Biomedical subjects

H Uenohara

Publications and source records attributed to H Uenohara.

At least 19 recordsLinked to original sources

PubMed2004

Use of intraoperative dynamic infrared imaging with detection wavelength of 7-14 microm in the surgical obliteration of spinal arteriovenous fistula: case report and technical considerations.

BACKGROUND AND OBJECTIVE: Although improvements of spatial and temporal resolution in infrared (IR) imaging have enabled intraoperative real-time acquisition of physiological and pathological information on living organs, the imaging qualities of anatomical delineation of blood vessels and functional delineation of blood flow were insufficient to serve as visual monitoring. The main reason was partly due to the lack of an appropriate IR detection IR band (formerly 3 - 5 micro m), and the broad dynamic range in previous modalities. METHODS: To make a good contrast between blood vessels and surrounding tissues, the detection wavelength was shifted to the long-wave (7 - 14 micro m) part of IR spectrum, which includes the peak IR wave from living tissue (9 - 10 micro m), and the dynamic range was confined to +/- 10 degrees C around 35 degrees C. The novel camera system (IRIS IV infrared imaging system) was used for the visual monitoring of blood flow during the obliteration of a spinal perimedullary arteriovenous fistula at Th 7 in 71-year-old male patient. The temperature resolution of camera was 0.15 degrees C, with its intensity resolution of 16 bit (320 x 240 pixels), and data were stored at a rate of 30 frames/second. High-quality delineation of blood vessels and blood flow was obtained all through the procedure without use of cold saline, which was an inevitable procedure to make contrast in the previously used thermography. However, the occasional use of an air blower was helpful to achieve adequate images in the deep and narrow area of the surgical field. The amount of shunt flow reduction was visualized by the intensity in the acquired imaging, which was also confirmed later by digital subtraction angiography. CONCLUSION: From the present experience, it is considered that this type of imaging may be able to substitute intraoperative blood vessel and blood flow monitoring in spinal and other neurosurgical disorders.

Aged↗

PubMed2003

Pulsed liquid jet dissector using holmium:YAG laser--a novel neurosurgical device for brain incision without impairing vessels.

BACKGROUND: Neurosurgery has long required a method for dissecting brain tissue without damaging principal vessels and adjacent tissue, so as to prevent neurological complications after operation. In this study we constructed a prototype of such a device and used it in an attempt to resect beagle brain cortex. METHOD: The prototype device consisted of an optical fibre, a Y adaptor, and a nozzle whose internal exit diameter was 100 microm. Cold physiological saline (4 degrees C) was supplied to it at a rate of 40 ml/h. Pulsed liquid jets were ejected from the nozzle by a pulsed Holmium:YAG) (Ho:YAG) laser at an irradiation energy of 300 mJ/pulse. The profile of the liquid jet was observed with a high-speed camera while changing the distance between the optical fibre end and nozzle exit (equivalent to the standoff distance). With this device (3 Hz operation), brain dissection of anaesthetized beagles was attempted while measuring the local temperature of the target. A histological study of the incised parts was also performed. FINDINGS: When the standoff distance was 24 mm, the liquid jet was emitted straight from the nozzle at a maximum initial velocity of 50 m/s. The brain parenchyma was cut with this device while preserving vessels larger than 200 microm in diameter and keeping the operative field clear. The local temperature rose to no more than 41 degrees C, below the functional heat damage threshold of brain tissue. Histological findings showed no signs of thermal tissue damage around the dissected margin. INTERPRETATION: The Ho:YAG laser-induced liquid jet dissector can be applied to neurosurgery after incorporating some minor improvements.

Animals↗

PubMed2003

Holmium:YAG laser-induced liquid jet dissector: a novel prototype device for dissecting organs without impairing vessels.

