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Masayuki Fujioka, Kazuo Okuchi, Hideaki Iwanaga, and Toshisuke Sakaki

✓ The case of a 63-year-old man with acute obstructive hydrocephalus is presented. To the authors' knowledge, this is the first reported case of acute obstructive hydrocephalus associated with nonketotic hyperosmolar diabetic coma. It is believed that the plasma hyperosmolality resulted in osmotic endothelial injury leading to brain-stem edema.

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Shoichiro Kawaguchi, Shuzo Okuno, and Toshisuke Sakaki

Object. The authors evaluated the effects of superficial temporal artery—middle cerebral artery (STA—MCA) bypass in the prevention of future stroke, including rebleeding or an ischemic event, in patients suffering from hemorrhagic moyamoya disease by comparing this method with indirect bypass and conservative treatment.

Methods. Twenty-two patients who had hemorrhagic moyamoya disease but no aneurysm comprised the study group. These patients' clinical charts were examined with respect to their treatment and clinical course after an initial hemorrhagic episode. The mean age of the patients was 43 years and the follow-up period ranged from 0.8 to 15.1 years, with a mean of 8 years. Eleven patients (50%) were conservatively treated. Among the 11 patients who were surgically treated, STA—MCA bypass was performed in six patients (27%) and encephaloduroarteriosynangiosis (EDAS) in the other five patients (23%). Nine patients (41%) presented with an ischemic or rebleeding event during the follow-up period. The incidence of future stroke events in patients who had undergone an STA—MCA bypass was significantly lower (p < 0.05) than that in patients who had been treated conservatively or with EDAS. Kaplan—Meier plots comparing stroke-free times in patients treated with direct bypass and those in patients who conservatively or with indirect bypass showed a significant difference (p < 0.05) in favor of direct bypass.

Conclusions. The effect of STA—MCA bypass on the prevention of recurrent hemorrhage or an ischemic event in patients with hemorrhagic moyamoya disease has been statistically confirmed in this study.

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Ryunosuke Uranishi, Hiroyuki Nakase, and Toshisuke Sakaki

Object. Although various mechanisms of the development of dural arteriovenous fistula (AVF) have been described, the exact course of its pathogenesis, including molecular processes mediating its genesis, is still unknown. Recently, the importance of sinus thrombosis and venous hypertension has been reported in experimental and clinical studies. Additionally, a role of angiogenic growth factors in the pathogenesis of vascular malformations of the central nervous system has been reported. In this study, the authors investigated the existence of sinus thrombosis in dural AVF and the expression of angiogenic growth factors (basic fibroblast growth factor [bFGF] and vascular endothelial growth factor [VEGF]) in nine patients with dural AVFs that were surgically resected.

Methods. The authors examined histological features of dural AVFs that involved the transverse/sigmoid sinus in seven patients and the superior sagittal sinus in two. Sinus thrombosis was verified angiographically in seven cases and histologically in all cases. In surgically resected specimens the angiogenic growth factors bFGF and VEGF were examined immunohistochemically in nine patients with dural AVFs, with five dural sinuses from cadavers with unrelated central nervous system diseases serving as a normal control group. The media and perivascular connective tissues of the arteries in the wall of the normal dural sinuses stained faintly for bFGF; on the other hand, the expression of VEGF was not detected. In all patients with dural AVFs, the thick wall of the dural sinus stained strongly for bFGF, mainly in the subendothelial layer and media of the strongly proliferative vessels in the sinus wall, in addition to the perivascular connective tissues. In all nine cases VEGF was expressed in the endothelium of the sinus and perivascular connective tissues. In two cases, VEGF was expressed in many capillaries proliferating in the granulation-like tissues in sinuses that were obliterated by organized thrombi.

Conclusions. It is concluded that the pathogenesis of dural AVF is still unknown, but that angiogenic growth factors, which might be produced by the healing process due to sinus thrombosis, may participate in the genesis of dural AVF. Understanding the mechanism of molecular pathogenesis in the development of dural AVF might aid in the establishment of a new therapeutic strategy for this dynamic vascular disease.

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Tetsuya Morimoto, Hiroyuki Ohtsuka, Toshisuke Sakaki, and Masahiko Kawaguchi

✓ This 32-year-old man had undergone C3–7 laminectomy for posttraumatic cervical myelopathy associated with spinal canal stenosis. He developed recurrent myelopathy 5 years after the initial operation. Dynamic magnetic resonance (MR) imaging of the cervical spine demonstrated spinal cord compression with diffuse canal stenosis while the neck was in the extended position, whereas no significant stenosis was visualized in the neutral position. Sagittal and axial MR images of the affected levels demonstrated striking changes in the cervical spinal cord configuration. Because of an associated hard osteophyte formation and protruded disc, as well as a hypertrophied posterior longitudinal ligament, an anterior decompression and fusion with plate fixation were performed from C-4 to C-7. The postoperative course was uneventful, with subsequent neurological improvement. It is concluded that dynamic MR imaging aids the search for the cause of recurrent postlaminectomy cervical myelopathy after initial improvement following decompressive surgery.

