Shunji Mugikura

Incidence and risk factors for symptomatic cerebral hyperperfusion after superficial temporal artery-middle cerebral artery anastomosis in patients with moyamoya disease

BACKGROUND Superficial temporal artery-middle cerebral artery anastomosis for moyamoya disease prevents cerebral ischemic attack by improving CBF, whereas recent evidence suggests that the temporary neurologic deterioration because of postoperative cerebral hyperperfusion could occur despite its low-flow revascularization. The present study investigates the incidence and the risk factors for symptomatic hyperperfusion after STA-MCA anastomosis in patients with moyamoya disease. METHODS We prospectively performed N-isopropyl-p-[(123)I]iodoamphetamine single-photon emission computed tomography 1 and 7 days after STA-MCA anastomosis on 80 hemispheres of 58 consecutive patients with moyamoya disease (approximately 2-62 years old, 34.4 years old in average). Mean follow-up period was 22.7 months. Symptomatic cerebral hyperperfusion was defined as the presence of the significant increase in CBF at the site of the anastomosis that is responsible for the apparent neurologic sign. RESULTS Twenty-one patients (22 sides, 27.5%) temporarily had symptomatic cerebral hyperperfusion, who were subjected to intensive blood pressure control. Postoperative magnetic resonance imaging/angiography showed the thick high signal of bypass without ischemic changes in all 21 patients. Adult-onset (P = .013) or hemorrhagic-onset patients (P = .027) had significantly higher risk for symptomatic hyperperfusion. There was no difference in intraoperative temporary occlusion time between each group. No patients had permanent neurologic deficit because of hyperperfusion. CONCLUSION The STA-MCA anastomosis is a safe and effective treatment of moyamoya disease, although adult-onset and/or hemorrhagic-onset patients had higher risk for symptomatic hyperperfusion. We recommend routine CBF measurement especially for these patients because the management of hyperperfusion is contradictory to that of ischemia.

Significance of Focal Cerebral Hyperperfusion as a Cause of Transient Neurologic Deterioration After Extracranial-Intracranial Bypass for Moyamoya Disease: Comparative Study With Non-Moyamoya Patients Using N-Isopropyl-p-[123I]Iodoamphetamine Single-Photon Emission Computed Tomography

BACKGROUND:Superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis prevents cerebral ischemic attack by improving cerebral blood flow in patients with occlusive cerebrovascular disease and hemodynamic compromise. Recent evidence suggests that focal cerebral hyperperfusion is a potential complication of this procedure for moyamoya disease. OBJECTIVE:To clarify the exact differences in the incidence and clinical manifestations of this phenomenon between patients with and without moyamoya disease. METHODS:N-isopropyl-p-[123I]iodoamphetamine single-photon emission computed tomography was performed 1 and 7 days after STA-MCA anastomosis on 121 hemispheres from 86 consecutive patients with moyamoya disease (2-67 years of age; mean, 34.3 years) and on 28 hemispheres from 28 non-moyamoya patients (12-67 years of age; mean, 56.5 years). The incidence of symptomatic hyperperfusion, defined as a significant focal increase in cerebral blood flow at the site of the anastomosis that is responsible for the apparent neurological signs, was compared between groups. RESULTS:Symptomatic cerebral hyperperfusion including mild focal neurological signs was seen in 25 patients with moyamoya disease (26 hemispheres, 21.5%) but in none of the patients without moyamoya disease (P = .0069). Multivariate analysis revealed that moyamoya disease was significantly associated with the development of symptomatic cerebral hyperperfusion (P = .0008). All patients with symptomatic hyperperfusion were relieved by intensive blood pressure control, and no patients suffered from permanent neurological deficit caused by hyperperfusion. CONCLUSION:Symptomatic cerebral hyperperfusion is a potential complication of STA-MCA anastomosis, especially in patients with moyamoya disease. Accurate diagnosis and adequate management of hyperperfusion are recommended, especially in patients with moyamoya disease.

