Temporary Artery Occlusion Research Articles

脳動脈瘤手術ｕｐｄａｔｅ 脳動脈瘤における軽度低体温麻酔下一時血行遮断の検討

To determine the efficacy of mild hypothermia in patients treated with temporary arterial occlusion during aneurysm surgery, we investigated postoperative neurological deficits relevant to the cerebral ischemia due to temporary occlusion and ischemic change on CT. There were 97 consecutive patients who underwent neck clipping with temporary occlusion under mild hypothermia (34ºC) anesthesia in the past 10 years at our hospital. Ten patients (10%) had transient neurological deficits including mainly hemiparesis and 2 patients (2%) had permanent hemiplegia. Preoperative neurological state, such as an unruptured aneurysm, mild or severe subarachnoid hemorrhage, and patient's age did not correlate with the frequency of postoperative neurological deficits. More than 20 minutes of temporary occlusion increased the frequency of ischemic neurological signs after surgery. Permanent hemiplegia occurred with occlusion times between 19 and 28 minutes. Temporary occlusion of the middle cerebral artery tended to raise the frequency of postoperative neurological deficits. Small infarction of the perforating artery territory was revealed on CT scan in 17 percent of 12 patients who presented neurological dysfunction. Temporary arterial occlusion was mainly applied to reduce dome pressure of the aneurysm and make a proper clip placement in cases of large domes and multi-dimensional neck geometry in 35 patients with unruptured aneurysm at a mean occlusion time of 6.5 minutes. In 62 patients with ruptured aneurysm, temporary arterial occlusion was used to prevent intraoperative rupture as well at a mean time of 12.9 minutes. Therefore, the option of mild hypothermia may be indicated for a complicated ruptured aneurysm surgery, which requires about 20 minutes of temporary arterial occlusion.

The evaluation of blood flow measurement using gravimetric plethysmograph.

Summary The gravimetric plethysmograph is a simple, robust and inexpensive device which measures blood flow in the limb in terms of the increase in weight which follows temporary venous occlusion. Validation of the instrument using an artificial circuit shows that it is accurate and gives reproducible results. The mean resting blood flow in the legs of 18 healthy volunteers was 3·95 ml 100 ml−1 tissue min−1 and this measurement was not reproducible. A 3-min period of arterial occlusion resulted in an immediate hyperaemic response of a mean 43·5 ml 100 ml−1 min−1, and this result was much more reproducible (r = 0·18). The mean resting blood flow of 45 patients with occlusive arterial disease of the legs was 2·1 ml 100 ml−1 min−1, and this flow rate was variable (r = 0·71). Their immediate hyperaemic response of 5·18 ml 100 ml−1 min−1 was much less than that in normal volunteers, but was quite reproducible (r = 0·93). Following arterial reconstruction, their mean immediate hyperaemic response rose to 10·35 ml 100 ml−1 min−1, which was a significant increase compared to their preoperative values (P < 0·0005, Student's t test) and was associated with concomitant improvement in symptoms, treadmill performance and ankle/brachial systolic pressure indices. Measurement of the immediate hyperaemic response to temporary arterial occlusion with the gravimetric plethysmograph may assist in the evaluation of patients with occlusive arterial disease of the legs, and in their medical and surgical management.

Temporary Partial Intra-iliac Balloon Occlusion for the Treatment of Acetabulum Fracture in a Jehovah??s Witness

Blunt trauma patients with acetabular fractures can lose as much as 2 L of blood after injury, and approximately 40% of these patients require blood transfusions. Fractures involving the anterior and posterior columns may require more than 1 surgery for adequate fracture fixation, increasing the potential for greater blood loss. Although blood transfusions may be medically necessary in these cases, Jehovah's Witnesses often refuse transfusion as a matter of religious conviction. The religious tenets of this faith preclude the use of blood transfusions and certain other blood products, based on an interpretation of Acts 15:29. To treat patients with these beliefs, various techniques have been developed to minimize blood loss as an alternative to transfusion. Temporary arterial balloon occlusion, also known as an "internal tourniquet," was first reported in 1954 for use in severe penetrating abdominal trauma. It was later used to control basilar artery bleeding and to limit blood loss in Jehovah's Witness patients undergoing revision total hip or knee arthroplasty. This case report documents the successful use of temporary balloon occlusion to minimize blood loss during an open reduction internal fixation of a both-column acetabulum fracture in a Jehovah's Witness patient. The method used for achieving this intra-iliac balloon occlusion is described in detail so that others also may implement this technique.