BACKGROUND AND OBJECTIVE: Neurosurgery has long required a method for dissecting brain tissue without damaging principal vessels and adjacent tissue, so as to prevent neurological complications after operation. In this study we fabricated such a prototype device and used it in an attempt to resect an animal liver, which, like the brain, contains many vessels. MATERIALS AND METHODS: The prototype device consisted of a jet nozzle and a suction tube. Pulsed liquid jets at 3 Hz were ejected from the nozzle by a pulsed holmium:YAG (Ho:YAG) laser at an irradiation energy of 230 mJ/pulse. The profile of the liquid jet was observed with a high-speed camera. With this device, liver dissections of anesthetized rabbits were attempted while measuring the local temperature of the target. A histological study of the incised parts was also performed. RESULTS: The liquid jet was emitted straight from the nozzle at an initial velocity of 38 m/sec. The liver parenchyma was cut with the device while preserving the tiny vessels and keeping the operative field clear. The local temperature rose to no more than 314 K (below the heat damage threshold of brain tissue). In the histological findings, there were no signs of hepatic degeneration or necrosis around the dissected margin. CONCLUSIONS: The Ho:YAG laser-induced liquid jet dissector can be applied to neurosurgical operations after incorporating some minor improvements.

Animals↗

PubMed2003

Intraoperative thermal artery imaging of an EC-IC bypass in beagles with infrared camera with detectable wave-length band of 7-14 microm: possibilities as novel blood flow monitoring system.

OBJECTIVE: In the past, the usefulness of thermal arterial imaging during coronary bypass surgery using an infrared camera has been reported by several investigators. The goal of this study is to apply this novel imaging system for intraoperative arterial imaging, as well as to develop new utilizations for a neurosurgical procedure. MATERIALS: We have attempted real-time imaging of anastomotic and flow status in an external carotid-internal carotid artery (EC-IC) bypass surgery using a new-generation infrared camera (IRIS IV thermographic imaging system) in beagles. No contrast medium or radiation was used to obtain the images. The detectable wave-length band of the infrared lens was 7-14 microm. After completion of bypass monitoring, an additional teflon tube was inserted into a branch of the STA to inject physiological saline of different temperatures to see the changes in cortical images. RESULTS: Anastomotic and flow status were clearly visualized throughout the operation without local surface cooling, which had been an inevitable procedure in coronary imaging to make a pronounced temperature difference between artery and adjacent tissue. In addition, cortical flow territory was visualized after injection of either cold or warm physiologic saline into the artery from an additionally inserted teflon tube into a branch of STA via bypass artery. CONCLUSION: From the present experience, it is considered that infrared imaging using a detectable wave length band of 7-14 microm may be applicable to a wide variety of near surface lesions, providing a non-invasive functional angiography.

Animals↗

PubMed2002

Clinical manifestations, character of aneurysms, and surgical results for unruptured cerebral aneurysms presenting with ophthalmic symptoms.

OBJECTS: Cases with unruptured cerebral aneurysms presenting with visual symptoms were investigated about their site, size, symptom, operative methods and results. MATERIAL: Between 1984 and 1999, 8 cases were treated in Sendai National Hospital. One man and 7 women, mean age 66.4 years. Ophthalmic symptoms were as follows: diplopia in 6, visual acuity deterioration in 2, impaired visual field in 2 and ptosis in 3. Aneurysm location was IC cavernous in 3, IC ophthalmic in 3, ICPC in 1 and Acom in 1. Aneurysms of more than 25 mm numbered 6 cases. RESULTS: Operative methods and results were as follows: Direct clipping 3 cases, parent artery occlusion + EC/IC bypass 4 cases, Aneurysm trapping + EC/IC bypass 1 case. One patient who underwent direct clipping died following intraoperative complication. Of the remaining 7 cases, visual symptoms were improved in 4, remained unchanged in 2 cases, worsened in 1 case. CONCLUSIONS: These results suggest that in cases with unruptured large or giant aneurysms presenting with ophthalmic symptoms, especially in IC cavernous or IC ophthalmic aneurysms, parent artery occlusion + EC/IC bypass is the safest operative procedure.

Aged↗

PubMed2002

A novel method of drug delivery for fibrinolysis with Ho:YAG laser-induced liquid jet.

