Improvement in cognitive decline after indirect bypass surgery in adult moyamoya disease: implication of 15O-gas positron emission tomography

Iodine-123-Iomazenil Single-Photon Emission Computed Tomography Revealed Recovery of Neuronal Viability in Association With Improvement of Cognitive Dysfunction After Revascularization in Moyamoya Disease

BACKGROUND AND OBJECTIVES

Recent studies indicate that 123I-iomazenil (123I-IMZ) single-photon emission computed tomography (SPECT) can demonstrate neuronal viability. Although cognitive dysfunction has been recognized as an important issue in adult patients with moyamoya disease (MMD), no standard neuroradiological methods to define such conditions have been established. We examined the relationship between cognitive function and 123I-IMZ SPECT before and after revascularization in patients with MMD.

METHODS

The study participants were 16 adult patients with MMD whose cerebrovascular reactivities were decreased only on the surgical sides of combined revascularization. Cognitive function was examined using the Mini-Mental State Examination (MMSE; cutoff: 27) and the Frontal Assessment Battery (FAB; cutoff: 16) before and at 3 to 6 months after surgery. 123I-iodoamphetamine (123I-IMP) SPECT with acetazolamide challenge and 123I-IMZ SPECT were performed concurrently while evaluating cognitive function. The radioreactivities of 123I-IMZ SPECT in regions with decreased cerebrovascular reactivities on 123I-IMP SPECT were investigated using affected-to-contralateral side asymmetry ratio (IMZ-ACR).

RESULTS

Twelve patients showed normal cognitive function (MMSE: 29.8 ± 0.4, FAB: 18 ± 0) before surgery. No evident laterality of 123I-IMZ uptake was seen (IMZ-ACR: 0.98 ± 0.04). Neither cognitive function nor 123I-IMZ SPECT worsened after surgery (MMSE: 29.8 ± 0.3, FAB: 18 ± 0, IMZ-ACR: 1.00 ± 0.04). By contrast, 4 patients presented cognitive dysfunction (MMSE: 24.3 ± 3.9, FAB: 14.8 ± 2.7) before revascularization. Preoperative imaging of these patients showed decreased 123I-IMZ uptake, and their IMZ-ACRs (0.83 ± 0.08) were significantly lower than those of the normal group. After revascularization, cognitive functions and 123I-IMZ uptake tended to ameliorate (MMSE: 27.5 ± 1.7, FAB: 16.3 ± 2.2, IMZ-ACR: 0.94 ± 0.09).

CONCLUSION

Preoperative cognitive function was associated with 123I-IMZ uptake in adult patients with MMD. After revascularization, cognitive function could be recovered in the viable areas of the brain, which is consistent with 123I-IMZ SPECT findings.

Neuropsychiatric Symptoms of Moyamoya Disease: Considerations for the Clinician

Neurocognitive impairment in moyamoya disease is common, under recognized, and potentially devastating. The purpose of this paper is to provide an updated overview on this topic for the practicing clinician. We searched PubMed for keywords including cognitive impairment, neurocognitive dysfunction, and neuropsychological recovery in moyamoya disease. We summarized the literature to provide a concise review of the treatment and management of neuropsychiatric symptoms associated with moyamoya disease. Neuropsychiatric sequelae have conventionally been attributed to chronic cerebral hypoperfusion and/or stroke. Cognitive dysfunction in adults with moyamoya disease is most commonly in the form of impaired executive function, whereas intelligence is the predominant impairment in children with moyamoya disease. Pharmacotherapy for treatment of the neuropsychiatric symptoms associated with moyamoya disease is appropriate and can improve quality of life; however, careful consideration is needed to avoid adverse cerebrovascular events. It remains unclear as to whether surgical revascularization improves or stabilizes cognitive performance and outcomes. Additional prospective studies are warranted to better understand the long-term impact of revascularization on cognitive functioning in moyamoya disease.