A novel approach in the management of a recurrent adenomatoid tumor of the uterus utilizing a Strassman technique

Adenomatoid tumors of the uterus are uncommon benign lesions derived from mesothelium, with a prevalence of 1.2% in one study of 1 000 unselected hysterectomy specimens. They are usually small and near the serosal surface; however, they may be large and diffuse (giant adenomatoid tumors). They coexist with leiomyomas in 60% of cases. A 33-year-old nulliparous woman was referred for severe menorrhagia and dysmenorrhea, thought to be due to a submucosal fibroid on ultrasound. This transpired to be an adenomatoid tumor, and she underwent three transcervical resections of the tumor (TCRT) over a period of 12 months for tumor recurrence and failure of symptom resolution. The last TCRT was performed with ultrasound guidance and laparoscopic visualization of the uterus to the resection point of blanching of the serosal surface. She failed to respond to a GnRH analogue throughout. A specialist opinion on the suitability of vascular embolization of the tumor judged that it would be ineffective for this lesion. She then underwent a Strassman procedure and removal of the adenomatoid tumor. This involved dissection of ureters and pelvic vasculature, selective temporary ligation of uterine arteries, hemisection of the uterus, and excision of the tumor with frozen sections to ensure clear tumor margins and resuturing of the uterine halves. Temporary vascular occlusion of the uterine arteries and ovarian vessels allowed a Strassman procedure, which resulted in successful resection of a recurrent giant adenomatoid tumor of the uterus, with fertility preservation in a young nulliparous woman. Two and a half years on there is no evidence of tumor recurrence.

A novel approach in the management of a recurrent adenomatoid tumor of the uterus utilizing a Strassman technique

Adenomatoid tumors of the uterus are uncommon benign lesions derived from mesothelium, with a prevalence of 1.2% in one study of 1 000 unselected hysterectomy specimens. They are usually small and near the serosal surface; however, they may be large and diffuse (giant adenomatoid tumors). They coexist with leiomyomas in 60% of cases. A 33-year-old nulliparous woman was referred for severe menorrhagia and dysmenorrhea, thought to be due to a submucosal fibroid on ultrasound. This transpired to be an adenomatoid tumor, and she underwent three transcervical resections of the tumor (TCRT) over a period of 12 months for tumor recurrence and failure of symptom resolution. The last TCRT was performed with ultrasound guidance and laparoscopic visualization of the uterus to the resection point of blanching of the serosal surface. She failed to respond to a GnRH analogue throughout. A specialist opinion on the suitability of vascular embolization of the tumor judged that it would be ineffective for this lesion. She then underwent a Strassman procedure and removal of the adenomatoid tumor. This involved dissection of ureters and pelvic vasculature, selective temporary ligation of uterine arteries, hemisection of the uterus, and excision of the tumor with frozen sections to ensure clear tumor margins and resuturing of the uterine halves. Temporary vascular occlusion of the uterine arteries and ovarian vessels allowed a Strassman procedure, which resulted in successful resection of a recurrent giant adenomatoid tumor of the uterus, with fertility preservation in a young nulliparous woman. Two and a half years on there is no evidence of tumor recurrence.

Hyperglycemia, excess weight, and history of hypertension as risk factors for poor outcome and cerebral infarction after aneurysmal subarachnoid hemorrhage

Stress-induced hyperglycemia has been shown to be associated with poor outcome after aneurysmal subarachnoid hemorrhage (SAH). The authors prospectively tested whether hyperglycemia, independent of other factors, affects patient outcomes and the occurrence of cerebral infarction after SAH. Previous diseases, health habits, medications, clinical condition, and neuroimaging variables were recorded for 175 patients with SAH who were admitted to the hospital within 48 hours after bleeding. The plasma level of glucose was measured at admission and the fasting value of glucose was measured in the morning after aneurysm occlusion. Factors found to be independently predictive of patient outcomes at 3 months after SAH onset and the appearance of cerebral infarction were tested by performing multiple logistic regression. Plasma glucose values at admission were found to be associated with patient age, body mass index (BMI), history of hypertension, clinical condition, amount of subarachnoid or intraventricular blood, shunt-dependent hydrocephalus, outcome variables, and the appearance of cerebral infarction. When considered independently of age, clinical condition, or amount of subarachnoid, intraventricular, or intracerebral blood, the plasma glucose values at admission predicted poor outcome (per millimole/liter the odds ratio [OR] was 1.24 with a 95% confidence interval [CI] of 1.02-1.51). After an adjustment was made for the amount of subarachnoid blood, the clinical condition, and the duration of temporary artery occlusion during surgery, the BMI was found to be a significant predictor (per kilogram/square meter the OR was 1.15 with a 95% CI of 1.02-1.29) for the finding of cerebral infarction on the follow-up computerized tomography scan. Hypertension (OR 3.11, 95% CI 1.11-8.73)--but not plasma glucose (OR 1.06, 95% CI 0.87-1.29)--also predicted the occurrence of infarction when tested instead of the BMI. Independent of the severity of bleeding, hyperglycemia at admission seems to impair outcome, and excess weight and hypertension appear to elevate the risk of cerebral infarction after SAH.

