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Yutaka Sawamura

Publications and source records attributed to Yutaka Sawamura.

9 recordsLinked to original sources
PubMed2003

Hypofractionated stereotactic radiotherapy alone without whole-brain irradiation for patients with solitary and oligo brain metastasis using noninvasive fixation of the skull.

PURPOSE: To evaluate the efficacy and toxicity of hypofractionated stereotactic radiotherapy (HSRT) using noninvasive fixation of the skull on solitary or oligo brain metastatic patients as an alternative to stereotactic radiosurgery (SRS) using invasive fixation. PATIENTS AND METHODS: The subjects were 87 patients who had 4 or fewer brain metastases (50 solitary, 37 oligometastases). Treatment was conducted on 159 metastases by using a linac-based stereotactic system. The median isocentric dose was 35 Gy in 4 fractions. Whole-brain irradiation was not applied as an initial treatment. For the salvage treatment of metachronous brain metastases, repeat HSRT or whole-brain irradiation was applied. RESULTS: The actuarial 1-year local tumor control rate was 81%. Treatment-related complications were observed in 4 patients in the early period (<3 months) and in 2 patients in the late period. The median survival period was 8.7 months. Metachronous brain metastases occurred in 30 patients, and none of the 18 patients who were eligible for salvage HSRT refused to receive it again. CONCLUSIONS: Hypofractionated stereotactic radiotherapy achieved tumor control and survival equivalent to those of SRS reported in the literature. The results suggested that HSRT could be an alternative for solitary or oligo brain metastatic patients with less toxicity and less invasiveness compared to SRS.

Actuarial Analysis↗
PubMed2003

Alternative approach using the combined technique of nerve crossover and cross-nerve grafting for reanimation of facial palsy.

An alternative approach, using a combination of nerve crossover and cross-nerve grafting technique in a single-stage procedure, was developed for the reconstruction of reversible facial palsy. This combined technique provides some benefits such as early facial reanimation resulting from the single-stage procedure, less morbidity and sufficient innervation with an application of the end-to-side anastomosis method, and efficient neural regeneration due to coaptation of the intratemporal facial nerve. Facial nerve rehabilitation, based on double innervation by hypoglossal and contralateral healthy facial nerves, takes advantage of reliable and physiological facial reanimation.

Aged↗
PubMed2003

Visualization of the eloquent motor system by integration of MEG, functional, and anisotropic diffusion-weighted MRI in functional neuronavigation.

BACKGROUND: In this study, we visualized the eloquent motor system including the somatosensory-motor cortex and corticospinal tract on a neuronavigation system, integrating magnetoencephalography (MEG), functional magnetic resonance imaging (fMRI), and anisotropic diffusion-weighted MRI (ADWI). METHODS: Four patients with brain lesions adjacent to the eloquent motor system were studied. Motor-evoked responses (MER) by finger-tapping paradigm were acquired with a 1.5-Tesla MR scanner, and somatosensory-evoked magnetic fields (SEF) by median nerve stimulation were measured with a 204-channel MEG system. In the same fMRI examination, ADWI and anatomic three-dimensional T1-weighted imaging (3-D MRI) were obtained. Activated areas of MER, estimated SEF dipoles, and the corticospinal tract on ADWI were coregistered to 3-D MRI, and the combined MR data were transferred to a neuronavigation system (functional neuronavigation). Intraoperative recording of cortical somatosensory-evoked potentials was performed for confirmation of the central sulcus. RESULTS: Combination of fMRI and MEG enabled firm identification of the central sulcus. Functional neuronavigation facilitated extensive tumor resection, having the advantage of sparing the motor cortex and corticospinal tract in all cases. CONCLUSIONS: The proposed functional neuronavigation allows neurosurgeons to perform effective and maximal resection of brain lesions, identifying and sparing eloquent cortical components and their subcortical connections. Potential clinical application of this technique is discussed.