Two of the problems inherent in the treatment of cerebral emboli are the narrow therapeutic time window and the severe side effects of fibrinolytic drugs. Thus, it is necessary to develop a new method of removing a cerebral thrombus more rapidly and with smaller quantities of fibrinolytics. The behaviour of a bubble formed by holmium (Ho):YAG laser irradiation in a capillary tube filled with pure water was observed at various stand-off distances (L; distance between the end of optical fibre and the capillary exit). Subsequently, a liquid-jet generator was created by insertion of an optical fibre (core diameter: 0.6 mm) into a catheter (6 Fr) filled with pure water, and a pulsed Ho:YAG laser (pulse duration time=350 micros, laser energy=230 mJ/pulse) was used to irradiate the optical fibre. The maximum penetration depth, into a gelatin artificial thrombus, of a liquid jet generated with this device was measured for various stand-off distances. Additionally, the phenomenon and the pressure around the catheter exit were captured via shadowgraph and PVDF needle hydrophone, respectively. The laser-induced bubble in the capillary tube grew rapidly in the direction of propagation and generated a liquid jet. The maximum penetration depth of this liquid jet into an artificial thrombus increased in proportion to L and reached a maximum value (9 mm) when L was around 13 mm. A shock wave whose overpressure at a point 4 mm away from the catheter exit exceeded 12 MPa was captured by shadowgraph. It was concluded that Ho:YAG laser irradiation within a water-filled catheter caused liquid jet formation, which could penetrate straight into an artificial thrombus. Hence, this jet is expected to promote fibrinolysis by means of injecting fibrinolytics deeply into the thrombus. After resolving some problems, this system will be applied to an endovascular therapy for cerebral embolisms in the near future.

Catheterization↗

PubMed2001

Enhancement of fibrinolytics with a laser-induced liquid jet.

BACKGROUND AND OBJECTIVE: There are several problems inherent in the treatment of cerebral embolisms, such as the narrow therapeutic time window and the severe side effects of fibrinolytic drugs. There is thus need of a new method of removing a cerebral thrombus more rapidly using smaller amounts of fibrinolytics. STUDY DESIGN/MATERIALS AND METHODS: The liquid-jet generator was made by insertion of an optical fiber (diameter: 0.6 mm) into a balloon catheter (6 Fr). A pulsed holmium (Ho) YAG laser (pulse duration time = 350 micros) was used as a laser source. The maximum penetration depth of a liquid jet generated with this device into a gelatin artificial thrombus was measured at various stand-off distances (L; distance between the optical fiber end and the catheter exit). Based on the result, a stand-off distance of 13 mm was chosen to investigate the enhancement of urokinase (UK) efficacy by only a single operation of the liquid-jet device in artificial thrombi made of human blood. RESULTS: Maximum penetration depth increased in proportion to L and reached a maximum value (9 mm) when L was around 13 mm. Fibrinolysis rates (%) after incubation with a small amount of UK for 10 and 30 minutes were predominantly raised by a single use of the laser-induced liquid jet (5.4 +/- 2.4 vs. 22.6 +/- 6.1 and 7.3 +/- 3.8 vs. 38.3 +/- 5.6, respectively (mean +/- SD, P < 0.001)). CONCLUSIONS: A laser-induced liquid jet effectively promoted fibrinolysis in vitro with use of only a small amount of fibrinolytics.

Analysis of Variance↗

PubMed2001

[A case of anaplastic astrocytoma arising 8 years after initial treatment by partial resection and irradiation for central neurocytoma].

A 31-year-old female developed the anaplastic astrocytoma in the right basal ganglia and temporal lobe 8 years after partial resection and irradiation of the central neurocytoma. Probably the malignant astrocytoma was an irradiation-induced tumor. Postoperative radiation therapy for the central neurocytoma appears to have a good effect on tumor local control. But it should be carefully decided whether to use radiation therapy for residual tumor because of the risk of delayed complications of irradiation, such as the present case.

Adult↗

PubMed2000

[Autopsied case of an extracranial internal carotid artery dissecting aneurysm].

