Biomedical subjects
Publications and source records attributed to J Minamikawa.
A very rare case of triplicate anterior communicating artery associated with ruptured aneurysm in a 21-year-old female is reported. The triplicate configuration was not predicted by preoperative cerebral angiography, but found intraoperatively. The aneurysm was trapped successfully, and she recovered with no neurological deficit.
We report MRI (magnetic resonance imaging) findings of 31 cases with subarachnoid hemorrhage (SAH) due to ruptured intracranial aneurysm. Among these cases, 25 were studied within 72 hours after onset of SAH. A resistive type MRI scanner operating at a field of 0.2 Tesla was used in obtaining inversion recovery (IR) and saturation recovery (SR) images. IR 1500/43/400 (T1 weighted image, T1W), SR 1000/60 (SR image) and SR 2000/100 (T2 weighted image, T2W) were chosen for analysis. The SR image was usually adopted and coronal and/or sagittal images were added when there was enough time for examination. Slice thickness was 10 mm and slice interval was 15 mm. The scan was not necessarily aimed at the visualization of aneurysm itself. 1) In the acute phase of SAH, subarachnoid spaces near the ruptured aneurysm were appeared as isointensity areas on T1W and as high intensity areas on SR image. In the subacute phase, they were depicted as high intensity areas on both T1W and SR images, and as high intensity areas on T2W. 2) Intraventricular hemorrhage was visualized as a niveau-like high intensity area, especially, within the posterior horns on the SR images. 3) SR and T2W images were suitable for detection of aneurysm itself. In a resistive-type scanner, small aneurysms were not easily visualized due to the lack of high resolution. However, 29% of aneuysms, which were not giant, could be visualized on MRI. 4) Identification of intracerebral hemorrhage and cerebral ischemia from various causes was easy on both T1W and T2W images.(ABSTRACT TRUNCATED AT 250 WORDS)
Dynamic computed tomographic (DCT) scans with iodine contrast enhancement were compared with simultaneously obtained xenon CT studies of cerebral blood flow (CBF) in 15 patients with subacute or chronic cerebrovascular ischemic disease. Specifically, the width and corrected first moment (cMT1), as demonstrated by DCT, were compared with the regional CBF (rCBF) data and the rCBF map obtained with xenon CT. The DCT and rCBF images were well correlated in patients without, but poorly correlated in those with, leptomeningeal anastomotic collateral circulation. The correlation of rCBF and 1/width with 1/cMT1 was significant (r = 0.78, p less than 0.01) in the former, but not in the latter. These data were thought to reflect a difference in the tracer inflow pattern between the patients with and those without leptomeningeal anastomoses. Our series did not include patients with acute cerebral infarction or recanalization, which are thought to be associated with marked changes in cerebral blood volume in the affected region. However, the influence of cerebral blood volume should be studied in detail in our subacute or chronic series.
Delayed neuronal deterioration of recovered neuronal function from cerebral ischemia was investigated in experiments using 25 cats. The neuronal function was evaluated by direct cortical response (DCR) and EEG. To induce cerebral ischemia clamps were applied to both the innominate and left subclavian arteries and were removed 15 minutes after complete loss of DCR. Following recovery of circulation, DCR and EEG were studied for at least 48 hours, along with the changes of cerebral blood flow (CBF) and intracranial pressure (ICP). In 7 of 25 cats CBF gradually or rapidly decreased after it was regained through recirculation due to the increase of ICP, resulting in no recovery of neuronal function. In the other 18 cats normal values of CBF and ICP were observed soon after the recirculation although temporary increase of ICP was found. The recovery of DCR and EEG was observed in 12 of these 18 cats, and these functions were maintained up to the end of the experiment in 9 of these 12 cats. In the other 3 cats and another 5 cats in which only DCR was recovered, these neuronal functions deteriorated 8 to 30 hours after recirculation. In one cat neither DCR nor EEE was recovered at all. Moreover, in the 9 cats mentioned ICP gradually increased before or after the deterioration of neuronal functions, and it finally reached the level of systemic blood pressure. These results indicate that the recovery of neuronal function from ischemic insults must be judged at least 48 hours after recirculation because of delayed neuronal deterioration, and pathogenesis of delayed neuronal dysfunction and delayed increase of ICP must be fully investigated thereafter.
