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Yutaka Sawamura

Publications and source records attributed to Yutaka Sawamura.

At least 19 recordsLinked to original sources
PubMed2006

Dissociated expressive and receptive language functions on magnetoencephalography, functional magnetic resonance imaging, and amobarbital studies. Case report and review of the literature.

Dissociated language functions are largely invalidated by standard techniques such as the amobarbital test and cortical stimulation. Language studies in which magnetoencephalography (MEG) and functional magnetic resonance (fMR) imaging are used to record data while the patient performs lexicosemantic tasks have enabled researchers to perform independent brain mapping for temporal and frontal language functions (MEG is used for temporal and fMR imaging for frontal functions). In this case report, the authors describe a right-handed patient in whom a right-sided insular glioma was diagnosed. The patient had a right-lateralized receptive language area, but expressive language function was identified in the left hemisphere on fMR imaging- and MEG-based mapping. Examinations were performed in 20 right-handed patients with low-grade gliomas (control group) for careful comparison with and interpretation of this patient's results. In these tests, all patients were asked to generate verbs related to acoustically presented nouns (verb generation) for fMR imaging, and to categorize as abstract or concrete a set of visually presented words consisting of three Japanese letters for fMR imaging and MEG. The most prominent display of fMR imaging activation by the verb-generation task was observed in the left inferior and middle frontal gyri in all participants, including the patient presented here. Estimated dipoles identified with the abstract/concrete categorization task were concentrated in the superior temporal and supramarginal gyri in the left hemisphere in all control patients. In this patient, however, the right superior temporal region demonstrated significantly stronger activations on MEG and fMR imaging with the abstract/concrete categorization task. Suspected dissociation of the language functions was successfully mapped with these two imaging modalities and was validated by the modified amobarbital test and the postoperative neurological status. The authors describe detailed functional profiles obtained in this patient and review the cases of four previously described patients in whom dissociated language functions were found.

Adult↗
PubMed2006

[Olfactory neuroblastoma: the Hokkaido University experience].

Olfactory neuroblastoma is such a rare malignancy that no consensus has been reached on its management. We analyzed 17 patients with olfactory neuroblastoma treated between April 1980 and March 2004--9 men and 8 women, aged 16 to 76 years old(mean: 50.4 years). Follow-up of current survivors was 1 year 8 months to 16 years 6 months (average: 7 years 9 months). Initially, 2 were treated with surgery alone, 5 with surgery and radiotherapy, and 2 with a combination of these and chemotherapy. Without surgery, radiotherapy alone was conducted in 3 and combined of radiation and chemotherapy in 5. Three of the 5 patients treated with surgery and radiotherapy survive without locoregional recurrence as do 2 with chemotherapy added. All 5 initially treated with craniofacial resection survived more than 5 years. Combined radiotherapy and chemotherapy without surgery was effective in 2. 5- and 10-year overall survival for all patients were 75.5% and 64.7%. Overall 5-year survival of 8 patients with low-grade tumors was 87.5% and of 6 with high-grade tumors 33.3%. In conclusion, combined craniofacial resection plus radiotherapy and chemotherapy seemed to improve survival. Histopathological grading is a prognostic factors.

Adolescent↗
PubMed2006

[Efficacy and safety of monotherapy with temozolomide in patients with anaplastic astrocytoma at first relapse--a phase II clinical study].

The efficacy and safety of temozolomide were evaluated in 32 patients with anaplastic astrocytoma at first relapse. Temozolomide was administered orally once daily for the first five days of a 28-day cycle, at a dose of 150 or 200 mg/m(2)/day. The response rate determined by independent central review of MRI was 34% (95% confidence interval: 18.6%-53.2%), with 3 complete response and 8 partial response. The rate of "no change or better" was 91% (95% confidence interval: 75.0%-98.0%). Progression-free survival (PFS) at 6 months was 40.6%, and the median PFS was 4.1 months. The incidence of constipation (50%) and nausea (25%) was high,but these events were all mild or moderate in severity except in one subject with constipation,and could be managed with standard laxatives and antiemetics. The main laboratory test abnormalities (total incidence and incidence of grade 3/4 change) were lymphocytopenia (50%, 25%), neutropenia (47%, 6%), leukopenia (38%, 3%), thrombocytopenia (31%, 9%), and increased GPT (25%, 3%). Temozolomide was shown to have good efficacy and tolerability in patients with anaplastic astrocytoma at first relapse.