The effect of hepatic blood inflow occlusion on hepatic cancer treated with diode-laser thermocoagulation

To assess the effect of temporary occlusion of hepatic blood inflow on hepatic cancer treated with diode-laser induced thermocogation (LITT). The carcinoma Walker-256 was implanted in 40 SD rat livers. Twelve days later, the animals were randomly divided into 4 groups. Group A received LITT alone; group B received hepatic artery temporary occlusion during LITT; group C received portal vein temporary occlusion during LITT; group D received hepatic artery and portal vein temporary occlusion during LITT. Tumors were exposed to 810 nm diode-laser light at 0.95 watts for 10 min from a scanner tip applicator placed in the tumor. At the same time, the intrahepatic temperature distribution in rats with liver tumors was measured per 2 min during thermocoagulation. Tumor control was examined immediately 7 and 14 d after thermocoagulation. There was significant difference of intrahepatic temperature distribution in rats with liver tumors among the 4 groups (P<0.05) except when group C samples were compared with group D samples at each time point, and group B samples were compared with group C samples at 120 s (P>0.05). Light microscopic examination of the histologic section samples revealed three separate zones: regular hyperthermic coagulation necrosis zone, transition zone and reference zone. Compared with the samples in group A and group B, group C and group D samples had more clear margin among the three zones. The hepatic blood inflow occlusion, especially portal vein hepatic blood inflow occlusion, or all hepatic blood inflow occlusion considerably increased the efficacy of LITT in the treatment of liver cancer.

Dose finding study of intravenous magnesium sulphate in transient focal cerebral ischemia in rats

During many neurovascular procedures temporary occlusion of cerebral arteries is inevitable. Neuroprotective drugs may reduce the risk of cerebral infarction in this situation. Increasing evidence indicates neuroprotective properties of magnesium in cerebral ischemia. Previous experimental studies on the neuroprotective efficacy of magnesium-treatment in transient focal ischemia provide widely differing results using different magnesium doses and treatment-regimens. The present study was conducted to find the maximum protective dose of intravenous magnesium sulphate in a rat model of transient focal ischemia. 45 male Sprague-Dawley rats were subjected to 90 minutes of middle cerebral artery occlusion (MCAO) by an intraluminal thread. Animals were randomly assigned to one of 4 treatment arms: (1) vehicle (2) MgSO(4) 1x0.75 mmol/kg (3) MgSO(4) 2x1 mmol/kg (4) MgSO(4) 1 mmol/kg+0.5 mmol/kg/h. Local cortical blood flow (LCBF) was continuously measured by laser-Doppler flowmetry. Functional deficits were quantified daily, infarct volumes were assessed histologically after 7 days. Magnesium serum levels below 3 mmol/l were well tolerated by the animals. Above 3 mmol/l cardiodepressive effects limited neuroprotection. Total infarct volumes in groups 3 and 4 were significantly reduced by 32% and 42%, respectively, compared to controls. Postoperative neurological recovery was significantly improved in magnesium-treated groups. Continuous magnesium-administration with stable serum concentrations between 2 and 3 mmol/l offered the best protection and was well tolerated. Serum concentrations above 3 mmol/l should not be exceeded. An elevation of magnesium serum levels could be useful for brain tissue protection during procedures which are prone to the risk of temporary vessel occlusion.

