PubMed Health⌕ Search

Biomedical subjects

Shigeaki Kobayashi

Publications and source records attributed to Shigeaki Kobayashi.

At least 19 recordsLinked to original sources
PubMed2006

Parkinsonism and midbrain dysfunction after shunt placement for obstructive hydrocephalus.

We report a patient in whom placement of a ventriculoperitoneal shunt for obstructive hydrocephalus secondary to non-neoplastic aqueductal stenosis was complicated by progressive parkinsonism and midbrain dysfunction. These sequelae were refractory to treatment, including shunt revision and levodopa therapy. These findings contradict the opinion from the literature that this type of parkinsonism is a reversible condition and levodopa therapy is effective for managing the symptoms. We discuss the pathophysiological mechanism of this complication.

Humans↗
PubMed2005

Postoperative vasospasm of unruptured paraclinoid carotid aneurysms: analysis of 30 cases.

This study was conducted to determine the incidence, severity, and causes of delayed vasospasm after clipping of unruptured paraclinoid aneurysms of the internal carotid artery (ICA). A retrospective analysis was made of 30 patients, who underwent clipping of unruptured paraclinoid aneurysms in our institution between 1991 and 1998. We compared angiograms before and after operation and classified them into two groups: vasospasm group and non-vasospasm group. Eleven variables were assessed as to their relationship to delayed vasospasm. There were 9 patients (30%) in the vasospasm group, of which 3 patients (10%) were clinically symptomatic. For all symptomatic patients, aggressive treatment, including triple-H therapy, was conducted with good outcome. The number of clips used (p<0.04) and temporary occlusion of the ICA (p<0.005) were statistically significant factors associated with the incidence of vasospasm. It is suggested that mechanical stimulation to the vascular wall of the ICA is responsible for causing spasm in addition to intraoperative bleeding around the dural ring.

Adult↗
PubMed2004

Pediatric embryonal tumor with epithelial immunophenotype showing absence of hSNF5/INI1 expression.

CASE REPORT: A case of a histologically unclassified brain tumor in a 32-month-old boy is reported. He presented with vomiting, appetite loss, and right motor weakness. MR images revealed a huge mass in the left frontoparietal region that was enhanced after the administration of Gd-DTPA. The mass was removed three times because of its recurrence. RESULTS: Histologically, the tumor was composed largely of small-undifferentiated round cells without any patterns of differentiation. Immunohistochemically, the tumor cells were positive for cytokeratin and focally for epithelial membrane antigen (EMA). Glial fibrillary acidic protein (GFAP), S-100 protein and neuronal markers were negative. Electron microscopic investigations demonstrated no evidence of specific differentiation. MIB-1 staining index was 10-40%. The origin of the tumor was not detected. Expression of the hSNF5/INI1 of this tumor was not detected by reverse transcription-polymerase chain reaction (RT-PCR). The patient has been in a good condition for 7 years after the first operation. CONCLUSIONS: Based on the immunohistochemical findings, the tumor was descriptively diagnosed as an embryonal tumor with an epithelial immunophenotype. The hSNF5/INI1 gene has recently been reported to act as a tumor suppressor in atypical teratoid/rhabdoid tumors. The hSNF5/INI1 gene may lead to tumorigenesis in this case.

Biomarkers↗
PubMed2004

Endovascular therapy versus surgical clipping for basilar artery bifurcation aneurysm: retrospective analysis of 117 cases.

