Surgical treatment of internal carotid (IC) artery aneurysms around the carotid siphon is discussed. We present 54 cases including 16 of giant aneurysms. The surgical approaches to the aneurysms in this region are as follows : 1) A frontotemporal approach with the patient in a 45° semi-sitting position to decrease venous pressure, 2) A Dolenc approach with incision of part of the dura mater of the superior orbital fissure to facilitate removal of the anterior clinoid process and unroofing of the optic canal, and 3) Opening of the medial triangle followed by transection of the optic canal and dural sheath. Carotid siphon aneurysms can be divided into three groups anatomically : aneurysms of the ophthalmic segment (C2), of the clinoid segment (C3), and of the horizontal segment (C4). We present 29 cases of aneurysms arising from the C2 or C2/3 segment, 14 cases arising from the C3 or C3/4 segment, and 11 cases arising from the C4 segment. The anatomic locations of the aneurysms were determined preoperatively using angiography and three-dimensional CT imaging. Small aneurysms of the opthal-mic segment projecting inferomedially can be clipped using a contralateral approach via the prechiasmatic route. Aneurysms of the ophthalmic segment projecting superiorly can be clipped following resection of the anterior clinoid process. The clinoid process should be resected intradurally with direct visualization of the aneurysms. Straight side-angled clips are suitable for these aneurysms. Carotid cave aneurysms, which include aneurysms of the ophthalmic segment oriented inferomedially and of the clinoid segment projecting posteromedially, can be clipped using curved fenestrated clips via Dolenc's extradural approach. For accurate clipping, opening of the medial triangle and full mobilization of the IC at the clinoid segment and optic nerve by unroofing of the optic canal are required. Aneurysms of the horizontal portion are clipped after full exposure of the artery in the cavernous sinus only when the aneurysms are large and symptomatic. We used the frontotemporal and Dolenc approaches and applied fenestrated clips to aneurysms oriented posteromedially and straight or oblique clips to aneurysms projecting anterolaterally. Forty aneurysms were clipped using these approaches with 36 cases (90%) resulting in favorable postoperative recovery. There were 3 deaths secondary to complications of vasospasm and 3 cases with postoperative visual loss. The classification of these aneurysms and the surgical techniques we employed are discussed in detail.

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Thirty-three patients with internal carotid artery-cavernous aneurysms (ICA-cav. AN.) were included in this study. ICA-cav. AN. were defined as aneurysms located proximal to the ophthalmic artery. The ICAs Were divided into three groups based on Fischer,s classification, such as C3, C4, and C5, and the aneurysms were classified into three groups by size : small (less than 14 mm), large (15-24 mm) , giant (more than 25 mm). The patients were 6 males and 27 females aged 14 to 74 years. Initial symptoms were mass sign in 23 cases, epistaxis in 2, SAH (subarachnoid hemorrhage) in 1 and incidental occasion in 7. ICA balloon occlusion tests (BOTs) were performed under normotension in 17 cases and under hypotension with CBF (cerebral blood flow) study in 8, prior to various treatments. The results of neurological examinations were negative in all cases, but CBF in the affected hemisphere after temporary ICA occlusion was reduced in the 6 cases of the hypotension challenge group. Twenty-six of the patients were treated using various methods. C3 small aneurysms were surgically clipped, large or giant aneurysm underwent intentional ICA occlusion. However recently large and giant aneurysms have been treated by endosaccular embolization using microcoils to preserve the parent artery. Perioperative complications included cerebral infarctions in case of large and giant C3 aneu-rysms treated by surgical trapping of the ICA after failed clipping and transient ischemic attacks (TIAs) in 3 of 18 cases in which intentional ICA occlusion was performed. In conclusion, surgical clipping or endosaccular embolization is the treatment of first choice in cases of C3 aneurysms and intentional ICA occlusion after BOT is the treatment of second choice in cases of large and giant aneurysms. In cases of C4, 5 aneurysms endosaccular coil embolization and intentional ICA occlusion after BOT are the treatments of first and second choice, respectively.