Analysis of Intraoperative Rupture in the Surgical Treatment of 1694 Saccular Aneurysms

Intraoperative rupture (IOR) of an aneurysm is a known risk in the surgical management of intracranial aneurysms. The purpose of this study was to determine the incidence of IOR in a modern surgical series and to assess which factors bear upon it. This study retrospectively examined 1269 patients with saccular aneurysms treated surgically between 1986 and 1998. Three vascular neurosurgeons performed 1435 operations on 1694 aneurysms. Multiple factors, including the magnitude and time of occurrence of IOR, aneurysm location, subarachnoid hemorrhage, timing of surgery, and use of temporary occlusion, were analyzed. There were 113 instances of IOR (7.9% per surgery; 6.7% per aneurysm; 8.9% per patient). If the 59 "minor leaks" are excluded (as in previously published reports), the incidence becomes 3.8% per surgery, 3.2% per aneurysm, and 4.3% per patient. Posteroinferior cerebellar artery and anterior and posterior communicating artery aneurysms were more liable to rupture intraoperatively. The IOR rate was greater in ruptured than unruptured aneurysms (10.7 versus 1.2%, P < 0.0001). There was a lower rate of IOR in operations using temporary arterial occlusion (3.1 versus 8.6%, P < 0.0001). The occurrence of IOR for early surgery was not significantly higher than for surgery performed more than 3 days after subarachnoid hemorrhage (11.1 versus 10.0%, P = 0.6234). The rate of significant IOR can be kept low. Aneurysm location, subarachnoid hemorrhage, and temporary arterial occlusion seem to be important factors affecting the incidence of IOR.

Upper basilar artery aneurysms: oculomotor outcomes in 163 cases

The purpose of this study was to identify factors predictive of postoperative oculomotor nerve palsy among patients who undergo surgery for distal basilar artery (BA) aneurysms. The data can be used to estimate preoperative risk in this population. The natural history of oculomotor nerve palsy in patients with good outcomes is also defined. The cases of 163 patients with distal BA aneurysms, who were treated surgically between 1996 and 2002, were retrospectively studied to identify factors contributing to oculomotor nerve palsy. After the data had been collected, stepwise logistic regression procedures were used to determine the predictive effects of each variable on the development of oculomotor nerve palsy and to create a scoring system. Factors that interfered with resolution of oculomotor dysfunction in patients with good outcomes were also studied. Postoperative oculomotor nerve palsy occurred in 86 patients (52.8%) with distal BA aneurysms. The following factors were associated with postoperative oculomotor dysfunction, as determined by a categorical data analysis: (1) younger patient age (p < 0.001); (2) poor admission Hunt and Hess grade (p < 0.001); (3) use of temporary arterial occlusion (p < 0.001); 4) poor Glasgow Outcome Scale score (p < 0.001); and (5) the presence of a BA apex aneurysm that projected posteriorly (p < 0.001). For patients with good outcomes, postoperative oculomotor nerve palsy resolved completely within 3 months in 31 patients (52%) and within 6 months in 47 patients (80%). The projection of the BA aneurysm was associated with incomplete oculomotor recovery at 6 months postoperatively (p = 0.019). The results of this study can help identify patients with a high risk for the development of oculomotor nerve palsy. This may help neurosurgeons in preoperative planning and discussions.

Clampage vasculaire temporaire

In many situations, temporary artery occlusion is an integral component of aneurysm surgery. The use of temporary clip may allow safer and easier aneurysmal dissection and clipping. Several points, concerning the duration and overall risks of temporary occlusion and the method of choice for cerebral function monitoring have to be discussed. Non exhaustive review of neurosurgical literature. Temporary clip application decreases the risk of intraoperative aneurysmal rupture. The analysis of data published in the literature showed that several questions remain open concerning the optimal method of neuroprotection and cerebral function monitoring, as well as the limit of occlusion duration. Other clinical trials are needed to assess the efficacy and safety of this technique.