OBJECTIVE: The purpose of this study was to retrospectively evaluate and compare the feasibility, indication and limitations of two treatment options, clipping and coil embolization, for basilar artery (BA) bifurcation aneurysms. MATERIALS AND METHODS: During the last 13 years, 117 patients with 117 BA bifurcation aneurysms were treated exclusively with direct surgery until February 1997, and with either direct surgery or coil embolization therapy since March 1997. Of them, 76 (65%) aneurysms were treated with direct clipping and 41 (35%) were treated with Guglielmi detachable coils (GDCs) embolization. The 76 surgically clipped aneurysms were analyzed on the basis of the pre-operative angiograms as to whether coil embolization would be feasible or not if each case had been attempted. The 41 embolized aneurysms, on the other hand, were analyzed as to whether clipping surgery would be feasible or not if it had been attempted. RESULTS: In the total 117 aneurysms, complete coil obliteration was judged to be possible and simple in 61 (52%) aneurysms, possible with complex techniques (difficult) in 29 (25%) and impossible in 27 (23%). Whereas, complete obliteration with direct clipping was judged to be simple in 66 (57%) aneurysms, difficult in 38 (32%) and impossible in the remaining 13 (11%). Linear correlation as to the technical difficulty was found in 61 (52%) aneurysms, but 14 (12%) had marked discrepancy between the two methods. Of the 76 patients treated with clipping surgery, 17 (22%) were left with some post-operative neurological deficits, and in six out of the 17 aneurysms, embolization might have been simple. There were complications in two patients; one procedure-related and the other with late re-bleeding due to aneurysmal re-growth, in the embolization, group. CONCLUSIONS: Endovascular therapy is an effective alternative for treating BA bifurcation aneurysms, although a quarter of the cases cannot be obliterated completely. It is important to select a suitable treatment option in each case depending on the patient's condition and the angiographical features of each aneurysm as well as the characteristics of the two methods.

Adult↗
PubMed2004

Re-occlusion of the superior sagittal sinus after surgical recanalisation.

A 24-year-old woman was struck on the head by a hammer. Because of early signs and symptoms of intercranial hypertension, she underwent surgery for elevation of the depressed fragments which was compressing the superior sagittal sinus (SSS). After operation, the intracranial pressure (ICP) once decreased, but it gradually increased again. After hypothermia and barbiturate therapy, she recovered fully except for partial visual field defect due to brain contusion. A carotid angiogram 28 days after injury revealed complete occlusion of the whole SSS with good collateral circulation. After brain edema had subsided, a follow-up angiogram revealed normal blood flow through the SSS. Elevation of depressed bony fragments is required for a case presenting with early signs and symptoms of intracranial hypertension due to sinus compression. In a case with severe destruction of the SSS, one needs to know that re-occlusion of the dural sinus may occur after surgical recanalisation.

Adult↗
PubMed2004

Temporal changes in pulmonary expression of key procoagulant molecules in rabbits with endotoxin-induced acute lung injury: elevated expression levels of protease-activated receptors.

Recently a new concept has emerged implicating thrombin signaling as the "bridge" that connects tissue damage to hemostatic and inflammatory responses. In view of this concept, we hypothesized that induction of protease-activated receptor (PAR) expression may play a critical role in endotoxin-induced tissue injury through the cellular actions of thrombin. Thus, in this study, temporal changes in expression of key precoagulant molecules, including PARs, in lungs from rabbits rendered endotoxemic by 100 microg/kg lipopolysaccharide (LPS) were examined with measurements of variables reflecting acute lung injury (ALI). ALI induction by LPS was confirmed by blood gas derangement, lung vascular hyperpermeability, and histopathological changes, and was characterized by the deposition of fibrin in the alveolar spaces, bronchioles and vessels. Plasminogen activator inhibitor-1 (PAI-1) and tissue factor (TF) were highly expressed in lungs after LPS injection. While the peaks in levels of PAI-1 and TF were comparable (12 approximately 13-fold from control), their expression time-courses were different: PAI-1 exhibited a bell-shaped expression pattern and peak at 6 h, whereas TF level reached maximum at 10 h. Of note, LPS induced a rapid and significant increase in levels of PAR-1 compared to control, with a peak level at 1 h (3.3-fold). Although declining thereafter, it remained significantly higher than the control level throughout the study period. Expressions of PAR-2, -3, and -4 were also increased by LPS with different time courses from PAR-1 expression. Immunofluorescence staining for PAR-1 were localized in blood vessels, bronchial epithelium, and alveolar pneumocytes after LPS. These results suggest that the increased expression levels of PARs, in addition to PAI-1 and TF, may, in part, underlie the development of ALI occurring during endotoxemia.

