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Tomio Ohta, Noboru Funatsu, Toshihiko Kuroiwa and Takayoshi Matsui

✓ A method for providing a saline drip during bipolar diathermy is described. Stainless steel tubing is incorporated in both blades of standard bipolar forceps and connected to the irrigating line. Irrigation is started when the forceps are closed and is stopped when they are open.

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Toshihiko Kuroiwa, Makoto Shibutani and Riki Okeda

✓ The effect of suppression of postischemic reactive hyperemia on the blood-brain barrier (BBB) and ischemic brain edema after temporary focal cerebral ischemia was studied in cats under ketamine and alpha-chloralose anesthesia. Regional cerebral blood flow (rCBF) was measured by a thermal diffusion method and a hydrogen clearance method. The animals were separated into three groups. In Group A, the left middle cerebral artery (MCA) was occluded for 6 hours. In Group B, the MCA was occluded for 3 hours and then reperfused for 3 hours; postischemic hyperemia was suppressed to the preischemic level by regulating the degree of MCA constriction. In Group C, the MCA was occluded for 3 hours and reperfused for 3 hours without suppressing the postischemic reactive hyperemia. The brain was removed and cut coronally at the site of rCBF measurement. The degree of ischemic edema was assessed by gravimetry in samples taken from the coronal section and correlated with the degree of BBB disruption at the corresponding sites, evaluated by densitometric determination of Evans blue discoloration.

The findings showed that 1) ischemic edema was significantly exacerbated by postischemic hyperemia during reperfusion in parallel with the degree of BBB opening to serum proteins, and 2) suppression of postischemic hyperemia significantly reduced the exacerbation of ischemic edema and BBB opening. These findings indicate that blood flow may be restored without significant exacerbation of postischemic edema by the suppression of postischemic hyperemia in focal cerebral ischemia.

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Toshihiko Kuroiwa, Matsutaira Tsuyumu, Hidenori Takei and Yutaka Inaba

✓ The effect of Nd:YAG and CO2 laser beams on cerebral microvasculature was examined in experimental animals. Soft x-ray microangiography and histological examination of the brain after Nd:YAG laser exposure revealed broad avascular or oligovascular zones in the irradiated and the surrounding edematous tissue, in which the surviving vessels were narrowed and tapered without significant leakage of blood. After CO2 laser exposure, a wedge-shaped tissue defect surrounded by layers of charring, coagulation, and edema was observed. The main finding in the surrounding coagulation and edematous layers was dilatation of the vessels. Hemorrhage was sometimes observed, mainly in the edematous layer. These findings seem to explain the effective hemostatic capability of the Nd:YAG laser and the occasional hemorrhage following CO2 laser exposure, especially at high energy output.

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Jun Deguchi, Makoto Yamada, Ryusuke Ogawa and Toshihiko Kuroiwa

✓ Purely intraorbital arteriovenous fistulas (AVFs) are rare, and their clinical management is controversial. The authors successfully treated a patient with an intraorbital AVF by transvenous embolization alone. An accurate distinction between an arteriovenous malformation (AVM), which is characterized by the existence of a nidus, and an AVF, which has no nidus, is important and requires superselective ophthalmic artery angiography. Treatment of an intraorbital AVF by transvenous embolization can improve visual function.

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Toshihiko Kuroiwa, Mitsuru Seida, Shuuichi Tomida, Hideo Hiratsuka, Riki Okeda and Yutaka Inaba

✓ The development of ischemic edema and blood-brain barrier (BBB) disruption during the 1st day of experimental cerebral infarction induced by transorbital occlusion of the middle cerebral artery (MCA) in cats was evaluated by computerized tomography (CT) scanning and compared to gravimetric and pathological studies. Regional cerebral blood flow was measured using the hydrogen clearance technique or stable xenonenhanced CT scanning. Edema was observed gravimetrically and microscopically as early as 1 hour after the onset of ischemia in the cortex and at 3 hours or later in both the cortex and white matter. However, a significant decrease of Hounsfield numbers on the CT scans was not detectable at 1 or 3 hours and was scarcely visible at 9 hours after occlusion. Disruption of the BBB was detected by leakage of Evans blue dye at 3 hours after the occlusion in two of six animals and at 9 hours in five of five animals. However, CT scanning after infusion of contrast material showed no significant increase in Hounsfield number even 24 hours after MCA occlusion. These discrepancies should be emphasized when the dynamics of ischemic edema and BBB disruption are evaluated for clinical therapy by CT scanning.