An autopsy case of extracranial internal carotid artery (ICA) dissecting aneurysm due to atherosclerosis was reported. A 74-year-old man was admitted to our hospital with the chief complaints of hoarseness and a pulsatile mass below the left mandibular angle. Neurological examination showed no obvious deficits except left recurrent laryngeal nerve palsy. Angiography revealed narrowing of the original segment of left ICA with dissection and aneurysmal dilation at the level of C3 vertebra. Seven days after admission, the patient had a sudden onset of consciousness disturbance. The second angiography showed no obvious changes compared with the first findings except slight narrowing in the distal portion above the aneurysmal dilation. The possible mechanism was thought to be recanalization following transient occlusion of the left ICA caused by extension of dissection or intracranial embolism due to a thrombus within the aneurysm. He was managed conservatively, but unfortunately he died of pneumonia. Macroscopic autopsy showed that the aneurysm was fusiform. Histologically, it demonstrated dissection of the hematoma between the media and adventitia layer. Hemorrhage in the atheromatous plaque with disruption of the elastic lamina were observed along with severe degenerative changes of the intima, media and, in part, adventitia layer due to atherosclerosis. In addition, a dissecting aneurysm of the right iliac artery and severe arteriosclerosis were observed in the systemic arteries. On the basis of these findings, the dissecting aneurysm presumably developed after disruption of a weak portion of the atherosclerotic wall, where intraplaque hemorrhage occurred earlier. We suggest that atherosclerosis be regarded as one of the pathogenic factors capable of causing dissecting aneurysm of the extracranial ICA in elderly patients.

Aged↗

PubMed1999

Liquid jets, accelerated thrombolysis: a study for revascularization of cerebral embolism.

A prior study has reported that a rapid recanalization therapy of cerebral embolism, using liquid jet impacts generated by the interaction of gas bubbles with shock waves, can potentially penetrate through thrombi in as little as a few microseconds with very efficient ablation (Kodama et al. 1997). The present study was undertaken to examine the liquid jet impact effect on fibrinolysis in a tube model of an internal carotid artery. First, the conditions for generating the maximum penetration depth of liquid jets in the tube were investigated. Gelatin was used to mimic thrombi. The shock wave was generated by detonating a silver azide pellet weighing about a few micrograms located in a balloon catheter. The collapse of the inserted gas bubbles and the subsequent liquid jet formation were recorded with high-speed photography. Second, thrombi were formed using fresh human blood from healthy volunteers. The fibrinolysis induced by the liquid jet impact with urokinase was explored. This was conducted under selected conditions based on the experiment using the gelatin. Fibrinolysis was calculated as the percentage of the weight loss of the thrombus. Fibrinolysis with urokinase alone and with a single liquid jet impact with urokinase was 1.9 +/- 3.7% (n = 16) and 20.0 +/- 9.0% (n = 35), respectively, for an incubation time of 60 min. Statistical differences were obtained between all groups (ANOVA). These results suggest that liquid jet impact thrombolysis has the potential to be a rapid and effective therapeutic modality in recanalization therapy for patients with cerebral embolism and other clinical conditions of intra-arterial thrombosis.

Carotid Artery, Internal↗

PubMed1999

Resumption of work after aneurysmal subarachnoid hemorrhage in middle-aged Japanese patients.

OBJECT: Previous reports on the results of treatment for aneurysmal subarachnoid hemorrhage (SAH) have been based only on activities of daily living after discharge, whereas resumption of work has received insufficient attention. Most Japanese work under a lifetime employment system, and it is best for those who have recovered from SAH to return to work for their previous employer. The present study was conducted to determine the extent to which discharged patients who have suffered an SAH resume their former occupations in Japan, focusing on those between 40 and 49 years of age, who usually have a strong desire to return to work. METHODS: The participants consisted of 193 patients with SAH. Based on the results of telephone interviews or written questionnaires, their work status at 1 year after onset was analyzed. The work resumption rates for patients with Hunt and Kosnik neurological Grades 1 or 2 on admission were higher than for those with Grades 3 or 4 (p = 0.015) and lower for patients with basilar artery aneurysms than for those with aneurysms at other sites (p = 0.028). With regard to premorbid occupation, the work resumption rates were high (80%) for professionals and engineers, many of whom were public servants, or teachers at junior or senior high schools. The resumption rates were also high for primary industry workers (80%), but lowest (20%) for professional drivers (p = 0.04-0.001). The work resumption rate was lower for women than for men (p = 0.01). CONCLUSIONS: These findings indicate that resumption of work is determined not only by medical factors, but also by social factors including gender, type of occupation, employment system, and socioeconomic background.