Adolescent↗
PubMed2002

Induction chemotherapy followed by low-dose involved-field radiotherapy for intracranial germ cell tumors.

PURPOSE: To investigate the efficacy of chemotherapy followed by low-dose involved-field radiotherapy for the treatment of intracranial germ cell tumors (GCTs). PATIENTS AND METHODS: Thirty-three patients with GCTs, including 16 pure germinomas, 11 human chorionic gonadotropin-beta (HCG-beta)-secreting germinomas, three mixed GCTs composed of immature teratomas plus germinomas (IMT/G), and three highly malignant mixed GCTs, were treated. Etoposide and cisplatin (EP) were used for the treatment of solitary pure germinomas, and ifosfamide, cisplatin, and etoposide (ICE) were used for the treatment of other GCTs. The dose schedule was 24 Gy for germinomas and 40 to 54 Gy for other GCTs. An involved-field set-up was used except for highly malignant GCTs, in which craniospinal irradiation was used. The median follow-up was 58 months (range, 18 to 102 months). RESULTS: Disease-related, overall, and relapse-free survival rates at 5 years were 100%, 93%, and 69% for all patients, 100%, 100%, and 86% for patients with pure germinomas, and 100%, 75%, and 44% for patients with HCG-beta-secreting germinomas, respectively. All six patients with nongerminomatous GCTs were alive at the last follow-up. All eight relapses (one pure germinoma, five HCG-beta-secreting germinomas, and two IMT/G), except one in a course of salvage treatment, were salvaged and free of disease at the last follow-up. No decline was observed in the full-scale, verbal, or performance intelligence quotient at 12 to 51 months after the treatment in 11 patients. CONCLUSION: Our results support an excellent prognosis after EP and ICE regimens followed by radiotherapy. Dose and volume can be reduced to 24 Gy in 12 fractions and involve a field set-up after EP chemotherapy for the treatment of pure germinomas.

Adolescent↗
PubMed2002

Three-dimensional conformal radiotherapy for astrocytic tumors involving the eloquent area in children and young adults.

PURPOSE: Although a gross total removal of astrocytic tumors offers a favorable prognosis, it is often difficult to achieve in the eloquent area of the brain. This study was conducted to investigate the possible gain of three-dimensional conformal radiotherapy (3DCRT) for astrocytic tumors located in the eloquent area in children and young adults. MATERIALS AND METHODS: Twenty patients with astrocytic tumors received the radiotherapy. The median age was 17 years, ranging from 4 to 30 years. Fourteen low-grade tumors (seven pilocytic and seven diffuse), and six high-grade tumors (five anaplastic, one malignant pilocytic) were included. Tumors were located at the thalamus/hypothalamus in 12 cases, optic tract in one case, and the deep cerebral/cerebellar hemisphere in seven cases. A specific fixation device was used for 3DCRT. Forty-six Gy for low-grade tumors and 54 Gy for high-grade astrocytomas with 1.8-2.0 Gy per fraction were in principle employed as the standard regimen. Nominal radiotherapy fields ranged from 2.0 x 2.0 to 15.0 x 11.0 cm2. The median follow-up period was 42 months, ranging from 3 to 108 months. RESULTS: The actuarial survival rate at 5 years was 68% +/- 13% for all patients. The actuarial survival rate for low-grade glioma was 79% +/- 14% at 5 years and 50% +/- 20% at 3 years for high-grade glioma. The actual progression-free survival rate was 83% +/- 11% at 5 years for low-grade glioma and 50% +/- 20% for high-grade glioma. A complete response was obtained in three (21%) of 14 patients with low-grade astrocytic tumors. Two patients with low-grade tumors and four of six with high-grade tumors died due to tumor progression with infield relapse but not marginal relapse. Twelve survivors with low-grade tumors showed no signs of relapse and no neurological, hormonal, or cognitive deterioration after radiotherapy and were able to attend their school or continue with a full-time job. CONCLUSIONS: 3DCRT is safe and effective for low-grade astrocytic tumors located in the eloquent area in children and young adults.

