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. INTERPRETATION: The dura may serve as a strong barrier against tumour invasion into the intradural space, which emphasises the importance of not injuring the dura, when the tumour is removed extradurally. For radical removal of clival chordoma, it will be necessary to remove the tumour extensively including normal bone and soft tissues surrounding the tumour, especially the mucous membrane, because the normal mucous membrane is surgically difficult to preserve by dissecting it from the invaded submucous layer.

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. The extradural origin had two patterns: one was that the ophthalmic artery penetrated the bony optic strut (trans-optic strut pattern) and the other was that it coursed into the optic canal proximally to the optic strut without bone penetration (supra-optic strut pattern). The origin of the intradural ophthalmic artery was commonly located at the medial third of the superior wall of the ICA (78%). The ophthalmic artery was commonly taking an S-shaped course in the intradural portion and entered the optic canal over the optic strut. The distal dural ring was tightly adherent to the internal carotid artery; circumferential sectioning of the dural ring is required to mobilize the internal carotid artery. When approaching juxtadural ring ICA aneurysms via the pterional route, it is important to recognize the extradural origin, especially the trans-optic strut type, and to precisely understand the microsurgical anatomy around the dural ring.

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. Data regarding surgical strategy, surgical complications and outcomes were analysed. Seven aneurysms were saccular (including one mycotic) and the other four were fusiform, dissecting, thrombosed and an infundibular dilatation. The locations of the aneurysms were at the P1 segment in two patients, P1-P2 junction in two, P2 segment in six and P3 segment in one. Six saccular non-mycotic aneurysms were treated with neck clipping and the other five aneurysms were treated each with proximal occlusion of the parent artery, excision of the aneurysm or wrapping. All aneurysms were satisfactorily exposed except one large saccular aneurysm. Surgical outcomes were either good recovery or moderate disability in 10 patients, and severe disability in one patient with a large aneurysm due to temporal lobe contusion. In conclusion it is the responsibility of the surgeon dealing with rare PCA aneurysms to be aware of these specific characteristics and to appreciate which surgical technique is appropriate for each patient.

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. The dura, which includes part of the entrance and interdural course of the vein, is reflected and retracted over the brain. In the transsylvian approach, when the bridging segment of the superficial sylvian vein becomes taut because of retraction of the temporal lobe, the dura is incised along the sphenoid ridge and is dissected and freed from the sphenoid bone. RESULTS AND CONCLUSION: This dura-reflecting technique facilitates brain retraction without exerting tension on the bridging vein of the cranial base and is expected to help avoid injury to bridging veins during neurosurgical procedures.

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. Her symptoms improved after ventriculoperitoneal shunt surgery. INTERVENTION: The tumor was totally removed in an en bloc fashion using the occipital interhemispheric transtentorial route. Light microscopy revealed that the tumor had marked pleomorphism and multinucleated, bizarre giant cells, but neither mitosis nor necrosis was seen. Glial fibrillary acid protein was immunohistochemically positive in a few tumor cells. Retinal soluble antigen was negative. No reticulin network between the tumor cells was observed. A histological diagnosis of atypical pleomorphic astrocytoma was made. CONCLUSION: No signs of recurrence have been observed for 7 years after surgery without adjuvant therapy. Histologically, the tumor resembled pleomorphic xanthoastrocytoma or pleomorphic granular cell astrocytoma, but the immunohistochemical findings were not completely compatible with either diagnosis. This benign astrocytoma in the pineal gland with unique features is the first such case reported.

Spoon retractors for soft mass.

We have designed spoon retractors for removing a soft mass. The retractor is composed of a main part which is eggshell like and concave in shape, with sizes varying from 5 mm to 4 cm in width, and a flexible shaft. The retractor enables retraction to hold a soft mass upward creating an ample space for dissecting it from surrounding structures in the depth. The spoon retractor has proven to be useful for gliomas and metastatic tumours, particularly for haemorrhagic lesions such as haemangioblastomas and arteriovenous malformations, because the retractor facilitates an en bloc removal of the mass by retracting it without causing laceration or rupture, and with feeding or draining vessels easily visualised.

Interdural origin of the ophthalmic artery at the dural ring of the internal carotid artery. Report of two cases.