Risk factors for ischemic lesions following aneurysmal subarachnoid hemorrhage

The aim of this study was to test whether enoxaparin treatment (40 mg subcutaneously once daily) reduces the risk of cerebral infarction after subarachnoid hemorrhage (SAH) and to investigate predictive risk factors for permanent ischemic lesions visible on follow-up computerized tomography (CT) scans obtained 3 months after SAH. After undergoing surgery for a ruptured aneurysm, 170 patients were randomized in a prospective, double-blind, placebo-controlled trial to test the effect of enoxaparin on the occurrence of ischemic lesions, which were demonstrated on follow-up CT scans available for 156 patients. The presence of lesions correlated highly with an impaired outcome, as assessed using both the Glasgow Outcome and modified Rankin Scales (p < 0.01). Lesions occurred in 101 (65%) of the 156 patients. In half of the patients (51 patients) no lesion was visible on the CT scan obtained on the 1st postoperative day in 51 patients. On univariate analysis, the presence of lesions at 3 months post-SAH was not associated with enoxaparin treatment but did correlate with several clinical, radiological, and prehemorrhage variables. Significant independent risk factors for lesions consisted of an impaired initial clinical condition (odds ratio [OR] 2.63, 95% confidence interval [CI] 1.03-6.73), amount of subarachnoid blood (OR 6.51, 95% CI 2.27-18.65), nocturnal occurrence of SAH (that is, between 12:01 a.m. and 8:00 a.m.; OR 4.32, 95% CI 1.28-14.52), fixed symptoms of delayed ischemia (OR 5.21, 95% CI 1.02-26.49), duration of temporary artery occlusion during surgery (OR 1.66 per minute, 95% CI 1.20-2.31), and body mass index (OR 1.13/kg/m2, 95% CI 1.01-1.28). The presence of ischemic lesions can be predicted by the severity of bleeding, delayed cerebral ischemia, excess weight, duration of temporary artery occlusion, and occurrence of nocturnal aneurysm rupture.

121 Dynamic Changes In Cerebral Blood Flow During Selective Head Cooling In Newborn Piglets

Background/Aim: Selective head cooling (SHC) is a promising therapy for hypoxic-ischaemic brain damage (HIBD) in neonates. Disturbance of cerebral blood flow (CBF) plays an important role in neonatal HIBD. Safe application of SHC will depend on a better understanding of the effects of hypothermia on CBF which is influenced by temperature. This research aimed to study dynamic changes in CBF following SHC in newborn piglets.Methods: Sixteen newborn piglets, 5 to 7 day old, were randomly assigned to one of the following groups: SHC in normal piglets (n= 4), SHC after HI (n= 6) and normal temperature after HI (n= 6). HI was induced using temporary occlusion of the bilateral carotid arteries and mechanical ventilation with low concentration of oxygen (6%) for 30 minutes. In SHC nasopharyngeal temperature was reduced to 35 °C, and then to 32 °C. During HI and SHC, heart rate, respiratory rate, arteria blood pressure, SpO2, blood glucose and haemoglobin were monitored. CBF was measured with colour microspheres before HI (as baseline) and 2, 4 (35 °C), 6 (32 °C ) and 8 hours (rewarming) after HI.Results: During HI and SHC, no differences in arteria blood pressure, SpO2, blood glucose and haemoglobin were seen among the three groups studied. In normal piglets during SHC, global CBF decreased to 68% and 50% of baseline at 35 °C and 32 °C, respectively, particularly in temporal lobe, parietal lobe, brainstem and cerebellum. In normal temperature newborn piglets after HI, global CBF was decreased to 78% and 60% of baseline at 2h and 4h, respectively, after HI, particularly in temporal lobe, parietal lobe, hippocampus and thalamus. In SHC piglets after HI, similar decrease in global CBF was observed at the same time point at 35 °C and 32 °C, but local CBF was increased at 35 °C, particularly in the hippocampus, striatum and thalamus. At 32 °C, however, local CBF tended to decrease, particularly in the cerebellum, brainstem and parietal lobe.Conclusion: Global CBF was decreased in piglets at 2h and 4h after HI. The decrease was not influenced by SHC, although global CBF was decreased in normal piglets during SHC. Local CBF in HI piglets during SHC was improved at 35 °C, and tended to decrease when temperature was reduced to 32 °C. Thus, after HI although SHC does not improve global CBF, it improves local CBF when the temperature remains at 35 °C.

