Tarumi Yamaki

CHANGES IN CEREBRAL BLOOD FLOW VELOCITY IN HEALTHY YOUNG MEN DURING OVERNIGHT SLEEP AND WHILE AWAKE

Using transcranial Doppler ultrasonography, we measured in 6 healthy young men cerebral blood flow velocity (CBFV) in the middle cerebral artery as well as oxygen saturation by a non-invasive method. Continuous recordings were taken starting from a point before the onset of sleep, throughout the duration of normal nighttime sleep, ending after awakening. During stages 2, 3 and 4, CBFV was approximately 15% lower than during the waking period preceding sleep. CBFV during rapid eye movement sleep did not differ from the presleep waking value, whereas the postsleep waking value was 6.6% lower. In 5 subjects CBFV showed a transient rise after sleep onset. Oxygen saturation was lower during sleep than during waking.

Chronological evaluation of acute traumatic intracerebral haematoma

SummarySerial computed tomographic (CT) studies were performed in 48 patients with brain contusion. Traumatic intracerebral haematoma (TIH) had developed within 6 hours in 56% of the cases, within 12 hours in 81% and 100% within 24 hours from the onset. TIH reached its maximal size in 84% of the cases within 12 hours. The incidence of the appearance of TIH from brain contusion was 52%. The performance of frequent CT examination within 24 hours following head injury would help to lower the mortality rate of such trauma.

Positron emission tomographic studies on cerebral hemodynamics in patients with cerebral contusion.

Positron emission tomography is currently one of the most useful methods for measurements of cerebral hemodynamics and oxygen metabolism, because it facilitates accurate analysis of the local cerebral circulation in three-dimensional quantitative images. In this study, we performed positron emission tomography studies to measure cerebral circulation in a total of 11 patients who sustained head injuries with contusion. Several parameters were measured including regional cerebral blood flow, regional cerebral blood volume, permeability, and regional cerebral metabolic rate for oxygen. Data from brains both with and without contusion were analyzed for chronological changes, in the subacute stage from the 8th to 29th day and in the chronic stage until 360 days after the injury and compared with similar data in a group of normal subjects. It was concluded that in the subacute stage, regional cerebral blood flow decreased (26 +/- 7 and 39 +/- 10 ml/100 g/min) and regional cerebral blood volume increased (5.6 +/- 1.8 and 5.4 +/- 0.9 ml/100 g) both in areas of cerebral contusion and in areas remote from cerebral contusion and that permeability increased in areas of contusion but not in remote brain areas. In the chronic stage, these parameters showed a tendency for recovery.

Value of Repeat Angiography in Patients With Spontaneous Subcortical Hemorrhage

BACKGROUND AND PURPOSE Neuroradiological investigations do not disclose a source of bleeding in some patients with spontaneous subcortical hemorrhage. These patients may harbor undetected vascular malformations and may be at risk of rebleeding in the future. We investigated patients with subcortical hemorrhage with use of repeat angiography and MRI to determine the incidence of occult vascular malformations and the risk of bleeding during follow-up. METHODS We reviewed a consecutive series of 137 patients with subcortical hemorrhage during a 10-year period (June 1987 through June 1997). If the patient was <65 years old and the first angiogram and/or MRI did not show a source of bleeding, repeat angiography was recommended. All angiographic and MRI studies were reviewed. The relationship between the identified bleeding source and clinical variables such as patient age, sex, and history of hypertension and the size and location of the hematoma were examined. RESULTS One hundred seven patients (78%) underwent angiography on admission, 10 (7%) had immediate surgery for hematoma without angiography, and 20 (15%) had neither angiography nor surgery. Overall, an etiology for the hemorrhage was found in 55 cases (40%). Vascular malformations were common in young patients without preexisting hypertension. A second angiogram was obtained in 22 patients, and 4 arteriovenous malformations were demonstrated. Rebleeding at the site of the initial hemorrhage was not observed after a mean follow-up of 68 months. CONCLUSIONS Angiography performed acutely after hemorrhage may not demonstrate vascular malformations. Consideration should be given to repeat angiography in patients who do not have a specific cause for hemorrhage.

Investigation of morphological change of lateral and midline fluid percussion injury in rats, using magnetic resonance imaging.

OBJECTIVE Investigating the time course of morphological changes in experimental traumatic brain injury (TBI) in vivo helps to clarify the mechanism of TBI and develop new therapeutic modalities. We examined the morphological changes in experimental TBI, using magnetic resonance imaging (MRI) in a rat model. METHODS We produced lateral fluid percussion injury (LFP) and midline fluid percussion injury (MFP) in rats, using the Yamaki fluid percussion device. The rats were divided into four groups: LFP, MFP, sham LFP, and sham MFP. MRI was performed with a 4.7-T magnetic resonance apparatus 2 days and 90 days after the induction of injury. T1-, T2-, and T2- weighted images were obtained using a surface coil. RESULTS Hemorrhage, contusion, and brain edema in LFP models were detected on the 2nd day after injury, and the necrotic tissue was absorbed and replaced by cerebrospinal fluid on the 90th day. In MFP animals, we detected a small hemorrhage in the corpus callosum with minimal brain edema around the hemorrhage on the 2nd day after injury, and on the 90th day, enlarged ventricles and cisterns were observed, indicating brain atrophy. CONCLUSION MRI, therefore, is useful for plotting morphological changes in experimental TBI in vivo. We report the novel and clinically important finding of brain atrophy after experimental TBI.