The authors report two cases in which the ophthalmic artery (OA) originated from the interdural portion of the internal carotid artery at the carotid dural ring and coursed within the dura. This configuration was observed during surgeries performed in 82 cases of juxta-dural ring aneurysms. In surgery for such an aneurysm, if the OA is not seen intradurally, an attempt should be made to find this kind of variation by using a Doppler flowmeter before sectioning the dural ring.

Risks of surgery for patients with unruptured intracranial aneurysms.

BACKGROUND: With the widespread use of less invasive imaging tools, such as magnetic resonance angiography and computed tomographic angiography, unruptured cerebral aneurysms are found much more often than in the past. This retrospective study was undertaken to determine the risk factors for surgical intervention in a patient with an unruptured intracranial aneurysm. METHODS: Over a 5-year period, 1,558 patients with intracranial aneurysms underwent surgery at our center. Of these, 310 patients (20%) with unruptured aneurysms were included in this study. RESULTS: Out of 310 patients with unruptured aneurysms, 292 (95%) had a favorable outcome, and only one patient (0.3%) with a giant vertebral artery aneurysm died. Aneurysm size larger than 15 mm and location of the aneurysm in the posterior circulation were independent risk factors associated with less favorable outcomes. Patients with a single aneurysm had a better outcome than did patients with multiple aneurysms. CONCLUSION: Our results support the contention that surgical treatment of unruptured intracranial aneurysms carries a low risk of morbidity and mortality and may improve the outcome in patients harboring cerebral aneurysms by preventing the devastating effects of subarachnoid hemorrhage. Aneurysm size, location, and number were risk predictors for surgical morbidity in patients with unruptured aneurysms.

Anchoring method for hemifacial spasm associated with vertebral artery: technical note.

OBJECTIVE: We describe an easy and useful method for treating hemifacial spasm related to the vertebral artery. METHODS: The technique entails the manufacture of a dural belt harvested from the cerebellar convexity dura and a dural bridge made at the petrous dura combined with the use of an aneurysm clip. The dural belt holds the vertebral artery and is anchored to the dural bridge by fixation with an aneurysm clip after the vertebral artery is transposed to an appropriate position. RESULTS: The technique proved to be safe and effective in a series of six patients with hemifacial spasm who were followed up for a period of 2 months to more than 10 years after surgery. All patients were affected on the left side. Multiple offending arteries were present in three cases. Hemifacial spasm completely disappeared in all patients. CONCLUSION: This method represents a feasible option for the treatment of hemifacial spasm caused by a tortuous, elongated, or enlarged vertebral artery.

[Giant cell tumor originating in the sphenoid bone: a case report].

The authors report a case of giant cell tumor originating in the sphenoid bone. A 29-year-old woman presented with headache and diplopia. Bilateral ophthalmoplegia developed and MRI showed rapid growth of the tumor in spite of transnasal removal and conventional radiation therapy. The second transnasal surgery was performed 3 weeks after completion of radiotherapy. The symptoms were relieved except for right abducens palsy. Chemotherapy with cisplatin and etoposide was started after the second operation. The patient regained full ocular movement several months after the operation. Clinical remission has continued for four years. We conclude that the combination of repeated operations in the initial phase of rapid tumor growth, irradiation and chemotherapy is important to achieve tumor control.

Clinical analysis of internal carotid artery aneurysms with reference to classification and clipping techniques.

An intraoperative classification of intradural internal carotid artery (ICA) aneurysms not related to the arterial division but based on their operative presentation and clipping techniques is introduced. On the basis of the surgeon's view of the operative field via the pterional approach in 156 operated intradural ICA aneurysms in 143 patients, these aneurysms were classified according to their location in relation to the long axis of the ICA as either proximal, middle or distal in type and also according to their relation to the cross section of the ICA as either lateral, medial, ventral or dorsal in type. Numerically the largest in frequency is the middle type of aneurysm by axial location and the lateral type of aneurysms by cross sectional location. Eighty five percent of the lateral type aneurysms were at the arterial division. The majority of the large to giant aneurysms were of the ventral type and no dorsal type aneurysms were seen. About one third of the ICA aneurysms in this series were located free of the arterial division. All dorsal type aneurysms and most of the medial type aneurysms were not related to the arterial division. Clipping techniques were classified into perpendicular and parallel clipping, as to the direction of the clip-blades in relation to the carotid axis. The parallel clipping was further classified into forward clipping, in which a clip was applied from the distal side of the ICA, and reversed clipping, in which a clip was applied from the proximal side of the ICA. Most of the aneurysms located at the arterial division required the perpendicular clipping and those free of the arterial division required the parallel clipping. Furthermore, the forward clipping was useful for proximal type aneurysms and the reversed clipping for distal type aneurysms. For the middle type aneurysms clipping was performed bidirectionally. This classification includes all types of the ICA aneurysms located at any points along its long axis and on its cross section, and is useful for planning safe and exact clipping of the ICA aneurysms.

