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Yoku Nakagawa, Mitsuo Tsuru, and Kenzoh Yada

✓ The pressure gradient of the venous pathway between the cortical vein and superior sagittal sinus was measured in adult mongrel dogs by recording the pressures of the bridging vein, lateral lacuna (proximal portion), and superior sagittal sinus, together with the systemic blood pressure while gradually increasing the intracranial pressure up to the level of mean systemic blood pressure. The pressure gradient between the lateral lacuna and the superior sagittal sinus was also measured under increased intracranial pressure. Pressures of the bridging vein and lateral lacuna were constantly 50 to 250 mm H2O higher than the intracranial pressure, regardless of the level of intracranial pressure. An abrupt drop in the intraluminal pressure was observed at a point 1 to 2 mm proximal to the junction of the lateral lacuna and the superior sagittal sinus, regardless of the level of intracranial pressure. It is concluded that gradual stenosis of the parasagittal venous pathways took place 1 to 2 mm proximal to the junction between the lacuna and the superior sagittal sinus, and thus cortical venous pressure was maintained 50 to 250 mm H2O higher than intracranial pressure. The authors believe that an “intracranial venous pressure regulation mechanism” exists at the junction of the lateral lacuna and the superior sagittal sinus.

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Masataka Endo, Nobuyuki Kawano, Yoshio Miyasaka, and Kenzoh Yada

✓ Currently, superficial temporal artery-middle cerebral artery (MCA) anastomosis, encephalomyosynangiosis (EMS), and encephalo-duro-arterio-synangiosis are used to treat moyamoya disease and are reported to effectively improve ischemic symptoms. All are methods of reversing the flow of blood from the external carotid artery system into the cortical branches of the MCA. As moyamoya disease advances, these operations alone will predictably not correct the deterioration in blood flow in the territory of the anterior cerebral artery. It was noted in a case of moyamoya disease with intraventricular hemorrhage that a burr hole, made in the frontal region for drainage purposes, induced marked neovascularization. Since then, similar frontal burr holes have been made in five juvenile cases of moyamoya disease; this procedure involved making a burr hole in both frontal bones and incising both the dura and the arachnoid membrane. In two cases a frontal burr hole was placed simultaneously with EMS, and in the others the frontal burr hole was made following EMS. The clinical symptoms improved after the frontal burr hole was made, and dynamic computerized tomography revealed improved circulation in the frontal regions. Together with conventional surgical therapy for juvenile cases of moyamoya disease, this operation is considered beneficial both to the circulation in the frontal region and for the protection of frontal brain function.

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Nobuyuki Kawano, Kenzoh Yada, Yoshihiro Ogawa, and Kenichi Sasaki

✓ A case of malignant astrocytoma in the frontoparietal parasagittal region with transgression into the overlying dura mater and the skull is presented. Spontaneous transdural extension of a glioma is an extremely rare growth pattern. A mode of transdural extension of this tumor is discussed and related reports are reviewed.

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Shigekuni Tachibana, Hideo Iida, and Kenzoh Yada

✓ Ten patients with syringomyelia associated with Arnold-Chiari Type I malformations were evaluated. In each patient, a manometric Queckenstedt test was performed with the neck in various positions. No patient showed evidence of a block to the flow of cerebrospinal fluid (CSF) with the neck in the extended position; however, all showed a complete CSF block with the neck in a flexed position. Posterior fossa decompression with a C1–2 laminectomy was performed in nine cases, after which Queckenstedt test demonstrated free CSF communication in all nine with the neck in extension, in a neutral position, and in flexion. Postoperative magnetic resonance imaging showed shrinkage of the syrinx in the patients who underwent surgery. It is suggested that obstruction of the CSF pathway at the foramen magnum produced by neck movement is of importance in the formation and progression of a syrinx.

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Kenzoh Yada, Yoku Nakagawa, and Mitsuo Tsuru

✓ The venous drainage system during increased intracranial pressure (ICP) was studied in dogs. The ICP was gradually increased to the level of the systemic blood pressure while related arterial and venous pressures were monitored. The blood flow through the parasagittal intradural venous channels (lateral lacuna) was also measured to test the collapsibility of these vessels. The cortical venous pressure was constantly 50 to 200 mm H2O higher than the ICP regardless of the degree of elevation, while the sagittal sinus pressure remained at 50 to 75 mm H2O unless the central venous pressure was elevated by respiratory disturbance. Flow through the lateral lacuna decreased as the ICP was increased. The authors conclude that the low pressure in the sinus and the consistency of the walls of the lateral lacuna allow gradual stenosis of the lacuna during increased ICP.

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Nobuyuki Kawano, Yoshio Miyasaka, Kenzoh Yada, Hideo Atari, and Kenichi Sasaki

✓ A case of diffuse cerebrospinal gliomatosis is presented, with widespread involvement of the brain, cranial nerves, and spinal cord. This case showed a far more extensive distribution of tumor cells than previously reported cases of gliomatosis cerebri. The clinical picture and oncogenesis of gliomatosis cerebri is briefly discussed.

