Biomedical subjects

K Houkin

Publications and source records attributed to K Houkin.

At least 91 records · Page 5Linked to original sources

PubMed1995

Cerebral hemodynamics and "re-build-up" phenomenon on electroencephalogram in children with moyamoya disease.

"Re-build-up" phenomenon, induced by hyperventilation, is a characteristic finding on electroencephalogram (EEG) in children with moyamoya disease, and suggests close correlation with cerebral ischemic attack. Its mechanism, however, remains obscure. In this study, we examined the relationship between the cerebral hemodynamics and this phenomenon before and after vascular reconstructive surgery. Regional cerebral blood flow and its reactivity to acetazolamide were analyzed using the xenon-133 inhalation method and single photon emission computed tomography in six children with moyamoya disease. These results were compared with the EEG. Regional vasoreactivity to acetazolamide was significantly lower in "re-build-up" -positive regions than in "re-build-up" -negative regions. Postoperative studies revealed a significant improvement of reactivity in the regions where the "re-build-up" phenomenon disappeared after surgery. These results suggest that the "re-build-up" phenomenon represents a focal reduction of the cerebral perfusion reserve in moyamoya disease.

Acetazolamide↗

PubMed1995

Regional cerebral hemodynamics in childhood moyamoya disease.

Regional cerebral blood flow (rCBF) and its reactivity to acetazolamide were analyzed in a series of 15 cases of childhood moyamoya disease, using the xenon-133 inhalation method and single photon emission CT (SPECT). Most of the patients had normal mean hemispheric cerebral blood flow (mCBF), comparable to that of age-matched healthy children. However, they had abnormal rCBF distribution and disturbed reactivity to acetazolamide in the territory of the internal carotid artery, especially in the frontal lobe. Surgical revascularization for the anterior circulation, which consisted of STA-MCA anastomosis and indirect synangiosis, dramatically improved these cerebral hemodynamics in the anterior circulation, including the frontal lobe, and reactivity to acetazolamide in the whole brain. These results suggest that surgical revascularization for the anterior circulation should be carried out in order to improve cerebral hemodynamics as widely as possible, especially in the frontal lobe, and may improve cerebral perfusion reserve in the posterior circulation.

Acetazolamide↗

PubMed1995

Proton magnetic resonance spectroscopy (1H-MRS) for the evaluation of treatment of brain tumours.

We investigated metabolic changes in brain tumours following treatment, using proton magnetic resonance spectroscopy. In meningiomas, effective therapeutic embolisation led to an acute increase in lactate. In radiosensitive tumours such as malignant lymphoma, a decrease in lactate and in increase in N-acetyl-aspartate occurred after radiotherapy, which preceded changes observed on magnetic resonance imaging. On the other hand, no significant changes in spectral patterns were observed in malignant gliomas resistant to therapy. Tissue characterisation of brain tumours by spectral patterns on proton magnetic resonance spectroscopy remains controversial. However, we have shown it to be sensitive to metabolic changes following treatment, which may reflect the efficacy of the therapy.

Astrocytoma↗

PubMed1995

Postsurgical observations of mean hemispheric cerebral blood flow with patients receiving high-flow EC-IC bypass using a radial artery graft (preliminary report, one-year observation of 10 hemispheres).

BACKGROUND: When we encounter an inaccessible internal carotid artery lesion, we sacrifice the inaccessible internal carotid artery and, at the same time, establish a high-flow extracranial-to-intracranial arterial bypass (EC-IC bypass). Questions and concerns remain, however, about the dynamics of the patient's cerebral blood flow postoperatively. METHOD: Ten hemispheres from 9 patients had received radial artery grafting as an EC-IC bypass with the simultaneous obstruction of the internal carotid artery. Their mean hemispheric cerebral blood flow (mCBF) was measured longitudinally during 1 year after surgery by single photon emission computed tomography (SPECT) and a 133Xenon-inhalation method. RESULTS: The serial mCBF values of the five hemispheres with giant aneurysm or paracavernous meningioma were attenuated during the postoperative 3-month period and then returned to the normal range. In only one case did the postoperative reduction of mCBF fail to return to normal; in addition there was a memory disturbance that had developed and progressed. Five hemispheres with the ICA stenosis did not present reduction in mCBF. In three out of five hemispheres, transient elevation of mCBF at 1 month after surgery was observed.

