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Katsuyoshi Miyashita, Yutaka Hayashi, Hironori Fujisawa, Mitsuhiro Hasegawa and Junkoh Yamashita

✓ Solitary fibrous tumor (SFT) is a benign and rare neoplasm. To date, only 37 patients with intracranial SFTs have been reported. Although a number of the tumors were recurrent and some later underwent malignant transformation, none of these lesions progressed to cerebrospinal fluid (CSF) dissemination. In this paper the authors report a case of SFT in which the lesion recurred several times and ultimately was disseminated by the CSF. The patient was a 63-year-old woman with multiple intracranial and spinal tumors. Fifteen years before this presentation, at the age of 48 she had been hospitalized for resection of a falcotentorial tumor. During the ensuing 15 years she underwent multiple surgeries and sessions of radiation therapy for recurrent lesions. The exclusive location of her tumors in the subarachnoid space at the end of this 15-year period indicate CSF dissemination of the tumor.

The tumor that was resected when the patient was 48 years old and the latest resected lesion were analyzed by performing immunohistological CD34, epithelial membrane antigen, vimentin, S100 protein, and reticulin staining, and determining the MIB-1 labeling index (LI). Most of the results were identical, and both tumors were diagnosed as SFT according to a staining pattern that showed a strong and diffuse positive reaction for CD34. Nevertheless, the authors noted that the MIB-1 LI increased from less than 1% in the original tumor to 13% in the latest tumor. The increased proliferation of MIB-1 indicates that the malignant transformation could have occurred during tumor recurrence with CSF dissemination.

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Yutaka Hayashi, Junkoh Yamashita, Naoki Muramatsu, Kazushige Sakuda and Hisashi Nitta

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Yutaka Hayashi, Masashi Kinoshita, Mitsutoshi Nakada and Jun-ichiro Hamada

Object

Disturbance of the arcuate fasciculus in the dominant hemisphere is thought to be associated with language-processing disorders, including conduction aphasia. Although the arcuate fasciculus can be visualized in vivo with diffusion tensor imaging (DTI) tractography, its involvement in functional processes associated with language has not been shown dynamically using DTI tractography. In the present study, to clarify the participation of the arcuate fasciculus in language functions, postoperative changes in the arcuate fasciculus detected by DTI tractography were evaluated chronologically in relation to postoperative changes in language function after brain tumor surgery.

Methods

Preoperative and postoperative arcuate fasciculus area and language function were examined in 7 right-handed patients with a brain tumor in the left hemisphere located in proximity to part of the arcuate fasciculus. The arcuate fasciculus was depicted, and its area was calculated using DTI tractography. Language functions were measured using the Western Aphasia Battery (WAB).

Results

After tumor resection, visualization of the arcuate fasciculus was increased in 5 of the 7 patients, and the total WAB score improved in 6 of the 7 patients. The relative ratio of postoperative visualized area of the arcuate fasciculus to preoperative visualized area of the arcuate fasciculus was increased in association with an improvement in postoperative language function (p = 0.0039).

Conclusions

The role of the left arcuate fasciculus in language functions can be evaluated chronologically in vivo by DTI tractography after brain tumor surgery. Because increased postoperative visualization of the fasciculus was significantly associated with postoperative improvement in language functions, the arcuate fasciculus may play an important role in language function, as previously thought. In addition, postoperative changes in the arcuate fasciculus detected by DTI tractography could represent a predicting factor for postoperative language-dependent functional outcomes in patients with brain tumor.

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Yutaka Hayashi, Mitsutoshi Nakada, Shingo Tanaka, Naoyuki Uchiyama, Yasuhiko Hayashi, Daisuke Kita and Jun-ichiro Hamada

Object

Fluorescence-guided surgery using 5-aminolevulinic acid (5-ALA) has been broadly recognized as a beneficial tool for the resection of glioblastoma multiforme (GBM). Fluorescence in the ventricular walls, which were apparently free of macroscopic tumor or MR imaging enhancement indicative of CSF dissemination, was detected during surgery for GBM. To evaluate the clinical significance of the 5-ALA fluorescence, the authors resected ventricle wall tissue together with the adjacent tumors for pathological examination and then followed up the clinical courses of the patients.

Methods

Seven consecutive GBMs located near the lateral ventricle were surgically treated using a fluorescence-guided technique with 5-ALA at the authors' hospital since acquiring instrumentation for the detection of 5-ALA fluorescence in 2007. All of the procedures were performed using a ventricular entry, and 5-ALA fluorescence of the ventricular wall was detected despite the absence of macroscopic tumor invasion of the wall.

