Computer-generated microsurgical anatomy of the paraclinoid area.

To represent multiple microstructures, including perforators, dura, and cranial nerves, and to allow understanding of the three-dimensional relations of the paraclinoid area, we made a computer graphics model. The source of the input data is a variety of publications showing the detailed anatomy of the paraclinoid area. To produce the model, we traced such data, input selected points for each structure, smoothed the lines with a spline program, and added depth using wire-framing and color alterations.

Odontoid compression of the brainstem without basilar impression-- "odontoid invagination".

We report five patients with odontoid invagination, in which the odontoid process bulges upward into the foramen magnum and compresses the brainstem without deformity of the occipital bone. Two patients had a craniovertebral abnormality associated with Chiari malformation without instability of the craniovertebral junction (stable odontoid invagination). The other three patients had dislocation of the craniovertebral junction due to iatrogenic destruction of the occipital condyle, rheumatoid arthritis or an anomaly of C2 (unstable odontoid invagination).

Thoracic dumbbell intra- and extramedullary schwannoma.

We present a rare case of a solitary dumbbell intra- and extramedullary schwannoma of the thoracic spine in a 54-year-old man without signs of von Recklinghausen's disease. The patient presented with motor weakness in the left lower extremity, bilateral sensory impairment below the T9 dermatome and rectovesical dysfunction. Preoperative magnetic resonance imaging was suspicious for an intradural extramedullary tumor.

Postoperative vasospasm of unruptured paraclinoid carotid aneurysms: analysis of 30 cases.

This study was conducted to determine the incidence, severity, and causes of delayed vasospasm after clipping of unruptured paraclinoid aneurysms of the internal carotid artery (ICA). A retrospective analysis was made of 30 patients, who underwent clipping of unruptured paraclinoid aneurysms in our institution between 1991 and 1998. We compared angiograms before and after operation and classified them into two groups: vasospasm group and non-vasospasm group.

Surgical experience with resection en bloc of intramedullary astrocytomas and ependymomas in the cervical and cervicothoracic region.

We performed 8 operations on 7 patients with benign intramedullary astrocytomas and ependymomas in the cervical and cervicothoracic region. All patients initially underwent gross total tumor resection en bloc. One patient with an astrocytoma showed tumor recurrence postoperatively, and underwent a second operation resulting in subtotal removal.

Symmetric dumbbell ganglioneuromas of bilateral C2 and C3 roots with intradural extension associated with von Recklinghausen's disease: case report.

Background: Ganglioneuromas are rare benign tumors arising most commonly from the sympathetic nervous system. They occasionally grow in a dumbbell fashion extending into the spinal canal extradurally. However, ganglioneuromas of the cervical spine with intradural extension or multiple locations or in association with von Recklinghausen's disease are rare.

Surgical experience of syringomyelia with reference to the findings of magnetic resonance imaging.

We present our surgical experience of 20 patients with syringomyelia, who were divided into two groups based on the findings of magnetic resonance (MR) imaging: a "non-visible cisterna magna" group, in which MR imaging did not reveal cerebrospinal fluid (CSF) in the cisterna magna, and a "visible cisterna magna" group. Patients with non-visible cisterna magna were associated with Chiari malformation (14 patients) or tight cisterna magna (4 patients) and underwent craniocervical decompression. Intradural exploration was performed when CSF movement in the cisterna magna or CSF outflow from the fourth ventricle appeared to be insufficient.

Gross total surgical removal of malignant glioma from the medulla oblongata: report of two adult cases with reference to surgical anatomy.

Surgery was performed on the medulla oblongata of two adult patients with malignant glioma. Gross total resection of the tumors, located laterally or medially in the upper half of the medulla respectively, was achieved. The patient with the medially located tumor experienced significant postoperative neurological deterioration including sleep apnea.

Repeat operations in the management of clival chordomas: palliative surgery.

Some chordomas have a very poor prognosis because of their aggressive growth nature, but the efficacy of repeat operations for these cases has not been well documented. This report concerns 3 patients with aggressive chordoma of the clivus, who underwent operations 6 to 12 times over a period of 8 to 17 years because of symptomatic regrowth. Overall mean interval between repeat operations was 18 months with a range from 5 to 57 months and survival times were 9 to19 years after the first surgery.

Spontaneous resolution of syringomyelia: report of two cases and review of the literature.

Objective And Importance: The natural history of syringomyelia is highly unpredictable, and some patients experience improvement or stabilization without surgery. However, the mechanisms of the formation and spontaneous resolution of syringomyelia remain controversial. This report concerns two patients with syringomyelia who demonstrated spontaneous reductions in syrinx size, accompanied by symptomatic improvement.

Dumbbell C2 schwannomas involving both sensory and motor rootlets: report of two cases.

Objective And Importance: Intradural-extradural dumbbell C2 schwannomas are rare. This report concerns two such cases with the intradural compartment located ventral to the spinal cord and involving both sensory and motor rootlets.

Clinical Presentation: One patient was a 57-year-old woman with sensory disturbances in the right extremities and hyperreflexia in the left extremities.

En Bloc removal of soft tumors within the brain parenchyma using spoon retractors: traction-dissection method. Technical note.

Background: En bloc removal of soft tumors within the brain parenchyma has rarely been performed. We describe a safe technique for en bloc removal of the tumors using a spoon retractor, which enables retraction while holding the soft mass upward.