Future of Endovascular and Surgical Treatments of Atherosclerotic Intracranial Stenosis

Intracranial atherosclerotic disease and resultant intracranial stenosis is a global leading cause of stroke, and poses an ongoing treatment challenge. Among patients with intracranial stenosis, those with hemodynamic compromise are at high risk for recurrent stroke despite medical therapy and risk factor modification. Revascularization of the hypoperfused territory is the most plausible treatment strategy for these high-risk patients, yet surgical and endovascular therapies have not yet shown to be sufficiently safe and effective in randomized controlled trials. Advances in diagnostic and therapeutic technologies have led to a resurgence of interest in surgical and endovascular treatment strategies, with a growing body of evidence to support their further evaluation in the treatment of select patient populations. This review outlines the current and emerging endovascular and surgical treatments and highlights promising future management strategies.

Long-term prognosis of 452 moyamoya disease patients with and without revascularization under perfusion-based indications

OBJECTIVES

To evaluate the long-term outcomes of patients treated under our perfusion-based strategy and assess whether conservative treatment without surgical treatment under our strategy is acceptable.

MATERIALS AND METHODS

A total of 315 adult and 137 pediatric MMD patients (follow-up period ≥ 3 years from 2001 to 2020) were included. Follow-up events in each patient group (pediatric or adult, surgically treated or conservatively treated) were evaluated and compared to each other using a log-rank test. Risk factors for stroke and nonstroke events were also investigated using a multivariate Cox proportional hazard model.

RESULTS

In adult-onset patients, the stroke event rates (person-year %) were not different between surgically treated patients and conservatively treated patients (2.00 % vs. 1.59 %, p = 0.558); however, conservative patients showed a higher stroke rate than surgically treated hemispheres (0.34 %; p = 0.025) and hemorrhagic stroke was the major type (18/26, 69.2 %). Hemorrhagic onset was associated with increased risk of stroke in adults (hazard ratio (95 % confidence interval) = 2.43 (1.10-5.36)). In pediatric-onset patients, no conservatively treated patients experienced stroke; however, nonstroke events occurred more frequently than in surgically treated hemispheres (4.86 % vs. 1.71 %, p = 0.020 for transient ischemic attack; and 7.91 % vs. 1.31 %, p < 0.001 for asymptomatic progression on magnetic resonance angiography).

CONCLUSIONS

In adult patients, conservatively treated patients experienced stroke more frequently, especially hemorrhagic stroke. An additive strategy to prevent stroke in hemorrhagic-onset patients without hemodynamic disturbance seems to be needed. Pediatric patients with mild hemodynamic disturbance can be safely observed without initial surgical intervention, but close follow-up for disease progression is necessary.

Encephalo-Duro-Pericranio-Synangiosis for the Treatment of Moyamoya Disease with Posterior Cerebral Artery Lesions

OBJECTIVE

We describe our experience performing encephalo-duro-pericranio synangiosis for the parieto-occipital region (EDPS-p) as a treatment for moyamoya disease (MMD) with hemodynamic disturbances caused by lesions of the posterior cerebral artery.

METHODS

From 2004 to 2020, 60 hemispheres of 50 patients with MMD (38/50 females, age 1-55 years) underwent EDPS-p as a treatment for hemodynamic disturbances in the parieto-occipital region. A skin incision was made on the parieto-occipital area to avoid the major skin arteries, and the pedicle flap was created by attaching the pericranium to the dura mater under the craniotomy with multiple small incisions. The surgical outcome was assessed on the basis of the following points: perioperative complications, postoperative improvement of clinical symptoms, subsequent novel ischemic events, qualitative assessment of the development of collateral vessels by magnetic resonance arteriography, quantitative assessment of postoperative perfusion improvement based on the mean transit time, and cerebral blood volume on dynamic susceptibility contrast imaging.

RESULTS

Perioperative infarction occurred in 7/60 hemispheres (11.7%). The transient ischemic symptoms observed preoperatively disappeared in 39/41 hemispheres (95.1%) during the follow-up period (12-187 months), and none of the patients experienced novel ischemic events. Collateral vessels supplied from the occipital arteries, middle meningeal arteries, and posterior auricular arteries developed postoperatively in 56/60 hemispheres (93.3%). Postoperative mean transit time and cerebral blood volume showed significant improvement in the occipital, parietal, and temporal areas (P < 0.001), as well as the frontal area (P = 0.01).