Results

A pathological examination of the resected ventricular wall tissues revealed tumor cells in 6 of the 7 cases and disruption of the ependymal cell layer in all 7 cases. Delayed communicating hydrocephalus followed surgery in all 7 patients, and ventricular wall enhancements on MR imaging were demonstrated after hydrocephalus in 2 of the patients.

Conclusions

Data in this study suggest that 5-ALA fluorescence of the ventricular wall may be predictive of postoperative hydrocephalus associated with CSF dissemination even in cases without evidence of CSF dissemination on MR imaging studies before surgery. The authors also speculate that postoperative radiotherapy covering the whole ventricular system may be a better therapeutic option for these patients.

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Masanori Kurimoto, Yutaka Hirashima, Nakamasa Hayashi, Shunro Endo, Masayoshi Ohi, Soushi Okamoto and Akira Takaku

✓ The authors report an extremely rare case of neurofibromatosis Type 1 (NF1) with a suboccipital meningocele presenting as a huge retropharyngeal mass. A 73-year-old woman with typical cutaneous manifestations of NF1 presented with nasal obstruction and dysphagia due to a retropharyngeal mass. Magnetic resonance imaging revealed a huge mass lesion extending from the right occipital bone defect to the retropharynx through the right paravertebral region. Computerized tomography scanning after intrathecal administration of contrast material confirmed that the mass was a meningocele protruding through a right occipital bone defect. The authors attempted to ligate this meningocele, most of which was excised via a suboccipital approach, but a second transcervical operation was required. Finally, the meningocele resolved and the patient was discharged without symptoms.

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Yutaka Hirashima, Nakamasa Hayashi, Osamu Fukuda, Hideki Ito, Shunro Endo and Akira Takaku

Object. The purpose of this study was to evaluate the involvement of platelet-activating factor (PAF) in the formation of edema surrounding meningiomas.

Methods. Volumes of tumor and peritumoral edema were calculated based on three-dimensional reconstructed magnetic resonance images in 31 patients with intracranial meningiomas. The authors measured tumor concentrations of PAF and localized PAF and leukocytes in the tumors by using immunohistochemical studies. A significant positive correlation was found between peritumoral edema and PAF concentration. Both PAF and leukocyte common antigen were localized to the interstitial tissue of the tumor. Edema production was related to the degree of leukocyte infiltration in meningiomas.

Conclusions. It appears that PAF, which may arise from infiltrating leukocytes, is important to the development of peritumoral edema in patients with meningioma.

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Hiromichi Yamamoto, Yutaka Hirashima, Hideo Hamada, Nakamasa Hayashi, Hideki Origasa and Shunro Endo

Object. The authors attempted to determine independent predictors that contribute to the recurrence of chronic subdural hematoma (CSDH).

Methods. A total of 105 consecutive patients who underwent surgery for CSDH were included in this study. Eleven patients underwent a repeated operation because the CSDH recurred. Univariate and multivariate analyses were performed to assess the relationships among various variables and CSDH recurrence. Finally, four variables were found to be independently associated with the recurrence of CSDH: 1) absence of a multiplicity of hematoma cavities on CT scans; 2) presence of a history of seizure; 3) width of the hematoma; and 4) absence of a history of diabetes mellitus (DM).

Conclusions. As previously reported, the width of the hematoma is related to the incidence of CSDH recurrence. In this study, the lack of a multiplicity of hematoma cavities was the favorite predictor of CSDH recurrence. In addition, histories of seizure and no past DM are closely related to the incidence of CSDH recurrence.

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Yutaka Hayashi, Masayuki Iwato, Mitsuhiro Hasegawa, Osamu Tachibana, Andreas von Deimling and Junkoh Yamashita

✓ A gangliocytoma/ganglioglioma with no atypical or malignant features was subtotally resected from the right temporal lobe of a 16-year-old woman. A second resection was performed 8 years later to treat a locally recurrent lesion with increased cellularity that was diagnosed as a World Health Organization Grade II ganglioglioma on the basis of neuropathological examination. Molecular analysis of the recurrent tumor revealed a TP53 gene mutation, but no amplification of the epidermal growth factor receptor (EGFR) gene. Radiotherapy (60 Gy) was administered after the second resection. The patient returned 1 year later with a second focal recurrence. The specimen obtained during the third resection of tumor exhibited exclusively astrocytic differentiation, cellular pleomorphism with multinucleated cells, high mitotic activity, and endothelial proliferation. Therefore, the tumor was diagnosed to be a glioblastoma multiforme (GBM). Molecular analysis of tumor DNA from the second recurrent tumor demonstrated the presence of the TP53 mutation, which previously had been observed in the first recurrent tumor, but again no evidence of EGFR amplification. Findings demonstrate that the presence of TP53 mutation in progressed gangliogliomas should be interpreted as a progression-associated mutation rather than a consequence of treatment. This is the first report to indicate that the molecular pathways of gangliocytomas/gangliogliomas progressing to become GBMs may parallel those of diffuse astrocytomas progressing to become GBMs.

