilateral MMV.

Cerebrovascular collaterals correlate with disease severity in adult North American patients with Moyamoya disease

BACKGROUND AND PURPOSE

Cerebrovascular collaterals have been increasingly recognized as predictive of clinical outcomes in Moyamoya disease in Asia. The aim of this study was to characterize collaterals in North American adult patients with Moyamoya disease and to assess whether similar correlations are valid.

MATERIALS AND METHODS

Patients with Moyamoya disease (n = 39; mean age, 43.5 ±10.6 years) and age- and sex-matched control subjects (n = 33; mean age, 44.3 ± 12.0 years) were graded via angiography. Clinical symptoms of stroke or hemorrhage were graded separately by imaging. Correlations between collateralization and disease severity, measured by the modified Suzuki score, were evaluated in patients with Moyamoya disease by fitting a regression model with clustered ordinal multinomial responses.

RESULTS

The presence of leptomeningeal collaterals (P = .008), dilation of the anterior choroidal artery (P = .01), and the posterior communicating artery/ICA ratio (P = .004) all correlated significantly with disease severity. The presence of infarct or hemorrhage and posterior steno-occlusive disease did not correlate significantly with the modified Suzuki score (P = .1). Anterior choroidal artery changes were not specific for hemorrhage. Patients with Moyamoya disease were statistically more likely than controls to have higher posterior communicating artery/ICA ratios and a greater incidence of leptomeningeal collaterals.

CONCLUSIONS

As with Moyamoya disease in Asian patients, the presence of cerebrovascular collaterals correlated with the modified Suzuki score for disease severity in North American patients with Moyamoya disease. However, anterior choroidal artery changes, which correlated with increased rates of hemorrhage in Asian studies, were not specific to hemorrhage in North Americans.

Outpatient (Same-day care) Neuroangiography and Neurointervention

Purpose

There have been few reports regarding same-day discharge following uncomplicated procedures such as cerebral angiography and neurointervention. We present same-day experience with cerebral angiography and neurointervention during the past three years.

Materials and Methods

Four hundred and fifty-three patients underwent cerebral angiography or neurointervention at Asan Medical Center between January 2009 and December 2011. Of these patients, 249 (55%) underwent diagnostic catheter cerebral angiography and 204 patients (45%) underwent neurointerventional procedures as same-day procedures. We analyzed any complications, the modified patient-care process, the yearly trend in patient increases, disease categories, and the additional duration of admission for these procedures.

Results

The number of overall patients increased by an average of 51% annually. The disease categories included aneurysm (51%), atherosclerosis (11%) and arteriovenous malformation (10%), etc. for which the patient underwent angiography, and aneurysm (42%), venous malformation (28%), and arteriovenous malformation (17%), etc. for which patients underwent neurointervention. Same-day care patients were admitted to the intermediary care unit in the angiosuite. Neurointervention patients were sent to the neurology intensive unit after the procedure. The same-day care patients stayed in angiosuite for six hours following the transfemoral procedure. The mean admission duration for neurointervention was 2.4 days. There were no reported complications for the same-day care procedures.

Conclusion

Our study revealed an increasing tendency toward same-day care for patients who require angiography and neurointervention. Further studies will be required to better define the cost-minimization effects of outpatient practice as well as the patient perception of this fast-tracking method. We propose that outpatient angiography and neurointervention will undoubtedly continue to increase over the next decade.

Ivy signs on FLAIR images before and after STA-MCA anastomosis in patients with Moyamoya disease

BACKGROUND

Leptomeningeal high signal intensity (ivy sign) on fluid-attenuated inversion-recovery (FLAIR) MR imaging is one of the features of Moyamoya disease. However, the correlation between ivy sign and cerebral perfusion status has not been fully evaluated.

PURPOSE

To characterize ivy sign on FLAIR images in Moyamoya disease and compare this finding with hemodynamic alterations on perfusion single-photon emission CT (SPECT) obtained before and after bypass surgery.

MATERIAL AND METHODS

Sixteen patients with angiographically confirmed Moyamoya disease who underwent superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis were included in the study. The presence of ivy sign on FLAIR images was classified as 'negative', 'minimal' and 'positive'. We evaluated the relationship between ivy sign and findings of SPECT, including cerebral vascular reserve (CVR) before and after surgery.

RESULTS

Minimal or positive ivy sign was seen in 13 (81%) of 16 patients, and 21 (66%) of 32 hemispheres. CVR in the areas with positive or minimal ivy sign was lower than that in the areas with negative ivy sign. After STA-MCA anastomosis, ivy sign disappeared or decreased in all 21 hemispheres demonstrating ivy sign. SPECT demonstrated apparent hemodynamic improvement in areas demonstrating disappearance or decrease of ivy sign.

CONCLUSION

Ivy sign on FLAIR image is seen in areas with decreased cerebral perfusion. The sign is useful for non-invasive assessment of cerebral hemodynamic status before and after surgery.

Intraoperative blood flow analysis of direct revascularization procedures in patients with moyamoya disease

Moyamoya disease is characterized by the progressive stenosis and often occlusion of the terminal internal carotid arteries, which leads to ischemic and hemorrhagic injuries. The etiology is unknown and surgical revascularization remains the mainstay treatment. We analyzed various hemodynamic factors in 292 patients with moyamoya disease, representing 496 revascularization procedures, including vessel dimension and intraoperative blood flow, using a perivascular ultrasonic flowprobe. Mean middle cerebral artery (MCA) flow rate was 4.4 ± 0.26 mL/min. After superficial temporal artery (STA)-MCA bypass surgery, flows at the microanastomosis were increased fivefold to a mean of 22.2 ± 0.8 mL/min. The MCA flows were significantly lower in the pediatric (16.2 ± 1.3 mL/min) compared with the adult (23.9 ± 1.0 mL/min; P<0.0001) population. Increased local flow rates were associated with clinical improvement. Permanent postoperative complications were low (<5%), but very high postanastomosis MCA flow was associated with postoperative stroke (31.2 ± 6.8 mL/min; P=0.045), hemorrhage (32.1 ± 10.2 mL/min; P=0.045), and transient neurologic deficits (28.6 ± 5.6 mL/min; P=0.047) compared with controls. Other flow and vessel dimension data are presented to elucidate the hemodynamic changes related to the vasculopathy and subsequent to surgical intervention.