Biomedical subjects

Yoshikazu Okada

Publications and source records attributed to Yoshikazu Okada.

12 recordsLinked to original sources

PubMed2006

Hypothalamic hamartoma associated with anterior paraclinoid aneurysm of the internal carotid artery.

A 15-year-old boy presented with a history of medically refractory gelastic seizures and cognitive impairments. Neuroimaging demonstrated a sessile type hypothalamic hamartoma, which was treated by gamma knife surgery. However, the gelastic seizures only partially decreased and the frequency of seizures remained unchanged. One year later, angiography before surgery detected anterior paraclinoid aneurysm of the left internal carotid artery. Blood pressure and endocrinological examinations showed no abnormality. Direct surgery was performed to treat the aneurysm and hamartoma. No sclerotic changes were noted in the arterial wall. The aneurysm was treated with clipping, and the hamartoma was partially removed. Postoperative course was uneventful and the gelastic seizures disappeared. No evidence for a causal relationship between the hamartoma and aneurysm was found.

Adolescent↗

PubMed2006

Intracystic papilloma in the breast of a male given long-term phenothiazine therapy: a case report.

We experienced a very rare case of intracystic papilloma in a 57-year-old man who came to our hospital complaining of a left subareolar mass and nipple discharge. The patient had a history of chronic schizophrenia, necessitating long-term treatment with phenothiazines. His serum prolactin levels were elevated. Mammography demonstrated a well defined mass with microcalcifications. Ultrasonography revealed a cyst with an intracystic component. The inner lesion of the mass enhanced on contrast-enhanced computed tomography. The carcinoembryonic antigen concentration of the cyst fluid was 400 ng/mL and no malignant cells were found by aspiration biopsy cytology. Excisional biopsy was performed under local anesthesia. Pathological examination revealed the intracystic component to be intracystic papilloma. There are ten reports of male intracystic papilloma including ours. We report the second case of a patient given long-term phenothiazine therapy, which is known to increase serum prolactin levels.

Antipsychotic Agents↗

PubMed2005

Scaled suction for microneurosurgery: technical note.

OBJECTIVE: We have developed scaled suction to facilitate the measurement of aneurysm neck width and tumor size during operations. METHODS: We constructed a new suction device scaled every 1 mm from the tip to 3 cm and every 5 mm from 3 to 5 cm. The scaled suction devices have been used in 50 aneurysm and brain tumor operations. RESULTS: The new suction device permits easy measurement of aneurysm neck width, tumor size, the extent of internal decompression of tumor, and depth from the surface of the brain to the lesion. CONCLUSION: Our scaled suction device is a simple and useful navigator for continuously measuring intraoperative variables such as lesion size and distance between the lesion and the surrounding vital structures.

Aneurysm↗

PubMed2005

Carotid tissue levels of argatroban after direct local delivery during carotid endarterectomy to prevent perioperative cerebral embolism.

OBJECTIVE: Argatroban is a synthetic direct thrombin inhibitor. We applied argatroban locally during carotid endarterectomy to prevent local mural thrombus formation. Although local delivery of argatroban is expected to be effective for inhibition of mural clot formation, there is no report of the evaluation of its clinical effectiveness or local drug concentration in humans. METHODS: Five mg of argatroban (0.5 mg/ml) was applied twice intraoperatively just after arteriotomy for measurement of intraplaque level of argatroban and during closure of the arteriotomy for preventing thrombus formation. After exposure of the carotid plaque to argatroban for a specified duration (0, 3, 5, or 10 min), argatroban was sufficiently washed with saline and the carotid plaque was removed for measurement of tissue concentration of argatroban. Intraplaque level of argatroban was determined by high-performance liquid chromatography. A second application was performed during closure of the arteriotomy. Argatroban was applied for 10 minutes, followed by washing with saline. Postoperative embolic cerebrovascular complications and carotid restenosis also were investigated to verify the efficacy of direct local application of argatroban. RESULTS: Tissue levels of argatroban in the carotid plaque after 3, 5, and 10 minutes of direct application were 24.0 +/- 13.7, 31.6 +/- 20.0, and 44.0 +/- 15.1 mug/g, respectively. The concentrations at all time points were significantly elevated compared with the control, and a significant difference in concentration was observed between 3 minutes and 10 minutes. In the present study, concentration at 3 minutes was much higher than the effective tissue levels of argatroban reported in experimental studies. No patient developed postoperative cerebrovascular complications. CONCLUSION: The results suggest that direct local application of argatroban during carotid endarterectomy for at least 3 minutes may deliver high local tissue levels. Argatroban may be effective for prevention of perioperative embolic cerebral complications during carotid endarterectomy.