Aged↗

PubMed1995

Cerebral haemodynamics and long-term prognosis after extracranial-intracranial bypass surgery.

The effectiveness of extracranial-intracranial arterial (EC-IC) bypass surgery for haemodynamic stroke remains controversial. In this study correlation of presurgical and postsurgical cerebral haemodynamics with long term prognosis was evaluated. Twenty eight patients (25 men, three women: mean age 61.4 (SD 8.2) years) with reduced cerebrovascular reserve due to steno-occlusive cerebral vascular disease formed the study group. Measurement of mean hemispheric cerebral blood flow (mCBF) and the cerebral vasodilatory capacity (% mCVR) with an intravenous acetazolamide injection were performed by a xenon-133 inhalation method and SPECT. Patients were treated with EC-IC bypass surgery and measurements of mCBF and % mCVR were made again about one month after surgery. The patients were then observed for a long period (range 27-115 months). During the observation period, four patients experienced subsequent ischaemic strokes. The presurgical and the postsurgical resting mCBF for the affected hemisphere were significantly reduced in the patients with strokes during follow up compared with the values in patients without strokes during follow up (P < 0.03 and 0.01 respectively). The % mCVR of the affected hemisphere was significantly raised after surgery in all patients except one (P < 0.01). The postsurgical change in resting mCBF was not unidirectional. In conclusion, resting mCBF was unchanged and % mCVR was improved after EC-IC bypass surgery in patients with reduced cerebrovascular reserve. The group of patients with a reduced presurgical and postsurgical resting mCBF continue to be a high risk group for subsequent ischaemic stroke seen after EC-IC bypass surgery.

Aged↗

PubMed1995

Ruptured dissecting vertebral artery aneurysm detected by repeated angiography: case report.

A case of a ruptured dissecting aneurysm of the vertebral artery, which was detected by repeated angiography (third time), is reported. A 59-year-old woman, whose preoperative angiogram showed no abnormality, underwent a bifrontal craniotomy and the total removal of the right frontal glioma. However, a subarachnoid hemorrhage was detected by computed tomography the day after the surgery. Conventional angiography performed on the same day revealed no definite abnormality. Nevertheless, 9 days after surgery, a second subarachnoid hemorrhage occurred. The dissecting aneurysm of the vertebral artery was revealed by angiography. It is important to suspect this type of aneurysm as a differential diagnosis when the cause of the subarachnoid hemorrhage is not clarified in the first angiogram.

Aortic Dissection↗

PubMed1995

Serial changes in metabolism and histology in the cold-injury trauma rat brain model--proton magnetic resonance imaging and spectroscopy study.

The serial changes in metabolism and histology during the first 24 hours in the cold-injury trauma rat brain model were investigated by proton magnetic resonance (MR) imaging and high-resolution proton MR spectroscopy. Edema developed extensively via the corpus callosum in the ipsi- and contralateral hemispheres during observation as shown by gradually increased signal intensity on proton MR images. Proton MR spectroscopy showed increased levels of acetate (Ace), lactate (Lac), and glutamine (Glmi) 1 hour after lesion formation. The elevated Glmi level slightly decreased, the level of alanine (Ala) increased substantially, and that of N-acetyl-aspartate (NAA) decreased markedly after 24 hours. Increased Lac, Ace, and Ala might reflect anaerobic glycolysis associated with mitochondrial dysfunction, while decreased Glmi and NAA reveal brain tissue breakdown. The relationship between brain edema and tissue viability can be analyzed in detail using this simple traumatic model and MR techniques which will be useful in the development of therapeutic agents for brain injury.

Acetates↗

PubMed1995

Surgical treatment of childhood moyamoya disease--comparison of reconstructive surgery centered on the frontal region and the parietal region.