Activities of Daily Living↗

PubMed1999

[A case of frequent intracerebral hemorrhage from mixed vascular malformation in a child].

We reported a rare case of frequent intracerebral hemorrhage from mixed vascular malformation in an infant. A 1-year and 4-month-old girl was admitted with seizure. She had been diagnosed as having febrile convulsion at the age of 8 months. Computed tomography (CT) indicated a multicystic mass without perifocal edema in the right frontal lobe. The mass was not enhanced by contrast media, but T1-weighted magnetic resonance imaging (MRI) revealed a multicystic mass with mixed signal intensity, while T2-weighted image demonstrated a heterogenous high signal intensity mass with a marginal low intensity rim. These findings suggested a cavernous angioma causing intracerebral hematomas. Because of this, total resection was achieved via a right fronto-temporal craniotomy without neurological deficits. Histologically, numerous dilated venous-type blood vessels interspersed within the normal brain parenchyma were seen. In parts, the vessel walls were abnormally thickened and the lesion coalesced with capillary-like vessels. We diagnosed mixed vascular malformation, mainly composed of venous malformation along with telangiectasia. The number of reports for this so-called mixed vascular malformation have thus been increased. The histopathological criteria for classification of vascular malformation should be reinvestigated carefully.

Cerebral Hemorrhage↗

PubMed1998

Innovative technology for tissue disruption by explosive-induced shock waves.

We have developed a novel, less invasive, shock wave source that can be introduced into an arbitrary position in a human body percutaneously. Using this technique we can disrupt cells locally. The shock wave source consists of an explosive, an optical fiber, a balloon catheter, and a Nd:YAG laser, which generates a spherical explosive shock wave. The destructive potential of the present source for injuring tissue was confirmed and the subsequent cell elongation and split in the direction of the shock wave has been observed.

Animals↗

PubMed1998

[Primary intracerebral malignant fibrous histiocytoma with adhesion to a dura: a case report].

A case of malignant fibrous histiocytoma (MFH) in a 29-year-old man was reported. CT scans revealed an iso density mass which was homogeneously enhanced by contrast medium. MRI demonstrated that the right frontal tumor showed slight low signal intensity in T1-weighted image, and iso signal intensity in T2-weighted image. Gadolinium-enhanced T1-weighted image showed a homogeneously enhanced multinodular tumor. Right carotid angiogram revealed a tumor stain fed by the precentral artery. On operation, en-bloc resection was performed successfully. Postoperatively, local irradiation of 60Gy was performed. Microscopically, fibroblast-like cells arranged in storiform pattern were observed, and bizarre multinucleated giant cells were also observed. Ki-67 labelling index was 54%. We considered the tumor was a MFH and arose from an intracerebral mesenchymal tissue. We reviewed some literature and briefly discussed clinicopathological features and therapy of intracranial MFH.

Adult↗

PubMed1997

A new technology for revascularization of cerebral embolism using liquid jet impact.

Revascularization time is the dominant factor in the treatment of acute cerebral embolism. In this paper we describe a rapid revascularization therapy using liquid jets generated by the interaction of gas bubbles with shock waves, which impact on the thrombi. The interaction of a shock wave with a gas bubble attached to an artificial thrombus which was inserted into a tube model of a cerebral artery was investigated. The shock wave was generated by detonating a microexplosive pellet. The overpressure of the shock wave was 3.0 +/- 0.6 MPa (n = 7) and 12.7 +/- 0.4 MPa (n = 3). The initial air bubble radii were varied from 0.87 mm to 2.18 mm. The subsequent collapse of the bubble was photographed using a high-speed framing camera, and the liquid jet penetrating into the artificial thrombus was visualized using x-ray photography. The penetration depth of the liquid jet increased with increasing bubble size. There was an optimal separation distance between the bubble and the shock wave source to obtain the maximum penetration depth. Liquid jets have the potential to penetrate through thrombi in as little as a few microseconds, and with very efficient ablation.