Neural Basis of Temporal Context Memory: A Functional MRI Study

Temporal context information is crucial to understanding human episodic memory. Human lesion and neuroimaging data indicate that prefrontal regions are important for retrieving temporal context memory, although the exact nature of their involvement is still unclear. We employed functional magnetic resonance imaging (fMRI) to elucidate the neural basis of two kinds of temporal context memory: the temporal order of items between lists and within a list. On the day of the fMRI experiment, subjects memorized a list of 30 pictures in the morning and another list of 30 pictures in the afternoon. During the scanning session, the subjects performed three tasks. In a between-lists task, they were asked to judge the temporal order between two items that had been presented in different lists. In a within-list task, they were asked to judge the temporal order between two items that had been presented in a single list. We found bilateral prefrontal activities during these two temporal context memory tasks compared with a simple item-recognition task. Furthermore, in direct comparison between these two tasks, we found differential prefrontal activities. Thus, right prefrontal activity was associated with temporal order judgment of items between lists, whereas left prefrontal activity was related to temporal order judgment of items within a list. These results indicate that retrieval processes of two kinds of temporal context memory are supported by different, but overlapping, sets of cerebral regions. We speculate that this reflects different cognitive processes for retrieving temporal context memory between separate episodes and within a single episode.

Comparison of ipsilateral activation between right and left handers: a functional MR imaging study.

WE used fMRI to compare the ipsilateral activation in the sensorimotor region (SMR) during dominant and non-dominant hand motor tasks between right and left handers. In right handers, the ipsilateral activation was significantly greater during non-dominant (left) hand task than dominant (right) hand task, while in left handers, it showed no significant difference. The ipsilateral activation was most pronounced in the precentral subregion (presumably corresponding to the premotor area) during either hand task in both groups. We conclude that the different patterns of ipsilateral activation might be mainly explained by the hemispheric dominance. The skill of the hand and complexity of tasks may be related to the predominant activation of the premotor area.

Usefulness of contrast-enhanced T1-weighted sampling perfection with application-optimized contrasts by using different flip angle evolutions in detection of small brain metastasis at 3T MR imaging: comparison with magnetization-prepared rapid acquisition of gradient echo imaging.

BACKGROUND AND PURPOSE: Early accurate diagnosis of brain metastases is crucial for a patients prognosis. This study aimed to compare the conspicuity and detectability of small brain metastases between contrast-enhanced 3D fast spin-echo (sampling perfection with application-optimized contrasts by using different flip angle evolutions [SPACE]) and 3D gradient-echo (GE) T1-weighted (magnetization-prepared rapid acquisition of GE [MPRAGE]) images at 3T. MATERIALS AND METHODS: Sixty-nine consecutive patients with suspected brain metastases were evaluated prospectively by using SPACE and MPRAGE on a 3T MR imaging system. After careful evaluation by 2 experienced neuroradiologists, 92 lesions from 16 patients were selected as brain metastases. We compared the shorter diameter, contrast rate (CR), and contrast-to-noise ratio (CNR) of each lesion. Diagnostic ability was compared by using receiver operating characteristic (ROC) analysis. Ten radiologists (5 neuroradiologists and 5 residents) participated in the reading. RESULTS: The mean diameter was significantly larger by using SPACE than MPRAGE (mean, 4.5 ± 3.7 versus 4.3 ± 3.7 mm, P = .0014). The CR and CNR of SPACE (mean, 57.3 ± 47.4%, 3.0 ± 1.9, respectively) were significantly higher than those of MPRAGE (mean, 37.9 ± 41.2%, 2.6 ± 2.2; P < .0001, P = .04). The mean area under the ROC curve was significantly larger with SPACE than with MPRAGE (neuroradiologists, 0.99 versus 0.88, P = .013; residents, 0.99 versus 0.78, P = .0001). CONCLUSIONS: Lesion detectability was significantly higher on SPACE than on MPRAGE, irrespective of the experience of the reader in neuroradiology. SPACE should be a promising diagnostic technique for assessing brain metastases.

