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Yoshiaki Shiokawa

Publications and source records attributed to Yoshiaki Shiokawa.

At least 19 recordsLinked to original sources
PubMed2005

Radiation-induced apoptosis of oligodendrocytes in the adult rat optic chiasm.

OBJECTIVES: The present study characterized glial cell injury provoked in adult rat chiasm within 24 hours after a single, high-dose irradiation of 20 Gy. METHODS: All chiasmal glial cells in a section were counted, and the percentage of TUNEL-positive glial cells exhibiting apoptotic morphology was defined as the apoptotic rate. RESULTS: Numbers of apoptotic cells increased significantly (p<0.0001) from 3 to 8 hours after exposure, but returned to baseline levels by 24 hours. Little evidence of apoptosis was observed in non-irradiated chiasms. Similar patterns of increase in apoptotic rate were observed in the genu of the corpus callosum, but the extent was significantly lower (p=0.047) in the optic chiasm, with a maximal rate of 1.9%. Immunohistochemically, apoptotic cells were positive for CNP, a marker for oligodendrocytes. DISCUSSION: These data indicate that chiasmal irradiation induces limited, but significant apoptotic depletion of the oligodendroglial population, and may participate in the development of radiation-induced optic neuropathy.

Analysis of Variance↗
PubMed2005

Meningeal melanocytoma associated with ipsilateral nevus of Ota presenting as intracerebral hemorrhage: case report.

OBJECTIVE AND IMPORTANCE: The authors report a rare case of meningeal melanocytoma presenting with unconsciousness, which was caused by an intracerebral hematoma and associated with a history of ipsilateral nevus of Ota. CLINICAL PRESENTATION: A 75-year-old woman developed nevus of Ota in the first and second divisions of the right trigeminal nerve territory, which had been treated with a skin graft 40 years earlier. She noticed right exophthalmos but left it untreated for 2 years and then became comatose owing to orbital and intracranial tumors, the latter manifesting with hemorrhage. INTERVENTION: She underwent craniotomy, during which the tumor was partially removed with intracerebral hematoma. Histopathologically, the tumor was diagnosed as meningeal melanocytoma. Western blot analysis demonstrated a retained protein expression of cell cycle inhibitor p16(INK4A) and a high level of antiapoptotic Bcl-2 in the resected tumor. CONCLUSION: The combination of nevus of Ota and meningeal melanocytoma has been reported in only four cases in the literature, including the current case. This is the first case coinciding with intracerebral hemorrhage, suggesting the necessity for careful follow-up with radiological images.

Aged↗
PubMed2005

Extradural anterior clinoidectomy. Technical note.

The anterior clinoid process (ACP), located on the skull base, is a relatively small structure, although its removal provides enormous gain in facilitating the management of lesions--either tumors or aneurysms--in the paraclinoid region and upper basilar artery. The extensive surgical field gained contributes to safer exposure of the neurovascular elements in the vicinity while avoiding excessive and hazardous retraction of the brain. In this report the authors present a technically simpler avenue for performing an extradural anterior clinoidectomy after reviewing the anatomy of the ACP and its anatomical variations. Additionally, the original Dolenc procedure and its subseqtient derivatives are compared and contrasted to the authors' simpler and less laborious technique. Different clinical situations in which to use the procedure are described based on the authors' experience from 60 cases (40 aneurysm cases and 20 tumor cases) during a 4-year period.

Brain Neoplasms↗
PubMed2005

[Targeted small craniotomy and evacuation for subscute subdural hematomas: technical report of two cases].

