We performed quantitative measurements of cerebral blood flow (CBF) using ^99mTc tracer by the Patlak Plot method with reference to normal aging and cerebrovascular reserve (CVR) capacity and then investigated a new evaluation method of CVR. Aging and decrease of ADL were significantly associated with reduction of the mean hemispheric CBF. In the acetazolamide (ACZ) stress test, these retrospective data showed some overlap in each ischemic grade on the relationship between rCBF and CVR response for the predictability of EC/IC bypass surgery. In these controversial problems, we must reconfirm the principle of cerebral hemodynamic perfusion in SPECT. First, retention tracer is distributed via the microcirculatory system to brain tissue. Second, therefore, we should understand not only the circulation of major vessels, but also the dynamics and rheology in parenchymal microcirculation to determine brain SPECT and CVR capacity. In the next step, we approached the new evaluation method of CVR capacity using ^99mTc tracer by a serial dynamic SPECT with a slip-ring rotational gamma camera. These preliminally findings suggest that a serial dynamic SPECT may be more useful for analyzing the pathophysiology on brain circulation and CVR than conventional approaches.

View full abstract

The anterior communicating artery (ACoA) is the most frequent site of aneurysms. This aneurysm is usually operated on via an interhemispheric or a pterional approach. The author routinely selects the pterional approach for the ACoA aneurysm because it allows the least brain retraction and excellent anatomical orientation. The interhemispheric approach was employed if the aneurysm was large, if the aneurysm was highly located, or if the distal anterior cerebral artery aneurysm was present. Of the author's 105 cases of ACoA aneurysms, 100 were clipped via a pterional approach, and the remaining 5 cases were clipped using an interhemispheric approach. I describe several important points, including preservation of the perforating arteries for the surgery of ACoA aneurysm via the pterional approach. The direction of the fundus is an important consideration in deciding the side of approach. Knowledge of the perforating arteries of the ACoA and the distal A1 segment is also mandatory. If the aneurysms project inferiorly, the right side is employed. If the aneurysms direct anteriorly or superiorly, the posteriorly locating A2 segment side is selected. If the aneurysms direct posteriorly, the anteriorly locating A2 segment side is selected. If the aneurysms project laterally, the aneurysms are approached from the dome side, not from the neck side. The most important points for the surgery of ACoA aneurysms via the pterional approach are the access to the aneurysm through a minimal retraction of the frontal lobe and the neck clipping of the aneurysm through a minimally invasive manipulation of the basal forebrain surrounding the aneurysms.

View full abstract

Neurosurgeons have 2 established approaches for the anterior communicating artery aneurysm (ACoAn): pterional (PT) and interhemispheric (IH). To elucidate which approach best suits various types of ACoAn, we studied angiograms from 202 consecutive operated cases. ACoAn can be classified into 4 groups by the direction of neck protrusion: anterior/inferior (AI: 43%), superior (SUP: 23%), posterior/superior (POST: 2%) and lateral (LAT: 32%). The LAT type is a peculiar aneurysm defined as protruding its neck and the dome sideways contralateral to the dominant A1. It is hard to recognize this type well on lateral projection angiogram because its neck and the dome are superimposed on the A1-A2 corner that the aneurysm arises from. In LAT, the dominant A1 is overwhelmingly on the left side (73.8%), while in the other types, the left A1 predominance is not observed (the left A1 dominant in 31.4%, the right A1 dominant in 32.8% and epui-A1 in 35.8%). Ninety percent of AI were operated on by PT. For the SUP type, both PT (48%) and IH (41%) were employed, depending on the size and shape of the dome and height of the neck from the frontal base. The LAT and POST type were clipped safely by IH (75.4 and 75.0%, respectively). Though LAT can be clipped by PT from the side of the neck protrusion getting over the dome (16%), this is apparently more difficult and risky than by IH. We present typical cases operated on both by PT or IH in each ACoAn type with annotations concerning surgical indications and techniques.

View full abstract

To evaluate the characteristics of the perforating artery injury, we reviewed 210 patients with anterior communicating aneurysm who underwent aneurysm clipping through the interhemispheric approach. One hundred fifty-one had ruptured aneurysms, and the other fifty-nine had unruptured ones. Perforating artery injuries occurred in 9 cases (4.3%): 6 (10.2%) in unruptured and 3 (2.0%) in ruptured. Six of 9 cases with perforating artery injury had large aneurysms more than 15 mm in diameter, and the dome of aneurysms adhered to blood vessels such as A2 or perforating artery in 4 cases. Since the anterior communicating aneurysm complex exists in a relatively small space, adhesion between the dome of aneurysms and vessels develops easily. The vascular injury on A2 or perforating artery has occurred during dissecting procedure. Care should be taken to dissect the aneurysm dome from the vessels.
In 6 cases, atherosclerotic changes were observed in the neck and/or dome of aneurysms. One of these 6 cases had perforating artery occlusion following aneurysm clipping. Because a clip can easily slip on an aneurysm dome with atherosclerotic changes, clipping may release the atheromatous plaque and occlude the perforating artery. It is important that the aneurysm neck keeps enough space for branching of the vessels following clipping. We also propose a new clip to prevent such slipping on the aneurysm dome. All the vessels, including the perforating artery in the anterior communicating artery complex, can be seen through the interhemispheric approach. However, surgery for large anterior communicating artery aneurysms has a risk of perforating artery injury. It is important to carefully perform dissection and clipping for such aneurysms.

