Biomedical subjects
Publications and source records attributed to Y Yonekawa.
Intracranial malignant peripheral nerve sheath tumors (MPNST) and intrasellar schwannomas are rare tumors. We describe a case of an intrasellar schwannoma with progression to a MPNST, a finding that, although very rare, extends the differential diagnosis of intrasellar lesions.
BACKGROUND AND PURPOSE: To evaluate the outcome of patients with aneurysmal subarachnoid hemorrhage (aSAH) developing intractable intracranial hypertension and treated by decompressive hemicraniectomy (DHC). METHODS: Of 193 patients with aSAH 38 patients were treated with DHC after early aneurysm clipping. Indications for DHC were 1. Signs of brain swelling during aneurysm surgery (group 1: primary DHC). 2. Intracranial pressure- (ICP)-elevation and epidural, subdural or intracerebral hematoma after aneurysm surgery (group 2: secondary DHC due to hematoma) 3. Brain edema and elevated ICP without radiological signs of infarction (group 3: secondary DHC without infarction). 4. Brain edema and elevated ICP with radiological signs of infarction (group 4: secondary DHC with infarction). RESULTS: Thirty-one patients (81.6%) suffered from high grade aSAH Hunt & Hess 4-5. 21 belonged to group 1, five to group 2, six to group 3 and six to group 4. Of a total of 38 patients a good functional outcome according to Glasgow Outcome Score (GOS 4 & 5) could be reached in 52.6% of the cases. 26.3% survived severely disabled (GOS 3), no case suffered from a vegetative state (GOS 2) but 21.1% died (GOS 1). After 12 months good functional outcome could be achieved in 52.4% of the cases in group 1, in 60% in group 2, in 83.3% in group 3 and in 16.7% in group 4. CONCLUSIONS: In more than half of the patients with intractable intracranial hypertension after aSAH a good functional outcome could be achieved after DHC. Patients with progressive brain edema without radiological signs of infarction and those with hematoma may benefit most. The indication for DHC should be set restrictively if secondary infarcts are manifest.
We evaluated islet transplantation from non-heart beating donors (NHBDs) with our Kyoto Islet Isolation Method. All patients had positive C-peptide after transplantation. The average HbA(1C) levels of the five recipients significantly improved from 7.8 +/- 0.4% at transplant to 5.2 +/- 0.2% currently (p < 0.01). Three patients with no or a single autoantibody became insulin independent while the other two patients with double autoantibodies reduced their insulin requirement but did not become insulin independent. C-peptide in patients who became insulin-independent gradually increased after each transplantation whereas C-peptide in patients who did not become insulin-independent from 3 months after the first transplantation to the next transplantation dramatically decreased. The beta-score of the three patients who became insulin independent was the best of eight. In conclusion, our method makes it feasible to use NHBDs for islet transplant into type 1 diabetic patients efficiently.
OBJECTIVE: A safe entry zone to tegmental lesions was identified based on intraoperative electrophysiological findings, the compound muscle action potentials (CMAP) from the extraocular muscles, and anatomic considerations. This entry zone is bordered caudally by the intramesencephalic path of the trochlear, laterally by the spinothalamic tract, and rostrally by the caudal margin of the brachium of the superior colliculus. METHODS: Four intrinsic midbrain lesions were operated upon via the safe entry zone using the infratentorial paramedian supracerebellar approach. All lesions involved the tegmentum and included an anaplastic astrocytoma, a metastatic brain tumor, a radiation necrosis, and a cavernous angioma. CMAP were bilaterally monitored from the inferior recti (for oculomotor function) and superior oblique (for trochlear nerve function) muscles. RESULTS: In three of four cases, CMAP related to the oculomotor nerve were obtained upon stimulation at the cavity wall after removal of the tumor. Stimulation at the surface of the quadrigeminal plate, however, did not cause any CMAP response. Using this monitoring as an indicator, the lesions were totally removed. CONCLUSIONS: In the surgery of tegmental lesions, CMAP monitoring from extraocular muscles is particularly helpful to prevent damage to crucial neural structures during removal of intrinsic lesions, but less so to select the site of the medullary incision. The approach via the lateral part of the colliculi is considered to be a safe route to approach the tegmental lesions.