Adolescent↗
PubMed2002

Diagnostic significance of soluble c-kit in the cerebrospinal fluid of patients with germ cell tumors.

OBJECT: Overexpression of the protooncogene c-kit has been suggested in a gonadal germ cell tumor (GCT). Recently, the soluble isoform of c-kit (s-kit) has been expressed in a variety of cell types. The goal of this study was to investigate the expression of c-kit and the clinical significance of s-kit in patients with GCTs. METHODS: The authors first conducted an immunohistochemical investigation of the expression of the c-kit protein in 27 surgical specimens. In all 18 specimens that contained germinomas, c-kit was diffusely expressed on the cell surface of the germinoma cells, but was not found on lymphocytes or interstitial cells. In seven of eight immature teratomas, only some mature components, such as cartilage and glands, were immunoreactive for c-kit. Syncytiotrophoblastic giant cells (STGCs) demonstrated negative findings as well, suggesting that primarily germinoma cells express c-kit. Next, 47 cerebrospinal fluid (CSF) samples collected from 32 patients with GCTs (15 samples from patients with pure germinomas, 16 from patients with STGC germinomas, 14 from patients with teratomas, and two from a patient with a choriocarcinoma) were analyzed using a sandwich enzyme-linked immunosorbent assay. The level of s-kit was significantly higher in CSF collected from patients with germinomas and STGC germinomas than in CSF collected from patients with teratomas or non-germ cell brain tumors, or in CSF collected from controls. The concentration of s-kit in CSF was correlated with the patient's clinical course: it was significantly higher in pretreatment samples obtained before and in samples obtained at the time of tumor recurrence than in samples collected from patients in whom the tumor was in remission. The level of s-kit was remarkably high in CSF collected from patients with subarachnoid tumor dissemination. CONCLUSIONS: These results indicate that the concentration of s-kit in CSF may be a useful clinical marker for germinomas, especially for detecting recurrence or subarachnoid dissemination of these lesions.

Biomarkers, Tumor↗
PubMed2002

Rapid identification of the primary motor area by using magnetic resonance axonography.

OBJECT: To identify the primary motor area (PMA) quickly and correctly, the authors used magnetic resonance (MR) axonography, including anisotropic diffusion-weighted (DW) MR imaging and three-dimensional anisotropic contrast (3DAC) imaging, which was performed to visualize the corticospinal tract mainly originating from the PMA. METHODS: All studies were obtained in 10 normal volunteers and in 17 patients with brain tumors affecting the central motor system. Data sets of anisotropic DW imaging and anatomical and functional (f)MR imaging were acquired while the participants executed simple hand movements. Offline processing of 3DAC MR axonography images was subsequently done to extract only the anisotropic components of the tract fibers. Somatosensory evoked fields (SSEFs) and intraoperative cortical somatosensory evoked potentials (SSEPs) were recorded after electrical stimulation of the median nerve. CONCLUSIONS: In normal volunteers, anisotropic DW imaging, 3DAC imaging, fMR imaging, and magnetoencephalography consistently localized the PMA in both hemispheres. In contrast, fMR imaging and SSEFs failed to identify the PMA in seven and one of the 17 patients, respectively, because of cortical dysfunctions due to brain tumor. The anisotropic DW imaging data acquired within 30 seconds with no patient tasks successfully identified the PMA in 12 patients, and failed in five patients because of the lesions involving the frontal lobe. The anisotropic axonal components were distinctly visualized on 3DAC images and indicated the PMA location, which was confirmed on intraoperative SSEPs in all 17 affected hemispheres. Swift and noninvasive PMA identification by rapid scanning with MR axonography is a promising method for routine clinical use and is especially beneficial for patients who have severe cortical dysfunction in the PMA.

Adult↗