Thirty-five patients (7 females and 28 males) with cerebral infarction and suspicion of cerebral infarction of 4 h to 27 months duration were studied 45 times with magnetic resonance (MR) imaging using Gd-DTPA. Spin echo (SE) images were obtained before and after the administration of Gd-DTPA (0.1 or 0.15 mmol/kg) and compared with the enhanced CT. MR imaging using Gd-DTPA was more sensitive than enhanced CT and very useful for detecting a new focus of cerebral infarction, especially in the cases with multiple infarcted areas and for showing the extent of cortical and subcortical infarction. In most cases the MR enhancement was obvious in the subacute stage, especially after cerebral embolism, and the signal intensity of the lesion tended to show a gradual increase. The diagnosis of embolism was accepted on the basis of acute onset without prior TIA, coupled with angiography showing the embolus itself and/or a capillary blush and a wide area of infarction.
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With few warnings signs, posterior fossa mass lesions can affect life-supporting brainstem systems directly and cause a precipitous failure of vital functions. Consequently, a technique, by which brainstem dysfunction could be detected at its reversible stage, would have clinical value. Recently manly reports have suggested that the evoked potentials might be advantageous in assessing a developing brainstem dysfunction and might be a more sensitive or reliable detector of deteriorating neurological function than the physical or neurological signs. To explore this possibility, we recorded somatosensory evoked potentials (SEP) and brainstem auditory evoked potentials (BAEP) serially during inflation and deflation of balloons placed in the suboccipital epidural space of cats, as a model of an acutely expanding posterior fossa lesion. The results were correlated simultaneously recorded cardiovascular and pupillary function and with supratentorial and infratentorial epidural pressure. In this study, N1 of cortical SEP (CSEP), wave IV of BAEP, and wave III of short latency SEP (SSEP) were found to be useful parameters in predicting the electrophysiological reversibility. Experimental results were as follows: 1) As the infratentorial epidural balloon was expanded, CSEP, wave IV of BAEP and wave III of SSEP showed remarkable changes both in latency and in amplitude. Decrease in blood pressure and pulse rate preceded or developed at the same time as the apparent change in CSEP. Futher expansion of the balloon resulted in Cushing phenomenon and lability of blood pressure.2) As long as wave IV of BAEP remained, and decompression was started within 15 minutes after N1 of CSEP were completely suppressed, changes in SEP. BAEP and cardiovascular function were all reversible.2+ decompression. (ABSTRACT TRUNCATED AT 250 WORDS)
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Magnetic resonance image (MRI) has been applied on central nervous system to evaluate the anatomical and functional aspects. On the other hand, gadolinium-diethylenetriamine-pentaacetic acid (Gd-DTPA) is considered to be a valuable contrast agent on MRI. This paramagnetic compound shortens the magnetic relaxation times of surrounding hydrogen nuclei by altering local magnetic environments. A molecular weight of this compound was 590, therefore this does not pass through the normal blood-brain barrier (BBB), and it may possible to detect a breakdown of BBB in vivo. In order to investigate the effect of Gd-DTPA as an indicator of BBB disruption on MRI, we measured T1 value of hemisphere of rat in osmotic BBB disruption model and experimental global cerebral ischemic model with and without Gd-DTPA. The MRI system employed was JNM-SMR 270 (JEOL) and the superconducting magnet was operated at a field strength of 6.34 tesla. Gd-DTPA was injected intra-venously through femoral vein and its dose was 0.5 mmol/kg. Osmotic BBB disruption model was made by intra-arterial injection of 25% mannitol through an internal carotid artery. Calculated T1 value of the ipsilateral hemisphere decreased with Gd-DTPA to 43.3 +/- 10.2% (n = 4) of control value immediately after BBB disruption with mannitol administration but no change of T1 value was recognized with Gd-DTPA in rats which Gd-DTPA was injected 4 hours after BBB disruption. Global ischemic insult was made by 3 vessel occlusion permanently and temporarily (30 or 120 minutes).(ABSTRACT TRUNCATED AT 250 WORDS)