Islet allotransplantation can achieve insulin independence in patients with type I diabetes. Recent reports show that the two-layer method (TLM), which employs oxygenated perfluorochemical (PFC) and UW solution, is superior to simple cold storage in UW for pancreas preservation in islet transplantation. However, UW solution has several disadvantages, including the inhibition of Liberase activity. In this study, we investigated the features of a new solution, designated M-Kyoto solution. M-Kyoto solution contains trehalose and ulinastatin as distinct components. Trehalose has a cytoprotective effect against stress, and ulinastatin inhibits trypsin. In porcine islet isolation, islet yield was significantly higher in the M-Kyoto/PFC group compared with the UW/PFC group. There was no significant difference in ATP content in the pancreas between the two groups, suggesting that different islet yields are not due to their differences as energy sources. Compared with UW solution, M-Kyoto solution significantly inhibited trypsin activity in the digestion step; moreover, M-Kyoto solution inhibited collagenase digestion less than UW solution. In conclusion, the advantages of M-Kyoto solution are trypsin inhibition and less collagenase inhibition. Based on these data, we now use M-Kyoto solution for clinical islet transplantation from nonheart-beating donor pancreata.
BACKGROUND: Aneurysms located on the distal posterior inferior cerebellar artery (PICA) are rare, and their underlying clinical features and surgical management are poorly understood. We report our series of 16 patients with 18 distal PICA aneurysms. METHOD: All patients with distal PICA aneurysms were treated between March 1996 and August 2004. We excluded all PICA aneurysms that involved the vertebral artery. Patients were analysed in the light of their clinical profiles, radiological studies, intraoperative findings and outcomes. All patients underwent non-enhanced and contrast enhanced CT scans followed by 4-vessel cerebral angiography on admission. The hemorrhagic patterns on initial CT scans were assessed using the Fisher Grading Score. The outcomes were documented using the Glasgow Outcome Scale at time of discharge and at three or twelve months follow-up. FINDINGS: The series included 6 men and 10 women. Massive intraventricular haemorrhage was found in 13 patients with proven CT subarachnoid haemorrhage, one patient revealed SAH without intraventricular components, one presented with only intraventricular blood in the occipital horns and 3 aneurysms were found incidentally without presence of blood. Fourteen aneurysms were saccular and four were fusiform. Nine cases were associated with another cerebrovascular lesion. A lateral transcondylar or a median suboccipital approach was used to secure the aneurysms in 15 patients, either by direct clipping (14 lesions) or vessel sacrifice (3 lesions). One aneurysm was treated by an endovascular approach. At long-term follow up, an excellent or good outcome was achieved in 75% of cases. One patient died due to pre-existing cardiopulmonary complications. CONCLUSIONS: Most of our cases of ruptured distal PICA aneurysms presented with haematocephalus. These were frequently associated with another vascular abnormality and 22% were fusiform or multilobulated. These specific features require special management strategies entailing an appropriate surgical approach to the aneurysm, clipping method, haematoma removal, ventricular drainage and when suitable choice of endovascular interventions.
Symptomatic cerebral vasospasm (CVS) with delayed ischemic neurologic deficits affects about one third of the patients after aneurysmal subarachnoid hemorrhage (SAH). In spite of the lack of definite evidence of large clinical trials, the devastating outcome of the natural history of symptomatic CVS demands an aggressive CVS treatment in a practically oriented, structured multimodal treatment regimen. With our treatment protocol good functional outcome could be reached in 66% of the patients with symptomatic CVS. This policy requires close and fast multidisciplinary collaboration between neurosurgeons, neuroradiologists, competent in endovascular interventions, and specialists for neurointensive care. We report on our experience with 79 cases with symptomatic CVS and delayed ischemic neurologic deficit (DIND) after aneurysmal SAH. The different treatment options with CVS are reviewed and practical guidelines for a step by step treatment are given.
