Takekane Yamaguchi

Plasma Concentrations of Brain Natriuretic Peptide in Patients with Acute Ischemic Stroke

Background: Acute blood pressure (BP) elevation and cardiac abnormalities are known to follow ischemic stroke. Brain natriuretic peptide (BNP), which is produced in response to such cardiovascular alterations, is expected to play a hemodynamic role. We measured plasma BNP concentrations in patients with cerebral infarction (CI) to determine the implications of BNP in acute ischemic stroke. Methods: Eighty-eight patients with CI, 59 with essential hypertension, 44 with spontaneous intracerebral hemorrhage, 22 with asymptomatic atrial fibrillation (Af), and 20 age- and sex-matched healthy volunteers were recruited in the study. CI patients were divided into 2 subgroups either having Af (27 patients) or not (61 patients). BNP levels were repeatedly measured in 58 patients with CI. BNP levels were compared between ischemic subgroups categorized by size of infarction. Correlation was investigated between BNP levels and hemodynamic parameters. Results: BNP levels in CI patients were significantly higher, but they decreased in the subacute period. BNP levels in CI patients without Af were correlated with mean arterial blood pressure (MAP) on admission or the degree of reduction in MAP at day 1, while in CI patients with Af BNP levels showed negative correlation with MAP on admission. Follow-up serum sodium levels in CI patients with Af were negatively correlated with BNP levels on admission. Conclusions: This study suggests the hemodynamic implications of BNP in acute ischemic patients.

Microphysiology of Selectively Vulnerable Neurons

Publisher Summary This chapter describes the changes of neuronal function and other physiological parameters. A common carotid artery (CCA) occlusion in Mongolian gerbils, as well as regional differences of these parameters is also described. In a method described in the chapter, bilateral CCA occlusion produces severe ischemia in both cortex and hippocampus. During CCA occlusion, the forebrain reveals severe ischemia followed by heterogeneous hyperemia after the occlusion is released. The chapter presents the morphological observations that reveal that five minutes of forebrain ischemia in gerbils lead to highly reproducible delayed destruction of neurons in the hippocampal CA1 subfield. With respect to CAlN, notable changes are observed first at two days following ischemia, at the time neurons show some loss of Nissl substance, a more accentuated staining of dendrites, and appearance of clear clefts in the cytoplasm. After three days, most of the CAlN shows severe ischemic injury, followed by neuronal disintegration at four days. The cortex showed no pathological changes during the whole observation period. The described changes of various parameters resulting from five minutes ischemia in gerbils demonstrate that ischemic death of CAlN takes place during the recirculation period.

Intraoperative monitoring of depth-dependent hemoglobin concentration changes during carotid endarterectomy by time-resolved spectroscopy

By measuring the adult human head during carotid endarterectomy, we investigate the depth sensitivity of two methods for deriving the absorption coefficient changes (Dmu(a)) from time-resolved reflectance data to absorption changes in inhomogeneous media: (1) the curve-fitting method based on the diffusion equation (DE-fit method) and (2) the time-independent calculation based on the modified Lambert-Beer law (MLB method). Remarkable differences in the determined values of Dmu(a) caused by clamping the external carotid artery and subsequently clamping the common carotid artery were observed between the methods. The DE-fit method was more sensitive to mu(a) changes in cerebral tissues, whereas the MLB method was rather sensitive to mu(a) changes in the extracerebral tissues. Our results indicated that the DE-fit was useful for monitoring the cerebral blood circulation and oxygenation during neurosurgical operations. In addition, the combined evaluation of mu(a) changes with the DE-fit and MLB methods will provide us with more available information about the hemodynamic changes in the depth direction.

Plasma concentrations of atrial and brain natriuretic peptides in a case with hypertensive encephalopathy

Abstract Hemodynamic mechanism for brain edema formation in patients with hypertensive encephalopathy is unclear. Potential roles of natriuretic peptides in the pathogenesis of hypertensive encephalopathy are discussed. A 32-year-old man presented with slight left hemiparesis. He was slightly confused, and his blood pressure was extremely high. Cranial plain computerized tomography scans revealed diffuse brain edema mainly in the supratentorial white matter region. Blood examination revealed that plasma concentrations of atrial and brain natriuretic peptides were significantly high. His left hemiparesis disappeared within a day, but he tended to be agitated. His altered mental status, however, resolved with control of blood pressure. Serial magnetic resonance imagings demonstrated that the magnitude of brain edema was attenuated in proportion to decline in plasma concentrations of natriuretic peptides. This case suggests that significant elevation of plasma concentrations of natriuretic peptides may contribute to an acute rise in blood pressure, and that these peptides potentially play an important role in development of brain edema in hypertensive encephalopathy. [Neurol Res 2002; 24: 627-630]

A case of internal carotid artery occlusion successfully treated by encephalo-duro-arterio-synangiosis

In many cases, intracranial occlusive strokes in children are treated symptomatically, with a diagnosis of acute infantile hemiplegia. This is because angiography is more difficult in children and, even if occlusive cerebral arterial disease is diagnosed, there is no definite therapeutic procedure. A case is reported of left internal carotid artery occlusion presenting with acute infantile hemiplegia and followed by repeated transient ischemic attacks. Encephalo-duro-arterio-synangiosis — developed as an operation for moyamoya disease — was performed on this patient, resulting in a marked revascularization of the brain in 8 postoperative months with good improvement in symptoms. This suggests that the operation may be effective in chronic cerebral ischemic diseases other than moyamoya disease.

