Shigekiyo Fujita

Cerebral Vasoreactivity and Internal Carotid Artery Flow Help to Identify Patients at Risk for Hyperperfusion After Carotid Endarterectomy

Background and Purpose— Hyperperfusion syndrome is a rare but potentially devastating complication after carotid endarterectomy (CEA). The aim of this study was to investigate whether preoperative measurement of cerebral vasoreactivity (CVR) and intraoperative measurement of internal carotid artery (ICA) flow could identify patients at risk for hyperperfusion after CEA. Methods— For 26 patients with unilateral ICA stenosis ≥70%, cerebral blood flow (CBF) and CVR were investigated before and 1 month after CEA, with resting and acetazolamide-challenge single-photon emission CT. CBF on the first postoperative day was also measured. ICA flow was measured before and after reconstruction by electromagnetic flowmeter during surgery. Results— Ipsilateral CBF on the first postoperative day significantly increased relatively (56.6±53.2%) as well as absolutely (37.9±8.8 to 57.7±18.0 mL/100 g per minute) in the reduced CVR group (CVR <12%) but not in the normal CVR group (CVR ≥12%) (10.3±15.5% and 40.6±7.9 to 43.9±5.7 mL/100 g per minute, respectively). One month later, this difference almost disappeared. Two patients showed ipsilateral CBF increase of ≥100%. A significant association of intracerebral steal with hyperperfusion (CBF increase ≥100%) on the first postoperative day was also observed. ICA flow increase after reconstruction significantly correlated with CBF increase on the first postoperative day in the reduced CVR group but not in the normal CVR group. The threshold of ICA flow increase for hyperperfusion was estimated to be 330 mL/min in the reduced CVR group. Conclusions— Single-photon emission CT with acetazolamide challenge and ICA flow measurement during surgery could identify patients at risk for hyperperfusion after CEA, in whom careful monitoring and control of blood pressure should be initiated even intraoperatively.

Effect of clot removal and surgical manipulation on regional cerebral blood flow and delayed vasospasm in early aneurysm surgery for subarachnoid hemorrhage

BACKGROUND Effect of clot removal and surgical manipulation on cerebral blood flow (CBF) and delayed vasospasm was studied in early aneurysm surgery for subarachnoid hemorrhage (SAH). METHODS Thirty-two patients in this study fulfilled the following criteria: ruptured anterior communicating aneurysms, computed tomography (CT) within 2 days and unilateral pterional approach within 3 days after the ictus, bilaterally symmetrical clots without intracerebral hematoma, no postoperative complication, and CBF studies with single photon emission computed tomography (SPECT) with 123I-IMP. RESULTS Postoperative regional hypoperfusion due to brain retraction was frequently recognized on 123I-IMP-SPECT without infarction. The regional CBF (rCBF) showed a continuous fall during the first 4 weeks after the ictus, followed by improvement. The rCBF in the vicinity of the surgical route was significantly lower, especially in the acute stage (Day 3-7). A significant association between decrease of cisternal blood after surgery and the degree of local vasospasm and local CBF values during spasm stage was observed in the interhemispheric cisterns, A2 and medial frontal cortex, but not in the sylvian fissure or insular cisterns, M1 or M2, and frontal watershed and temporal cortex. CONCLUSIONS The present study provides evidence for the effectiveness of direct clot removal by early surgery for SAH on local vasospasm and CBF reduction. However, a potential improvement in local CBF with clot removal could be masked by brain retraction, which was demonstrated to affect rCBF adversely. Therefore, it is critical to perform brain retraction as gently as possible.