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we report 1 2 cases of surgically treated symptomatic intracavernous internal carotid artery (ICA) aneurysm. Neurological examination reveled oculomotor nerve palsy in 6 cases abducens nerve palsy in 10 cases, and trigeminal nerve dysfunction in 4 cases. preoperatively, the patients. underwent EEG, CT scan. MRI and angiogra-phy. IC occlusion test (balloon matas test ; BMT) was performed during the examination for deficits, EEG and/ or SPECT. In 7 cases in which the BMT result was negative we performed superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis with ligation of the cervical part of the ICA. In the five cases in which the BMT result was positive we performed an extracranial -intracranial bypass with radial artery graft (high-flow bypass). No surgical complications developed except 1 case in which a small, asymptomatic intracerebral hematoma developed after high-flow bypass. The postoperative angiograms showed that bypass patency was achieved in all ceses. The aneurysms thrombosed and decreased in size within a few weeks postsurgery and the cranial nerve palsy disappeared in 4 cases, markedly improved in 7 cases, and partially improved in 1 case. These finding-s indicate that above-described treatment is satisfactory for symptomatic intracavernous ICA aneurysms.

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Aneurysms detected in the cavernous sinus are usually asymptomatic. Before surgical intervention for an asymptomatic aneurysm is decided on, the following should be considered : 1 ) The natural course of an asymptomatic aneurysm in the cavernous sinus is generally benign. 2 ) Surgical complications including cranial nerve palsy are frequent. 3 ) The incidence of rupture causing subarachnoid hemorrhage is unclear. Asymptomatic aneurysms in the cavernous sinus were detected in 23 patients. All cases were followed up without treatment for 1.7-9.4 years (mean, 4.6 years). In the 23 patlents, 29 aneurysms were observed : 22 in the C3 segment, 5 in the C4 segment and 2 in the C5 segment. Seventeen of the C3 aneurysms with medial projection (which might cause subarachnoid hemorrhage) were detected in 14 patients. None of the patients in the cases which were followed up have developed symptoms due to the aneurysm in the cavernous sinus during the follow-up period. The complication rate and mortality among 123 patients who underwent direct surgery were calculated using published data to be 17.1% and 3.3%, respectively. These results indicate that surgery shound not always be recommended. Surgical intervention for an asymptomatic aneurysm in the cavernous sinus should be recommended only when symptoms are presented.

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To evaluate the outcome of a posterolateral fusion (PLF) for patients with severe lumbago and/or leg symptoms indicating an unstable lumbar spine, the results in 51 consecutive cases given a PLF between 1988 to 1994 were clinically and radiologically evaluated. The follow-up period of these cases ranged from 8 to 72 months (mean 32.6 months), and all patients had undergone a combination of decompessive surgery and a PLF, with a single-1evel PLF provided for 46 cases and a two-1evel PLF for 5 cases. The degree of fusion achieved was divided into three classifications : "Solid union", "Fibrous union", and "Non union" These classifications were based on the findings of dynamic lumbar spine X-rays obtained at least 6 months after the surgery. The clinical results were evaluated as "Good", "Fair", or "Poor" based on the criteria described by Stauffer. The PLF results were as follows : 53% were a Solid union, 33% were a Fibrous union, and 12% showed a Non-union". Further, the relationship between the degree of fusion and the clinical results were as follows : 74% "Good", 26% "Fair", and O%"Poor" for the Solid union cases 79% "Good",11% "Fair" and 10% "Poor" for the "Fibrous union" cases, whereas for the Non-union cases, the clinical results were 30% each for "Good" and "Fair", and 40% "Poor". The rate of a "Solid union" was lower than that of previous reports however the clinical results of the "Solid" and "Fibrous union" cases were satisfactory in comparison. Further the rate of good results was almost identical between the "Solid" and the"Fibrous union" cases As for the "Poor" result case, the preoperative maximum anterior displacement was more than 10 mm, and/ or the preoperative slip angle was more than 10 degrees. In the surgical repair of these cases, the use of instrumen-tation should be taken into consideration. With respect to the vertebral angle between unstable spines, many cases preoperatively manifested kiphosis. However, in 79% of the PLF cases that manifested preoperative kiphosis, the postoperative condition improved to mild kiphosis or was changed to lordosis. Paraspinal muscle in preoperative state of the "Good" results (3.63±0.49 cm) was significantly thicker than that of the "Fair" results (2.91±0.52 cm) ,who postoperatively complained of lumbago or of quick fatigue of lower back (P⁢0.0002). Based on these findings, we have concluded that a PLF is useful in remedying the clinical symptoms and in lessening the kiphotic deformities in many cases with an unstable lumbar spine. If the maximum anterier displacement and/or slip angle between the unstable lumbar spines is more than 10 mm or 10 degrees, respectively, the use of instrumentation with an autologous bone graft may be indicated for the spinal fusion.