The etiology and proper treatment of symptomatic subacute subdural hematomas remains to be elucidated. We describe two cases of this entity successfully treated with small craniotomy and evacuation. Both patients initially treated conservatively for traumatic thin subdural hematomas because of poor medical condition and mild neurological symptoms, but suffered abrupt neurological deterioration between 2 and 3 weeks after the admission. CT scan showed decreased density of hematomas with minimal increase in volume, and significant swelling of ipsilateral cerebral hemisphere. Urgent two-burr-hole small craniotomy was effective for evacuation of partially organized hematoma. During surgery, definite hematoma membrane was not confirmed. Postoperatively, brain swelling rapidly disappeared and both patients discharged ambulatory without neurological deficit. The present cases are a reminder of this peculiar type of hematoma in patients with delayed neurological deterioration after nonsurgical management of acute subdural hematoma. The rationale for use of small craniotomy is discussed in terms of current understanding of pathogenetic mechanism for this unusual condition.

Aged↗
PubMed2005

[Our current technique for basic pterional craniotomy].

Pterional cnaniotomy is frequently used in neurosurgical practice, but still poses significant cosmetic and functional drawbacks. Here, we describe our modified technique to overcome such problems as the sterilization of the scalp without brush and razor, preemptive analgesia, preservation of the periostium for reconstruction, retrograde dissection of the temporal muscle, and complete sphenoidotomy using chisel or drills. The tips of our pterional craniotomy offer suitable size and depth of working field around the paraclinoidal regions, maintaining cosmetic satisfaction of the patients.

Anesthesia↗
PubMed2005

Postoperative assessment of extracranial-intracranial bypass by time-resolved 3D contrast-enhanced MR angiography using parallel imaging.

PURPOSE: Our goals were to assess image quality of time-resolved contrast-enhanced MR angiography (CE MRA), by using 3D data acquisition along with a parallel imaging technique that can improve temporal resolution and to compare this technique with 3D-time-of-flight (TOF) MRA in the postoperative assessment of extracranial (EC)-intracranial (IC) bypass surgery. METHODS: On a 1.5T imaging system, we performed CE MRA by using a 3D fast field-echo sequence in combination with a parallel imaging technique, to obtain images in the coronal plane centered at the postoperative site. Our patient group comprised 17 patients, including 13 after superficial temporal artery-middle cerebral artery (MCA) anastomosis, 3 after external carotid artery-MCA anastomosis, and one after extracranial vertebral artery-posterior cerebral artery anastomosis. Visualization of the anastomosis and the distal flow on the CE-MRA images was assessed comparatively with that on 3D-TOF MR angiograms obtained at the same time. In 6 patients, we also compared the efficiency of visualization on CE-MRA images with that on conventional angiograms. RESULTS: A temporal resolution of 0.8 s/frame could be achieved with the technique employed. The bypass was better demonstrated postoperatively on CE-MRA images than on 3D-TOF MR angiograms in 13 patients (76%), whereas the 2 methods were equivalent in 4 patients (24%). Good correspondence of results was observed in the 6 patients for whom CE MRA and conventional digital subtraction angiography (DSA) images were compared. CONCLUSION: CE MRA by using the parallel imaging technique can increase image acquisition speed with sufficient image quality. This technique is at least equivalent to 3D-TOF MRA to evaluate the postoperative status of EC-IC bypass.

Adult↗
PubMed2004

Morphologic changes in neo-intimal proliferation in an experimental aneurysm after coil embolization: effect of factor XIII administration.

We investigated histological changes in aneurysmal orifices after embolization with Guglielmi detachable coils (GDCs) and determined the effects of the wound-healing factor, factor XIII, on promoting intimal proliferation by scanning electron microscopy (SEM). GDC embolization was performed in an experimental model of aneurysm in swine. In the control group (17 aneurysms), the aneurysms were resected immediately after surgery, at 1 and 3 weeks after the procedure. In the factor XIII-administered group (13 aneurysms), the swine received factor XIII postoperatively, and the aneurysms were excised at 1 and 3 weeks. The endothelial cell proliferation changes in the aneurysm orifices in both groups were evaluated by SEM. The histological changes at the orifices began immediately after the procedure, and endothelialization was observed at 1 week. One week after the procedure, the rate of endothelial cell proliferation was significantly higher in the factor XIII group (P<0.05). But no difference was observed at 3 weeks, when endothelialization of the orifices was essentially completed. The process of intimal proliferation after coil embolization was similar to the wound-healing process after vascular intimal injury. Administration of the wound-healing factor, factor XIII, would contribute rapid intimal proliferation and may be effective to facilitate complete obliteration of aneurysms after coil embolization.