CONCLUSIONS

EDPS-p seems to be an effective surgical treatment for patients with MMD who suffer hemodynamic disturbances caused by posterior cerebral artery lesions.

The profile of cognitive impairment and hemodynamic compromise in moyamoya: a single-center prospective cohort study

OBJECTIVE

Patients with moyamoya vasculopathy often experience cognitive impairments. In this prospective single-center study, the authors investigated the profile of neurocognitive impairment and its relation with the severity of ischemic brain lesions and hemodynamic compromise.

METHODS

Patients treated in a Dutch tertiary referral center were prospectively included. All patients underwent standardized neuropsychological evaluation, MRI, digital subtraction angiography, and [15O]H2O-PET (to measure cerebrovascular reactivity [CVR]). The authors determined z-scores for 7 cognitive domains and the proportion of patients with cognitive impairment (z-score < -1.5 SD in at least one domain). The authors explored associations between patient characteristics, imaging and CVR findings, and cognitive scores per domain by using multivariable linear regression and Bayesian regression analysis.

RESULTS

A total of 40 patients (22 children; 75% females) were included. The median age for children was 9 years (range 1-16 years); for adults it was 39 years (range 19-53 years). Thirty patients (75%) had an infarction, and 31 patients (78%) had impaired CVR (steal phenomenon). Six of 7 cognitive domains scored below the population norm. Twenty-nine patients (73%) had cognitive impairment. Adults performed better than children in the cognitive domain visuospatial functioning (p = 0.033, Bayes factor = 4.0), and children performed better in processing speed (p = 0.041, Bayes factor = 3.5). The authors did not find an association between infarction, white matter disease, or CVR and cognitive domains.

CONCLUSIONS

In this Western cohort, cognitive functioning in patients with moyamoya vasculopathy was below the population norm, and 73% had cognitive impairment in at least one domain. The cognitive profile differed between adults and children. The authors could not find an association with imaging findings.

Clinical Outcome, Cognition, and Cerebrovascular Reactivity after Surgical Treatment for Moyamoya Vasculopathy: A Dutch Prospective, Single-Center Cohort Study

Background: It remains unclear whether revascularization of moyamoya vasculopathy (MMV) has a positive effect on cognitive function. In this prospective, single-center study, we investigated the effect of revascularization on cognitive function in patients with MMV. We report clinical and radiological outcome parameters and the associations between clinical determinants and change in neurocognitive functioning. Methods: We consecutively included all MMV patients at a Dutch tertiary referral hospital who underwent pre- and postoperative standardized neuropsychological evaluation, [15O]H2O-PET (including cerebrovascular reactivity (CVR)), MRI, cerebral angiography, and completed standardized questionnaires on clinical outcome and quality of life (QOL). To explore the association between patient characteristics, imaging findings, and change in the z-scores of the cognitive domains, we used multivariable linear- and Bayesian regression analysis. Results: We included 40 patients of whom 35 (27 females, 21 children) were treated surgically. One patient died after surgery, and two withdrew from the study. TIA- and headache frequency and modified Rankin scale (mRS) improved (resp. p = 0.001, 0.019, 0.039). Eleven patients (seven children) developed a new infarct during follow-up (31%), five of which were symptomatic. CVR-scores improved significantly (p < 0.0005). The language domain improved (p = 0.029); other domains remained stable. In adults, there was an improvement in QOL. We could not find an association between change in imaging and cognitive scores. Conclusion: In this cohort of Western MMV patients, TIA frequency, headache, CVR, and mRS improved significantly after revascularization. The language domain significantly improved, while others remained stable. We could not find an association between changes in CVR and cognitive scores.

