Masahiko Wanibuchi

Surgical management of petroclival meningiomas: defining resection goals based on risk of neurological morbidity and tumor recurrence rates in 137 patients.

OBJECTIVE:Meningiomas arising from the petroclival region remain a challenging surgical problem. Because of the substantial risk of neurological morbidity, uniformly pursuing a gross total resection (GTR) to minimize tumor recurrence rates may not be justified. We sought to define optimal resection goals based on risk factors for postoperative neurological morbidity and tumor recurrence rates. METHODS:This series represents our experience with 137 meningiomas arising from the petroclival region resected between June 1993 and October 2002. There were 38 male and 99 female patients with a mean age of 53 years. RESULTS:GTR was achieved in 40% of patients, and near total resection (NTR) was achieved in 40% of patients. One operative death occurred. Twenty-six percent of patients experienced new postoperative cranial nerve deficits, paresis, or ataxia when assessed at a mean follow-up of 8.3 months. The risk of cranial nerve deficits increased with prior resection (P < 0.001), preoperative cranial nerve deficit (P = 0.005), tumor adherence to neurovascular structures (P = 0.046), and fibrous tumor consistency (P = 0.005). The risk of paresis or ataxia increased with prior resection (P = 0.001) and tumor adherence (P = 0.045). Selective NTR rather than GTR in patients with adherent or fibrous tumors significantly reduced the rate of neurological deficits. Radiographic recurrence or progression occurred in 17.6% of patients at a mean follow-up of 29.8 months. Tumor recurrence rates after GTR and NTR did not differ significantly (P = 0.111). CONCLUSION:Intraoperatively defined tumor characteristics played a critical role in identifying the subset of patients with an increased risk of postoperative deficits. By selectively pursuing an NTR rather than a GTR, neurological morbidity was reduced significantly without significantly increasing the rate of tumor recurrence.

Pathogenesis of hyponatremia following subarachnoid hemorrhage due to ruptured cerebral aneurysm

BACKGROUND Hyponatremia following subarachnoid hemorrhage (SAH) occurs due to the inappropriate secretion of antidiuretic hormone (SIADH). However, this condition is also sometimes associated with certain dehydration states. METHODS To clarify the pathogenesis, daily values of urine volume, water balance, and sodium balance (Na Bal) were correlated with plasma levels of atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), and plasma renin activity (PRA) in 31 cases of SAH. RESULTS Na Bal was markedly negative on days 2 and 3. Cumulative Na Bal showed continuous negative values until day 10 following SAH. ANP values showed a consistent elevation, while ADH showed only an initial surge. PRA, as the gross indicator of circulatory volume, showed a lack of suppression, indicating no increase in the circulatory volume. CONCLUSION Hyponatremia following SAH therefore appears to be the result of increased natriuresis, due to the inappropriate elevation of ANP rather than SIADH. In this situation, water restriction should not be recommended, since the circulatory volume is decreased.

Characteristics of aneurysms arising from the horizontal portion of the anterior cerebral artery

BACKGROUND Aneurysms arising from the proximal portion of the anterior cerebral artery (A1: horizontal portion) are quite rare and are considered to be unique, because they are usually connected with other vascular anomalies and are sometimes part of a multiple aneurysm occurrence. A1 aneurysm cases experienced over the past seven and a half years are summarized in this paper. METHODS A total of 413 patients were surgically treated including 142 patients with subarachnoid hemorrhage (SAH); the remaining 271 patients had unruptured aneurysms. Among them, nine cases were categorized as constituent A1 aneurysms, three with SAH and six with unruptured aneurysms. RESULTS The shape of the aneurysm was saccular in all nine cases. Three of the nine cases had associated vascular malformations. The average aneurysm diameter in the three cases with SAH was 4.0 mm, which is smaller than other common aneurysms presenting with SAH. Eight aneurysms developed at the takeoff point of perforating arteries-the medial lenticulostriate artery in five cases and the recurrent artery of Heubner in three cases. In the remaining case, the aneurysm originated from the proximal end of the associated A1 fenestration. All nine patients had an excellent outcome after surgery. CONCLUSION A1 aneurysms require surgical elimination even if they are small. We emphasize the importance of preserving the blood flow of these perforating arteries by avoiding compression with either the clip blade or the clip body itself.

