Y Ishikawa

University of the Ryukyus, Okinawa, Okinawa, Japan

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Publications (8)1.25 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Activated astrocytes, intrinsic components of both local and remote (axonal target regions) central nervous system injury responses, are now recognized as active metabolic and regulatory mediators in many neurological disorders. To further define these responses, we devised a new ventral surgical approach to unilaterally lesion the inferior olivary nuclear complex, which has a single predominant remote target, the cerebellum. Activated astrocyte number, volume, and density, as well as the total volume of brainstem involved in the astrocytic response, all peaked at postlesion day (pld) 4, returning toward, but not to, unoperated control values at pld 24 (p < 0.05). In contrast, the peak astrocyte response in the cerebellum was delayed, being greatest at pld 6 (p < 0.05 compared to control or pld 2). These responses were associated with increases in overexpression of S100 beta, an astrocyte-derived neurite growth factor, and with an increase in cerebellar steady-state levels of a neuronal injury response protein, the beta-amyloid precursor protein (beta-APP). This is similar to correlated increases in these two proteins that are found in epilepsy and Alzheimer disease. Our studies defining remote astrocytic and neuronal responses may be important for understanding glial-neuronal mechanisms underlying the spread of neuropathological changes in conditions such as Alzheimer disease.
    No preview · Article · Aug 1997 · Molecular and Chemical Neuropathology
  • J Momoji · J Mukawa · K Yamashiro · Y Ishikawa · K Okuyama · T Toda
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    ABSTRACT: Two cases of dural arteriovenous malformation (DAVM) of the posterior fossa were presented and a histopathological examination was described. After embolization of the feeding arteries, DAVMs of the posterior fossa were removed with the adjacent sinus. Serial sections of the surgical specimens showed an abnormal mass with dilated, tortuous vessels of varying diameters in the sinus wall, and partially hyalinized connective tissue around the vessels. The elastic lamina of the sinus wall was interrupted and a mass of abnormal vessels developed into the subintimal layer of the sinus. Fistulas, about 200 microns in diameter, were formed between arterialized dural veins and dural arteries which had obvious internal elastic lamina. An opening of the fistula of the abnormal vessel, 25 microns in diameter, to the sinus lumen was also seen. No stage of organized thrombus could be seen in the sinus lumen. These findings strongly suggested that physiologically existing arteriovenous fistulas within the dura mater, which have been reported by Kerber et al, had developed due to many factors which increase intracranial pressure. They protruded into the sinus lumen in such a way that it could cause stenosis or obstruction of the sinus. In conclusion it can be said that an obstructive lesion of dural sinus is considered of itself to be DAVM in most cases and sinus thrombosis is the result of the DAVM.
    No preview · Article · Mar 1997 · No shinkei geka. Neurological surgery
  • H Koga · J Mukawa · M Nakata · H Miyazato · Y Ishikawa · O Sakuta · A Hokama · Y Terada
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    ABSTRACT: Cerebellar tonsillectomy is a controversial treatment for Chiari type I malformation combined with syringomyelia. To demonstrate the validity of this procedure, we evaluated the postoperative clinical course, the histopathological finding in the resected cerebellar tonsils and the MR images of four patients. The patients were all women, ranging in age from 27 to 58 years old (mean: 43 years). The postoperative follows-up period lasted from 28 to 51 months (average: 38 mos), and the neurological symptoms and signs improved in all patients. Histopathological examination of the resected tonsils revealed a loss of Purkinje cells and granule cells. Vacuolated degeneration and chromatolysis were also seen, and modified Bielschowsky stain revealed axonal degeneration. These findings appeared to be irreversible. Postoperative T1-weighted MR images of the cervical and thoracic spine demonstrated a decrease in the size of the syrinx and the disappearance of evidence of tonsillar herniation in all patients. Postoperative phase-contrast MR images showed good CSF pulsation in the subarachnoid space at the craniocervical junction in all three patients examined. It was possible to avoid surgical complications by using careful microsurgical techniques. Based on these results, we concluded that cerebellar tonsillectomy is an adequate surgical strategies for treating Chiari type I malformation associated with syringomyelia.
    No preview · Article · Dec 1995 · Nō to shinkei = Brain and nerve
  • Y Ishikawa · J Mukawa · T Kinjo · S Mekaru · H Miyazato · E Takara · H Kuda
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    ABSTRACT: Metabolic depression in the contralateral cerebellar hemisphere caused by a supratentorial lesion is called crossed cerebellar diaschisis (CCD). In order to investigate diaschisis based on the location and extension of lesions, time course and prognosis, 31 patients with putaminal hemorrhage were examined by the Xe-133 clearance method (67 studies in all). They consisted of 20 males and 11 females, from 40 to 77 years old (mean: 57.1 +/- 8.9). Small hematomas (mean volume: 16.1 +/- 8.4 ml) in 18 patients were treated nonsurgically, whereas medium and large hematomas (mean volume: 57.5 +/- 29.9 ml) in 13 patients were treated by craniotomy for evacuation. rCBF was measured using a BI 1400 rCBF Analyzer (Valmet, Denmark), and CCD was considered positive when the percentage difference in cerebellar blood flow was 10.1% (mean + 2SD) greater than obtained in 21 normal controls. CCD was observed in 10 patients (55.6%) in the non-surgical group and in 9 patients (69.2%) in the surgical group. In the non-surgical group, CCD was positive in 5 of the 7 cases (71.4%) involving the posterior limb of the internal capsule and in 7 of the 11 cases (63.6%) involving the corona radiata. The surgical group was divided into three types based on the time course of CCD after surgery, i.e., type A: persistent CCD found two months later, type B: postoperative CCD had resolved two months later, and type C: no CCD observed after surgery. Mean hematoma volume was significantly greater in type A (79.0 +/- 19.8 ml) than in type B (44.6 +/- 8.5 ml) or type C (30.7 +/- 3.7 ml) (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