Delayed intracerebral hemorrhage after superficial temporal artery–middle cerebral artery anastomosis in a patient with moyamoya disease: possible involvement of cerebral hyperperfusion and increased vascular permeability

BACKGROUND Postoperative intracerebral hemorrhage is a rare complication after surgical revascularization for moyamoya disease, and its mechanism is totally undetermined. CASE DESCRIPTION A 47-year-old woman with moyamoya disease, experiencing crescendo transient ischemic attack on her left hand, underwent STA-MCA anastomosis on the right hemisphere. Postoperative MR imaging 1 day after surgery demonstrated asymptomatic vasogenic edema without ischemic change at the subcortex under the site of the anastomosis that expanded the next day, and STA-MCA bypass was apparently patent with the strong high signal by MR angiography. N-isopropyl-p-[(123)I]iodo-amphetamine single-photon emission CT showed marked increase in the CBF on the hemisphere operated on. Four days after surgery, the patient complained of sudden headache and experienced severe monoparesis in her left hand due to the intracerebral hemorrhage at the corresponding lesion to the prior vasogenic edema. Edema around hematoma was prolonged for as long as a month; while intensive blood pressure control and the use of adrenocorticosteroid gradually relieved her symptoms. The patient completely recovered from her symptoms 2 months later, and she was discharged without neurologic deficit. Her transient ischemic attacks completely disappeared postoperatively. CONCLUSION Early increase in CBF associated with vasogenic edema formation at the site of the anastomosis could be the warning sign for subsequent hemorrhagic complication, and intensive blood pressure control is warranted in such patients. Alternatively, it would be necessary to elucidate the biochemical mechanism of the deleterious cascade during reperfusion in moyamoya disease to avoid this rare complication.

Predominant Involvement of Ipsilateral Anterior and Posterior Circulations in Moyamoya Disease

Background and Purpose— We encountered several patients with childhood onset of moyamoya disease in whom the ipsilateral anterior and posterior circulations were predominantly involved. This study investigated whether this is an angiographic characteristic of this disease. Methods— We evaluated steno-occlusive lesions on angiograms of 85 patients with pediatric onset of moyamoya disease, using two 4-stage angiographic classification scales for the internal carotid artery and posterior cerebral artery systems (ICA and PCA staging, respectively) and determined whether lesions with more advanced ICA and PCA stages were on ipsilateral sides. Results— When positive laterality was defined as the presence of a difference by ≥1 stage between the stages on both sides, lateralities in the ICA stages and in the PCA stages were present in 40 (47%) and 27 patients (32%), respectively. Lesions with more advanced ICA and PCA stages were on the same side, with significant probability (P =0.024, Fisher’s exact test). Lateralities in both ICA and PCA lesions were found in 17 patients. In 14 (82%) of the 17 patients, the more advanced side of ICA lesions was the same as that of PCA lesions, while it was contralateral in 3 patients (18%). Conclusions— In pediatric-onset moyamoya disease, asymmetrical involvement of bilateral ICAs and PCAs was common, and the ipsilateral ICA and PCA tended to be predominantly involved.

Changes in brain activation associated with use of a memory strategy: a functional MRI study

It has been confirmed that some kinds of what are called memory strategies dramatically improve the performance of memory recall. However, there has been no direct research to examine changes in brain activity associated with the use of the method of loci within individuals. In the present study, using fMRI, we compared brain activations before and after instruction in the method of loci during both the encoding and recall phases. The resulting behavioral data showed that the use of the method of loci significantly increased scores for memory recall. The imaging data showed that encoding after instruction in the method of loci, relative to encoding before it, was associated with signal increases in the right inferior frontal gyrus, bilateral middle frontal gyrus, left fusiform gyrus, and bilateral lingual gyrus/posterior cingulate gyrus. Comparison of recall after instruction in the method of loci with that before it showed significant activation in the left parahippocampal gyrus/retrosplenial cortex/cingulate gyrus/lingual gyrus, left precuneus, left fusiform gyrus, and right lingual gyrus/cingulate gyrus. The present study demonstrated the changes in brain activation pattern associated with the use of the method of loci; left fusiform and lingual activity was associated with both the encoding and recall phases, bilateral prefrontal activity with the encoding phase, and activity of the posterior part of the parahippocampal gyrus, retrosplenial cortex, and precuneus with the recall phase. These findings suggest that brain networks mediating episodic encoding and retrieval vary with how individuals encode the same stimuli.