Hearing preservation in surgery for large vestibular schwannomas

OBJECT Hearing preservation remains a challenging problem in vestibular schwannoma (VS) surgery. The ability to preserve hearing in patients with large tumors is subject to particular difficulty. In this study, the authors focus on hearing preservation in patients harboring large VSs. METHODS A total of 344 consecutive patients underwent surgical removal of VSs over the past 9 years. Of these 344 cases, 195 VSs were > 20 mm in maximum cisternal diameter. Of the 195 cases, hearing preservation surgery was attempted for 54 patients who had a Class A, B, C, or D preoperative hearing level; that is, a pure tone average <or= 60 dB and speech discrimination score >or= 50% according to the Sanna/Fukushima classification. The tumors were classified as moderately large (21-30 mm based on the largest extrameatal diameter), large (31-40 mm), and giant (>or= 41 mm) according to the international criteria. The authors categorized patients with Class A, B, C, D, or E hearing (pure tone average <or= 80 dB and speech discrimination score >or= 40%) as having preserved hearing postoperatively. RESULTS Forty-one tumors (75.9%) were totally removed and 13 (24.1%) had near-total removal. Of the 54 patients, 29 maintained their hearing postoperatively; the overall hearing preservation rate was 53.7%. Analysis based on the preoperative hearing level showed that hearing was preserved in 14 (77.8%) of 18 cases for Class A; in 8 (47.1%) of 17 cases for Class B; in 4 (57.1%) of 7 cases for Class C; and in 3 (25.0%) of 12 cases for Class D. In addition, according to the analysis based on the tumor size, 20 (52.6%) of 38 patients with moderately large tumors retained their hearing, as did 5 (50.0%) of 10 patients with large tumors and 4 (66.7%) of 6 patients with giant tumors. Complications included 2 cases of bacterial meningitis that were cured by intravenous injection of antibiotics, 3 cases of subcutaneous CSF leakage that resolved without any surgical repair, and 1 case of temporary abducent nerve palsy. There were no deaths in this series. CONCLUSIONS The results indicate that successful hearing preservation surgery in large VSs is possible with meticulous technique and attention to adhesions between the tumor and the cochlear nerves.

New Method for Obliterative Treatment of an Anterior Wall Aneurysm in the Internal Carotid Artery: Encircling Silicone Sheet Clip Procedure—Technical Case Report

OBJECTIVE AND IMPORTANCE Aneurysms on the anterior surface of the internal carotid artery (ICA) have been shown to be somewhat different from ordinary berry aneurysms because they are rather small, grow rapidly in a short time, and easily lead to rupture, especially during surgery. The most difficult problem is that this type of aneurysm cannot be eliminated easily by an ordinary clipping procedure without causing apparent arterial stenosis or occlusion. CLINICAL PRESENTATION A 52-year-old man experienced a subarachnoid hemorrhage because of a ruptured aneurysm located on the anterior surface of the ICA. The tiny aneurysmal body, which was covered with a layer of brain tissue, was successfully exposed. The ICA seemed to be atherosclerotic, and the aneurysmal portion was solitary and had a reddish color. TECHNIQUEA large silicone sheet encircling clip (Vascwrap; Mizuho Ikakogyo Co., Ltd., Tokyo, Japan) was selected for this patient. The proximal margin of the silicone sheet was incised with a V-shaped cut, and the middle part of the sheet, which covered the diagonal part of the ICA, was trimmed to make it shorter. The blade of the fenestrated clip was applied to obliterate the aneurysm and was attached to the normal arterial wall together with this modified Vascwrap sheet to create a small space between the normal arterial wall and the surrounding Vascwrap sheet. Then tiny pieces of Teflon fiber (E.I. duPont de Nemours and Co., Wilmington, DE) was inserted from both margins, and the whole Vascwrap sheet was sealed with fibrin glue to ensure good adhesion. CONCLUSIONThis method seemed adequate in treating this difficult aneurysm without causing postoperative regrowth or occlusion of the patient’s ICA.