Temporary occlusion of the uterine arteries for symptomatic myomas: Evidence of myoma necrosis using MRI and histology

Temporary occlusion of the uterine arteries for symptomatic myomas: Evidence of myoma necrosis using MRI and histology

Reoxygenation with 100 or 21% Oxygen after Cerebral Hypoxemia-Ischemia-Hypercapnia in Newborn Piglets

We tested if reoxygenation with 100% O₂ was superior to 21% O₂ after combined cerebral hypoxemia-ischemia-hypercapnia (HIH) in newborn piglets. Twenty-eight piglets were randomized to reoxygenation with 100 or 21% O₂ following asphyxia. Asphyxia was induced by ventilation with 8% O₂, adding CO₂, and temporary occlusion of both common carotid arteries. After 20 min, reoxygenation-reperfusion was started with 21% O₂ (HIH 21% group, n = 13) or 100% O₂ (HIH 100% group, n = 11) for 30 min followed by 21% O₂. All piglets were observed for 2 h. We measured mean arterial blood pressure (MABP), changes in microcirculation in the cerebral cortex (laser Doppler), and extracellular concentrations of hypoxanthine in the cortex and amino acids in the striatum (microdialysis). We found significantly higher MABP and better restoration of microcirculation after reoxygenation with 100% compared with 21% O₂, but no differences in biochemical markers were found between the groups. This indicates that the brain tolerated reoxygenation with 21% as well as with 100% O₂ in the present model of experimental asphyxia in spite of the differences in MABP and cerebral microcirculation.

Laparoscopic partial nephrectomy with temporary arterial occlusion: description of technique and renal functional outcomes

Objectives To report our laparoscopic partial nephrectomy experience and the impact of temporary arterial occlusion during laparoscopic partial nephrectomy on postoperative renal function. Laparoscopic partial nephrectomy is increasingly popular but remains technically challenging. Methods Laparoscopic partial nephrectomy was performed in 27 patients, with arterial occlusion in 15 cases. Postoperative renal function was evaluated with serum creatinine in all patients and postoperative technetium-99m mercaptoacetyl triglycine renal scans in a subset of patients after arterial occlusion. Results The group with arterial occlusion (n = 15) did not differ from those without arterial occlusion (n = 12) with respect to age, body mass index, American Society of Anesthesiologists score, lesion size, operative time, blood loss, or complications. In patients undergoing arterial occlusion, the mean warm ischemia time was 43 ± 10 minutes (range 25 to 65). The preoperative and postoperative serum creatinine levels were unchanged in patients with (1.07 ± 0.4 to 1.15 ± 0.4 ng/dL; P = 0.24) and without (0.96 ± 0.22 to 1.07 ± 0.27 ng/dL; P = 0.14) arterial occlusion. The tumor size on imaging correlated with postoperative serum creatinine ( r 2 = 0.450, P = 0.04). Nuclear renography was performed in 9 patients (60%) after renal artery occlusion. The mean differential renal function of the operated kidney (49%) was similar to that of the contralateral kidney (51%) and was not associated with warm ischemic time or tumor size. Conclusions Temporary arterial occlusion during laparoscopic partial nephrectomy does not appear to affect short-term renal function adversely. We believe that this technique can be safely performed when significant bleeding or entry into the collecting system is anticipated. Additional study is warranted to identify the maximal time of warm ischemia and ways to reduce potential renal injury.

Vascular reconstruction for cerebral aneurysms in the anterior circulation

Vascular reconstruction for complicated cerebral aneurysms is sometimes required in order to prevent ischemic complications during the temporary occlusion of the parent arteries. In this paper, the authors discuss the usefulness and the effectiveness of vascular reconstruction in surgical treatments of cerebral aneurysms. Methods and Materials: (a) An STA–MCA anastomosis is performed in order to monitor the pressure of MCA while the large or giant middle cerebral aneurysms are clipped. The STA–MCA bypass provides a way of checking the patency of both the radial artery graft and the M2 portion. Checking the pressure of the MCA also acts to confirm the functioning of the radial artery graft or temporary radial artery bypass. As a side note, it should be known that the patient's arm must be lifted and held in position in order to perform temporary radial artery bypass. The STA–MCA anastomosis works as a back-up bypass during anastomosis of both the radial artery and the M2 portion of the MCA. (b) The radial artery graft is performed in the cavernous portion of carotid giant aneurysms with a proximal ligation of the cervical internal carotid artery. (c) Temporary radial artery bypass is used when clipping the carotid C1 and C2 portions of giant aneurysms. This prevents ischemic troubles during the temporary occlusion of the internal carotid artery. (d) When clipping anterior communicating aneurysms, A2z-A3 aneurysms, and dissecting aneurysms of ACA, an A3–A3 side-to-side anastomosis is performed in order to preserve blood flow to the distal anterior cerebral artery. Discussion: The STA–MCA bypass is a basic technique in cerebrovascular surgery, and is especially useful when performing cerebral aneurysm surgery. It acts primarily as an insurance, and secondarily as a way of restoring parent arteries after trouble, such as a laceration of the aneurysmal neck or a laceration of the parent artery. Although the temporary radial artery bypass cannot secure the ischemia of perforators, such as anterior choroidal arteries, it is an effective and useful method of preventing ischemic troubles within intracranial main trunk arteries. The A3–A3 bypass secures blood flow to the distal anterior cerebral artery and is therefore applicable in the combined unilateral A2 stenosis or A2 occlusion in the clipping of Acom aneurysms. In addition, an A3–A3 bypass can be used when dealing with large or giant aneurysms around the anterior communicating artery.

