Large randomized controlled clinical trials demonstrate that carotid endarterectomy (CEA) can be beneficial for patients with symptomatic and asymptomatic carotid stenosis exceeding 60 to 70% diameter reduction. Since these results are dependent upon medical centers and surgeons having perioperative morbidity and mortality rates lower than 6% for symptomatic stenosis and 3% for asymptomatic stenosis, we have to perform CEA with minimum complications, even though Japanese neurosurgeons are generally not familiar with this surgical procedure. Here we report standard surgical techniques of CEA and the clinical results. The results show that CEA can also be performed for Japanese patients with sufficiently low mortality and morbidity rates.

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During the surgery for cerebral aneurysms there is chance for expecting some serious complications and it is important to expect such intraoperative complications which can be predicted preoperatively. It is also significant to consider how it can be avoided and dealt with at the time of the occurrence. The following are the risk factor of the intraoperative complications and how to manage such complication : 1) Intraoperative rupture of cerebral aneurysms 2) Exact neck clipping without inducing arterial stenosis or residual aneurysms 3) Preservation of the perforating arteries 4) Preservation of the venous system and avoidance of brain compression and damage 5) Surgical procedures for acute phase of subarachnoid hemorrhage This article describes measures taken to avoid complications occurring during cerebrovascular operation, particularly that for cerebral aneurysms, and incomplete operation and the know-how of the avoidance, with reference to our clinical cases.

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The purpose of this paper is to provide an overview of the intraoperative problems and preventive measures in the surgery of the basilar tip aneurysms. The main topics include perforator injuries, intraoperative rupture, incomplete clipping, ischemic injury due to temporary occlusion, arterial injury, venous injury, and cranial nerve injuries. Injury of the posterior thalamoperforating arteries is a specific and especially serious postoperative complication. This is due to unique anatomical problems inherent to the basilar tip aneurysms. Recent advances in skull base surgical techniques have contributed to the solution of this problem. The surgical difficulties can be judged by various factors, including the size, location, and direction of the aneurysms. In particular, size is an important factor and it is advisable to use a combination of various surgical approaches and intraoperative angiography for large aneurysms (>10 mm) of the basilar artery. Neither the permissible time of temporary occlusion of the basilar artery nor the appropriate method of intraoperative monitoring is fully understood. Consequently, most neurosurgeons use the intermittent temporary occlusion method for brief periods. Recently, mild hypothermia has been re-evaluated as a promising method for prolonging the safety period of temporary occlusion and further clinical Investigation is warranted.

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We describe complications of skull base surgery, and emphasize the importance of preoperative planning and strategies for their avoidance. A requirement of skull base reconstruction is water-tight closure of the dural defect with free pericranium or fascia lata. Vascularized tissues may then be utilized, depending on the degree of the tissue defect, to disclose communications to nasootologic regions and to minimize dead space. Postoperative cerebrospinal fluid leakage can be cured by spinal drainage if reconstruction is performed correctly. Small bridging veins and cortical veins should not be sacrificed during approach, since they can support collateral circulation for patients with venous injury around the tumor during resection. A severed facial nerve should undergo primary repair either by direct suturing or by nerve grafting, because of its high capacity for regeneration. Taking into consideration the complications related to each skull base approach, surgical strategy should be planned based on the individual case.

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The aim of this article is to illustrate several techniques for avoiding surgical complications in acoustic tumor surgery, as well as to report surgical results of 100 cases of acoustic tumors that have been operated on by the author (T.S.). Requisites for successful tumor removal are as follows : clear understanding of the three-dimensional relationship between the facial nerve, the vestibulocochlear nerve and the tumor, identification of the facial nerve using both electrical stimulation and visual inspection, continuous monitoring of the facial and cochlear nerve functions using evoked electromyogram and auditory brain stem response respectively, and finally, meticulous manipulation. Anatomic facial nerve preservation was achieved in 96 out of 100 cases (96%). Of these patients, 60% experienced normal or nearly normal (House-Brackmann grades 1 & 2) facial nerve function upon discharge. At a 6 month follow-up, the rate improved to 83%. Out of 19 patients with preoperative hearing of Gardner's class 1, 9 patients (47%) retained the same class 1 hearing, while 3 patients (16%) belonged to Gardner's class 2 after surgery, making the rate of useful hearing preservation of this group 63%. In another 12 patients with preoperative hearing of Gardner's class 2, 4 patients (33%) retained class 2 hearing after surgery. Of all the 31 patients with useful hearing before surgery, 52% (16/31) of the patients retained useful hearing (classes 1 & 2) after surgery.