Adult↗
PubMed2006

[Temozolomide in the treatment of recurrent malignant glioma].

Temozolomide (TMZ) has demonstrated activity and acceptable toxicity for the treatment of recurrent malignant gliomas in carious prospective phase II studies. No information is, however, available on TMZ treatment for recurrent malignant glioma in Japanese patients. We report Hokkaido University Hospital experience on 35 adult patients with a recurrent malignant glioma, including 13 glioblastomas, 9 anaplastic astrocytomas, and 13 anaplastic oligondendroglial tumors. The median age was 52 years. The starting dose of TMZ was 150 mg/m2/day for 5 days. When no remarkable toxicity was observed, the dose was increased to 200 mg/m2 for subsequent cycles, every 4 week. In the 35 patients, the overall objective response rate (partial response) was 12% and 74% of the patients achieved disease stabilization. The median progression-free survival was 28 weeks and the median overall survival was 43 weeks. Although hematological toxicity was the most frequent adverse event (CTC grade 3 or 4 in 6 patients), overall toxicity was generally mild. Four patients required hospitalization due to the toxicity, but 28 patients had been treated with TMZ at our outpatient clinic. These results suggested that the reported efficacy and toxicity profile of TMZ for the treatment of Japanese patients with recurrent malignant glioma is reproducible from the setting of clinical trials in the western countries.

Administration, Oral↗
PubMed2005

Congenital gemistocytic astrocytoma in a fetus.

INTRODUCTION: Congenital brain tumors, especially tumors diagnosed before birth, are very rare. This report presents a case of a congenital gemistocytic astrocytoma diagnosed by antenatal intrauterine ultrasound. CASE REPORT: An intrauterine MRI revealed hydrocephalus and a mass lesion including massive hemorrhage in the right occipital lobe of a fetus. The patient was delivered by cesarean section and a total excision of the hemorrhagic tumor was carried out on the third day of his life. The histological study revealed gemistocytic astrocytoma (WHO grade II). Neither adjuvant chemotherapy nor radiation was given after the first surgery. Ten months after his birth, a recurrent tumor was depicted on follow-up MRI. The second total excision of the recurrent tumor and chemotherapy using cisplatin and vincristine were performed. OUTCOME: The patient is free of disease at the age of 2 years and 6 months.

Adult↗
PubMed2005

A tumor in the medulla oblongata producing beta-HCG and AFP.

A 23 year-old woman presented with dysarthria, hoarseness, dysphasia, ataxia and dyspnoea. MRI showed a mass of heterogeneous intensity at the dorsal medulla oblongata. Laboratory studies revealed high serum alpha-fetoprotein (AFP) and beta-subunit human chorionic gonadotropin (beta-HCG) levels. No other tumours were found on systemic investigation. An intracranial non-germinomatous germ cell tumour (NGGCT) was strongly suspected. The patient received combination chemotherapy using ifosfamide, cisplatin, and etoposide and local irradiation to a total of 52 Gy. Serum AFP and beta-HCG levels normalized after four cycles of chemotherapy and she became asymptomatic apart from mild postural hypotension. A follow-up MRI showed only a tiny residual lesion in the medulla oblongata, which has been stable for more than three years. Surgical resection should be carefully considered in patients with brainstem tumours with elevation of serum tumour markers as chemo- and radiotherapy may be effective for brainstem NGGCT.

Adult↗
PubMed2005

Functional identification of the primary motor area by corticospinal tractography.