Animals↗
PubMed2004

[Treatment of craniopharyngiomas in children].

PURPOSE: The purpose of this article is to assess, in a 25-year retrospective study, the clinical outcome in children with craniopharyngioma. PATIENT AND METHODS: From 1978 to 2002, 12 children younger than 15-year-old underwent treatment with surgery and/or radiotherapy for craniopharyngioma. The clinical course and outcome were reviewed. RESULTS: The median age was 7.3 years (range, 3 to 12 years) at the time of initial surgical resection. With a mean follow-up period of 132 months (range, 29 to 255 months), 1 patient died of tumor progression due to malignant transformation at 205 months after the initial surgery and the overall outcome was good in 11 patients. Out of 12 patients 4 presented a recurrence of their tumor, 2 after an apparently gross total removal. Because of tumor recurrence, 2 received conventional radiation therapy and 3 received gamma knife radiosurgery. There was neither operative mortality nor major complication. All patients required hormonal replacement postoperatively. CONCLUSIONS: The goal in the treatment of craniopharyngiomas is to achieve total removal without morbidity. Our results compared favorably with the previous reports in the literature. MRI follow-up should be performed even in patients whose primary tumor is resected "completely". Suitable combination of open surgery, conventional radiotherapy and gamma knife radiosurgery may result in optimal functional outcome. Recovery from postoperative pituitary dysfunction can be occasionally expected.

Child↗
PubMed2004

[Pulmonary emboli in sclerotherapy for peripheral vascular malformations under general anesthesia; a report of two cases].

Sclerotherapy with absolute ethanol and/or polidocanol is a well-established therapeutic modality for the treatment of peripheral vascular malformations, although systemic complications such as hemoglobinuria and pulmonary embolism could occur. We report two cases of pulmonary embolism associated with sclerotherapy for peripheral vascular malformations. Two patients, a 17-year-old man and a 17-year-old woman, undergoing absolute ethanol sclerotherapy for vascular malformations of the leg developed pulmonary embolism after injection of ethanol. Pulmonary embolism, suspected by the clinical symptoms such as hypoxia and hypocapnia, was confirmed by the pulmonary scintigraphy showing minimal pulmonary defects. Hemoglobinuria was also observed with injection of ethanol. Patients recovered rapidly with heparin and urokinase therapy. The review of perioperative complications with sclerotherapy for peripheral vascular malformations in our institution for past four years revealed that complications were observed in 18 out of 88 patients (20.5%), and in 32 out of 183 cases (17.5%). Major complications were hemoglobinuria, pulmonary embolism, shivering and delayed emergence from general anesthesia. We conclude that sclerotherapy for vascular malformations under general anesthesia is a risky procedure and this must be carefully managed with keen monitoring of Spo2 and Etco2.

Adolescent↗
PubMed2003

Aneurysm at the posterior inferior cerebellar artery of extradural origin for preoperative evaluation of safe clipping: case report and review of the literature.

BACKGROUND: As far as we know, 6 cases of extracranial (including craniocervical junction) intradural aneurysms of the posterior inferior cerebellar artery have been previously reported. However, preoperative detailed evaluation of the origin site and a course of the posterior inferior cerebellar artery by means of angiography were not reported in previous papers. CASE DESCRIPTION: We report a rare case of aneurysm of the posterior inferior cerebellar artery, which originated extradurally from the right vertebral artery. A 69-year-old woman experienced a sudden headache 16 years ago and a computed tomography scan showed a subarachnoid hemorrhage around the midbrain. Four-vessel cerebral angiography, however, failed to disclose a source of the hemorrhage. Magnetic resonance angiography incidentally revealed an aneurysm at the craniocervical junction 16 years after the subarachnoid hemorrhage. The aneurysm was exposed and clipped via a suboccipital route. At surgery, it was of no use to apply a temporary clip on the intradural segment of the vertebral artery, because the posterior inferior cerebellar artery was found to enter the intradural space separately from the vertebral artery. The blood flow to such an aneurysm cannot be stopped with this procedure. CONCLUSIONS: Careful neuroimaging study is essential for the accurate diagnosis and successful treatment of such a rare aneurysm.