Adult↗

PubMed2004

Preoperative mapping for patients with supplementary motor area epilepsy: multimodality brain mapping.

Surgical management and strategies for the supplementary motor area (SMA) epilepsy are described. The following is our preoperative evaluations. The steps include functional magnetic resonance imaging (fMRI), interictal dipole tracing (DT), subdural electrodes mapping, measurements of movement-related cortical potential (MRCP), and the use of the intraoperative open MRI under conscious craniotomy. Six patients with SMA epilepsy underwent surgery after the mapping procedures and are now seizure-free. Combinations of preoperative (fMRI, subdural electrodes mapping) and intraoperative mapping allow exact localization and identification of the critical functional areas. Early postoperative deficits in motor and speech function were profound but patients recovered rapidly. It is concluded that the step of mapping procedures plays an important role in the management of SMA epilepsy surgery.

Adolescent↗

PubMed2004

Development of hybrid integrated endoscope-holder system for endoscopic microneurosurgery.

OBJECTIVE: Endoscopic techniques in the field of neurosurgery are under development. To perform sophisticated bimanual procedures in the delicate surgical fields of neurosurgery, rigid endoscope fixation devices with accurate locking and a safe releasing system are required. Here, we report the development of a new hybrid integrated endoscope-holder system. INSTRUMENTATION: The basic concepts of the holding device were as follows: 1) it should combine both video system and holding device; 2) it should have easy maneuverability and accurate fixation and be equipped with a safe releasing mechanism; and 3) it should be able to be used universally either in a primary or an assisting endoscopic procedure. A negatively actuated air-locking system and a bayonet-shaped endoscope were newly developed. Clinical trials of 25 patients were performed, and each prototype was tested and modified until the functional requirements were fulfilled. The final version was tested for accuracy and security in fixation and releasing mechanism. RESULTS: Eight problems were encountered in the clinical trials and improved. Accuracy in fixation of the final version was superior to the most advanced endoscope-holder on the market. No dangerous events were observed during repetitive insertion, fixation, and release in the simulated deep surgical field in the cadaveric skull. No apparent complications were noted in the clinical application. CONCLUSION: We have developed a highly reliable, accurately fixable, and easily maneuverable hybrid endoscope-holder system. To achieve a safer, more accurate, and less invasive surgery in the current socioeconomic demands, commercial manufacturers and surgeons in multiple centers need to combine their efforts to create useful techniques.

Adult↗

PubMed2004

Magnetic resonance angiography demonstrating adult moyamoya disease progressing from unilateral to bilateral involvement--case report.

A 21-year-old woman presented with moyamoya disease manifesting as speech disturbance and right quadrant hemianopsia on October 22, 1994. Magnetic resonance (MR) angiography showed occlusion of the left internal carotid artery (ICA) with the normal right ICA. The diagnosis was "unilateral" moyamoya disease by conventional angiography. Follow-up MR angiography revealed further occlusive changes of the right middle cerebral artery (MCA) trunk on July 30, 1995, which progressed to occlusion of the MCA on March 25, 1997. Conventional angiography confirmed occlusion of the right terminal ICA to MCA with basal moyamoya vessels. The diagnosis was "bilateral" moyamoya disease. She was successfully treated by bilateral superficial temporal artery-MCA anastomosis. Follow-up MR angiography should be performed in relatively young patients with "unilateral" moyamoya disease to detect any progression to bilateral moyamoya disease.

Adult↗

PubMed2004

Intraoperative hemodynamic measurements of the vertebral artery and common carotid artery.

The hemodynamics in the vertebrobasilar artery (VBA) system were investigated in patients with vertebrobasilar insufficiency (VBI). Vertebral artery (VA) stump pressure and blood flows in the VA and common carotid artery (CCA) were intraoperatively measured in 45 patients who underwent surgical correction of the first segment of the VA (V1) for angiographic tortuosity, kinking, and/or stenosis manifesting as symptomatic VBI. The effects of changes in the systemic arterial blood pressure (SABP) induced by trimethaphan, phenylephrine, and cervical epidural anesthesia were also investigated. The VA stump pressure was 79.3 +/- 13.6 (mean +/- SD) mmHg and the ratio of the VA stump pressure to the SABP was 0.87 +/- 0.08. The baseline values were SABP 90.5 +/- 10.1 mmHg, VA blood flow 53.4 +/- 33.0 ml/min, and CCA blood flow 204.3 +/- 50.3 ml/min. During changes in the SABP, autoregulation of the blood flow in the VA appeared tighter than in the CCA. During cervical epidural anesthesia, blood flows in both the VA and CCA were significantly reduced in response to SABP reduction. This study demonstrated that the VBA system maintains excellent autoregulation with good collateral flows and cervical sympathetic nerve function. However, this autoregulatory capacity may be overwhelmed by unexpected occlusion of the VA due to postural changes associated with tortuosity, kinking, and/or stenosis of the V1 segment.