Saccular Aneurysms of the Proximal (M1) Segment of the Middle Cerebral Artery

We report A series of 20 consecutive patients with 21 saccular aneurysms of the proximal (M1) segment of the middle cerebral artery. The incidence of M1 aneurysms was 3.0% among 660 patients with intracranial aneurysms and 12.9% among 155 patients with middle cerebral artery aneurysms in our center. Of the 20 patients, 2 were men and 18 were women. The aneurysms were classified into two types: the superior wall type (9 cases), arising at the origin of the lenticulostriate or fronto-orbital artery, and the inferior wall type (12 cases), arising at the origin of the early temporal branches. Twelve (60%) patients had ruptured M1 aneurysms. The incidence of multiple aneurysms was high (nine patients, 45%), and M1 aneurysms were responsible for subarachnoid hemorrhage in four patients. Of 14 M1 aneurysms greater than 5 mm in diameter, 11 (78.6%) ruptured. In contrast, only one (14.3%) of seven small (< or = 5 mm) aneurysms ruptured. In 12 patients with ruptured M1 aneurysms, intracerebral hematomas were recognized in 6 (50%). Intracerebral hematomas by the superior wall M1 aneurysms were located in the frontal lobe, and those by the inferior wall M1 aneurysms were in the temporal lobe. Fifteen patients (75%) made a useful recovery 6 months after surgery. Four patients (20%), who were in poor grade condition preoperatively, remained severely disabled. One patient died of sepsis 2 months after she recovered well from the operation. Special attention to the lenticulostriate arteries to avoid injury is critical for successful surgical treatment.

Influence of degree of carotid artery stenosis and collateral pathways and effect of carotid endarterectomy on cerebral vasoreactivity.

OBJECTIVE The goal was to determine the influence of the degree of internal carotid artery (ICA) stenosis and collateral pathways on cerebral vasoreactivity (CVR). The effect of carotid endarterectomy on CVR is also presented. METHODS For 36 patients with unilateral ICA stenosis of at least 70%, regional cerebral blood flow (rCBF) and regional CVR (rCVR) were investigated before and after carotid endarterectomy, with resting and acetazolamide-challenge single photon emission computed tomographic scans. The degree of ICA stenosis and the status of the collateral pathways (sizes of the A1 segment and the posterior communicating artery) were evaluated by angiography. RESULTS Thirteen patients were classified as Type N/N (normal rCBF and normal rCVR), 5 as Type R/N (reduced rCBF and normal rCVR), 6 as Type N/R (normal rCBF and reduced rCVR), and 12 as Type R/R (reduced rCBF and reduced rCVR). The degree of ICA stenosis correlated with rCVR status. The size of the A1 segment was a second-rank factor and was less effective in affecting rCVR. The size of the posterior communicating artery was not associated with rCVR. The predictive value of reduced rCVR for postoperative improvement (100%) was significantly higher than that of reduced rCBF (50%). CONCLUSION The present results indicate that the degree of ICA stenosis is a more significant determinant of CVR than are the collateral pathways in patients with carotid artery stenosis. The high predictive rate of reduced rCVR for postoperative improvement implies that acetazolamide-challenge single photon emission computed tomographic scanning might be useful in selecting patients with asymptomatic ICA stenosis who might benefit from carotid endarterectomy.

Computed tomographic grading with Hounsfield number related to delayed vasospasm in cases of ruptured cerebral aneurysm.

The relationship between cisternal high density calculated by Hounsfield number (HN) in computed tomography and the subsequent development of cerebral infarction due to delayed vasospasm was studied retrospectively in 36 cases of ruptured cerebral aneurysm. All patients were hospitalized within 24 hours and underwent operation within 48 hours after subarachnoid hemorrhage. Extensive removal of cisternal blood clots was carried out after obliteration of the aneurysm. The patients were divided into two groups according to the occurrence of vasospasm. In the group without vasospasm, the average HN was 65.7 preoperatively; after operation, the HN declined significantly to 62.2. In the group with vasospasm, the average HN was 77.6 preoperatively and 77.5 postoperatively. The relation between HN in postoperative computed tomography and vasospasm was as follows. When HN was 68 or less, vasospasm did not occur in any case. When HN ranged from 68 to 73, the incidence of vasospasm was 50%. When HN was 73 or more, vasospasm occurred in all cases. We propose a new system using HN to predict the incidence of vasospasm. This system is useful in deciding the timing of operation and determining the amount and location of clots to be removed.