Aged↗
PubMed2003

The sympathomimetic actions of l-ephedrine and d-pseudoephedrine: direct receptor activation or norepinephrine release?

UNLABELLED: The basic mechanisms by which ephedrine is preferred over other vasopressors in obstetric anesthesia have not been clearly defined. We examined the sympathomimetic effects of l-ephedrine, currently used as a vasopressor, and d-pseudoephedrine, currently used as a decongestant. In anesthetized rats, l-ephedrine and d-pseudoephedrine caused dose-dependent increases in arterial blood pressure and heart rate, and these effects disappeared after destruction of the sympathetic nerve terminals with 6-hydroxydopamine (6-OHDA) pretreatment. The two ephedrine isomers produced concentration-dependent increases in tension of anococcygeal muscle and sinus rate of right atrium from rats. However, the anococcygeal and atrial responses to d-pseudoephedrine were abolished after 6-OHDA pretreatment, whereas approximately 50% of the responses to l-ephedrine were 6-OHDA-resistant. In human umbilical artery and vein, the two isomers failed to generate any contraction when given at the concentration that is capable of producing significant effects on anococcygeal and atrial tissues. Although direct adrenoceptor activation with l-ephedrine was detectable at tissue levels, the pressor response in vivo was entirely attributable to norepinephrine release from sympathetic nerves. This indirect mechanism could partly explain why l-ephedrine is better at increasing maternal arterial blood pressure while preserving the uteroplacental blood flow that is devoid of the involvement of the sympathetic innervation. IMPLICATIONS: The indirectly sympathomimetic property of l-ephedrine may be one of the mechanisms to explain why ephedrine is preferred over alpha-adrenergic agonists as a vasopressor for treatment of intraspinal anesthesia-induced hypotension in obstetrics.

Animals↗
PubMed2003

Internal carotid artery rotation technique to expose an aneurysm neck: technical note.

OBJECTIVE: Full exposure of a neck of an aneurysm is important to obliterate it completely. METHODS: A 51-year-old woman in whom an unruptured aneurysm projecting medially under the optic nerve was incidentally found underwent clipping surgery. The edge of the circumferentially cut distal dural ring was pulled with forceps to rotate the internal carotid artery and to expose the neck of the aneurysm. RESULTS: The neck of the aneurysm was completely obliterated under direct vision. CONCLUSION: This single, neat method exposes the neck of an unruptured paraclinoid aneurysm of the internal carotid artery.

Carotid Artery Diseases↗
PubMed2003

Double-insurance bypass for internal carotid artery aneurysm surgery.

OBJECTIVE: The aim of this article is to present the usefulness of a double-bypass method in the surgical treatment of complex internal carotid artery (ICA) aneurysms. For patients with clippable but complex aneurysms of the ICA having poor collateral circulation, bypass surgery is needed before temporary occlusion of the ICA. We propose a double bypass for safety. METHODS: The superficial temporal artery was anastomosed to the distal cortical branch of the middle cerebral artery (MCA), followed by anastomosis between the radial artery and the inferior trunk of the MCA. For patients with clippable ICA aneurysms, the radial artery was temporarily anastomosed to the inferior trunk of the MCA by raising the ipsilateral forearm to the head after the radial artery was harvested. After the aneurysm had been clipped, the anastomosed radial artery was cut close to the anastomosed site and repositioned back to the original arm. RESULTS: This double-bypass procedure was performed in two patients, and no ischemic complications related to revascularization were observed. Temporary occlusion times of the MCA for superficial temporal artery-to-MCA anastomosis and radial artery-to-MCA anastomosis were 30 and 46 minutes in one patient and 28 and 55 minutes in another. CONCLUSION: This surgical procedure, which we called "double-insurance bypass," can reduce the risk of ischemic complications associated with revascularization of the ICA.