Animals↗
PubMed2004

Acute carotid arterial occlusion after burr hole surgery for chronic subdural haematoma in moyamoya disease.

Ischaemic strokes and neurological deterioration have been described after revascularisation surgery in patients with moyamoya disease, but accelerated acute occlusion of the internal carotid artery after burr hole surgery has not been reported in this setting. A 66-year-old woman with known moyamoya disease who presented with right motor weakness underwent burr hole surgery for a bilateral chronic subdural haematoma. Postoperatively, the patient had a crescendo transient ischaemic attack and then deteriorated. Angiography showed complete occlusion of the left internal carotid artery. Burr hole surgery may cause postoperative acute occlusion of a preexisting stenotic artery in patients with moyamoya disease.

Aged↗
PubMed2004

High plasma concentration of brain natriuretic peptide in patients with ruptured anterior communicating artery aneurysm.

The purpose of this study is to investigate the mechanism of increased atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in patients with subarachnoid hemorrhage due to ruptured aneurysms. ANP and BNP plasma concentrations were measured by immunoradiometoric assay in 53 patients at the day of onset of ruptured aneurysm, the correlation between values of increased ANP or BNP, and sex, age, location of ruptured aneurysm, degree of SAH, and severity of WFNS were statistically studied. The concentration of BNP in ruptured anterior communicating artery aneurysm (A-com) shows a significant elevation compared with other site aneurysms (p = 0.0007). The patients classified as WFNS Grade V, show a significantly higher concentration of BNP, compared with the patients classified as Grade I-IV (p =0.01). It is concluded that the hypersecretion of BNP, but not ANP, is caused by direct mechanical damage at the anterior hypothalamus by ruptured A-com aneurysm and a higher increase of BNP is also observed in cases suffering from severe neurological deficit.

Adult↗
PubMed2003

white-eyed shunt.

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Cerebral Angiography↗
PubMed2003

[Clinical significance of natriuretic peptides in patients with aneurysmal subarachnoid hemorrhage].

Hyponatremia and hypovolemia following aneurysmal subarachnoid hemorrhage (SAH) might be speculated by exaggerated secretion of natriuretic peptides and resulted ischemic sequela caused by cerebral vasospasm. We measured serum concentration of natriuretic peptides and investigated their influence on post-SAH hyponatremia. Among 49 patients of SAH, their plasma concentration of the natriuretic peptides (atrial natriuretic peptide: ANP and brain natriuretic peptide: BNP) were measured at the day of ictus and 7th day of SAH. The correlation between concentration of natriuretic peptides and location of aneurysm, severity of SAH, incidence of hyponatremia and symptomatic vasospasm were elucidated. The plasma concentration of ANP did not alter on admission and 7th day post SAH, whereas that of BNP increased in the patients with moribund SAH and those with ruptured A-com aneurysm. The initial increase of BNP following SAH could be attributed to direct damage of SAH on the hypothalamus. Hyponatremia and symptomatic vasospasm tended to occur in the patients who had persistent increase of plasma BNP concentration during one week post SAH. Therapeutic intervention to maintain normonatremia by fluid-management decreased occurrence of symptomatic vasospasm, even though patients with increased plasma BNP concentration. It might be concluded that increased secretion of BNP following SAH is caused by direct effect to the hypothalamus and prolonged hyper secretion of BNP resulted hyponatremia, hypovolemia and exaggerated symptomatic vasospasm.

Aneurysm, Ruptured↗