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  • Author or Editor: Yutaka Inaba x
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Umeo Ito and Yutaka Inaba

✓ A method is described which has been found capable of detecting subarachnoid hemorrhage (SAH) up to 15 to 17 weeks after its occurrence. The episode of SAH was confirmed by bloody and/or xanthochromic cerebrospinal fluid (CSF) at the time of SAH onset. In this study, 47 samples of lumbar CSF from diagnostically confirmed SAH patients were used. The CSF cells were collected onto slides and stained with May-Gruenwald-Giemsa or Perl's reagent. Iron-positive cells were detected at 1 week, increased by 4 to 6 weeks to 8.5% of total nucleated cells, and decreased to 1% by 15 to 17 weeks. All 27 samples obtained at 2 to 9 weeks after SAH showed iron-positive cells. No iron-positive cells (false-negative samples) were noted in 25% (one of four) of samples obtained during the first week, and in 33% (one of three) of samples obtained 10 to 12 weeks and 15 to 17 weeks after SAH. Of the total samples (37) obtained within 17 weeks after SAH, 8.1% (three of 37) were false negative. No iron-positive cells were detected in samples obtained later than 21 weeks after the SAH episode (10 samples).

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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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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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Hideo Hiratsuka, Hitoshi Tabata, Shin Tsuruoka, Masaru Aoyagi, Kodai Okada and Yutaka Inaba

✓ Hydrocephalus was induced in 13 dogs by injecting kaolin into the cisterna magna and was evaluated by computerized tomography (CT) scans. Modification of periventricular hypodensity was observed by metrizamide-enhanced CT ventriculography. Periventricular hypodensity was seen as early as 12 hours after kaolin injection. On CT ventriculography, metrizamide stayed longer in the ventricles of hydrocephalic dogs than in those of normal dogs, and migrated into the areas of periventricular hypodensity; the changes became significant within 12 to 24 hours. Four of the dogs were killed immediately after CT ventriculography, and the iodine concentration was measured. Iodine concentration was highest in the periventricular white matter, followed by the basal ganglia, and it was low in the cerebral and cerebellar cortex. When the change in Hounsfield units found by CT ventriculography at the regions of interest was compared to the actual iodine concentrations, the figures were quite compatible. Similarly, the specific gravity was measured in tissue from various parts of the brain of two hydrocephalic dogs, and compared against the value of that from five normal dogs. The specific gravity values were particularly low in the periventricular white matter of the hydrocephalic brains, suggesting a higher water content in that region. Since the increased migration of metrizamide occurred at the same region, it is suggested that development of periventricular hypodensity is due to increased transit of cerebrospinal fluid from the ventricles to the white matter.