The authors described methodological improvement and quantitative evaluation in measurement of cerebral blood volume (CBV) by reflectance spectrophotometry. The measurement of blood volume by this method has not been applied to the brain tissue because of the methodological difficulties. In order to obtain the accurate CBV values with this method, it is necessary to keep the proper contact between the sensor for the measurement and the brain tissue to be measured. For this purpose we developed a balance arm. A sensor for CBV measurement was fixed with the one side of the arm and a weight was installed to the other side. The pressure of the sensor to the brain can be adjusted by moving the weight, and the sensor was placed on the brain tissue with the proper pressure. Moreover, the sensor was attached with an acryl-made cap to make the pressure adjustment easier by enlarging the contact surface and to enable to observe the vasculature on the surface of the brain. With this improved method the reasonable changes of CBV could be obtained when the CO2 gas was inhalated and cerebral ischemia was produced in cats. The possibility of the quantitative evaluation was investigated using the homogenized brain tissue of cats. After the elimination of the blood from the brain by the perfusion with the saline, the brain was removed and homogenized. Then, the definite volume of blood, of which hemoglobin volume was already known, was added and measured by this method.(ABSTRACT TRUNCATED AT 250 WORDS)
Five patients (1 female and 4 males) with cerebral infarction of 4 h to 27 months duration were studied 9 times with magnetic resonance (MR) using Gd-DTPA. Spin-echo (SE) MR images (MRI) were obtained before and after the administration of Gd-DTPA, and correlative CT scans were performed on the same day. In 2 cases, 4 h and 27 months after the ictus, there was no enhancement with Gd-DTPA. There was faint enhancement in 2 cases with cerebral infarction of about 24 h duration and obvious enhancement in all cases in the subacute stage. Compared with enhanced CT, MR using Gd-DTPA demonstrated more obvious enhancement of infarcted areas. MR enhancement using Gd-DTPA showed a gradual increase and the accumulated Gd-DTPA in infarcted areas slowly diffused to the periphery. MR enhancement with Gd-DTPA is similar to that of enhanced CT, but may be more sensitive in the detection of blood brain barrier breakdown.
The possibility of quantitative evaluation of cerebral blood flow (CBF) by thermal diffusion has been reported, when the thermal gradient was created by a Peltier stack. We already described the linear relationship between the CBF and the inverse of thermal gradient elsewhere when the CBF measured by hydrogen clearance (Hydrogen CBF) was compared to the values estimated by thermal diffusion. In this paper, the correlation of linear relationship between the thermal CBF and hydrogen CBF in each animal was first investigated. Secondary, the possibility of in vitro calibration for quantitative evaluation was discussed. Two kinds of probes were manufactured. One was treated not to leak the heat from the Peltier stack except the sensors for the experimental or intraoperative use, and the other was not treated to minimize the size of probe for the long-term use by implantation into the subdural space. When the thermal CBF was compared to hydrogen CBF in each of 3 cats, a linear relationship was obtained in each and the values showing gradient and constant of the regression line were similar in each cat. Moreover, a good linear relationship was also observed when all measurements in 3 cats were included. These results suggested that there is no difference between each animal in the relationship of thermal and hydrogen CBF when the same probe is employed. In addition, the probe can be characterized with two values, and these are gradient and constant of the linear relationship. The fact that the blood flow is proportional to the heat conductivity indicates that the heat conductivity of some material is equivalent to some CBF value in the brain tissue.(ABSTRACT TRUNCATED AT 250 WORDS)