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The inhibitory effect of diltiazem or nitroglycerin (GTN) on the contraction of isolated vascular muscle in canine basilar artery induced by 12-deoxy-phorbol 13-isobutyrate (DPB) was examined. The muscle tension and cytosolic Ca^<2+> level ([Ca^<2+&Gt;]_i) were recorded simultaneously using a fluorescent Ca^<2+> indicator, fura-2. Ca^<2+->free solution was made by removing Ca^<2+> and adding 0.5 mM EGTA to physiological salt solution (PSS). Contraction was induced by high K^+ (72.4 mM) and DPB (10^<-6>M) . DPB induced sustained contraction with a transient increase followed by a decrease in [Ca^<2+>]_i below the resting level in PSS. Although [Ca^<2+>]i decreased below the resting level in Ca^<2+->free solution, DPB induced transient contraction, the tension of which was similar to that in PSS. These results suggest that DPB increased the sensitivity of contractile elements to Ca^<2+>. Single administration of diltiazem or GTN inhibited DPB-induced contraction only slightly without changing [Ca^<2+>]_i in PSS, and did not inhibit contraction in Ca^<2+>free solution without chafing [Ca^<2+>]_i. combined administration of diltiazem and GTN inhibited DPB-induced contraction only slightly without changing [Ca^<2+>]_i. These results suggest that the increase in Ca^<2+> sensitivity induced by DPB was too great to be inbibited by the single administration of diltiazem or GTN, orby their combined administration.

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Since the beginning of the nineties, stereotactic radiosurgery has been spreading rapidly in Japan, and in July 1995, the 4th Meeting of the Japanese Society of Stereotactic Radiosurgery (JSSR) was held in Sendai. Using this opportunity to present the latest thinking on radiosurgery, we prepared a questionnaire to elicit the current status of radiosurgery in Japan. This questionnaire, which asked whether radiosurgery is being used and contained other technical and clinical queries about radiosurgery, was sent to the members of the JSSR, the directors of neurosur-gery and radiology of all university hospitals, and the directors of category-A clinics of the Japan Neurosurgical Society. This questionnaire also solicited individual opinions about the indications for radiosurgery for model cases that presented different pathologies. A total of 114 clinics and 140 individuals responded to this questionnaire, and it was thus found that 20 radiosurgical linear accelerators (LINACs) , 14 gamma knives, and 2 charged-particle facilities are currently in use in Japan. Further, another 21 sites are preparing to use this equipment. Also, at the neurosurgeon's initiative, most gamma knife sites are treating more than 100 patients per year. In contrast, besed on the radiologist's initiative or in partnership with the neurosurgeon, most LINAC sites treat less than 50 patients per year. The value of radiosurgery for treating small surgically inaccessible arteriovenous malformations (AVMs) is well understood by many doctors, and to some extent, widening indicafion to surgically accessible AVM is accepted, as well. Radiosurgical treatment of acoustic tumors of less than 3 cm in diameter and of recurrent and bilateral tumors has become accepted as well. However, for treating surgiccaly removable meningiomas, many doctors, especially neurosurgeons, regard radiosurgery as a contraindication. Most doctors perfomming radiosur-gery believe that radiosurgery is the best treatment modility for metastatic tumors if the tumor is small, whereas many doctors who do not perform radiosurgery do not. Whether radiosurgery can be indicated for gliomas and cavernous angiomas requires greater exploration.

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An extracranial metastasis of a primary intracranial tumor is rare, and we report a case of 56-year-old male with an extracranial metastasis that extended to the lumbar spine 8 years after the initial operation involving a falx hemangiopericytoma. Metastatic lesions were verified by magnetic resonance imaging, and an open biopsy showed the same histological features as those of the original intracranial tumor. These lesions were effectively treated by radiation. This case and the clinical features of an extracranial metastasis of a hemangiopericytoma are discussed.