OBJECTIVE: For quick and stable identification of the primary motor area (PMA), diffusion tensor imaging (DTI) data were acquired and corticospinal tractography was mathematically visualized. METHODS: Data sets of DTI, anatomic magnetic resonance imaging, and functional magnetic resonance imaging with finger-tapping tasks were acquired during the same investigation in 30 patients with a brain lesion affecting the motor system. Off-line processing of DTI data was performed to visualize the corticospinal tract, placing a seed area in the cerebral peduncle of the midbrain, where the corticospinal tract is densely concentrated. Somatosensory evoked magnetic fields and intraoperative cortical somatosensory evoked potentials were recorded with electrical stimulation of the median nerve to confirm the results of the corticospinal tractography. RESULTS: Functional magnetic resonance imaging and somatosensory evoked magnetic fields failed to identify the PMA in eight patients (16.7%) and one patient (3.8%) investigated, respectively, because of cortical dysfunctions caused by brain lesions. DTI data were acquired within 3 minutes without patient tasks. Using the appropriate seed area and fractional anisotropy, corticospinal tractography successfully indicated the PMA location in all patients. The suspected PMA and central sulcus locations were confirmed by the cortical somatosensory evoked potentials. CONCLUSION: Corticospinal tractography enables identification of the PMA and is beneficial, particularly for patients who present with dysfunction of the PMA.

Adolescent↗
PubMed2005

Two-year follow-up of chronic stimulation of the posterior subthalamic white matter for tremor-dominant Parkinson's disease.

OBJECTIVE: To determine the efficacy and safety of unilateral deep brain stimulation on the posterior subthalamic white matter, including the zona incerta (ZI) and the prelemniscal radiation (PRL), for tremor-dominant parkinsonian patients and to determine the exact location of electrodes that were most effective. METHODS: Eight parkinsonian patients with severe resting tremor underwent unilateral stimulation of the ZI/PRL by use of stereotactic guidance. Electrophysiological targeting was obtained by macrostimulation and by somatosensory evoked potentials recorded directly through a quadripolar deep brain stimulation lead. Postoperative computed tomographic scans and magnetic resonance images were performed to confirm anatomic location of the electrode. Parkinsonian motor disabilities were evaluated by use of the Unified Parkinson's Disease Rating Scale in the medication-off state before surgery and every 6 months after electrode implantations. RESULTS: The mean location of the clinically effective contacts was in the posterior subthalamic white matter, including the ZI and the PRL (mean, 5.6 +/- 1.2 mm posterior to the midcommissural point, 3.2 +/- 1.1 mm inferior to the anterior commissure-posterior commissure line, and 10.5 +/- 1.2 mm lateral to the midline). At 24 months after operation, ZI/PRL stimulation resulted in significant improvement in mean Unified Parkinson's Disease Rating Scale motor score by 44.3%, contralateral tremor by 78.3%, contralateral rigidity by 92.7%, and contralateral akinesia by 65.7% above the "off-stimulation" scores. Handwriting, posture, and gait were also improved. There were no or only mild adverse events. CONCLUSION: Unilateral ZI/PRL stimulation is a reliable and long-term therapeutic modality and can be considered another surgical target for the treatment of tremor-dominant Parkinson's disease.

Aged↗
PubMed2005

Bilateral germinoma involving the basal ganglia and cerebral white matter.

We describe radiologic findings of germinoma involving bilateral basal ganglia and cerebral white matter. In the early stage, T1-weighted MR images showed hyperintense areas in the bilateral globi pallidi. Later, T2-weighted images showed hyperintense areas involving bilateral white matter. The MR imaging findings reported here could help facilitate the early diagnosis of germ cell tumors in young patients.

Basal Ganglia Diseases↗
PubMed2004

Impact of margin for target volume in low-dose involved field radiotherapy after induction chemotherapy for intracranial germinoma.

PURPOSE: We previously published a report stating that germinomas with elevated serum beta human chorionic gonadotropin (HCG-beta) had a poor relapse rate, but these findings have not been supported by a multi-institutional trial. The margin for initial gross tumor volume (GTV) before surgery and chemotherapy of the same materials was investigated by retrospective review. METHODS AND MATERIAL: The 27 patients reported on in the previous paper were analyzed. The two-dimensional margin from the initial GTV to 90% of the prescribed dose of 24 Gy was 2.0 cm for a solitary lesion in the protocol. This margin was measured retrospectively without knowledge of the serum HCG-beta level. The whole ventricle field was used for patients with multifocal disease and whole central nervous system field was used for disseminated disease, respectively. RESULTS: Six relapses were seen in 18 patients with solitary tumors, and were treated with the minimum margin of 1.5 cm or less to the initial GTV. Five of the 6 had initially elevated serum HCG-beta at the median of 7.4 mIU/mL, ranging from 0.7-233 mIU/mL. No relapses were seen in the 9 patients who were treated with whole ventricle or whole central nervous system field. CONCLUSIONS: An inadequate margin and elevated serum HCG-beta were equally determined to be candidates that caused the poor local control. The whole ventricle is recommended as the smallest target volume for germinoma with or without elevated HCG-beta after induction chemotherapy.

