Hiroyasu Kamiyama

Surgical Therapy for Adult Moyamoya Disease Can Surgical Revascularization Prevent the Recurrence of Intracerebral Hemorrhage

BACKGROUND AND PURPOSE It is well recognized that revascularization surgery using direct and/or indirect bypass provides effective surgical management for pediatric moyamoya disease. However, surgical treatment of the adult hemorrhagic type remains controversial. In this study, the effect of surgery for adult moyamoya disease was investigated. METHODS We analyzed 35 patients with adult moyamoya disease (patient age, over 20 years), 24 patients with initial onset of intracerebral hemorrhage, and 11 patients with initial onset of cerebral ischemia who underwent both direct bypass surgery of the superficial temporal artery to the middle cerebral artery anastomosis and indirect revascularization of encephalo-duro-arteriomyo-synangiosis. RESULTS Of 24 patients with hemorrhagic-type disease, 3 showed rebleeding: of 11 patients with the ischemic type, 2 showed intracerebral hemorrhage after surgery. Overall, 5 of 35 patients (14.3%) had hemorrhage after revascularization surgery (mean follow-up period, 6.4 years). Postoperative angiography revealed that direct anastomosis is effective whereas indirect revascularization is not always effective for adult moyamoya disease. Moyamoya vessels, which are supposed to be responsible for hemorrhage, decreased in 25% of patients. CONCLUSIONS Revascularization surgery cannot always prevent rebleeding. However, a decrease in moyamoya vessels was induced by surgery, which may reduce the risk of hemorrhage more effectively than conservative treatment. In cases of adult moyamoya disease, direct bypass is particularly important, since the indirect revascularization is not as useful in adult cases as in pediatric cases.

Clinicopathological Study of Intracranial Fusiform and Dolichoectatic Aneurysms Insight on the Mechanism of Growth

BACKGROUND AND PURPOSE Intracranial fusiform aneurysms can be divided into 2 clinically different subtypes: acute dissecting aneurysms and chronic fusiform or dolichoectatic aneurysms. Of these 2, the natural history and growth mechanism of chronic fusiform aneurysms remains unknown. METHODS A consecutive series of 16 patients with chronic fusiform aneurysms was studied retrospectively to clarify patient clinical and neuroradiological features. Aneurysm tissues were obtained from 8 cases and were examined to identify histological features that could correspond to the radiological findings. RESULTS Four histological features were found: (1) fragmentation of internal elastic lamina (IEL), (2) neoangiogenesis within the thickened intima, (3) intramural hemorrhage (IMH) and thrombus formation, and (4) repetitive intramural hemorrhages from the newly formed vessels within thrombus. IEL fragmentation was found in all cases, which suggests that this change may be one of the earliest processes of aneurysm formation. MRI or CT detected IMH, and marked contrast enhancement of the inside of the aneurysm wall (CEI) on MRI corresponded well with intimal thickening. Eight of 9 symptomatic cases but none of 7 asymptomatic cases presented with both radiological features. CONCLUSIONS Data suggest that chronic fusiform aneurysms are progressive lesions that start with IEL fragmentation. Formation of IMH seems to be a critical event necessary for lesions to become symptomatic and progress, and this can be monitored on MRI. Knowledge of this possible mechanism of progression and corresponding MRI characteristics could help determine timing of surgical intervention.

Acetazolamide Test in Detecting Reduced Cerebral Perfusion Reserve and Predicting Long-Term Prognosis in Patients with Internal Carotid Artery Occlusion

In a series of 32 patients with internal carotid artery occlusion, regional cerebral blood flow (rCBF) and regional cerebral vasoreactivity (rCVR) were measured by xenon-133 single photon emission computed tomography and the acetazolamide test. We evaluated its usefulness in detecting the reduced cerebral perfusion reserve and predicting long-term prognosis. All Type 1 patients (normal rCBF and rCVR) were medically treated and experienced no recurrent ischemic attack. Cerebral hemodynamics remained unchanged. Type 2, 3, and 4 patients underwent superficial temporal artery-middle cerebral artery double anastomosis, if they consented to surgery. All Type 2 (normal rCBF and reduced rCVR) and Type 3 (reduced rCBF and rCVR) patients, who underwent surgery, showed no further ischemic attacks, as well as long-term normalization of rCVR, although long-term rCBF normalization was obtained in only three of seven Type 3 patients. Cerebral hemodynamics remained unchanged in Type 4 patients after surgery. In follow-up periods, major completed stroke occurred in all 3 Type 2 and Type 3 patients who were medically treated. These results suggest that the acetazolamide test is valuable in assessing the cerebral perfusion reserve and predicting long-term prognosis in patients with internal carotid artery occlusion, although further long-term or randomized studies are needed.