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Yoshinaga Kajimoto, Tomio Ohta, Hiroji Miyake, Masanori Matsukawa, Daiji Ogawa, Kohji Nagao and Toshihiko Kuroiwa

Object. The purpose of this study is to clarify the whole pressure environment of the ventriculoperitoneal (VP) shunt system in patients with successfully treated hydrocephalus and to determine which factor of the pressure environment has a preventive effect on overdrainage.

Methods. Thirteen patients with hydrocephalus who had been treated with VP shunt therapy by using a Codman– Hakim programmable valve without incidence of overdrainage were examined. The authors evaluated intracranial pressure (ICP), intraabdominal pressure (IAP), hydrostatic pressure (HP), and the perfusion pressure (PP) of the shunt system with the patients both supine and sitting.

With patients supine, ICP, IAP, and HP were 4.6 ± 3 mm Hg, 5.7 ± 3.3 mm Hg, and 3.3 ± 1 mm Hg, respectively. As a result, the PP was only 2.2 ± 4.9 mm Hg. When the patients sat up, the IAP increased to 14.7 ± 4.8 mm Hg, and ICP decreased to −14.2 ± 4.5 mm Hg. The increased IAP and decreased ICP offset 67% of the HP (42.9 ± 3.5 mm Hg), and consequently the PP (14 ± 6.3 mm Hg) corresponded to only 33% of HP.

Conclusions. The results observed in patients indicated that IAP as well as ICP play an important role in VP shunt therapy and that the increased IAP and the decreased ICP in patients placed in the upright position allow them to adapt to the siphoning effect and for overdrainage thereby to be avoided.

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Toshihiko Kuroiwa, Harushi Tanabe, Hiroyuki Takatsuka, Motohiro Arai, Nobuyoshi Sakai, Shiro Nagasawa and Tomio Ohta

✓ The rapid spontaneous resolution of two traumatic acute hematomas, one extradural and one subdural, is reported in a 17-year-old young man. The authors believe that this is the first report of simultaneous resolution of both types of hematoma.

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Yoji Tamura, Teppei Uesugi, Adam Tucker, Tohru Ukita, Masao Tsuji, Hiroji Miyake and Toshihiko Kuroiwa

Colloid cysts of the third ventricle presenting with acute obstructive hydrocephalus due to intracystic and intraventricular hemorrhage are extremely rare. The authors report a case of a 43-year-old man with a hemorrhagic colloid cyst that was treated using endoscopic surgery. A small colloid cyst of the third ventricle was initially diagnosed in the patient, and he was treated conservatively at that time. On admission to the authors' institution he presented with sudden headache onset without neurological deficits. Computed tomography and MRI demonstrated a round hemorrhagic mass lesion in the third ventricle with bilateral intraventricular hemorrhage. Endoscopic resection was performed using a flexible videoscope. Only partial removal of the cyst was performed because of a tough cyst wall with highly viscous, hemorrhagic cystic contents. Histological examination revealed a typical colloid cyst wall and hemorrhage mixed within a mucinous substance. Postoperative serial neuroimaging demonstrated a gradual reduction in the residual cyst size and normalization in the lateral ventricle size.

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Toshihiko Kuroiwa, Tsukasa Nagaoka, Masato Ueki, Ichiro Yamada, Naoyuki Miyasaka, Hideaki Akimoto, Shizuko Ichinose, Riki Okeda and Kimiyoshi Hirakawa

Object. The authors examined the correlation between changes in the apparent diffusion coefficient, regional water content, and tissue ultrastructure after vasogenic brain edema.

Methods. Vasogenic edema was induced in the white matter of six cats by cortical cold lesioning. The trace of diffusion tensor (Trace[D]) obtained from magnetic resonance imaging to measure the orientationally averaged water diffusibility was compared with the corresponding tissue water content determined by gravimetric studies and with ultrastructural water localization. Edema fluid had spread to the subcortical and deep white matter by 4.5 hours postlesioning. The increase in Trace(D) showed a significant linear correlation with the increase in tissue water content, both in the subcortical and deep white matter as follows: y = 45.5x − 2367 (r = 0.94) and y = 37.0x − 1769 (r = 0.93), respectively, where x is the water content (gram water/gram tissue) and y the Trace(D) (× 10−6 mm2/second). On histological examination, nerve fibers were found to be dissociated in the white matter and the extracellular space was markedly enlarged with protein-rich fluid. No noticeable hydropic swelling of the cellular components was observed.

Conclusions. A linear correlation was observed between increases in Trace(D) and increases in extracellular water volume in in vivo vasogenic brain edema. A similar correlation between the subcortical and deep white matter showing different arrangements of nerve fibers (parallel compared with intermingled, respectively) indicated that measurement of Trace(D) is a suitable parameter for the evaluation of vasogenic brain edema.