Surgical anatomy of the juxta-dural ring area.

OBJECT: The authors report on the surgical anatomy of the juxta-dural ring area of the internal carotid artery to add to the information available about this important structure. METHODS: Twenty sides of cadaver specimens were used in this study. The plane of the dural ring was found to incline in the posteromedial direction. Medial inclination was measured at 21.8 degrees on average against the horizontal line in the anteroposterior view on radiographic studies. Posterior inclination was measured at 20.3 degrees against the planum sphenoidale in the lateral projection, and the medial edge of the dural ring was located 0.4 mm above the tuberculum sellae in the same projection. The lateral edge of the dural ring was located 1.4 mm below the superior border of the anterior clinoid process. The carotid cave was situated at the medial or posteromedial aspect of the dural ring; however, two of the 20 specimens showed no cave formation. The carotid cave contained the subarachnoid space in 13 sides, the arachnoid membrane only in three sides, and the extraarachnoid space in two sides. The authors propose that the marker of the medial side of the dural ring, which is more proximal than the lateral, is the tuberculum sellae in the lateral view on radiographic studies. In the medial aspect of the dural ring the intradural space can be situated below the level of the tuberculum sellae because of the existence of the carotid cave. CONCLUSIONS: An aneurysm arising from the medial side of the juxta-dural ring area even below the tuberculum sellae is a potential cause of subarachnoid hemorrhage.

Experimental cranioplasty and skeletal augmentation using an alpha-tricalcium phosphate/dicalcium phosphate dibasic/tetracalcium phosphate monoxide cement: a preliminary short-term experiment in rabbits.

Calcium phosphate cement consisting of alpha-tricalcium phosphate (alpha-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was implanted into surgically created full-thickness defects in the cranial bone (bone defect experiment) and directly onto the cranial bone under the periosteum (augmentation experiment). Three months after the implantation, the implants were retrieved with the surrounding tissues and studied histologically and micrographically to evaluate if the cement can be used as a cranioplasty and skeletal augmentation material. In the bone defect experiment, successful reconstruction of the defect was seen in 8 out of 12 specimens. Four specimens, where bleeding control was difficult at the time of implantation, showed partial loss of the cement. Histological and microradiographic studies of the successfully implanted cement revealed that new bone surrounded the implant nearly completely and united directly with the cement surface. In the augmentation experiment, the augmented area maintained the hemispherical shape and was connected tightly with the host bone. Histology and microradiography demonstrated that new bone formation was seen in the gap between the cement and the host bone, and on the outer surface (periosteum side) of the cement at the edge of the implant. From this preliminary short-term study, it could be concluded that the cement is a promising material for cranioplasty and skeletal augmentation with indications that it has good osteoconductivity.

Factors influencing surgical outcome of the basilar bifurcation aneurysms.

To contribute to a better understanding of the clipping operation of the basilar bifurcation aneurysm, factors influencing the surgical outcome were analyzed in 80 patients. The age range of the patients was 34-74 years, with a mean age of 58.4 years, and there were 61 females and 19 males. Fifty-eight patients had been admitted because of subarachnoid hemorrhage and a basilar bifurcation aneurysm ruptured in 49 patients. The size of the aneurysms ranged between 2 and 19 mm with a mean of 7.9 +/- 3.9 mm. The height of the aneurysm neck was between -10 and 17 mm measured above a biclinoid line with a mean of 4.8 +/- 5.2 mm. Pterional approach was utilized in 72 patients and subtemporal in eight. Optic unroofing or removal of anterior clinoid process were performed in five patients, zygomatic osteotomy in 10, posterior clinoid removal in seven, and anterior petrosectomy in one. A bridging vein of the temporal lobe was divided in 16 patients. A short and/or hypoplastic posterior communicating artery was divided in 11 patients. Temporary occlusion of the basilar trunk was performed in 39 patients. Surgical outcome (Glasgow Outcome Scale) at 3 months after the operation was good recovery in 42 (53%), moderately disabled in 23 (29%), severely disabled in five (6%), vegetative survival in two (3%), and dead in eight (10%). The aneurysm size proved to be a single preoperative factor which significantly correlated with the surgical outcome (Spearman's rank correlation test, p < 0.0001). Division of the posterior communicating artery significantly contributed to the surgical outcome as an intraoperative factor (Mann-Whitney's U test, p = 0.01). The larger the aneurysm size was, the more often the posterior communicating artery was sectioned. Extreme care should be taken to obliterate a large aneurysm with a clip graft especially when division of the posterior communicating artery is required.