Progress in the correlation of postoperative cognitive dysfunction and Alzheimer's disease and the potential therapeutic drug exploration

Postoperative cognitive dysfunction (POCD) is a decrease in mental capacity that can occur days to weeks after a medical procedure and may become permanent and rarely lasts for a longer period of time. With the continuous development of research, various viewpoints in academic circles have undergone subtle changes, and the role of anesthesia depth and anesthesia type seems to be gradually weakened; Alzheimer's disease (AD) is a latent and progressive neurodegenerative disease in the elderly. The protein hypothesis and the synaptic hypothesis are well-known reasons. These changes will also lead to the occurrence of an inflammatory cascade. The exact etiology and pathogenesis need to be studied. The reasonable biological mechanism affecting brain protein deposition, neuroinflammation, and acetylcholine-like effect has a certain relationship between AD and POCD. Whereas there is still further uncertainty about the mechanism and treatment, and it is elusive whether POCD is a link in the continuous progress of AD or a separate entity, which has doubts about the diagnosis and treatment of the disease. Therefore, this review is based on the current common clinical characteristics of AD and POCD, and pathophysiological research, to search for their common points and explore the direction and new strategies for future treatment.

Delayed development of cerebral atrophy after cerebral hyperperfusion following arterial bypass for adult patients with ischemic moyamoya disease: supplementary analysis of a 5-year prospective cohort

BACKGROUND

Adult patients with moyamoya disease (MMD) occasionally exhibit cerebral hyperperfusion after arterial bypass surgery, leading to persistent cognitive decline. The present supplementary analysis of a prospective 5-year cohort study aimed to determine whether cerebral hyperperfusion after arterial bypass surgery for adult patients with misery perfusion due to ischemic MMD causes cerebral atrophy, and whether the development of cerebral atrophy is related to persistent cognitive decline.

METHODS

In total, 31 patients who underwent arterial bypass surgery also underwent fluid-attenuated inversion recovery (FLAIR) magnetic resonance imaging (MRI) and neuropsychological testing before surgery and at the end of a 5-year follow-up. The development of cerebral hyperperfusion and hyperperfusion syndrome after surgery was defined based on brain perfusion single-photon emission computed tomography (SPECT) findings and clinical symptoms. Univariate and multivariate logistic regression analyses of factors related to the development of cerebral atrophy on FLAIR MRI or cognitive decline on neuropsychological testing at the end of the 5-year follow-up were performed.

RESULTS

Eleven patients (35%) developed cerebral atrophy in the frontal lobe where the superficial temporal artery was anastomosed. Cerebral hyperperfusion on brain perfusion SPECT (odds ratio [OR], 50.6; p = 0.0008) or cerebral hyperperfusion syndrome (OR, 41.8; p = 0.0026) was independently associated with the development of cerebral atrophy, and cerebral atrophy development was significantly associated with cognitive decline (OR, 47.7; p = 0.0010).

CONCLUSIONS

Cerebral hyperperfusion after arterial bypass surgery for adult patients with misery perfusion due to ischemic MMD can cause cerebral atrophy related to persistent cognitive decline.

A Novel Proposal for an Index for Regional Cerebral Perfusion Pressure – A Theoretical Approach Using Fluid Dynamics

Cerebral blood flow (CBF) / cerebral blood volume (CBV) ratio derived by [¹⁵O] H₂O/ CO₂ and CO positron emission tomography (PET) examination has been used as an index for cerebral perfusion pressure (CPP). CBF/CBV was demonstrated to be related mean arterial pressure (MAP) in baboons. However, this formula has not been confirmed to be proportionate to CPP. We have developed a new index for CPP using the Poiseuille equation based on a simple model. Our model suggests that CBF/CBV² is proportionate to CPP and that it is mathematically a more accurate index than CBF/CBV. This new index needs experimental validation in the future.

De Novo Cerebral Microbleeds and Cognitive Decline in Cerebral Hyperperfusion After Direct Revascularization for Adult Moyamoya Disease

OBJECTIVES

Adult patients with moyamoya disease (MMD) occasionally develop cognitive decline due to cerebral hyperperfusion following direct revascularization surgery. However, how the hyperperfusion phenomenon contributes to declines in cognitive function remains unclear. The present supplementary analysis of a prospective study aimed to determine whether cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion leads to development of de novo cerebral microbleeds (CMBs) and whether postoperative cognitive decline is related to these CMBs.

MATERIALS AND METHODS

In total, 32 patients who underwent direct revascularization surgery also underwent T2*-weighted magnetic resonance imaging (T2*WI) and neuropsychological testing before and 2 months after surgery. Development of cerebral hyperperfusion and hyperperfusion syndrome following surgery was defined based on brain perfusion single-photon emission computed tomography (SPECT) findings and clinical symptoms.