Indirect revascularization procedures centered on the parietal region, such as encephalo-myo-arterio-synangiosis (parietal synangiosis) and direct procedures centered on the frontal region using both the anterior and the posterior branches of the superficial temporal artery (STA), such as STA to middle cerebral artery anastomosis combined with encephalo-duro-arterio-myo-synangiosis (frontal anastomosis) were compared in childhood moyamoya disease patients. The parietal synangiosis group consisted of 10 sides in five patients, and the frontal anastomosis group consisted of 30 sides in 15 patients. The development of postoperative collateral circulation was assessed by external carotid angiography, the neurological outcome was monitored for 2 years after surgery, and the intelligence quotient (IQ) was measured at least 6 months after surgery. Frontal anastomosis achieved superior results compared to the parietal synangiosis assessed by development of collateral circulation, in particular to the orbitofrontal artery, the prefrontal artery, and the precentral artery (p < 0.01), and reduction in the incidence of ischemic attacks, such as transient ischemic attacks (p < 0.05). The mean IQ in the frontal anastomosis group was higher than that in the parietal synangiosis group. Vascular reconstruction centered on the frontal region utilizing both the anterior and posterior branches of the STA is more efficacious than only synangiosis centered on the parietal region.

Arteriovenous Anastomosis↗

PubMed1995

[A case of surgical retrieve of migrated microcatheter].

This is a report of an accidental breakaway of a microcatheter during endovascular embolization for cerebral arteriovenous malformation occurring in a 48-year-old female. She had a sudden onset of cerebral herniated signs caused by a large hemorrhage in the region of the right parietal lobe. An angiogram showed a large arteriovenous malformation in the same region. 48 days after emergency evacuation of the hematoma and clipping of a feeding artery, we performed endovascular embolization using a microcatheter as assistant therapy for total removal of the nidus. However, accidentally, the microcatheter broke and migrated to the distal middle cerebral artery. Although we tried to retrieve the catheter using a loop snare, we had no success. We eventually retrieved it by open surgery next day. Fortunately the migrated catheter could be seen through a cortical artery, so after trapping it by using elastic thread and cutting off the artery we were able to extract the migrated catheter. Finally we were able to remove the nidus totally without other complications. Since breaking and migration of a microcatheter is a rare but possible accident, we should be prepared to cope with it appropriately.

Catheterization↗

PubMed1994

Localized proton spectroscopy of focal brain pathology in humans: significant effects of edema on spin-spin relaxation time.

Localized proton nuclear magnetic resonance (NMR) spectroscopy of human brain in two common focal pathologies producing brain edema (peritumor edema and acute edematous ischemic stroke) was performed utilizing point resolved spectroscopy (PRESS). The spectra obtained from the pathological tissues were characterized by a reduced N-acetyl-aspartate (NAA) to total creatine (Cr) ratio (NAA/Cr) and high level of lactate. While the spin lattice relaxation time (T1) of the main metabolite resonances, namely, those of NAA, Cr, and choline containing compounds (Cho), showed values similar to those of normal brain, the spin-spin relaxation time (T2) of these metabolites exhibited a dramatic shortening in pathological tissues. Serial postoperative measurements of T2 in two patients with peritumor edema showed a gradual recovery of the T2 shortening corresponding to improvement of the edema. The majority of localized spectroscopy studies in humans is performed using a sequence which utilizes spin echo signals with a fixed single echo time. Hence, the signal intensities of the metabolite resonances obtained are inherently T2 dependent. The current study underscores that cautious interpretation of clinical data with respect to metabolite quantification is warranted.

Adult↗

PubMed1994

A high-field magnetic resonance imaging study of experimental vasogenic brain edema and its response to AVS: 1,2-bis (nicotinamido)-propane.