Adult↗

PubMed2004

Intra-arterial vasopressin injection for the treatment of massive bleeding from the external carotid artery after craniofacial trauma--technical note.

Vasopressin (0.8-1.0 IU), diluted with saline (10 IU vasopressin per 100 ml saline), was selectively injected into the external carotid artery (ECA) to control massive hemorrhage caused by inaccessible serious craniofacial injuries in two patients. This method produced remarkable angiographic vasoconstriction at the involved ECA branches and resulted in immediate hemostasis. Intra-arterial vasopressin injection is a useful option for the treatment of intractable traumatic hemorrhage from inaccessible ECA branches.

Adult↗

PubMed2003

Evaluation of image qualities on the international standard video-conferencing.

International standard-based video-conferencing systems are widely used in telemedicine activities worldwide. Through our experiences with these systems, it is apparent that the image quality is high enough to conduct educational and conferential sessions. However, because the terminals are intended for common use, we evaluated their qualities. After having an international standard system evaluated by a general practitioner using medical images, we prepared non-medical graphic images to examine the characteristics of the video-conferencing equipment. ROC (Receiver Operation Characteristic) analysis was employed for the evaluation. We concluded that the international standard video-conferencing systems are of sufficient quality for medical presentations, and that their interactivity and the use of proper software will aid the understanding of images in specific medical areas.

Internationality↗

PubMed2002

International concerted action on collaboration in telemedicine: recommendations of the G-8 Global Healthcare Applications Subproject-4.

The main objectives of the G-8 Global Healthcare Applications Subproject-4 (G-8 GHAP-SP-4) were to establish an international concerted action on collaboration in telemedicine, telehealth, and health telematics (hereafter referred in this paper as telemedicine). In order to promote and facilitate the implementation of telemedicine or health telematics networks around the world, it was considered necessary to address certain key issues. Five thematic solution-seeking forums were held between May 1998 and December 1999. Each addressed a key issue, including interoperability of telemedicine and telehealth systems, impact of telemedicine on health care management, evaluation and cost effectiveness of telemedicine, clinical and technical quality and standards, and medico-legal aspects of national and international applications. The main objectives of these forums were to establish best practices and a thorough review of the issues and discussions among experts to determine the best solutions for the facilitation of global international telemedicine networks. More than 650 invited participants from 16 countries attended the five forums, which were of 2-3 days in duration. These forums provided a foundation for the exchange of ideas resulting in the initiation of collaborative activities. Based on these deliberations, a series of 21 recommendations were prepared by the national representatives of the G-8 GHAP SP-4. These recommendations propose to political leaders and health care managers of the G-8 and other countries roadmaps to follow in order to accelerate the achievement of a Global Society of Healthcare via Telemedicine, Telehealth, and Health Telematics. The 21 recommendations are presented in this report.

Humans↗

PubMed2002

Efficacy and safety of nicardipine prolonged-release implants for preventing vasospasm in humans.

BACKGROUND AND PURPOSE: Despite extensive investigative efforts, there are few treatments that can prevent vasospasm after subarachnoid hemorrhage. This study was conducted to examine the efficacy and safety of nicardipine prolonged-release implants (NPRI) for humans, which have already been proven in dogs. METHODS: Twenty consecutive subarachnoid hemorrhage patients with thick subarachnoid clot were treated with NPRI (a pellet of diameter 2 mm, length 10 mm, containing 4 mg of nicardipine) during surgery after clipping of their aneurysm. The number and location of pellets depended on the amount and site of subarachnoid clot on preoperative CT and on craniotomy. RESULTS: Two to 10 pellets were implanted in the cistern of the internal carotid, middle cerebral, and/or anterior cerebral artery, where thick clots existed and therefore vasospasm related to delayed ischemic neurological deficits was highly likely. Delayed ischemic neurological deficits and cerebral infarctions were seen in 1 patient. Angiography performed on days 7 to 12 revealed no vasospasm in any arteries near which NPRI were placed. No complications were experienced. CONCLUSIONS: Vasospasm was completely prevented for the arteries in thick clot cisterns, when NPRI were placed adjacent to the arteries during surgery. This drug-delivery system offers a promising approach for preventing vasospasm.

Aged↗