Effects of alpha-phenyl-N-tert-butyl nitrone (PBN)on brain cell membrane function and energy metabolism during transient global cerebral hypoxia-ischemia and reoxygenation-reperfusion in newborn piglets.

We sought to know whether a free radical spin trap agent, α-phenyl-N-tert-butyl nitrone (PBN) influences brain cell membrane function and energy metabolism during and after transient global hypoxia-ischemia (HI) in the newborn piglets. Cerebral HI was induced by temporary complete occlusion of bilateral common carotid arteries and simultaneous breathing with 8% oxygen for 30 min, followed by release of carotid occlusion and normoxic ventilation for 1 hr (reoxygenation-reperfusion, RR). PBN (100 mg/kg) or vehicle was administered intravenously just before the induction of HI or RR. Brain cortex was harvested for the biochemical analyses at the end of HI or RR. The level of conjugated dienes significantly increased and the activity of Na+, K+-ATPase significantly decreased during HI, and they did not recover during RR. The levels of ATP and phosphocreatine (PCr) significantly decreased during HI, and recovered during RR. PBN significantly decreased the level of conjugated dienes both during HI and RR, but did not influence the activity of Na+, K+-ATPase and the levels of ATP and PCr. We demonstrated that PBN effectively reduced brain cell membrane lipid peroxidation, but did not reverse ongoing brain cell membrane dysfunction nor did restore brain cellular energy depletion, in our piglet model of global hypoxic-ischemic brain injury.

脳血管障害における術中経頭蓋ＭＥＰモニタリングの有用性

We clinically examined the efficacy of motor evoked potential (MEP) by transcranial high-voltage electrical stimulation for intraoperative monitoring in cerebro-vascular disease. In 49 neurosurgical operations for cerebro-vascular disease, transcranial MEP (TCMEP) was recorded by 300-1000 V bipolar stimulation using the screw electrodes with the anode on the affected side. Surface electrodes for electromyographic responses were placed on the bilateral abductor pollicis brevis (APB) and bilateral abductor hallucis (AH) muscles. To remove effects of muscle relaxants on TCMEP, compound muscle action potential (CMAP) by supra-maximum stimulation of the median nerve 2 seconds after transcranial stimulation was recorded in 30 recent operations. In all 40 operations under propofol anesthesia and 6 among 7 cases under volatile anesthesia, MEP was successfully recorded. Postoperative motor paresis occurred in 6 limbs of 4 patients among 54 limbs of 30 patients who had received TCMEP compensated by CMAP by peripheral nerve stimulation and all compensated relative amplitude indexes (CRAIs) of these 6 limbs were less than 0.2. In contrast, in all 48 limbs of 26 patients who had no postoperative motor dysfunction, CRAI had been more than 0.2. These results suggest that our intraoperative TCMEP monitoring by relatively low-voltage (300-400 V) stimulation and compensated by CMAP after peripheral nerve stimulation was safe, easy (no need to expose the motor cortex), relatively accurate and less invasive, and useful especially in cerebro-vascular disease, which often requires a temporary occlusion of the cerebral arteries.

Expression of the endoplasmic reticulum chaperone GRP94 gene in ischemic gerbil brain.

GRP94 (glucose regulated protein 94) gene expression in the ischemic-hippocampus of gerbils, which was induced by a temporary occlusion of the bilateral common carotid arteries (CCAs), was tested by Northern blot analysis. The maximum GRP94 gene expression level was detected at the occipital lobe 10 min after the induction of ischemia. In the hippocampus, GRP94 gene expression reached a maximum 15 min after inducing ischemia. Following reperfusion, the maximum expression level was shown at 12 h and continuing thereafter.