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We report the rare case of a 34-year-old woman with a solitary bone cyst in the left frontal bone. On consulting another hospital, since a localized swelling appeared in the left frontal area, a lipoma or a hematoma in the scalp was suspected. This swelling then disappeared about one month later, but the area gradually began to depress. At this point the patient sought our advice. Plain skull X-rays showed an osteolytic lesion in the left frontal bone, but the preoperative diagnosis remained obscure. Surgery was performed, and a histological examination of a specimen of the bone defect showed a cyst wall consisting of fibrous connective tissue and normal surrounding bone. On magnified microscopic inspection, neither epithelial nor endotherial cells were seen and the cyst wall was found to consist of non-specific fibrous connective tissue. Thus, the diagnosis was solitary bone cyst. A solitary bone cyst is most frequently encountered in long bones and rarely in the mandible, the maxilla, or the zygoma. Seldom does it occur in the skull. Of the long bone cyst cases that have been reported, in approximate-ly half of the patients who were treated by curettage and given an incomplete packing of the cyst had a long-bone recurrence of the cyst. Therefore, total excision of a bone cyst of the skull and an artificial cranioplasty is recommeded. Although a solitary bone cyst of the skull is extremely rare, this possibility should be considered when achieving a differential diagnosis, based on plain X-rays revealing an osteolytic lesion of the skull.

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The authors report the case of 61-year-old man with intravascular lymphomatosis (neoplastic angioendoth-eliomatosis). The patient presented progressive dementia and left hemiparesis. Magnetic resonance imaging (MRI) showed multiple small infarctions in the corpus callosum and cerebral white matter. Four months after presenting the initial symptoms, he died of respiratory failure. Postmortem findings revealed a multiple intravascular proliferatlon of atypical mononuclear cells in the brain, the lungs, the adrenals, and in the other organs. The immunohistochemical findings revealed that the malignant cells were of B-lymphoid origin. In a review of the literature and including this case, only seven cases have reported on the MRI findings of this disease. Based on our findings, we feel that when marking a differential diagnosis of rapidly progressive dementia and a multifocal vascular disease, intravascular lymphomatosis should be considered among the possible causes.

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We report the case of a 47-year-old female who developed a spinal subarachnoid hematoma after removal of spinal drainage without any alteration in her hemostatic mechanisms. The patient had undergone the clipping of a ruptured anterior communicating artery aneurysm followed by continuous spinal drainage. However, on removal of the catheter, she experienced a severe back pain and manifested paraplegia. Magnetic resonance imaging (MRI) revealed an acute hematoma compressing the spinal cord and cauda equina at the L1 to L4 levels of the vertebral body. An emergency laminectomy was thus performed, and the hematoma was totally evacuated. Postoperatively, however, she remained paraparetic. The underlying pathology and clinical course of this disorder is reviewed. An intraspinal hematoma that develops after a lumbar puncture is infrequent and usually is an insignificant complication. Epidural hematomas are the most often that occur, followed by subdural hematomas. Subarachnoid hematomas, on the other hand, are extremely rare, and most cases show a bleeding tendency, multiple punctures, and a pre-existing, narrow spinal canal. The prognosis for functional recovery is related to the extent of the preoperative deficit, its duration, and the rapidity of the progression of the symptoms. A prompt diagnosis of these lesions is a necessity, so that quick surgical intervention may maximize the chances of recovery.

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The authors report a method for preserving the temporomandibular joint (TMJ) in the infratemporal fossa approach for cadaver dissection. We perform en block resection of the mandibular condyle with the tomporal base including the glenoid fossa, and the mandibular process (TMJ complex), using a sagittal saw, air drill and bone chisel. It is important to preserve intact the articular capsule of the mandibular condyle, and also not to injure the internal carotid artery. The internal margins of the temporal base resection are drilled off along the foramen spinosum and foramen ovale. The TMJ complex is rigidly and three-dimensionally fixed to the lateral temporal bone with titanium miniplates. The TMJ sometimes appears to be sacrificed in cases of lateral skull base surgery, and it has been reported that ankylosis, pain, decreased functional range of motion, and facial asymmetry are found postoperatively. The TMJ should thus be reconstructed in order to preserve mandibular function.

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The cranio-orbital zygomatic approach (A1-Mefty) for skull base lesions can cause a depressed deformity at anterior temporal region which is unsightly. To cover this deformity, we have designed an orbital flap made of Ceratite^[○!R], a bioceramic composed of hydroxyapatite and tricalciumphosphate, which was used in a case of orbital Langerhans cell histiocytosis that we herein report. The patient, 3-year-old boy manifested right exophtalmos. Plain skull X-rays showed multiple osteolytic lesions. Thus, surgery was indicated and the destroyed orbital bone was removed. The orbital wall was reconstruct-ed by using an orbital flap made of Ceratite^[○!R]. The postoperative course was uneventful, and three-dimensional CT scans have shown a well-positioned artificial bone. It thus is felt that our designed orbital flap made of Ceratite^[○!R] achieves a good cosmetic result.

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