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Technical standards and way to avoid surgical complications for microsurgical resection of craniopharyngioma via frontobasal interhemispheric translamina terminalis approach are described. This approach ensures a wider operative field with better surgical orientation and views of vital structures, such as the optic nerves and the chiasma, perforating arteries from the internal carotid arteries, and the lateral walls of the third ventricle. Whereas, incidences of postoperative infection, anosmia, and hemorrhagic infarction of the medial aspect of the frontal lobes had been reported higher than those of the other conventional approaches. Technical details to avoid these complications are as follows. Opened frontal air cell should be packed and covered with the periosteal flap. Both olfactory nerves should be separated free from the bottom of the frontal lobes. Anterior part of the falx should be cut and large frontal ascending veins should be dissected widely to minimize the traction force by retraction.

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Parasagittal meningiomas generally originate in the lateral wall of the superior sagittal sinus and the adjacent convexity dura, so that they fill the space between the convexity dura, the lateral wall of the superior sagittal sinus and the falx. They account for 21 to 31% of all intracranial meningiomas in surgical series. Clinical symptoms and signs depend upon the location of the tumors. Anterior third parasagittal tumors most commonly cause headache, seizure, and later on, changes in mental status, and can sometimes become huge in size. Middle third tumors cause seizures and focal weakness. Unilateral motor findings are most common and are usually greater in the leg than in the arm or face. Posterior third tumors most commonly causes headache and visual changes. In Surgical resection, it is very important to define the arachnoid plane around the tumor, and to be careful to preserve the adjacent parasagittal draining veins. The authors prefer first to detach the tumor from the main feeding arteries which exist on the falx or convexity dura and debulk the center of the tumor centrally to reduce the size, allowing development of the arachnoid planes and tumor margins. Small pial branches going directly to the tumor from the anterior or middle cerebral arteries are coagulated and devided. Eventually, a globular portion of the tumor is removed. When the parasagittal sinus or the adjacent parasagittal draining veins are invaded by the tumor, but not occluded, the authors prefer simply to reset the globular portion of the tumor and allow recurrent tumor to slowly occlude the sinus or veins, allowing venous collateral circulation develop. The tumor can be resected when the sinus and veins are occluded at recurrence. Recently, we have begun considering stereotactic radiosurgery as an option in the treatment for these tumors.

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A case of an 8-year-old boy with a cervical spinal neuroblastoma was admitted to our hospital due to left C6-C7 radiculopathy. A MRI showed an intra- and extra-dural mass at the level of the C6-C7, exhibiting a dumbbell shape. One month after admission. 21 second MRI revealed it's rapid growth. Subtotal removal of the tumor followed by irradiation and systematic chemotherapy to the residual tumor were performed. Two years later, he died of respiratory insufficiency due to obstructive hydrocephalus. The histological diagnosis was neuroblastoma. Cervical spinal neuroblastoma is rare and it usually exists extradurally. The absence of urinary vanilmandelic acid (VMA) and homovanillic acid (HVA) suggests the origin of this tumor to be the dorsal root ganglion of the spinal cord.

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Accurate placement of the cardiac tip of a ventriculoatrial shunt is important for effective treatment of hydrocephalic patients and it is technically more difficult than placing a ventriculoperitoneal shunt. In 3 hydrocephalic patients and using contrast echocardiography, we have developed a simple and precise technique for placement of a cardiac tube into the right atrium. A cardiac tube is inserted into the right atrium through a peel-away introducer placed in the internal jugular vein. Real-time ultrasonographic monitoring is used to observe changes in the position of the tip within the right atrium. Injection of saline containing air micro-bubbles into the cardiac tube allows the tip of the cardiac tube to be seen accurately. We believe this method can provide a more correct localization of the tip in the right atrium than other methods which have been reported.

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