The treatment and natural course of unruptured cerebral aneurysms were analyzed in 615 patients with 712 unruptured cerebral aneurysms registered from seven Japanese national hospitals and Zurich University hospital. For 209 aneurysms in 181 cases, the natural course of the aneurysms was observed without surgical treatment. During the follow-up period of 3,862 months (321.8 years), 11 of these aneurysms ruptured giving a rupture rate of 3.42%/year. Five of these 11 aneurysms were less than 10 mm in diameter. Seventeen aneurysms of these 209 untreated aneurysms had blebs. Seven of these 17 aneurysms ruptured yielding the high rupture rate of 28.3%/year. The likelihood of unruptured cerebral aneurysms to rupture was not exceedingly low even when the aneurysms were smaller than 10 mm. Since the risk of rupture and morbidity in relation to surgical treatment cannot be predicted by size alone, the morphology, especially the presence of blebs, should be considered when treating unruptured cerebral aneurysms. In 434 patients, 503 cerebral aneurysms were treated surgically either by craniotomy in 472 aneurysms or endovascular coil embolization in 31 aneurysms. Surgical outcome was influenced by the presence of concurrent diseases, patient age, size and location of the aneurysms. Complications after surgical treatment of 128 incidentally found aneurysms were reported in four cases; three cases of hemiparesis and one case showing disturbance of higher brain function, with a morbidity rate of 3.1%. These results suggest that surgical treatment may be acceptable in cases of incidentally found cerebral aneurysms, especially when blebs are present.
In patients suffering from subarachnoid haemorrhage (SAH) and presenting with multiple intracranial aneurysms (MIA) two questions have to be decided on: 1st when is the ideal moment to eliminate the ruptured aneurysm and 2nd when to treat the coexisting aneurysms. In our series we retrospectively analysed 124 SAH-patients presenting with a total of 323 aneurysms. In 57 patients the ruptured aneurysm and all coexisting aneurysms were clipped during the first operation, whereas in 9 patients only some of the coexisting aneurysms (group-A; age in median 55 years) were clipped besides the ruptured one. In 55 patients (group-B; age in median 55 years) the first operation was restricted to clipping the ruptured aneurysm, dealing with the coexisting aneurysm subsequently. Immediately after admission 3 patients passed away. One of the 64 patients waiting (average 60 days, median 14 days) for the subsequent clipping of the not yet secured aneurysms suffered a SAH. Six to 12 months after the initial SAH, 78% of the cases in both groups reached a Glasgow Outcome Score of 4 or 5. Even if in patients with coexisting unruptured intracranial aneurysms the elimination of each and every aneurysm is recommended, the advantages of an unstaged procedure versus the additional strain caused by the prolongation of the procedure, e.g. approach over the midline, 2 or more craniotomies, and the risk of additional ischemic damage to the brain, caused by increased manipulation of cerebral arteries and brain tissue, have to be carefully considered. This is of special importance in dealing with patients in higher Hunt and Hess grades.
Three special cases of AVM finally treated with conventional microsurgical method are presented. Two cases of medium sized AVMs were located at the central region, one of them was primarily treated with Gamma-knife followed by endovascular embolization having been complicated with growing cyst formation followed ultimately by microsurgical removal. The AVM of another case was embolized three times, followed by removal of the residual nidus under awake surgery. The third AVM located at the hypothalamus in the vicinity of the optic nerve was considered unsuitable for embolization and Gamma-knife therapy, and therefore removed by microsurgery using special approaches after a trial of embolization. In terms of microsurgical removal, preoperative embolization, embolization material, awake surgery and selection of special approaches are discussed.
Over the past 6 years we at the Neurosurgery Department in Zürich have had the opportunity to manage increasing numbers of patients, especially children, with Moyamoya angiopathy. With increasing awareness of presence of this angiopathy in Europe the number of referrals from all across Europe is constantly on the increase. We have also been able to readdress the presence of the entity of Moyamoya angiopathy i.e. both the Moyamoya disease and the Moyamoya syndrome in the European population. Thorough presurgical workup is mandatory for evaluation of surgical candidates for the type of effective revascularisation procedure and therefore for their successful management. Apart from scrutinizing the routine yet indispensable presenting symptomatology with clinical examination of the patients, our preoperative diagnostic workup mainly consists of a 6 vessel cerebral angiography, cerebral perfusion studies with HMPAO-SPECT and H(2)15O-PET examinations and transcranial Doppler. Longterm follow-up of these patients is indispensable and of great interest to us in terms of etiology and progression of the disease process as well as the choice of effective revascularisation procedure especially in our European population.