Adult↗

PubMed1996

Regional cerebral blood flow measured with 99mTc-HMPAO based on two-dimensional 133Xe study in ischemic brain.

Two-dimensional regional cerebral blood flow (rCBF) was measured using the xenon-133 inhalation method, and used to calibrate the rCBF measured by single photon emission computed tomography (SPECT) in the non-affected middle cerebral artery (MCA) area. The value of the rCBF in the target area could then be measured by SPECT and compared between patients. Technetium-99m-d,l-hexamethyl-propylene-amine-oxime and technetium-99m-diethylenetriaminepenta-acetic acid-human serum albumin D were used to measure rCBF and regional cerebral blood volume (rCBV), respectively, in the ischemic area of 16 patients who underwent surgical revascularization in the chronic stage. No significant increase in rCBF was obtained after the bypass surgery. The delta rCBF and delta CBF/CBV ratio correlated well with the extent of vascularization in the MCA area on postoperative angiograms. Patients with a low CBF/CBV ratio on preoperative SPECT scans tended to show favorable postoperative vascularization and rCBF in the MCA area. Since the angiographic findings and the delta rCBF or delta CBF/CBV were correlated well, this simple and non-invasive method could be used for the analysis of rCBF in a group of patients.

Aged↗

PubMed1995

[A neonate case of dural arteriovenous shunt presenting with cerebellar hemorrhage].

A rare case of dural arteriovenous shunt (dAVS) manifested as cerebellar hemorrhage in a neonate is reported. Seven days after birth, a neonate was referred to our hospital because of consciousness disturbance. CT scan revealed cerebellar hemorrhage, subarachnoid hemorrhage, subdural hematoma, and a high density mass lesion at the torcular herophili. Retrograde brachial angiogram failed to show any vascular lesions. He underwent an evacuation of the cerebellar hematoma. Postoperative course was uneventful. However, at the age of four months, he was admitted again because of consciousness disturbance and cardiac failure. CT scan revealed hydrocephalus and an enlarged mass lesion at the torcular herophili. Angiogram disclosed dural AVS. Its feeding arteries were as follows; the bilateral middle meningeal arteries (MMA), the occipital arteries (OA), dural branches of the bilateral posterior inferior cerebellar arteries, arteries consisting of transdural anastomosis from the left posterior cerebral artery. The arterial flow from these feeding arteries was shunting directly to the torcular herophili, the posterior part of the superior sagittal sinus, and the straight sinus. He underwent a venticulo-peritoneal shunting. Then, after treatment for cardiac failure, superselective embolization of the bilateral MMAs and the OAs resulted in diminution of shunting flow. The initial onset of this case was at seven days after his birth. Dural AVS is very rare in the pediatric population, particularly in the neonate. The clinical features, pathogenesis, and the treatment for this rare entity are discussed.

Arteriovenous Malformations↗

PubMed1994

[MR imaging of a case of cerebral tuberculoma--correlation between MRI and histological findings].

A case of cerebral tuberculoma is reported with its representative MRI findings and the corresponding histological appearance. A 46-year-old female admitted to our hospital with complaint of left hemifacial seizure. CT scan discoled a slightly high density tumor (1.5cm in diameter) located in the right frontal lobe. This tumor was enhanced homogeneously by contrast media. While, MRI revealed three concentric layers within this tumor; the central core showed iso- and low signal intensity (SI) in T1- and T2-weighted imagings (T2WI), respectively. The middle layer showed low and high SI in T1- and T2-WI, respectively. The outer layer appeared iso- and low SI in T1- and T2-WI, respectively. Only the middle layer was enhanced by Gd-DTPA. The total resection of the tumor was performed. The histological appearance corresponded well to those MRI findings. The central core was caseous necrosis, and the middle layer contained Langhans giant cells and epithelioid cells with substantial edema. The outer layer was the capsule that consisted of collagenous fibers. The peculiar relationship between the MRI and histological findings is discussed in detail.

Brain Diseases↗