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Yoshinari Okumura, Toshisuke Sakaki, and Hidehiro Hirabayashi

✓ The pathophysiology of primary arachnoid cysts of the middle cranial fossa is still unclear, and no widely accepted therapeutic criteria for this condition have been established. The authors present the case of a 7-year-old boy with this cyst accompanied by temporal lobe hypoplasia. On the basis of computerized tomography taken on the 2nd day after birth and magnetic resonance imaging upon admission, the arachnoid cyst in this case was attributed to brain hypoplasia secondary to abnormal arachnoid development and was confirmed to have developed primarily during infancy. Experience with this case yielded new findings useful in clarifying the pathophysiology of this condition and establishing therapeutic criteria for such a case.

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Takeshi Matsuyama, Takahide Shimomura, Yoshinari Okumura, and Toshisuke Sakaki

✓ The authors describe a technique for mobilization of the internal carotid artery (ICA) for basilar artery (BA) aneurysm surgery. Using the epidural approach, the anterior clinoid process, orbital roof, and optic canal are drilled away. The ICA is made mobile to the C3 segment by cutting the dural ring and dissecting the ICA from the carotid groove. The ophthalmic artery is then dissected from the optic canal. This mobilization of the ICA secures wide operative fields on both its medial and lateral sides and permits complete clipping of BA aneurysms.

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Takeshi Matsuyama, Tetsuya Morimoto, and Toshisuke Sakaki

✓ Bow hunter's stroke results from vertebrobasilar insufficiency caused by mechanical occlusion or stenosis of the vertebral artery (VA) at the C1–2 level on head rotation. Surgical treatment of this condition may be chosen to avoid life-threatening accidents or because patients complain that conservative treatments such as verbal warnings or use of a neck brace to limit head and neck rotation are ineffective and thus restrict their lifestyle. Posterior fusion involving C1–2 has long been used to limit atlantoaxial rotational movements. However, it has the serious disadvantage that the range of head motion is severely reduced. Recently, decompression of the atlantoaxial portions of the affected VA has been used because it does not limit physiological neck movements. However, no long-term follow-up review of patients who have undergone this procedure has been conducted, and it is unclear whether this procedure always provides relief of symptoms. To answer this question, the results of C1–2 posterior fusion were compared with decompression of the VA for the treatment of bow hunter's stroke.

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Takanobu Kaido, Hiroyuki Nakase, Ryunosuke Uranishi, and Toshisuke Sakaki

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Takanobu Kaido, Tohru Hoshida, Toshiaki Taoka, and Toshisuke Sakaki

Object. The lateral occipital cortex in humans is known as the “extrastriate visual cortex.” It is, however, an unexplored field of research, and the anatomical nomenclature for its surface has still not been standardized. This study was designed to investigate whether the lateral occipital cortex in humans has retinotopic representation.

Methods. Four right-handed patients with a diagnosis of intractable epilepsy from space-occupying lesions in the occipital lobe or epilepsy originating in the occipital lobe received permanently implanted subdural electrodes. Electrical cortical stimulation was applied directly applied to the brain through metal electrodes by using a biphasic stimulator. The location of each electrode was measured on a lateral skull x-ray study. Each patient considered a whiteboard with vertical and horizontal median lines. The patient was asked to look at the midpoint on the whiteboard. If a visual hallucination or illusion occurred, the patient recorded its outline, shape, color, location, and motion on white paper one tenth the size of, and with vertical and horizontal median lines similar to those on, the whiteboard. Polar angles and eccentricities of the midpoints of the phosphenes from the coordinate origin were measured on the paper. On stimulation of the lateral occipital lobe, 44 phosphenes occurred. All phosphenes were circular or dotted, with a diameter of approximately 1 cm, except one that was like a curtain in the peripheral end of the upper and lower visual fields on stimulation of the parietooccipital region. All phosphenes appeared in the visual field contralateral to the cerebral hemisphere stimulated. On stimulation of the lateral occipital lobe, 22 phosphenes moved centrifugally or toward a horizontal line. From three-dimensional scatterplots and contour maps of the polar angles and eccentricities in relation to the x-ray coordinates of the electrodes, one can infer that the lateral occipital cortex in humans has retinotopic representation.

Conclusions. The authors found that phosphenes induced by electrical cortical stimulation of the lateral occipital cortex represent retinotopy. From these results one can assert that visual field representation with retinotopic relation exists in the extrastriate visual cortex.

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Jun Karasawa, Haruhiko Kikuchi, Seiji Furuse, Junichiro Kawamura, and Toshisuke Sakaki

✓ Moyamoya disease is a chronic occlusive cerebrovascular disease of unknown etiology for which no effective treatment has been found. The authors report the results of 23 superficial temporal-middle cerebral artery (STA-MCA) anastomoses and seven encephalomyosynangioses, performed on 13 cases with moyamoya disease and on four additional atypical cases. There were 10 children and seven adults in this study. The follow-up period ranged from 1 year and 4 months to 4 years and 1 month postoperatively; nine patients had excellent results, five good, and one fair; two patients were unchanged. The anastomotic procedure was most effective for transient ischemic attacks, reversible ischemic neurological deficits, and even minor or moderate neurological symptoms. The STA-MCA anastomosis appears to be an effective treatment for moyamoya disease.