The Leptomeningeal "Ivy Sign" on Fluid-Attenuated Inversion Recovery MR Imaging in Moyamoya Disease: A Sign of Decreased Cerebral Vascular Reserve?

BACKGROUND AND PURPOSE: Moyamoya disease is an idiopathic occlusive cerebrovascular disorder with abnormal microvascular proliferation. We investigated the clinical utility of leptomeningeal high signal intensity (ivy sign) sometimes seen on fluid-attenuated inversion recovery images in Moyamoya disease. MATERIALS AND METHODS: We examined the relationship between the degree of the ivy sign and the severity of the ischemic symptoms in 96 hemispheres of 48 patients with Moyamoya disease. We classified each cerebral hemisphere into 4 regions from anterior to posterior. In 192 regions of 24 patients, we examined the relationship between the degree of the ivy sign and findings of single-photon emission CT, including the resting cerebral blood flow (CBF) and cerebral vascular reserve (CVR). RESULTS: The degree of the ivy sign showed a significant positive relationship with the severity of the ischemic symptoms (P < .001). Of the 4 regions, the ivy sign was most frequently and prominently seen in the anterior part of the middle cerebral artery region. The degree of the ivy sign showed a negative relationship with the resting CBF (P < .0034) and a more prominent negative relationship with the CVR (P < .001). CONCLUSIONS: The leptomeningeal ivy sign indicates decreased CVR in Moyamoya disease.

Efficacy of prophylactic blood pressure lowering according to a standardized postoperative management protocol to prevent symptomatic cerebral hyperperfusion after direct revascularization surgery for moyamoya disease.

Background: Cerebral hyperperfusion is a potential complication of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis for moyamoya disease, but the optimal postoperative management has not been determined. Aggressive blood pressure lowering is controversial because of the risk of ischemic complications. Objective: To establish the optimal postoperative management protocol to prevent symptomatic cerebral hyperperfusion in moyamoya disease. Methods: N-isopropyl-p-[123I]-iodoamphetamine single-photon emission computed tomography was performed 1 and 7 days after STA-MCA anastomosis on 152 hemispheres from 108 consecutive patients with moyamoya disease (2–69, mean 33.3 years). Between 2004 and 2007 (period 1), 65 patients were maintained under normotensive conditions after 93 operations, and only patients with cerebral hyperperfusion underwent blood pressure lowering. Between 2008 and 2010 (period 2), all 43 patients were prospectively subjected to intensive blood pressure lowering (<130 mm Hg of systolic blood pressure) immediately after 59 operations. Then the incidence of symptomatic cerebral hyperperfusion was compared between the two groups. Results: Systolic blood pressure the day after surgery was significantly lower in period 2 (mean, 120.9 mm Hg) than in period 1 (133.9 mm Hg) (p < 0.0001). Symptomatic cerebral hyperperfusion was seen in 22 patients during period 1 (23 hemispheres, 24.7%), but only in 4 patients during period 2 (6.7%, p = 0.0047). Multivariate analysis revealed that prophylactic blood pressure lowering was significantly associated with the prevention of symptomatic cerebral hyperperfusion (p = 0.015). Symptomatic cerebral hyperperfusion was relieved in all patients without developing a permanent neurological deficit due to cerebral hyperperfusion. Conclusion: Prophylactic blood pressure lowering prevents symptomatic cerebral hyperperfusion after STA-MCA anastomosis in patients with moyamoya disease. Accurate diagnosis of cerebral hyperperfusion and blood pressure lowering, and considering the severity of hemodynamic compromise in the contralateral and/or remote areas are essential for postoperative management of moyamoya disease.