View full abstract

This study demonstrated cognitive impairment among a group of patients undergoing open surgery for ruptured anterior communicating artery (Acom) aneurysms. We used the Wechsler Adult Intelligence Scale-Revised (WAIS-R), Wechsler Memory Scale-Revised (WMS-R), and Wisconsin Card Sorting Test (WCST) for the neuropsychological assessment. WAIS-R is one of the most famous assessment tools for cognitive impairment and is widely used because it has become the published norm and was evaluated by intelligence quotient.
The subjects comprised 51 of 241 patients who recovered social life with the rupture of Acom aneurysms that had been clipped neurosurgically between April 1, 1982, and July 31, 2000. The WAIS-R score showed impairment in 12 patients (24%), the WMS-R score showed impairment in 20 patients (39%) and the WCST score showed impairment in 33 patients (65%), the highest impairment rate in these tests. None of these patients showed impairment only in the WAIS-R. There was no significant correlation between the various clinical factors such as the age, Hunt & Kosnik grading, Fisher group, approach side, infarction, shunt, removal of gyrus rectus and the neuropsychological impairment. However, there was a significant correlation between the age and the WCST score.
Although it was difficult to detect the cause of cognitive impairment, some causes are associated with SAH itself whereas others are due to medial frontal lobe disorder for general effects of neurosurgery or other factors such as the disturbance of the perforating arteries.

View full abstract

We examined 33 patients with ruptured anterior communicating artery aneurysms (AcomA ANs) treated in Keio University Hospital between May 1997 and October 2000 and analyzed memory disturbance, resumption of work and factors affecting 23 patients from the 33 who had either made a good recovery (GR, n=16) or remained moderately disabled (MD, n=7). The 16 GR patients comprised 7 businessmen, 2 cooks, 1 doctor, 1 part-time worker, 4 housewives and 1 male retiree. Two GR patients (12%) demonstrated memory disturbance due to vasospasm and primary brain damage, respectively. Except for 4 housewives and 1 retiree, 2 of the remaining 11 GR patients (18%) could not return to their previous job positions. One of the cooks suffered from mild memory disturbance at discharge, and he quit his previous job but continued to run the restaurant with the support of his family. The young part-time worker resigned from her job although her condition had returned to normal. The 7 MD patients comprised 2 businessmen, 2 administrative staffers, 1 novelist and 2 retirees. Five of the 7 showed memory disturbance, which in 2 patients was due to the primary brain damage, and in another 2 to surgical complications and a vasospasm, respectively. Only 1 of these 5 patients was able to return to his previous job, which was writing as a novelist, although he suffered vasospasm-related weakness in the lower extremities.
In conclusion, the rate of resumption of work was satisfactory in GR patients, but was not so in MD patients, and memory disturbance caused by primary brain damage, surgical complications and vasospasm was the leading factor. Although it can be expected that patients with a ruptured AcomA AN may well show a high incidence of memory disturbance because of the damage to the basal forebrain perfused by the AcomA, this was probably not a factor in the memory disturbance or resumption of work in this series.

View full abstract

The mechanism through which ischemic manifestations develop in patients with middle cerebral artery (MCA) stenosis is still uncertain. It may cause ischemic symptoms through both embolic and hemodynamic mechanisms. In this study, we compared the findings from cerebral angiograms with single photon emission computed tomography (SPECT) in patients with M1 stenosis to determine the pathogenesis of ischemia.
At our hospital from 1994 to 2000, 14 patients (12 males and 2 females; mean age, 60.9; range, 31 to 85 years) with angiographically demonstrated symptomatic M1 stenosis were enrolled in this study. In 10, their stenotic lesion was located at the proximal site of the perforating arteries and for the other 4, stenosis was found at the distal site. Nine presented with transient ischemic attack (TIA) and 5 with completed stroke for an initial episode. The discrepancy in regional cerebral blood flow (rCBF) was evaluated in relation to the site and degree of stenosis, type of ischemic presentation, and frequency of ischemic events.
There was no significant difference in CBF between the patients with stenosis involving the proximal site and those with distal stenosis; but the cortical CBF decreased significantly in those with severe stenosis compared with moderate stenosis.
The cortical CBF of those who had a complete stroke is similar to that of the patients with TIA; but CBF of BGA decreased significantly in those with a complete stroke. The single ischemic event group showed a significant decrease in cortical CBF. On the other hand, the group with multiple ischemic events exhibited normal hemodynamics.
We concluded that multiple ischemic events that occurred in M1 stenosis are caused by an embolic mechanism.