Trigeminal schwannomas: skull base approaches and operative results in 105 patients.

BACKGROUND: Trigeminal schwannomas make up 0.8% to 8% of all intracranial schwannomas. OBJECTIVE: To analyze our surgical experience with trigeminal schwannomas. METHODS: We performed 107 operations on 105 patients harboring trigeminal schwannomas over the past 30 years. We classified the tumors as peripheral, ganglion cavernous, posterior fossa root, and dumbbell types according to the portion of the nerve that gave rise to the tumor. RESULTS: Fourteen were peripheral-type tumors (13.1%), 39 (36.4%) were ganglion cavernous type, 22 (20.6%) were posterior fossa root type, and 32 (30.0%) were dumbbell type. Sixty-five tumors were solid, 35 were mixed, and only 7 were cystic. Among solid tumors, 14 were vascular, fibrous, and adherent to adjacent structures. Total or near-total removal was performed in 86 cases (81.9%), and subtotal removal was achieved in 18 (17.1%). The most common symptom was facial hypesthesia, occurring in 69 patients. This symptom improved in 11 patients, persisted in 50 patients, and worsened in 8 patients after surgery. New postoperative hypesthesia was observed in 8 patients. The second most common symptom was facial pain, observed in 24 patients. Facial pain subsided in 22 and persisted in 2 patients after surgery. Diplopia was observed in 21 patients. This symptom improved postoperatively in 14 patients, persisted in 6 patients, and worsened in 1 patient. CONCLUSION: The present series demonstrates acceptable results using microsurgical treatment to remove trigeminal schwannomas. Pain and diplopia may be relieved after surgery; however, hypesthesia frequently remains or may be worsened by surgery.

Glioblastoma simultaneously present with adjacent meningioma: case report and review of the literature

The simultaneous occurrence of multiple primary intracranial tumors has been reported previously. However, most of these tumors arise after cranial radiotherapy or in association with familial tumor syndromes. Double tumors of different histologies that are unrelated to radiotherapy or genetic disorders are very rare. We present a case of two primary intracranial tumors occurring simultaneously at adjacent sites. Preoperative gadolinium-enhanced magnetic resonance imaging of these tumors revealed a single continuous lesion. Postoperative histological examination revealed the presence of two distinct tumors, meningioma and glioblastoma multiforme. To elucidate the mechanism of synchronous tumor formation, we performed immunohistochemical analysis of the proteins involved in the receptor tyrosine kinase, Wnt, and Notch signaling pathways. These analyses showed that platelet-derived growth factor (PDGF) receptors-α and β were overexpressed in both tumors, thereby indicating the oncogenic effects of activated signaling of these receptors. The PDGF-mediated paracrine system may induce one tumor from another.

Bilateral cortical hyperactivity detected by fMRI associates with improved motor function following intravenous infusion of mesenchymal stem cells in a rat stroke model.

Intravenous transplantation of mesenchymal stem cells (MSCs) derived from bone marrow ameliorates functional deficits in rat cerebral infarction models. In this study, MSCs were intravenously administered 6h after right middle cerebral artery occlusion (MCAO) induction in rat. Functional MRI (fMRI) during electrical stimulation of the left forepaw and behavioral testing (treadmill stress test) were carried out at day 1, 4, 7, 14, 21, 28 and 42 following MCAO. In medium infused group (n=20) electrical stimulation of the left forepaw elicited a unilateral (right cortex) activated signal detected by fMRI in the infarcted somatosensory cortex. In the MSC infused animals two fMRI patterns were observed: unilateral (n=17) and bilateral (n=19) activation of sensorimotor cortex. In the MSC group both unilateral and bilateral cortical activated animals displayed significantly improved motor function compared to the medium infused group. However, the bilateral activated pattern in the MSC group showed the greatest functional recovery. Lesion volume as calculated from high intensity signals using T2WI was less in the MSC groups as compared to the medium group, but the lesion volume for the unilateral and bilateral signals in the MSC group was the same. These results suggest that the presence of a bilateral signal in sensorimotor cortex as detected by fMRI was more predictive of improved functional outcome than lesion volume alone.