We clearly represented brain structures of rats and permitted a rapid assessment of water gradient of the brain edema by cortical freezing utilizing a high-field (7T) proton magnetic resonance imaging (MRI). The typical time course of vasogenic edema and the efficacy of AVS; 1,2-bis (nicotinamide)-propane upon the edema were presented. Twelve rats with edema induced by cortical freezing were divided into two groups; one group of animals received 0.5 ml of physiological saline with 100 mg (/kg) AVS every eight hours intraperitoneally. The other group of untreated animals received only saline. One three, six, 12, and 24 hours after lesion production, the profiles of edema fluid spreading and the maximum signal intensity (MI) of some regions of interest (ROI) were assessed by T2 weighted images (TE = 70 ms, TR = 3500 ms). One hour after lesion production in the untreated group, a low heterogeneous intensity area was seen mainly in the primarily injured cortex. Two hours later, the margin of the lesion gradually increased in intensity and MI of ROIs around the lesion also gradually increased. Twenty-four h after lesion production edema extended contralaterally via corpus callosum. AVS reduced edema fluid spreading beginning from about six hours after lesion production. The MIs of the AVS treated group were significantly lower than in the untreated group (p < 0.01). We conclude that sequential observation of edema using MRI is a quite practical technique for evaluation of the efficacy of any therapeutic agent.

Animals↗

PubMed1994

Familial occurrence of moyamoya disease. Magnetic resonance angiography as a screening test for high-risk subjects.

The authors report four cases of familial occurrence of moyamoya disease. Although the pathogenesis of moyamoya disease is not clear, there is extensive evidence that this disease has a tendency to show multifactorial inheritance. Therefore, a screening test for those at high risk, i.e., who have a moyamoya patient among their blood relatives, is clinically important. Magnetic resonance angiography (MRA) successfully revealed abnormal findings specific to moyamoya disease in members of the four probands families. MRA is a powerful and noninvasive way of detecting individuals at high risk of developing moyamoya disease.

Anastomosis, Surgical↗

PubMed1994

Cerebral metabolic changes in delayed carbon monoxide sequelae studied by proton MR spectroscopy.

The pathogenesis of delayed sequelae of carbon monoxide (CO) exposure is still unknown. We repeatedly examined a 55-year-old woman with the interval form of CO poisoning, using proton magnetic resonance spectroscopy (MRS). When the clinical picture was severe, MRS revealed markedly lowered N-acetyl-aspartate (NAA)/creatine and phosphocreatine (Cr) ratio and slightly increased choline containing compounds (Cho)/Cr ratio. Subsequently, NAA and Cho/Cr ratio tended to return to normal, reflecting clinical improvement. Proton MRS shows the previously unrecognised neuronal activity in CO poisoning and precisely reflects the severity of symptoms. We stress the superiority of proton MRS over the conventional radiological examinations in CO poisoning.

Brain↗

PubMed1994

Magnetic resonance angiography (MRA) of ruptured cerebral aneurysm.

The purpose of this study was to evaluate the high resolution magnetic resonance angiography (MRA) as pre-operative angiography for the detection of ruptured cerebral aneurysms. MRA was performed on 1.5 tesla system using the 3-dimensional time of flight (3D-TOF) method. The field of view was 16 cm or 20 cm and matrix size was 192 x 256 or 256 x 512. Twenty patients with ruptured cerebral aneurysms and 35 cases of non-ruptured aneurysms (incidental aneurysm) examined by both conventional angiography and MRA were included in this study. All the ruptured aneurysms were operated on based on the information obtained from conventional angiography and MRA. Aneurysms smaller than 3 mm in size were difficult to visualize on MRA. However, most ruptured aneurysms were clearly visualized because they were generally larger than 3 mm. The image quality of MRA was satisfactory for planning surgery. Screening for non-ruptured cerebral aneurysms using MRA is controversial. However, in ruptured aneurysms larger than 3 mm in size, MRA clearly revealed the aneurysm, and MRA findings were informative enough to plan surgery. It is concluded that this noninvasive examination can be selected as a first-choice examination especially in cases of ruptured aneurysm.

Aortic Dissection↗

PubMed1994

Proper usage of brain retractors in the interhemispheric fissure based on MRI microanatomy: technical note.

The authors present a method of the surgical dissection of the interhemispheric fissure based on high resolution magnetic resonance images (MRI). The dissection of the interhemispheric space is not easy because the brain surfaces are tightly adherent in the interhemispheric fissure. In other words, in the interhemispheric fissure, the apices of the gyri are touching and are tightly bound together. This microanatomy is clearly revealed using high resolution three-dimensional MRI. The principle of the usage of the brain retractor is to apply them symmetrically in order to give an even tension to both sides. However, in the interhemispheric dissection, this principle should be slightly modified. Namely the brain retractors should be placed on the crest of gyri on both sides to avoid the injury of small arteries located in the sulci by the edge of the brain retractors.