View full abstract

The role of combined carotid endarterectomy (CEA) and coronary artery bypass grafting (CABG) in patients with severe carotid artery stenosis and concurrent coronary artery stenosis is still controversial. However, patients with severe carotid stenosis experience a higher rate of perioperative cerebrovascular events, compared with those without serious stenosis. Simultaneous operations have been performed in our institute since 1999, and we report the efficacy of combined CEA and CABG especially without cardiopulmonary bypass (off-pump CABG=OPCABG).
Five combined oprations were performed between December 1999 and March 2001. All patients had multiple coronary lesions with more than 75% unilateral carotid stenosis. One patient had contralateral internal carotid occlusion and 1 had the tandem lesions at the distal internal carotid artery and middle cerebral artery concomitantly. Four were asymptomatic neurologically and 1 was symptomatic. Cerebral hemodynamics in all patients was examined with single photon emission CT (SPECT) and cerebral angiography, but none of them demonstrated hemodynamic compromise before operation. Three patients were treated with CEA and off-pump CABG, and 2 were CEA and CABG with cardiopulmonary bypass. CEA preceded CABG, but the saphenous veins were taken in the course of endarterectomy. After CEA, the operative field was turned over to the cardiovascular team with the cervical wound being opened. Subsequently the cardiovascular team performed CABG with off-pump or pump. Off-pump CABG brought less blood loss from the cervical wound for the minimum anticoagulant than CABG with cardiopulmonary bypass.
No cardiac event occurred perioperatively, but 1 patient with transient neurological ischemic attack with tandem lesions had a transient neurological ischemic attack during hemodialysis on the day after the operation. All the patients were discharged without neurological deterioration.
Preoperative screening to the supra-aortic artery is helpful for evaluating the presence of carotid or intracranial vessels in patients undergoing CABG, and cerebral blood flow studies to clarify the cerebral hemodynamics are important for patients with both carotid and coronary occlusive diseases. It is still not clear what patients are suitable for the combined operation, but all the patients with high grade carotid stenosis can undergo the combined operation with off-pump CABG with the benefits of low morbidity and patient convenience.

View full abstract

To decide optimal treatment for various cerebral arteriovenous malformations (AVMs) is a highly complex issue. We retrospectively examined the clinical course of 24 cases of AVMs in reference to angiographic features, and performed clinical decision analysis to develop a logical therapeutic strategy. Annual bleeding rate was calculated in each group with specific angioarchitecture. The average bleeding rate was estimated at 3.2% per year. The rate was higher in the group with more hazardous angioarchitectures: 8.6% with intranidal aneurysm, and 5.5% with venous stenosis, respectively. Decision analysis demonstrated that Spetzler grade III AVM patients of 56 years or younger can expect better results from surgery than from conservative treatment. In grade IV, those of 48 years or younger can also expect better results from surgery. Because bleeding tends to develop more frequently in patients with intranidal aneurysm, older patients with this angioarchitecture (grade III: up to 70 years, grade IV: up to 60 years) can still expect better results from surgery. Clinical decision analysis is a helpful approach to plan a logical therapeutic strategy for AVMs.

View full abstract

We examined the value of synthetic patch grafts in patients undergoing carotid endarterectomy (CEA). Patch grafting using a Hemashield was adopted in 22 CEA procedures. Mild hypothermia at 34°C was induced in the patients to reduce the risk of cerebral ischemia during carotid clamping. Monitoring by two kinds of cerebral oximetry was undertaken continuously to evaluate the cerebral blood flow. Cardiac output (CO) was calculated two times during normothermia and at 34°C. Systemic heparinization was induced intraoperatively, and was then continued 5 days postoperatively. The average clamping time of the carotid artery was 72 min.
By inducing hypothermia, the jugular bulb venous oxygen saturation was raised by 2% on average (n=10). On the other hand, the CO did not change (n=7). The diameter of the internal carotid bulb was increased by 31% compared with that in primary closure. We did not encounter any cerebral ischemic events during the perioperative period. Postoperative follow-up has been continued for 20 months on average, and no restenosis of the internal carotid artery has been experienced in the patients. CEA with a patch graft under mild hypothermia was effective for reducing the occurrence of restenosis and the risk of cerebral ischemia.

View full abstract