Skull base training and education using an artificial skull model created by selective laser sintering.

IntroductionPracticing skull base approaches on cadavers affords the surgeon a chance to learn complex anatomical relationships and to practice surgical skills. However, there are ethical or legal problems in obtaining cadaver material in some countries. In addition, there is always risk of transmitting infections with cadaveric material. In order to get around these problems, we created a whole skull model which reproduces the detailed anatomy within the skull base using a selective laser sintering (SLS) technique.Materials and methodsThe first author’s head was scanned using multidetector-row computed tomography. The data were reconstructed and converted into the standard triangulation language file system. Powdered material comprised of polyamide nylon and glass beads was laser-sintered in accord with the data derived from the head CT. The model was dissected under a surgical microscope using a high-speed drill, suction, and other surgical instruments.Results and discussionThe appearance of both inner and outer cranial surfaces, including sutures, foramens, fissures, and protrusions, were clearly demonstrated. The artificial mastoid did not melt from the heat of the drill when a mastoidectomy was performed. The anatomical structures inside the mastoid and of paranasal sinuses were accurately reproduced in the model.ConclusionThe model created using SLS should be very useful for the teaching skull base approaches avoiding the ethical, legal, and infection problems inherent in cadavers.

Intravenous infusion of mesenchymal stem cells inhibits intracranial hemorrhage after recombinant tissue plasminogen activator therapy for transient middle cerebral artery occlusion in rats

OBJECTIVE Reperfusion therapy with intravenous recombinant tissue plasminogen activator (rtPA) is the standard of care for acute ischemic stroke. However, hemorrhagic complications can result. Intravenous infusion of mesenchymal stem cells (MSCs) reduces stroke volume and improves behavioral function in experimental stroke models. One suggested therapeutic mechanism is inhibition of vascular endothelial dysfunction. The objective of this study was to determine whether MSCs suppress hemorrhagic events after rtPA therapy in the acute phase of transient middle cerebral artery occlusion (tMCAO) in rats. METHODS After induction of tMCAO, 4 groups were studied: 1) normal saline [NS]+vehicle, 2) rtPA+vehicle, 3) NS+MSCs, and 4) rtPA+MSCs. The incidence rate of intracerebral hemorrhage, both hemorrhagic and ischemic volume, and behavioral performance were examined. Matrix metalloproteinase-9 (MMP-9) levels in the brain were assessed with zymography. Quantitative analysis of regional cerebral blood flow (rCBF) was performed to assess hemodynamic change in the ischemic lesion. RESULTS The MSC-treated groups (Groups 3 and 4) experienced a greater reduction in the incidence rate of intracerebral hemorrhage and hemorrhagic volume 1 day after tMCAO even if rtPA was received. The application of rtPA enhanced activation of MMP-9, but MSCs inhibited MMP-9 activation. Behavioral testing indicated that both MSC-infused groups had greater improvement than non-MSC groups had, but rtPA+MSCs provided greater improvement than MSCs alone. The rCBF ratio of rtPA groups (Groups 2 and 4) was similar at 2 hours after reperfusion of tMCAO, but both were greater than that in non-rtPA groups. CONCLUSIONS Infused MSCs may inhibit endothelial dysfunction to suppress hemorrhagic events and facilitate functional outcome. Combined therapy of infused MSCs after rtPA therapy facilitated early behavioral recovery.