Cerebral Ischemia Model Using Mongolian Gerbils—Comparison Between Unilateral and Bilateral Carotid Occlusion Models

We permanently occluded unilaterally and/or bilaterally the carotid arteries of anesthetized Mongolian gerbils (60-80 g) and compared the two models. In the former, stroke-positive animals were selected by calculating the stroke index score of the conscious animals. Selection was not made in the latter. We measured the rCBF of the cerebral cortex, hippocampus, and diencephalon using the (3)H-nicotine scintillation method; analyzed the EEG using the wave-form recognition method (Fujimori); measured ATP, PCr (phosphocreatine), lactate, and glucose content in the cerebral hemisphere using the Lowry method; and measured infarct size on HE-stained coronal sections. All parameter values were uniform in the gerbils of the unilateral model, whereas great variation was observed in the right and left cerebral cortex, hippocampus, and diencephalon in the bilateral occlusion model. Therefore, we have discarded the bilateral model and used the stroke-positive unilateral model only.By changing the length of time of the unilateral carotid occlusions and intervals, we found that two 10-min unilateral carotid occlusions with a 5-h interval between them achieved a threshold ischemic insult in gerbils, which produced uniform cortical focal infarctions that evolved in the maturing DSNN on the coronal surface sectioned at the chiasmatic level (Face A). This model showed a marked reduction in the occurrence of ischemic epilepsy and death.

A Clinical Study on Shunt Revision: Comparison in children and adults

Three hundred and fifty nine shunt procedures in 182 patients (51 children and 131 adults) were evaluated retrospectively for dysfunction and complications.

Experience with Shunting Operations Using Double Lumen Ventricular Catheters in Hydrocephalic Patients

From October 1967 to September 1986, 51 children and 118 adults with nontumoral and tumoral hydrocephalus received cerebrospinal fluid shunt operations which included both ventriculoperitoneal shunts and ventriculoatrial shunts. The results of shunting operations with double lumen ventricular catheters were compared with the ones with other kinds of ventricular catheters. Fifteen children underwent shunt operations using double lumen ventricular catheters in which 6 cases had 24 shunt revisions. Only one shunt revision in one case was done due to trouble at the ventricular site. In contrast, 36 children had shunt operations using one of the other kinds of ventricular catheters like Pudenz and Denver in which 22 cases needed 48 shunt revisions. Fourteen shunt revisions in 12 cases were based on occlusion of ventricular site.

CT Diagnosis of Brain Tumors

This report is mainly based on experiences of CT in 195 cases of brain tumor, 39 cases of which were examined by sequential delayed enhanced CT. The CT findings of these were compared with those of delayed radioisotope scan, operative and histological findings. The results are as follows. Malignant glioma has usually lower density than normal brain tissue on plain CT, and has a ring or irregular shaped circular high density zone on contrast enhanced CT. The density of cystic or necrotic portion increases gradually and reaches its peak in 3 hours after intravenous contrast media injection (ivcmi). In radioisotope scanning, these tumors show higher uptake in delayed scan than early scan. The density of astrocytoma with large or multiple small cysts is very low on CT, and does not increase on enhanced CT. However, in the case of solid astrocytoma with cyst, the density of cystic area reaches its peak in 3 hours after ivcmi. Meningioma is more sharply delineated than other tumors on CT, and its density becomes homogeneously highest immediately after ivcmi for a short time (30 min.), and then begins to decrease rapidly; in radioisotope scan, early scan reveals higher uptake than delayed scan. Acoustic neurinoma is usually characteristic of its major low density area on plain CT, which takes high density after ivcmi in some cases. In metastatic tumor, a large amount of low density area is detected around the metastatic nodules, and the finding of multiplicity offers considerable evidence of its diagnosis. The increase in density of brain tumor on CT after ivcmi is probably due to its high vascularity and/or increased permeability of vessels in tumor and/or adjacent tissue, and contrast enhancement of cyst in brain tumor is presumably caused by the exudation and/or transudation of contrast media through the cyst wall. In general, the sequential increase and decrease of density of brain tumor on CT after intravenous administration of contrast media is approximate to the sequential change of uptake of radioisotope in tumor on R I scan. We have classified the brain tumor into 4 groups by its sequential pattern of contrast enhancement on CT; immediate, delayed, continuous, and no enhancement.