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Masashi Kinoshita, Harumichi Shinohara, Osamu Hori, Noriyuki Ozaki, Fumiaki Ueda, Mitsutoshi Nakada, Jun-ichiro Hamada and Yutaka Hayashi

Object

Recently, intraoperative mapping has disclosed that, in addition to the classic language centers (that is, the Broca and Wernicke centers), other cortical regions may also play an important role in language organization. In the prefrontal cortex, although the lateral superior frontal gyrus (LSFG) could have language-related functions, there are no detailed reports that demonstrate the anatomical connection between the LSFG and other well-known language cortices, such as the Broca center. To show the existence of the structural connection, white matter association fibers between the inferior frontal gyrus (IFG) and the LSFG were examined using fiber dissection (FD) and diffusion tensor (DT) imaging–based tractography.

Methods

Eight cadaveric cerebral hemispheres were dissected to reveal the association fibers between the IFG and LSFG. The DT imaging–based tractography studies targeting the prefrontal cortex were obtained in 53 right-handed patients who had no organic cerebral lesions.

Results

The association fiber tract between Brodmann area 44/45 (the Broca center in the dominant hemisphere) and LSFG were detected in all specimens by FD. In the DT imaging–based tractography studies, the tract was identified in all patients bilaterally, except for the 4 in whom the tract was detected only in the left hemisphere. This tract was spread significantly wider in the left than in the right hemisphere, and left lateralization was evident in male patients.

Conclusions

Based on its character, this tract was named the Broca-LSFG pathway. These findings suggest a close relationship between this pathway and language organization. The structural anatomy of the Broca-LSFG pathway may explain speech disturbances induced by LSFG stimulation that are sometimes observed during intraoperative language mapping.

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Masashi Kinoshita, Riho Nakajima, Harumichi Shinohara, Katsuyoshi Miyashita, Shingo Tanaka, Hirokazu Okita, Mitsutoshi Nakada and Yutaka Hayashi

OBJECTIVE

Although the right prefrontal region is regarded as a silent area, chronic deficits of the executive function, including working memory (WM), could occur after resection of a right prefrontal glioma. This may be overlooked by postoperative standard examinations, and the disabilities could affect the patient's professional life. The right prefrontal region is a part of the frontoparietal network and is subserved by the superior longitudinal fasciculus (SLF); however, the role of the SLF in spatial WM is unclear. This study investigated a persistent spatial WM deficit in patients who underwent right prefrontal glioma resection, and evaluated the relationship between the spatial WM deficit and the SLF.

METHODS

Spatial WM was examined in 24 patients who underwent prefrontal glioma resection (right, n = 14; left, n = 10) and in 14 healthy volunteers using a spatial 2-back task during the long-term postoperative period. The neural correlates of spatial WM were evaluated using lesion mapping and voxel-based lesion-symptom mapping. In addition, the spatial 2-back task was performed during surgery under direct subcortical electrical stimulation in 2 patients with right prefrontal gliomas.

RESULTS

Patients with a right prefrontal lesion had a significant chronic spatial WM deficit. Voxel-based lesion-symptom mapping analysis revealed a significant correlation between spatial WM deficit and the region that overlapped the first and second segments of the SLF (SLF I and SLF II). Two patients underwent awake surgery and had difficulties providing the correct responses in the spatial 2-back task with direct subcortical electrical stimulation on the SLF I, which was preserved and confirmed by postoperative diffusion tensor imaging tractography. These patients exhibited no spatial WM deficits during the postoperative immediate and long-term periods.

CONCLUSIONS

Spatial WM deficits may persist in patients who undergo resection of the tumor located in the right prefrontal brain parenchyma. Injury to the dorsal frontoparietal subcortical white matter pathway, i.e., the SLF I or SLF I and II, could play a causal role in this chronic deficit. A persistent spatial WM deficit, without motor and language deficits, could affect the professional life of the patient. In such cases, awake surgery would be useful to detect the spatial WM network with appropriate task during tumor exploration.