Cerebral blood flow (CBF) of 6 patients with poor outcome after subarachnoid hemorrhage is analyzed. Neurological grades of these patients were grade III in 2 and grade IV in 4 patients, and subarachnoid hemorrhage on CT was diffuse and thick in all patients. Cerebral blood flow was continuously measured for 7 to 19 days by the thermal diffusion flow probe with a peltier stack which was left on the cerebral cortex at the surgery for ruptured aneurysm. Moreover, CBF studies by cold xenon CT and 133Xe inhalation methods were also performed in discussing cases. At the same time intracranial pressure was monitored. Cerebral angiography was carried out in all except for 2 patients who died due to severe cerebral vasospasm. The initial CBF value of all patients was 20 to 40 ml/100 g/min (mean value: 27 ml/100 g/min), and these were significantly low compared to normal value (50 ml/100 g/min). Moreover, these CBF was substantially decreased several days after surgery in all patients, and it was marked in 3 patients who died. From these results it was clear that the degree of vasospasm is important to determine the prognosis. One of 3 patients who died had ruptured left posterior cerebral artery aneurysm with occlusion of bilateral internal carotid arteries. In this case further decrease of CBF due to vasospasm was observed in addition to low initial CBF resulting diffuse low flow in both hemispheres although extracranial to intracranial bypass was performed. On the other hand, it was also shown that the intracranial pressure was an important factor to influence the outcomes.(ABSTRACT TRUNCATED AT 250 WORDS)
In order to evaluate the blood flow by means of thermal diffusion, relationship between blood flow and parameters induced by thermal diffusion was investigated. Flow probe employed for measurement by thermal diffusion incorporated a Peltier stack which contained a small semiconductor and two L-shaped gold plates. These two plates were attached to both sides of the semiconductor by one side of each gold plate and the other side was surfaced with a tissue to be measured. Temperature gradient is created with current applied to the Peltier stack between two plates, one cooled and the other heated, and it is affected only by tissue blood flow. Two kinds of parameters of thermal diffusion were subjected to compare to blood flow. One was temperature gradient when the constant current was applied to the Peltier stack. The other was a current required to maintain a definite temperature gradient which was determined before hand. From the theoretical principle in thermodynamics, the correlations between blood flow and each of thermal diffusion parameters were defined by the following equations: (Formula: see text) where F is blood flow, delta V is voltage converted from temperature gradient, and Ci and Cv are constants. Each of phi v and phi i indicates the characteristics of each probe. Experimental study was carried out to confirm the above relationship using cortex of experimental animals. Under the general anesthesia, a cat was placed in prone position. After the craniotomy, dura mater was opened and a small flow probe, 10 mm in diameter, 5 mm in height and 5 g in weight, was placed on the cortex and blood flow was continuously evaluated by two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)
Total three patients with arteriovenous malformation (AVM) in basal ganglia or thalamic region were treated by intraoperative liquid embolizations. These procedures were decided because of repeated hemorrhagic episodes. In the case with AVM in the head of the caudate nucleus which was fed by several anterior perforating arteries originated from anterior cerebral artery (A1 portion) and middle cerebral artery (M1 portion), frontotemporal craniotomy was performed. After the microsurgical dissection of these feeders, one of the feeders lenticulostriate artery, was cannulated with a small-caliber polyethylene catheter, 0.6 mm in outer diameter and 0.3 mm in inner diameter. A small amount of isobutyl 2-cyanoacrylate (IBCA) was injected through the catheter. Same procedure was carried out one month later. Postoperative angiograms revealed about 90% loss of AVM. In two cases with AVM which involved almost entire thalamus, subtemporal craniotomy was done. Feeding vessels which originated from posterior communicating artery and posterior cerebral artery (PCA) were carefully dissected under the operative microscope and one of them was prepared for cannulation with small catheter. When the small amount of IBCA was injected, proximal PCA and internal carotid artery were temporarily occluded. In both cases intraoperative embolization was carried out twice. Postoperative angiograms revealed that the size of AVM was decreased to 20% in one and 40% in the other. Although temporary postoperative deterioration of neurological deficits such as hemiparesis and visual disturbance was slightly noted in all cases, no hemorrhagic episode was experienced for 6 months, 1.5 and 2 years in each after embolization.