Methods: Dissection of a tumor mass is performed under traction of the surrounding brain tissue by retracting the mass using a spoon retractor.

Simple cervical spine traction using a halo vest apparatus: technical note.

Background: A halo vest apparatus, commonly used for external immobilization and protection of the cervical spine, offers several advantages. We present here a simple, accurate, easy, and safe cervical traction technique using a halo vest apparatus.

Methods: The distinguishing feature of our technique is that, after application of a halo vest apparatus, the halo crown is distracted gradually and stepwise by turning the bilateral screw bolts that hold the halo crown over a period of one to several weeks.

Syringomyelia without hindbrain herniation: tight cisterna magna. Report of four cases and a review of the literature.

Idiopathic syringomyelia, which is not associated with any definite pathogenic lesions, has been treated mainly by shunting of the syrinx and rarely by craniocervical decompression. The authors report four cases of syringomyelia thought to be idiopathic syringomyelia but treated by craniocervical decompression with favorable results. Syringomyelia was present without hindbrain herniation.

Arm-down Concorde position: a technical note.

Background: When the surgeon's approach is from behind the patient's shoulder via the infratentorial supracerebellar approach in the prone position (Concorde position), the patient's shoulder nearest the surgeon occasionally interferes with the visual route and surgical manipulation. To avoid this difficulty the author developed a modified Concorde position.

Methods: In the prone position, the patient's arm at the surgeon's side hangs down over the head end of the operating table, with elbow flexion supported by an arm-holder.

Malignant astrocytoma of the conus medullaris treated by spinal cordectomy.

We present a case of malignant astrocytoma of the conus medullaris in a 48-year-old man treated by spinal cordectomy. Preoperative examination revealed a tumor at the T12 to L1 level, and intraparenchymal invasion up to T8. The spinal cord was amputated caudally to the root entry zones of the T9 sensory roots.

Degloving transfacial approach with Le Fort I and nasomaxillary osteotomies: alternative transfacial approach.

Objective: We present surgical results obtained with the use of an alternative transfacial approach to the central cranial base.

Methods: A degloving transfacial approach, which is a combination of the midface degloving procedure, the Le Fort I osteotomy with a pediculated cartilaginous septum, and a nasomaxillary osteotomy, was used in 13 procedures for 8 patients. The lower clivus and upper cervical spine were approached via a submucosal route, without opening of the oropharyngeal mucosa.

Atypical pleomorphic astrocytoma in the pineal gland: case report.

Objective And Importance: We report a rare case of pleomorphic astrocytoma in the pineal region that took a benign course despite pleomorphism.

Clinical Presentation: A 30-year-old woman suddenly developed right hemiparesis followed by loss of consciousness. A computed tomographic scan revealed a mass in the pineal region accompanied by obstructive hydrocephalus.

Histological study on local invasiveness of clival chordoma. Case report of autopsy.

Background: It is well known that clival chordomas invade bony structures; however, their invasiveness of other structures has rarely been reported. We report an autopsy case of clival chordoma in a 61-year-old woman, who underwent surgery 6 times for a period of 8 years, with special reference to its local invasiveness.

Method And Findings: The histological studies showed that the tumour grew in the loose connective tissue in multilayers or multilobular fashion, invading the submucous layer in addition to the bone; however, it did not invade other soft tissue, particularly vital neurovascular structures or the dura itself, even in the advanced stage.

Microsurgical anatomy of the ophthalmic artery and the distal dural ring for the juxta-dural ring aneurysms via the pterional approach.

Microsurgical anatomy for the pterional approach was studied regarding the origin and the course of the ophthalmic artery and the distal dural ring using human cadaveric specimens, with special reference to the surrounding bony structures. In 50 human adult formalin-fixed cadaveric cerebral hemispheres and 10 block specimens of the skull base region including the ophthalmic artery and the carotid dural ring were examined under magnification using an operating microscope. The ophthalmic artery originated from the intradural portion of the internal carotid artery (ICA), except in 5% where the ophthalmic artery originated extradurally.

Surgery of a cavernous angioma making a tunnel between the fourth ventricle and tubercle.

We removed a cavernous angioma, making a tunnel between the fourth ventricle and tubercle using the traction-dissection method. Cavernous angioma with such a distribution is extremely rare, and we manipulated the mass differently to minimize surgical damage. Intraoperative findings and technical considerations are made.

Specific characteristics and management strategies of cerebral artery aneurysms: report of eleven cases.

Owing to the deep location of the posterior cerebral artery (PCA) and its close relationship with the brainstem and surrounding vital structures, surgical treatment of aneurysms in this region is complex. This study was undertaken in an attempt to better delineate the surgical risks of PCA aneurysms. A retrospective analysis was undertaken in 11 patients with PCA aneurysm surgically treated between 1988 and 1996 at Shinshu University and its affiliated hospitals.

Preservation of large bridging veins of the cranial base: technical note.

Objective: Sacrifice of a bridging vein in the cranial base occasionally may cause significant postoperative morbidity. We report a simple method for preserving large bridging veins of the cranial base by reflecting the dura when a subtemporal or transsylvian approach is used.

Methods: In the subtemporal approach, when a larger bridging vein enters the dura attached to the bone of the temporal base before it empties into the dural sinus, the dura is dissected widely from the bone and is cut vertically toward the medial side of the temporal base in front of the entrance of the vein into the dura.