Adolescent↗
PubMed2004

Clinico-pathological features of pilomyxoid astrocytoma of the optic pathway.

Five cases of pilomyxoid astrocytoma (PmA) characterized by a monophasic pattern with a myxoid background were selected for a clinicopathological study from 23 cases previously diagnosed as pilocytic astrocytoma (PA). All PmA patients were either infants or young children (mean age 2.1 years), and all tumors were located in the optic chiasm/hypothalamus region. All cases received chemotherapy, which reduced tumor size, and the location of the tumor became confined to the optic chiasm. In two cases, tumor recurrence occurred 3 and 7 years after chemotherapy. Histology of the recurrent tumors showed the biphasic pattern of classical PA. Hence, we conclude that PmA might be an infantile form of PA and speculate that a subset of PmA in the optic pathway/hypothalamus originates from the optic chiasm, possibly derived from radial glia existing in the embryonic optic chiasm.

Astrocytoma↗
PubMed2004

Gradual recovery from dyslexia and related serial magnetoencephalographic changes in the lexicosemantic centers after resection of a mesial temporal astrocytoma. Case report.

Letter-perception centers are not held in as high regard as motor- and language-related cortices during planning of neurosurgical procedures, and there have been no reports suggesting cortical reorganization of reading ability. The authors describe a patient with a left mesial temporal glioma in whom two letter-perception centers (the anterior portion of the left superior temporal gyrus and the left fusiform gyrus) were successfully localized before surgery by performing magnetoencephalography (MEG) during reading tasks. Control MEG examinations of 15 healthy volunteers were also performed to assist in a careful interpretation of patient results. Although a radical resection of the mesial temporal glioma, which involved the left fusiform gyrus, caused severe dyslexia, the patient's impaired reading skills improved gradually during a 1-year postoperative period. In the meantime, the spared left superior temporal gyrus displayed an overshot recovery of MEG responses. During the postoperative period there was no obvious recovery in MEG signals and no compensatory activity in the contralateral fusiform gyrus. This case demonstrates that lexicosemantic centers involved in the reading process can be noninvasively localized using MEG and that the results obtained are highly reliable for surgical planning. The results of the repeated MEG reflected sequentially the patient's recovery from dyslexia. This is the first report in which MEG studies have been shown to predict preoperatively the risk of dyslexia and demonstrate its serial physiological recovery.

Adult↗
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↗
PubMed2003

Expression of the oligodendroglial lineage-associated markers Olig1 and Olig2 in different types of human gliomas.

Because a specific group of oligodendrogliomas is susceptible to adjuvant therapy, it is important to elucidate the biological characteristics of these tumors. In situ hybridization analyses have revealed that Olig genes are expressed in oligodendroglial lineage cells and are highly expressed in oligodendrogliomas. To clarify whether OLIG is a tumor-specific marker for oligodendrogliomas, we have investigated the expression of Olig transcripts by semiquantitative RT-PCR assay and OLIG2 protein with a new antibody in a variety of glial tumors. The semiquantitative RT-PCR revealed that high levels of expression of Olig1 and Olig2 mRNAs were present in anaplastic oligodendrogliomas and anaplastic astrocytomas, while expression of these mRNAs in grade IV glioblastomas was lower than in grade II and grade III gliomas (p < 0.01). Immunohistochemical analyses demonstrated that the mean immunopositive proportion of OLIG2 was 82% in anaplastic oligodendrogliomas but only 34% in anaplastic astrocytomas. Therefore, although OLIG2 expression was detected in a range of gliomas not specific for oligodendrogliomas, the expression level in anaplastic oligodendrogliomas was more uniform and intense than that in other glial tumors. In conclusion, combining Olig mRNA expression and immunohistochemistry of OLIG2 enables oligodendrogliomas to be distinguished from glioblastomas and other astrocytic glial tumors.

Adolescent↗