    No preview · Article · May 1994 · Nō to shinkei = Brain and nerve
  • H Koga · J Mukawa · K Miyagi · Y Ishikawa · M Samura · K Ishikawa · M Kudaka
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    ABSTRACT: Intraosseous tumor was found in a 63 year old male patient with lung cancer during metastatic work-up study. Plain skull X-ray film showed a large osteolytic lesion in the left temporo-parietal bone. Bone and Ga scintigrams revealed an increased activity in this lesion. CT scan demonstrated an isodense lentiform configuration, which was homogeneously enhanced with contrast medium. It was iso-intense in T1, and high-intense in T2 and proton weighted MR images. The tumor was removed en bloc with surrounding normal bone. The attached dura was markedly thickened, but there was no tumor infiltration. Histological diagnosis was transitional meningioma with psammoma body. Postoperatively he was transferred back to Okinawa Hospital and right lower lobectomy was performed for the lung tumor. Histological diagnosis was well-differentiated adenocarcinoma. We examined immunohistochemically p53 protein expression, but p53 immunoactivity was observed in neither tumor. Multiple neoplasms associated with brain tumor are relatively rare, but the incidence will increase in the future as the diagnostic work-up develops. Pathological diagnosis will give us the decisive opportunity for proper treatment. It is to be stressed that, in multiple neoplasms, care should be taken to avoid misdiagnosis of metastasis.
    No preview · Article · Jul 1993 · No shinkei geka. Neurological surgery
  • H Koga · J Mukawa · K Miyagi · S Nakasone · T Kinjo · H Miyazato · Y Ishikawa · K Ito · Y Higa
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    ABSTRACT: Metastasis to the brain from esophageal carcinoma is rare. Recently we had four cases, all treated by tumor removal. Three received postoperative whole or local brain irradiation. Anticancer pellets were implanted in two. The postoperative 1-year survival rate was 37.5%, which suggests the prognosis is not worse than for other metastatic brain tumors.
    No preview · Article · Sep 1991 · Neurologia medico-chirurgica
  • T Kinjo · J Mukawa · E Takara · S Nakasone · H Kuda · Y Ishikawa
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    ABSTRACT: A case of moyamoya disease associated with the persistent primitive trigeminal artery (PTA) is reported. 5 such cases reported in literature are reviewed. A 16-year-old female patient was admitted to our clinic, having complained of right hemiparesis for 8 years. CT scan revealed multiple low density areas in the left frontal, temporal and parietal lobes. In left carotid angiogram, the internal carotid artery was occluded at the C3 portion and basal moyamoya (stage IV) was found. In right carotid angiogram, the internal carotid artery was occluded at the C3 portion and basal moyamoya (stage V) was found. Furthermore the persistent primitive trigeminal artery was seen with marked moyamoya vessels from the posterior cerebral artery. In vertebral angiogram, the posterior cerebral artery was seen bilaterally with moyamoya vessels. In 133Xe-rCBF study, compared with the mean flow in each hemisphere, the flow decreased at the temporal lobe, but, in contrast, increased at the parieto-occipital lobes. Reviewing the literature, the following conclusions are suggested. 1. Persistent primitive trigeminal artery will promote the stage of moyamoya disease. 2. It will protect the brain from hemorrhage and/or ischemia in moyamoya disease.
    No preview · Article · Sep 1988 · No shinkei geka. Neurological surgery
  • T Kinjo · J Mukawa · K Miyagi · E Takara · S Mekaru · Y Ishikawa
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    ABSTRACT: A 41-year-old male patient was admitted in our Ryukyu University Hospital complaining of parosmia. He had a history of miliary tuberculosis 21 years ago. Neurologically he showed left anosmia and hyperreflexia of the right upper extremity. Plain skull X-P and CT scan revealed a calcified mass, 25mm in diameter, at the left frontal base. In MRI, the mass showed isointensity using the T1 weighted inversion recovery sequence and heterogenously low intensity using the T2 weighted spin echo sequence. Surgery was performed by bifrontal craniotomy. Then the tumor was removed totally including two coexisting small tumors. Histologically, they consisted of calcified caseous tissue and thick collagen capsule, suggesting old calcified tuberculomas. Postoperative course was uneventful and did not result in meningitis. Antituberculous therapy of streptomycin, isoniazid and rifampin was given for 2 weeks, started on the operative day. MRI findings were presented in detail and the guideline of antituberculous therapy to the tuberculoma was discussed.
    No preview · Article · Jun 1988 · No shinkei geka. Neurological surgery

Publication Stats

52 Citations
1.25 Total Impact Points


  • 1991-1997
    • University of the Ryukyus
      • • Department of Medicine
      • • Department of Neurosurgery
      Okinawa, Okinawa, Japan