OBJECTIVE: To evaluate the outcome of patients with most severe cerebral venous and dural sinus thrombosis (CVT) after decompressive craniectomy. Indications and techniques for decompressive craniectomy and intensive care regimen are discussed. METHODS: Between 2000 and 2004 15 patients with CVT and intracerebral hemorrhage were treated at the Department of Neurosurgery, University Hospital Zurich. Among them, four patients with the most severe illness course were treated with decompressive craniectomy. Indications for decompressive craniectomy were deterioration of level of consciousness with CT signs of space occupying brain edema, venous infarction and congestional bleeding with mass effect, midline shift and obliteration of the basal cisterns. RESULTS: Among 15 patients with CVT and intraparenchymatous hemorrhage four patients were treated with decompressive craniectomy. Glasgow Coma Scale (GCS) immediately before the operation was in mean 10.2 (range 6 to 13). No patient showed signs of unilateral or bilateral third nerve palsy before surgery. No surgical complications were observed. All four patients who underwent decompressive craniectomy recovered with favourable functional outcome (Glasgow Outcome Scale; GOS 4 and 5). Anticoagulation therapy with heparin was reconvened 12 hours postoperatively with half dosage and 12 hours later with full dosage. No enlargement of existing intraparenchymatous hematoma or other intracranial bleeding complications occurred. CONCLUSIONS: Favorable functional outcome in selected patients with most severe courses of CVT can be achieved after decompressive craniectomy. Postoperative anticoagulation therapy with full dose heparin 24 hours after craniotomy seems to be safe. Precise indications and techniques for combined surgical decompression and thrombectomy deserve to be evaluated in future studies.
Surgical treatment of paraclinoid aneurysms is considered to be difficult due to their complicated anatomical location in the vicinity of important neural, vascular and bony structures. We present our clinical experience of the past 10 years of conventional microsurgical treatment of 81 paraclinoid aneurysms in 75 patients with the use of selective extradural anterior clinoidectomy SEAC and discuss the method of therapy option by reviewing recent reports on results of endovascular coiling method and the combination of these with conventional microsurgical therapy. The favorable surgical results with the use of SEAC and no recurrence of the treated aneurysm after clipping procedure in our series indicate that direct surgery can still be a standard technique for paraclinoid aneurysms in view of the fact that the endovascular aneurysm coiling methods are still associated with a considerable percentage of incomplete occlusion and present the problem of coil packing.
Basilar bifurcation aneurysms are lately treated frequently with endovascular technique. Microsurgical clipping occlusion technique has, however, still its solid position because of its completeness. This standard technique is required often due to unfeasibility and/or incompleteness at the time of application of the endovascular technique for aneurysms of this location. The authors suggest following strategies and tactics for safe and secure occlusion of aneurysms of this location: pterional approach, selective extradural anterior clinoidectomy SEAC, no transection of the posterior communicating artery, isolation of perforating arteries at the time of neck clipping with oxycellulose and combination of the use of fenestrated clip and conventional clip (especially for aneurysms projected posteriorly), controlled hypotension (systolic pressure of around 100 mmHg), temporary clipping (trapping) procedures of usually less than 15 min. All these are aimed for prevention of intraoperative premature rupture, and of injury of perforating arteries and for complete occlusion of aneurysms in the narrow depth of the operative field.
AIMS: It is important to have clinically relevant large animal models, especially nonhuman primates, to improve the efficacy of islet isolation and transplantation prior to clinical trials. The aim of this study was to improve the efficacy of islet isolation by analyzing large-scale nonhuman primate islet isolations. METHODS: Sixty-one islet isolations were evaluated using nonhuman primates. An automated isolation method was scaled down for islet isolation. Islet yields of prepurification, postpurification, and postculture, purity of islets, viability of islets, and functionality with glucose stimulation test were assessed. Initially, we analyzed relationships between endpoints then analyzed additional factors for successful islet isolation. Those factors included donor characteristics, the two-layer method (TLM) of pancreas preservation, trypsin inhibition during digestion, and digestion and collection time. RESULTS: Prepurification islet yields were strongly correlated with postpurification yields and postculture yields. It weakly but significantly correlated with purity, viability, and functionality. The average prepurification yield was 16,267 IE/g with each case divided into either above-average (high-yield group) or below-average groups (low-yield group). In 8 cases, TLM and trypsin inhibition were used and all cases belonged to the high-yield group. There were no significant differences between high- and low-yield groups in terms of donor age, body weight, pancreas weight, and cold ischemic time. The high-yield group had significantly longer digestion times and shorter collection times. CONCLUSIONS: TLM, trypsin inhibition, complete digestion, and quick collections were key for successful islet isolation. Analysis of nonhuman primate islet isolation techniques provided useful information, which should help to improve clinical islet transplantation.