The cerebrospinal fluid in patients with moyamoya disease (spontaneous occlusion of the circle of Willis) contains high level of basic fibroblast growth factor

The level of basic fibroblast growth factor (bFGF) in cerebrospinal fluid (CF) was measured by an EIA in 15 patients with moyamoya disease, in 11 patients with atherosclerotic occlusive disease, and in 8 patients with spinal disc disease. In the moyamoya patients, bFGF was found in 13 out of 15 CF samples with a mean value of 101 pg/ml. However, bFGF was detected in only 4 out of 11 patients with atherosclerotic disease with a mean of 8 pg/ml. In all the patients with disc disease, bFGF was not detected. The elevated level of bFGF may play a crucial role in the pathogenesis of moyamoya disease.

Effects of surgical revascularization on peripheral artery aneurysms in moyamoya disease: report of three cases.

OBJECTIVE AND IMPORTANCE The beneficial effects of surgical revascularization on rebleeding in moyamoya disease remain unclear. This report is intended to clarify the effects of surgical revascularization on peripheral artery aneurysms, which represent one of the causes of intracranial bleeding in moyamoya disease. CLINICAL PRESENTATION Findings for three female patients who experienced intracranial bleeding are presented. Cerebral angiography revealed that intracranial bleeding resulted from the rupture of peripheral artery aneurysms arising from dilated collateral vessels such as the lenticulostriate artery. INTERVENTIONThe patients successfully underwent superficial temporal artery-middle cerebral artery anastomosis combined with encephaloduromyoarteriosynangiosis. Angiography demonstrated obliteration of the peripheral artery aneurysms, together with the disappearance or decrease in caliber of the parent collateral arteries, after surgery. None of the patients experienced rebleeding during the follow-up period (up to 52 mo). CONCLUSIONThe results strongly suggest that surgical revascularization potentially improves cerebral circulation and decreases hemodynamic stress on collateral vessels, obliterating peripheral artery aneurysms.

Surgical Approaches for the Treatment of Aneurysms on the P2 Segment of the Posterior Cerebral Artery

OBJECTIVE The P2 segment of the posterior cerebral artery has remained a challenging region to expose surgically. We establish a surgical strategy for P2-segment aneurysms. METHODS Each segment of the posterior cerebral artery was classified according to Zeal and Rhotons classification. Fourteen of 18 P2-segment aneurysms were surgically treated. The patients outcome, the aneurysm location, and the surgical procedures were evaluated. A cadaveric study was performed to clarify the surgical view obtained via three different surgical approaches. RESULTS Nine aneurysms were clipped, two were trapped, one was coated, and one was excised with parent artery reconstruction. Cerebral revascularization techniques were used for three patients. The pterional approach exposed the anterior half of the P2a segment. The subtemporal approach revealed the P2a segment, but its exposure was restricted by its localization in the ambient cistern. Via the occipital interhemispheric transtentorial approach, the P2p segment was visible and could be manipulated. When the posterior half of P2a segment was high on a coronal view of magnetic resonance imaging, it was extremely hard to access via any approach. CONCLUSION A surgical strategy for the P2 aneurysm can be planned with accurate prediction of the aneurysm location. When the localization of an aneurysm on the posterior half of P2a segment is high, a resection of brain tissue may be required.

Combined revascularization surgery for childhood moyamoya disease: STA-MCA and encephalo-duro-arterio-myo-synangiosis

We present surgical techniques for optimal revascularization in childhood moyamoya disease. During the past 10 years we performed revascularization surgery for childhood moyamoya disease using direct revascularization with superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis and indirect revascularization of encephalo-duro-arterio-myo-synangiosis (EDAMS) 43 times. Points of this surgery are as follows: (1) craniotomy and durai opening for the most extensive possible exposure of the brain surface, (2) protective manipulation of the STA, temporal muscle and middle meningeal artery, (3) STA-MCA anastomosis to the frontal branch of the MCA to improve cerebral circulation of the frontal lobe using a small branch of the STA, and (4) a small opening in the arachnoid membrane and watertight closure.