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Nobuyuki Kawano, Takashi Matsuno, Shichiro Miyazawa, Hideo Iida, Kenzoh Yada, Nobumitsu Kobayashi, and Yoshinobu Iwasaki

✓ The authors describe three cases of cervical radiculomyelopathy caused by calcium pyrophosphate dihydrate crystal deposition disease (CPPDcdd). Radiological investigations revealed nodular calcifications, 5 to 7 mm in diameter, in the cervical ligamentum flavum compressing the spinal cord. Light microscopic, scanning electron microscopic, and x-ray diffraction studies were performed on all three surgical specimens obtained by laminectomy. In two of the cases x-ray microanalysis and transmission electron microscope studies were also performed.

This study defined the presence of two patterns of crystal deposition in the ligamentum flavum. One is a nodular deposit, in which hydroxyapatite crystals are seen in the central part of the nodules, with calcium pyrophosphate dihydrate (CPPD) being distributed thinly around them. The other pattern is a linear deposit seen in multiple ligaments and composed of pure CPPD, which causes minimal thickening of the ligaments. A transitional pattern between the two types was also observed. This study revealed details of the nodular deposition of crystals in the ligamentum flavum and demonstrates that CPPDcdd and so-called “calcification of the ligamentum flavum” are the same disease: namely, CPPDcdd. Hydroxyapatite is assumed to have been transformed from CPPD.

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Akira Kurata, Yoshio Miyasaka, Takatomo Yoshida, Masatake Kunh, Kenzoh Yada, and Shinichi Kan

✓ A case is presented of tentorial dural arteriovenous malformation (AVM) associated with visual hallucinations and quadrant hemianopsia. Computerized tomography (CT) and magnetic resonance imaging showed an ischemic region, mainly affecting the white matter of the right occipital lobe, that was defined as an area of increased blood volume on dynamic CT scans and as a decrease in cerebral blood flow on N-isopropylp-123I-iodoamphetamine single-photon emission CT scans. Angiography demonstrated venous congestion, probably because the retrograde arterial inflow from the dural AVM into the corticomedullary vein was direct and not via the sinuses. The symptoms and radiological findings improved immediately after endovascular treatment. The origin of these symptoms was fully evaluated and confirmed to be a reversible ischemic change caused by disturbance of the volume of venous return over an extensive area.

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Hidemitsu Sakai, Hiroshi Takagi, Hirotoshi Ohtaka, Takamaru Tanabe, Takashi Ohwada, and Kenzoh Yada

✓ The authors report the cases of 37 patients encountered during the past 4 years who exhibited acute extradural hematoma but were initially treated conservatively because no or only small hematomas were observed on admission. The frequency of hematoma enlargement, hematoma size, and changes in the level of consciousness and intracranial pressure (ICP) were examined in these patients. The hematomas enlarged in 24 (64.9%) of the 37 patients, and attained a maximum thickness of 25 mm or greater in 19 patients (51.3%). The level of consciousness could be closely observed during enlargement of the hematomas in 13 patients: the level remained unchanged in eight, deteriorated in two, and improved in three, indicating relative stability in the state of consciousness despite the marked changes in hematoma size. The patients whose hematoma enlarged after the initial examination included three who underwent initial CT examination 5 hours after the injury. In five patients enlargement of extradural hematomas was observed unexpectedly during conservative treatment under ICP monitoring.

The ICP also remained stable in three patients until the follow-up examination, but showed a rapid increase in two after a period of stability. However, there was no difference in the final size of the hematomas between the patients showing an increase in ICP and those who did not. These findings suggest that extradural hematomas enlarge progressively at rates varying with the condition of the source of hemorrhage. Moreover, a period of stability in the level of consciousness, such as the lucid interval seen in patients with extradural hematoma, is considered to be a period during which compensatory mechanisms can maintain the stability of the intracranial condition during progressive enlargement of the hematoma.

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Yoshio Miyasaka, Kenzoh Yada, Takashi Ohwada, Takao Kitahara, Akira Kurata, and Katsumi Irikura

✓ The authors studied the venous drainage system and its impairment in relation to risk of hemorrhage in 108 cases of supratentorial arteriovenous malformation (AVM). The proportion of AVM's undergoing hemorrhage (hemorrhagic rate) was calculated in relation to: 1) the number of draining veins (one, two, or three or more); 2) the presence or absence of impairment in venous drainage (severe stenosis or occlusion in draining veins); and 3) the location of draining veins (deep venous drainage alone, superficial venous drainage alone, or a combination of the two). Statistical analysis demonstrated that AVM's with the following characteristics had a high risk of hemorrhage: 1) one draining vein (hemorrhagic rate 89% in 54 patients); 2) severely impaired venous drainage (hemorrhagic rate 94% in 18 patients); and 3) deep venous drainage alone (hemorrhagic rate 94% in 32 patients).

The present study suggests that the venous drainage system of AVM's is significantly associated with the risk of hemorrhage of these lesions. Therefore, careful preoperative angiographic evaluation of the venous drainage system is mandatory for decision making in the management of patients with AVM's.