BACKGROUND: Current success in islet transplantation will lead to a donor shortage. Living donor islet transplantation could be an alternative approach to expand the potential donor pool. In this study we describe the first successful living donor islet transplantation for unstable diabetes, performed at Kyoto University Hospital on January 19, 2005. METHODS: The donor was a healthy 56-year-old woman and mother of the recipient. The recipient was a 27-year-old woman with insulin-dependent diabetes since the age of 15 years. She experienced frequent hypoglycemic unawareness episodes. Her blood glucose concentration was difficult to control and C-peptide level was negative after glucagon stimulation. She needed an average 28 of units of insulin per day. The donor underwent a distal pancreatectomy and islets were isolated from the resected pancreas graft. The total islet yield was 408,114 islet equivalents and isolated islets were immediately transplanted into the recipient's liver. RESULTS: After transplant, the blood glucose level of the recipient was tightly controlled without hypoglycemic episodes. She was discharged on day 37 with a normal oral glucose tolerance test (OGTT). The recipient remained insulin-independent for >3 months, since day 22 posttransplant. The donor's postoperative clinical course was uneventful. She was discharged on postoperative day 18 and returned to her job within 1 month. CONCLUSIONS: We report the first successful living donor islet transplantation for the treatment of unstable diabetes. We believe that living donor islet transplantation may become an option in the treatment of insulin-dependent diabetes.
BACKGROUND: Evaluation of engraftment is important to assess the success of islet transplantation. Recently we developed secretory unit of islet transplant objects (SUITO) index for simple evaluation of engraftment. Assuming that normal subjects aged <40 years have 100% pancreatic beta-cell function, SUITO index was calculated by the formula: 1500 x fasting C-peptide immunoreactivity [ng/dL]/(fasting blood glucose [mg/dL] - 63). In this study, we compared the efficacy of islet transplantation from cadaveric and living donors using the SUITO index. METHODS: We performed eight islet transplantations with non-heart-beating donors (NHBDs) into five patients. Two patients received fresh islets once, one patient received fresh islets twice, one patient received cultured islets once, and one patient received cultured islets twice plus fresh islets once. In addition, one patient received fresh islets from a living donor. We calculated the SUITO index from postoperative days 3 to 30 for each case. RESULTS: Mean SUITO index after one fresh islet transplant was 11.7 +/- 1.0, after two fresh islet transplants was 28.5 +/- 3.4, after one cultured islet transplant was 2.1 +/- 0.4, after two cultured islet transplant was 12.1 +/- 1.9, and after two cultured islet transplant plus one fresh islet transplant was 26.7 +/- 1.7. The mean SUITO index after single living donor islet transplant was 40.7 +/- 2.6, which was significantly higher compared with all other groups. Insulin independence was obtained when the SUITO index was >26, which might reflect that 26% beta-cell mass was required for insulin independence. CONCLUSION: SUITO index is useful to evaluate islet engraftment and to predict the possibility of insulin independence.
BACKGROUND: The specific aim of this study was to develop an effective technique for pancreas procurement for islet transplantation from a non-heart-beating donor (NHBD). METHODS: Between January 2004 and November 2004, 11 human pancreata were procured and processed for islet isolation at a cell processing center. After confirmation of brain-death status, a double-balloon catheter was inserted to prevent warm ischemic damage to the donor pancreas by using an in situ regional organ cooling system that was originally developed for kidney procurement. RESULTS: Warm ischemic time was controlled with the modified in situ regional cooling system at 6.0 +/- 0.9 minutes (mean +/- SE). The operations for procurement of the kidneys and pancreata lasted 48.1 +/- 3.6 minutes and 9.9 +/- 4.8 minutes, respectively. The islet yield per isolation was 396,767 +/- 142,842 IE (islet equivalents). Ten of the 11 cases met the criteria for pancreatic islet transplantation based on the Edmonton protocol. CONCLUSIONS: We developed a novel procurement technique in cooperation with our kidney procurement team. This protocol for the procurement of pancreas and kidney from an NHBD enabled us to transplant islets into a type 1 diabetic patient and kidney into a renal failure patient.