Longitudinal changes in proton magnetic resonance spectroscopy in cerebral infarction.

Background and Purpose Proton magnetic resonance spectroscopy has revealed changes in lactate and JV-acetyl-aspartate in acute cerebral infarction. However, the details of these drastic changes and subsequent chronic changes have not been clarified. The purpose of this study was to disclose longitudinal changes in spectra seen in proton magnetic resonance spectroscopy. Methods Six patients with completed cerebral infarction were examined longitudinally with localized proton magnetic resonance spectroscopy. Results (1) In the acute stage (within 2 days after onset), two drastic changes were observed: JV-acetyl-aspartate decreased rapidly and severely within 2 days after onset, and lactate increased immediately and reached a high level in the acute stage after onset. (2) In the chronic stage (more than 1 month after onset), two features were observed: lactate, which had increased in the acute stage, remained high for more than 1 month, and other signals such as those of N-acetyl-aspartate, choline, and phosphocreatine/creatine decreased dramatically. Conclusions These results suggest that N-acetyl-aspartate and lactate as revealed by proton magnetic resonance spectroscopy can be useful indicators of the ischemic damage to the brain in clinical cases of cerebral infarction.

Regional cerebral hemodynamics in childhood moyamoya disease.

Regional cerebral blood flow (rCBF) and its reactivity to acetazolamide were analyzed in a series of 15 cases of childhood moyamoya disease, using the xenon-133 inhalation method and single photon emission CT (SPECT). Most of the patients had normal mean hemispheric cerebral blood flow (mCBF), comparable to that of age-matched healthy children. However, they had abnormal rCBF distribution and disturbed reactivity to acetazolamide in the territory of the internal carotid artery, especially in the frontal lobe. Surgical revascularization for the anterior circulation, which consisted of STA-MCA anastomosis and indirect synangiosis, dramatically improved theses cerebral hemodynamics in the anterior circulation, including the frontal lobe, and reactivity to acetazolamide in the whole brain. These results suggest that surgical revascularization for the anterior circulation should be carried out in order to improve cerebral hemodynamics as widely as possible, especially in the frontal lobe, and may improve cerebral perfusion reserve in the posterior circulation.

The frequency of postoperative stroke in moyamoya disease following combined revascularization: a single-university series and systematic review

OBJECT Although combined direct and indirect anastomosis in patients with moyamoya disease immediately increases cerebral blood flow, the surgical procedure is more complex. Data pertinent to the postoperative complications associated with combined bypass are relatively scarce compared with those associated with indirect bypass. This study investigated the incidence and characteristics of postoperative stroke in combined bypass and compared them with those determined from a literature review to obtain data from a large population. METHODS A total of 358 revascularization procedures in 236 patients were retrospectively assessed by reviewing clinical charts and radiological data. PubMed was searched for published studies on surgical treatment to determine the incidence of postoperative complications in a larger population. RESULTS Seventeen instances of postoperative stroke were observed in 16 patients (4.7% per surgery, 95% CI 2.8%-7.5%). Postoperative stroke was more frequent (7.9% per surgery) in adults than in pediatric patients (1.7% per surgery, OR 4.07, 95% CI 1.12-14.7; p < 0.05). Acute progression of stenoocclusive changes were identified in the major cerebral arteries (anterior cerebral artery, n = 3; middle cerebral artery, n = 1; posterior cerebral artery, n = 2). The postoperative stroke rate was comparable with that (5.4%) determined from a literature search that included studies reporting more than 2000 direct/combined procedures. No differences in the stroke rates between the direct/combined and indirect procedures were found. In the literature review, direct/combined bypass was more often associated with excellent revascularization (angiographic opacification greater than two-thirds) than indirect bypass (p < 0.05). CONCLUSIONS This experience of 358 consecutive procedures is one of the largest series for which the postoperative stoke rate for direct/combined bypass performed with a unified strategy has been reported. A systematic review confirmed that the postoperative stroke rate for the direct/combined procedure was comparable to that for the indirect procedure.