Treatment of subdural effusion with hydrocephalus after ruptured intracranial aneurysm clipping.

OBJECTIVE This study was conducted to determine whether a ventriculoperitoneal shunt alone was effective in treating subdural effusion with hydrocephalus. METHODS Using only a ventriculoperitoneal shunt, we successfully treated eight patients who had subdural effusion with hydrocephalus after ruptured intracranial aneurysmal clipping, despite ventricular deformity and midline shift. RESULTS For all of the patients, both the subdural effusion and ventriculomegaly subsided and clinical symptoms lessened after surgery. CONCLUSION Ventriculoperitoneal shunting alone is an effective and satisfactory procedure; no subdural peritoneal shunt is needed for patients with subdural effusion accompanied by hydrocephalus. To-and-fro communication between the subdural effusion and ventricles is considered to be present in these patients. When selecting the treatment for subdural effusion, it is important to consider whether hydrocephalus (disturbance of cerebrospinal fluid circulation) is present.

The use of an external-internal shunt in the treatment of extracranial internal carotid artery saccular aneurysms: technical case report

BACKGROUND Extracranial internal carotid artery aneurysms (EICAA) are rare lesions. Resection and grafting is the preferred method of management. However, the details of shunt use in surgery for this type of aneurysm has been described in few articles. We describe an external-internal shunt with intra-aneurysmal trans-orifice insertion. CASE REPORT A 55-year-old woman presented with a 5-year history of a progressively enlarging pulsatile neck mass. An examination revealed no neurological deficit. Right carotid angiogram showed a saccular EICAA involving the ICA distal to the bifurcation, with kinking of the internal carotid artery (ICA). The dome of the EICAA extended from the upper border of C4 to the midportion of C2 and the maximum diameter was 4 cm. RESULTS Using the shunt technique, we successfully removed the aneurysm and reconstructed the ICA. The end-to-end anastomosis was easy because the shunt was involved only in the distal free end of the ICA, but not in the proximal free end of the ICA. CONCLUSION This technique could be an option for the treatment of EICCA when a shunt is needed to maintain the cerebral circulation.

A Transcondylar Approach to the Arteriovenous Malformation at the Ventral Cervicomedullary Junction: Report of Three Cases

Arteriovenous malformation at the cerevicomedullary junction is a rare disorder, usually presenting with subarachnoid hemorrhage. The diagnosis is difficult because of its anatomical location. In addition, the ventral location of these arteriovenous malformations makes surgical treatment difficult. We describe three cases surgically treated with a transcondylar approach. The usefulness of digital subtraction angiography and magnetic resonance imaging is discussed. The technique of the transcondylar approach is also described, including C1 hemilaminectomy, unroofing of the transverse foramen of C1 to obtain control of the vertebral artery, and partial resection of the occipital condyle and lateral atlantal mass by extradural drilling. This approach provides direct access to the ventral portion of the cervicomedullary junction.

Hemodynamics before and after the total removal of a dural arteriovenous malformation of the posterior fossa. Case report

The hemodynamic change before and after the successful total removal of a dural arteriovenous malformation was reported. Preoperative dynamic computed tomography scan showed the prolongation of the cerebral circulation time, and postoperative dynamic computed tomography scan demonstrated improvement of the cerebral hemodynamics, despite total resection of transverse sinus and sigmoid sinus. These findings suggest that, when angiography shows either retrograde venous filling or sinus occlusion, total removal could be done safely.

Consideration of the operative indications for posterior fossa venous angiomas

The case of a patient with a venous angioma located in the midline of the posterior fossa and responsible for a cerebellar hemorrhage is reported. The patient had a good recovery after removal of the hematoma. We reviewed this and seven other cases of venous angioma in the posterior fossa reported in the literature. It appears that those venous angiomas that occur in the cerebellar hemisphere and produce a cerebellar hematoma can be successfully removed.