Brain↗

PubMed1994

Diagnosis of moyamoya disease with magnetic resonance angiography.

BACKGROUND AND PURPOSE: Present criteria for the diagnosis of moyamoya disease emphasize the use of conventional cerebral angiography as an indispensable requirement. However, magnetic resonance angiography (MRA) is fast becoming a reliable diagnostic modality for occlusive cerebrovascular diseases. The purpose of this study is to assess the accuracy of MRA compared with conventional angiography. METHODS: Thirty-nine patients (23 children and 16 adults) with moyamoya disease confirmed by conventional angiography (78 side views) were examined with MRA (three-dimensional time-of-flight technique with a 256 x 256 or 256 x 512 matrix). T1- and T2-weighted MR images were also taken. RESULTS: The stenotic or occlusive change at the carotid fork was clearly revealed by MRA, which correlated well with conventional angiography (83% good correlation, 17% overestimation). Apparent moyamoya vessels were clearly shown as a signal void on the MR image and fine unusual vessels on MRA, particularly in children with moyamoya disease (82%). However, small moyamoya vessels were poorly shown on both MR images and MRA, particularly in adults (63%). CONCLUSIONS: MRA can be an alternative to conventional angiography in typical moyamoya disease cases (the bilateral type of moyamoya disease in children). However, in the early or the end stages of moyamoya disease, diagnosis by means of MRA should be carefully evaluated.

Adolescent↗

PubMed1994

Cytoarchitecture of periendothelial cells in human cerebral venous vessels as compared with the scalp vein. A scanning electron microscopic study.

Three-dimensional cytoarchitectures of the periendothelial cells of human cerebral venous vessels as well as a scalp vein were studied by scanning electron microscopy after removal of extra-cellular connective tissue matrices with a KOH-collagenase digestion method. Postcapillary venules appeared covered with pericytes, while collecting venules had stellate periendothelial cells which formed a basket-like network around the vessel wall. As the size of the venous vessels increased, the stellate periendothelial cells became flat in shape and dense in arrangement. Although they had some characteristics similar to the smooth muscle cells in surface structure, no spindle-shaped smooth muscle cells were recognizable even in the superficial cerebral veins. On the other hand, the scalp vein was densely covered with spindle-shaped smooth muscle cells running circularly. These findings suggest that the cerebral venous vessels cannot constrict strongly as compared with the scalp vein, but probably regulate blood volume by mildly changing the caliber of the vessels.

Adult↗

PubMed1994

Scanning electron microscopic studies of the medial smooth muscles in human major intracranial arteries.

The three-dimensional arrangement of the medial smooth muscle cells of human major intracranial arteries was studied by scanning electron microscopy after removal of extracellular connective tissue matrices with a KOH-collagenase digestion method. In the straight portion of the major arteries, the smooth muscle cells were arranged roughly circularly, whereas the arrangement was somewhat random in the vertebral, basilar, and internal carotid arteries. Groups of the longitudinal muscle cells were also found in the vertebral, basilar, and internal carotid arteries, but were absent in the anterior, middle, and posterior cerebral arteries. At a higher magnification, smooth muscle cells in these arteries formed anastomosed bundles about 5-30 micrograms in diameter. The smooth muscle cells in the dichotomous branching and the uniting portions were arranged circularly, but multidirectionally and longitudinally oriented smooth muscle cell groups were present in the facial and dorsal walls of the forked vessels. These multidirectional muscle cell groups were small in number in the portion where the major arteries gave off lateral branches at a right angle. So called "medial defects" were found at the crotch of the bifurcating region in two cases out of four. Smooth muscle cells near the defects tapered off toward the center of the defect where internal elastic lamina with oval fenestrations were exposed. However, no special arrangement of the smooth muscle cells was observed around the "medial defects" as compared with that in the ordinary bifurcating region.

Adult↗