Chronological Positron Emission Tomographic Study of Severe Diffuse Brain Injury in the Chronic Stage

Cerebral blood flow and metabolism were investigated in five patients with severe diffuse brain injury in the chronic stage, using positron emission tomography (PET). Regional cerebral blood flow, regional oxygen extraction fraction, regional cerebral blood volume, regional cerebral metabolic rate for oxygen, and regional cerebral metabolic rate for glucose were measured bilaterally in the frontal, temporal, occipital, and parietal gray matter, as well as the white matter of the centrum semiovale. In 4 of 5 patients, a follow-up PET study was also performed. In three cases, below-normal regional cerebral blood flow and regional cerebral metabolic rate for oxygen values accompanied by above-normal regional oxygen extraction fraction values, as well as low metabolism, were demonstrated in the initial PET studies. In two of three cases, clinical improvements were observed, and follow-up PET data also improved. These findings suggest that chronological PET studies may be able to assess quantitatively clinical improvements in patients with diffuse brain injury.

Kissing aneurysms of distal anterior cerebral arteries demonstrated by magnetic resonance angiography

BACKGROUND Multiple aneurysms, associated with distal anterior cerebral artery (ACA) aneurysm, are not rare; therefore, it is important to examine multiplicity of the aneurysms preoperatively. CASE REPORT A case of ruptured distal ACA aneurysm, associated with another one in a mirror position, is reported. A 43-year-old woman suffered subarachnoid hemorrhage. Conventional angiography demonstrated a saccular aneurysm on the bifurcation of the right or left distal ACA; however, magnetic resonance angiography (MRA) revealed two mirror-image aneurysms on both bifurcations. CONCLUSION MRA was useful for preoperative diagnosis of kissing aneurysms on distal ACAs.

Cognitive dysfunction and histological findings in rats with chronic-stage contusion and diffuse axonal injury

The Morris water maze (MWM) technique is well known as a prominent method of evaluating learning acquisition and memory retention impairments in rats. We previously reported on a modified fluid percussion device that is able to consistently produce experimental cortical contusion (CC) and diffuse axonal injury (DAI) in separate groups of rats. The purpose of the present protocol is to evaluate the differences in learning acquisition and memory retention impairments between these two types of injured rats in the chronic stage using the MWM technique. CC and DAI rats are respectively induced by lateral and midline fluid percussion. We also compare the histological differences between these two different types of traumatic brain injury. The results show statistically significant differences in learning acquisition impairment between the sham and CC rats and between the sham and DAI rats. However, a difference in memory retention impairment was expected to be seen only between the sham and DAI rats. Histologically, the loss of CA3 pyramidal cells in the hippocampus was observed ipsilaterally in the CC and bilaterally in DAI. Neuronal cell loss was observed in bilaterally in layer II of the entorhinal cortex in DAI, but not in CC.

Evaluation of learning and memory dysfunction and histological findings in rats with chronic stage contusion and diffuse axonal injury

We previously reported a modified fluid percussion device capable of consistently producing experimental cortical contusion (CC) and diffuse axonal injury (DAI) in separate groups of rats by lateral and midline fluid percussion, respectively. The purpose of the present study was to compare the differences in learning acquisition and memory retention impairments between these two types of injured rats in the chronic stage using the Morris water maze technique. We also compared the histological differences between these two different types of traumatic brain injury. The results showed a statistically significant difference in learning acquisition impairment between the sham and CC rats and also between the sham and DAI rats. However, a significant difference in memory retention impairment was observed only between the sham and DAI rats. Histologically, the neuronal cell loss of CA3 pyramidal cells in the hippocampus was observed on the ipsilateral side in the CC and bilaterally in DAI. The neuronal cell loss was seen in bilateral entorhinal cortex layer II in DAI, but it was not seen in CC. From these results, we speculate that the marked cell loss in the hippocampus CA3 region in both CC and DAI rats was related to the impairment of spatial learning acquisition. The marked cell loss in entorhinal cortex layer II in DAI rats may be one of the important factors in the impairment of spatial memory retention.

Rapidly growing aneurysm

A rare case of rapidly growing intracranial aneurysm is reported. The enlarged aneurysmal wall was extirpated and studied histologically. The cause of the rapid growth of the aneurysm is discussed.