Aged↗
PubMed2003

Characteristics of distal posteroinferior cerebellar artery aneurysms.

OBJECTIVE: Distal posteroinferior cerebellar artery (PICA) aneurysms are rare and have not been well investigated previously. We report our series of 24 patients with 27 distal PICA aneurysms. METHODS: All patients with distal PICA aneurysms that were surgically treated at Shinshu University Hospital and its affiliated hospitals between 1983 and 2001 were reviewed retrospectively. Data relating to clinical, radiological, and intraoperative findings were analyzed. RESULTS: In our series, distal PICA aneurysms reached an incidence of 0.28 and 0.38% of all intracranial aneurysms and ruptured aneurysms, respectively. There were 23 ruptured and 4 unruptured distal PICA aneurysms. Of these, 74.1% were saccular, 7.4% fusiform, and 18.5% dissecting aneurysms. Primarily the telovelotonsillar segment of the PICA was affected. Usually, the surgical outcome was favorable and was influenced by the obstructive hydrocephalus and the preoperative grade. It was sometimes difficult to detect the ruptured distal PICA aneurysm on the initial angiogram, and an extracranial origin of the PICA was sometimes observed. CONCLUSION: This review summarizes the presentation and outcome of a large series of 24 patients with 27 distal PICA aneurysms, and we conclude that distal PICA aneurysms are benign entities compared with vertebral artery-PICA aneurysms. Characteristics that should be considered in the treatment of distal PICA aneurysms are discussed.

Adult↗
PubMed2003

What is the best method for reporting tumor diameter in vestibular schwannoma?

OBJECTIVE: Various methods have been used to report the tumor diameter of vestibular schwannomas. To clarify the most appropriate method to represent the tumor volume, tumor diameters according to various measuring methods were statistically compared with the actual tumor volume. METHODS: Tumor volume was measured by three-dimensional constructive interference in steady state images in 52 unselected vestibular schwannomas. Pearson's correlation coefficient was obtained between the tumor volume and various tumor diameters, such as diameter parallel to the petrous edge (a); a pons-to-petrous diameter (b); ab, a maximum diameter of the portion in the cerebellopontine angle cistern (max CPA); a maximum diameter of the whole tumor (Max); and a diameter through an axis of the internal auditory canal (Axis). The tumors were divided into three groups on the basis of tumor volume, as follows: Group I (small, <0.5 cm(3)), Group II (medium, 0.5-2 cm(3)), and Group III (large, >2 cm(3)). RESULTS: Max and Axis correlated best with the tumor volume in Group I and correlated least with the tumor volume in Group II. Any of these measurements was acceptable in Group III tumors. The max CPA consistently revealed good correlation with the tumor volume in all three tumor groups. CONCLUSION: The max CPA measurement is the simplest and most appropriate way to represent the tumor volume in unselected tumors. Max or Axis is better only when small tumors (<0.5 cm(3) in volume) are being assessed-that is, those with a max CPA of less than 1 cm.

Adult↗
PubMed2003

Protective dural flap for bone drilling at the paraclinoid region and porus acusticus--technical note.

A new method was developed to avoid the risk of injury to the cranial nerves and vessels during intradural bone resection at the paraclinoid region and porus acusticus. The semicircular dural flap is pulled out with a thread over the anterior clinoid process or the porus acusticus. The flap is extended over the underlying structures with a tapered spatula to create adequate space for drilling the bone. The site for drilling was adequately exposed and bone was drilled away smoothly without damaging the underlying vessels and nerves in 10 patients with paraclinoid aneurysms and in seven patients with vestibular schwannomas. This "protective dural flap" method provides wide exposure for drilling, protects the underlying structures, and allows quick inspection during bone resection.