RESULTS

Cerebral hyperperfusion on brain perfusion SPECT (95% confidence interval [CI], 1.1-10.8; p = 0.0175) or cerebral hyperperfusion syndrome (95%CI, 1.3-15.3; p = 0.0029) was significantly associated with postoperatively increased CMBs on T2*WI. Postoperatively increased CMBs were significantly associated with postoperative cognitive decline (95%CI, 1.8-20.4, p = 0.0041). For patients with cerebral hyperperfusion on brain perfusion SPECT, the incidence of postoperative cognitive decline was significantly greater in patients with than in those without postoperatively increased CMBs (p = 0.0294).

CONCLUSIONS

Cerebral hyperperfusion following direct revascularization surgery for adult MMD with ischemic presentation and misery perfusion contributes to the development of de novo CMBs and postoperative cognitive decline is related to these CMBs.

Imaging Pattern and the Mechanisms of Postoperative Infarction After Indirect Revascularization in Patients with Moyamoya Disease

OBJECTIVE

To develop preventive strategies against postoperative infarction after indirect revascularization surgery in patients with moyamoya disease (MMD), we evaluated clinical information, with a specific focus on the imaging pattern of postoperative infarction.

METHODS

We retrospectively evaluated 421 surgical procedures performed in 354 (262 pediatric and 159 adult) patients with MMD from April 1991 to March 2021 at our institute. In addition to clinical information, raw images of postoperative infarction were collected and categorized into subtypes by the location of the infarction.

RESULTS

Symptomatic and asymptomatic postoperative infarction occurred in 47 and 12 patients (11.1% and 2.6%), respectively, and more than half (51.7%) of these cases of postoperative infarction occurred immediately or the day after the surgery. Cortical infarction around the craniotomy site was the most frequent pattern observed (50/59, 84.8%), and some of these cases seemed to occur under local compression from epidural or subdural hematomas (15/50, 30.0%). Ipsilateral white matter infarctions located in the watershed area (9/59, 15.3%) and contralateral infarctions (3/59, 5.1%) were also observed. Four patients (1.0%) showed sudden occlusions of ipsilateral or contralateral large intracranial arteries immediately after surgery. Postoperative infarction caused permanent neurologic deficits in 7 patients (1.7%), and all included the cortex outside the craniotomy site.

CONCLUSIONS

Local cortical irritation, hemodynamic fluctuation, and thromboembolic events were suggested as possible mechanisms of postoperative infarction after indirect revascularization in patients with MMD. Minimizing cortical irritation, maintaining adequate cerebral blood flow, and perioperative antiplatelet agents might decrease the incidence of postoperative infarction.

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.

Clinical Management of Moyamoya Patients

Moyamoya angiopathy (MMA) is a peculiar cerebrovascular condition characterized by progressive steno-occlusion of the terminal part of the internal carotid arteries (ICAs) and their proximal branches, associated with the development of a network of fragile collateral vessels at the base of the brain. The diagnosis is essentially made by radiological angiographic techniques. MMA is often idiopathic (moyamoya disease-MMD); conversely, it can be associated with acquired or hereditary conditions (moyamoya Syndrome-MMS); however, the pathophysiology underlying either MMD or MMS has not been fully elucidated to date, and this poor knowledge reflects uncertainties and heterogeneity in patient management. MMD and MMS also have similar clinical expressions, including, above all, ischemic and hemorrhagic strokes, then headaches, seizures, cognitive impairment, and movement disorders. The available treatment strategies are currently shared between idiopathic MMD and MMS, including pharmacological and surgical stroke prevention treatments and symptomatic drugs. No pharmacological treatment able to reverse the progressive disappearance of the ICAs has been found to date in both idiopathic and syndromic cases. Antithrombotic agents are usually prescribed in ischemic MMA, although the coexisting hemorrhagic risk should be considered. Surgical revascularization techniques, which are currently the best available treatment in symptomatic MMA, are associated with good long-term outcomes and reduced ischemic and hemorrhagic risks. Given the lack of dedicated randomized clinical trials, current treatment is mainly based on observational studies and physicians’ and surgeons’ expertise.