Aneurysm surgery in Asia--Japanese situation.

This report is based on the results of the questionnaires conducted for the Japan Stroke Surgery Meeting 1996 (President: S. Kobayashi). The questionnaires were sent to all neurosurgical training institutions approved by The Japan Neurosurgical Society, numbering 959. The response rate was 54.2% (520 institutions). All statistics dealt with cases from January 1995 to December 1995. The total number of aneurysm surgery performed was 13,166. The average operative case number per institution during the year was 25. About 20% of the institutions exceeded 35 cases. Of all operative cases, 76.3% were ruptured aneurysms and 23.7% were nonruptured. Giant aneurysms were 2.9%; dissecting aneurysms 2.4%. Surgical procedures performed were clipping in 90.3%, wrapping in 5.2%, proximal ligation 1.6%, and bypass in 0.7%. Intravascular surgery was performed for 2.3% of the cases. Sugita clips were mainly used in 80.5% of the institutions, Yasargil clips in 6.6%, and both in 12.9%. For anterior communicating artery aneurysms pterional approach was mainly used in 81.0% of the institutions, interhemispheric in 7.2%, and both in 11.7%. For basilar terminal aneurysms, pterional approach was mainly used in 88.3% of the institutions, subtemporal approach in 6.6%, and both in 5.1%. The nonoperative cases included 24.9% of the ruptured aneurysms, 31.7% of the unruptured aneurysms, 38.4% of the giant aneurysms, and 52.1% of the dissecting aneurysms. The above statistics suggest that aneurysms are treated in Japan in most training institutions and that open surgical treatment is still the main procedure of choice.

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. The computer graphic model of the paraclinoid area showing perforators, dural ring, optic nerve, and so forth, was made using a paint method for hidden line removal. It can be rotated and viewed from any direction and thus allows understanding of the relations of the area. Using our method, it may be possible to obtain a more detailed model of various anatomies including the skull base, and such data would be useful for preoperative simulation to understand relative regional relations for a specific case and as a new navigational system for open microneurosurgery. Concepts and technical details of the method are described.

Fenestrated oculomotor nerve caused by internal carotid-posterior communicating artery aneurysm: case report.

OBJECTIVE AND IMPORTANCE: The fenestrated oculomotor nerve associated with the internal carotid-posterior communicating artery aneurysm is very rare. CLINICAL PRESENTATION: A 48-year-old woman had a history of subarachnoid hemorrhage caused by a ruptured right middle cerebral artery aneurysm, which was wrapped with good postoperative course. Twenty years later, the patient suffered frontal headache with a mild oculomotor nerve paresis in the right side. Follow-up neuroimaging studies demonstrated a de novo right internal carotid-posterior communicating artery aneurysm. INTERVENTION: The aneurysm was exposed and clipped via a right pterional route. The fenestrated oculomotor nerve associated with the aneurysm was confirmed at surgery. CONCLUSION: We speculated that the fenestration was most likely caused, by the growth of the aneurysm.

Brain spatula with transparent tip: technical note.

A newly developed brain spatula with transparent tip for brain retraction is introduced. The high-molecular polymer plastic material is used only for the tip of the new spatula whilst rest of the spatula is made up of the ordinary malleable metal. The transparent nature of the spatula tip helps us in observing the retracted brain vessels and cranial nerves in continuity with the main operating area. The extent of distortion as a result of the retraction can be directly observed assisting in prevention of an inadvertent injury. The new brain spatula with transparent tip is helpful for microneurosurgery under high magnification. Various shapes and sizes of the spatula can be used.