Brain Diseases↗
PubMed2003

Feasibility of using the potassium titanyl phosphate laser with micromanipulators in robotic neurosurgery: a preliminary study in the rat.

OBJECT: Robotic surgery can be used as a novel technology in ultramicrosurgery. A microscopic-manipulator (micromanipulator) system, which has a rigid neuroendoscope and three guiding manipulators, was developed in Japan for less invasive telerobotic neurosurgery. To apply this system in a clinical setting, it is necessary to confirm that it is capable of performing various surgical procedures including cutting, coagulation, and bleeding control. The authors chose the potassium titanyl phosphate (KTP) laser for such procedures. The aim of this paper was to evaluate the feasibility of this system mounted with the KTP laser. METHODS: A prototypical micromanipulator system was tested in rats. Two kinds of in vivo experiments were performed using the KTP laser: coagulation and biopsy. The coagulated lesions were precisely aligned and their maximum depths were proportional to the energy applied during the coagulation experiment. The diagnosable specimens were obtained during the biopsy experiment. The micromanipulator system was able to perform all surgical procedures accurately. There was no complication relating to the use of the micromanipulator system such as brain injury or uncontrollable bleeding. CONCLUSIONS: The results from this study proved that this system works precisely and safely and will become a new neurosurgical tool in managing lesions that are difficult to treat using conventional microsurgery or neuroendoscopic surgery.

Animals↗
PubMed2003

Growth pattern and rate in residual nonfunctioning pituitary adenomas: correlations among tumor volume doubling time, patient age, and MIB-1 index.

OBJECT: Surgical cure can be achieved in pituitary adenomas when they are completely removed. It is controversial whether postoperative radiation therapy should be given to prevent recurrence, and whether an early reoperation should be performed for residual adenomas, because we have little information about the natural history of postoperative residual adenomas. METHODS: The residual tumor volume was serially measured in 40 nonfunctioning pituitary adenomas (NFPAs) and the tumor volume doubling time (TVDT) was calculated. Correlations between the patients' age, tumor volume, log TVDT, and MIB-1 index were examined. Other factors including the patient's sex, cavernous sinus (CS) invasion by the tumor, or presence of an intratumoral cyst were analyzed to assess their influence on the TVDT. Values are expressed as the means +/- standard deviations. Thirty-eight adenomas increased in volume and two decreased during a follow-up period ranging from 4 to 141 months (mean 52.5 months). Exponentially linear tumor growth was observed in the 38 growing adenomas regardless of the residual tumor volume, with the TVDT ranging from 506 to 5378 days (mean 1836 days). The patients' age was 57.1 +/- 15.7 years (range 15-79 years), the tumor volume at the beginning of the magnetic resonance imaging observation period was 2.5 +/- 2.2 cm3 (range 0.07-14.5 cm3), and the MIB-1 index was 0.73 +/- 0.68% (range 0.1-2.9%). There was a correlation between the log TVDT and patient age (R = 0.73), an inverse correlation between the log TVDT and MIB-1 index (r = -0.49), and an inverse correlation between the MIB-1 index and patient age (r = -0.61). A significant difference (p = 0.0001) was noted between the TVDT (1,106 days) in the 19 patients younger than 61 years of age and the TVDT (2566 days) in the 19 patients who were 61 years of age or older. There was also a significant difference (p = 0.0002) between the age (50.8 +/- 15.3 years) of the patients with rapidly growing tumors (TVDT < 1,836 days, 24 patients) and the age (69.1 +/- 7.6 years) of the patients with slowly growing tumors (TVDT> 1836 days, 14 patients). Other factors including the patients' sex, CS invasion, and intratumoral cyst formation did not affect the TVDT of residual NFPAs. CONCLUSIONS: The tumor growth rate of residual NFPAs is strongly influenced by the patient's age. The TVDT in elderly patients is much longer than that previously reported. Treatment strategies that take into consideration the natural history of residual adenomas should be established especially in the elderly population.

Adenoma↗