Masahiko Tosaka

Dr. Masahiko Tosaka


Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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13 January 2016 in British Journal Of Neurosurgery
Verified
Journal Article
Closed access
PDF file
YIYoko Ibe
Yoko Ibe
MTMasahiko Tosaka
Masahiko Tosaka
KHKeishi Horiguchi
Keishi Horiguchi
KSKenichi Sugawara
Kenichi Sugawara
TMTakaaki Miyagishima
Takaaki Miyagishima
YYYuhei Yoshimoto
Yuhei Yoshimoto
Objective The supplementary motor area (SMA) is important for the prediction of post-operative symptoms after surgical resection of gliomas. We investigated the relationships between clinical factors and the resection range of SMA gliomas, and the post-operative neurological symptoms. Methods We retrospectively studied 18 consecutive surgeries for gliomas involving the SMA proper performed in 13 patients. Seven cases were recurrence of the tumour. Clinical factors and details of specific resection of the SMA proper (resection of posterior part, medial wall) and cingulate motor area (CMA) were examined. Results Eight cases suffered new post-operative neurological deficits. Six of these eight cases had transient deficits. Permanent deficits persisted in two cases with partial weakness or paresis, after rapid improvement of post-operative global weakness or hemiplegia, respectively. The risk of post-operative neurological deficits was not associated with the resection of the posterior part of the SMA proper or the CMA, but was associated with resection of the medial wall of the SMA proper. Surgery for recurrent tumour was associated with post-operative neurological deficits. The medial wall was frequently resected in recurrent cases. Discussion The frequency of post-operative neurological symptoms, including SMA syndrome, may be higher after resection of the medial wall of the SMA proper compared with the resection of only the lateral surface of the SMA proper.

1 June 2015 in World Neurosurgery
Verified
Journal Article
Closed access
YTYosuke Tomita
Yosuke Tomita
MTMasahiko Tosaka
Masahiko Tosaka
MAMasanori Aihara
Masanori Aihara
KHKeishi Horiguchi
Keishi Horiguchi
YYYuhei Yoshimoto
Yuhei Yoshimoto

1 January 2015 in Neurologia medico-chirurgica
Verified
Journal Article
Open access
MTMasahiko Tosaka
Masahiko Tosaka
KSKoji Sato
Koji Sato
MAMakoto Amanuma
Makoto Amanuma
THTetsuya Higuchi
Tetsuya Higuchi
MAMotohiro Arai
Motohiro Arai
YYYuhei Yoshimoto
Yuhei Yoshimoto
Superficial siderosis is a rare condition caused by hemosiderin deposits in the central nervous system (CNS) due to prolonged or recurrent low-grade bleeding into the cerebrospinal fluid (CSF). CNS tumor could be one of the sources of bleeding, both pre- and postoperatively. We report an extremely rare case of superficial siderosis associated with purely third ventricle craniopharyngioma, and review previously reported cases of superficial siderosis associated with CNS tumor. A 69-year-old man presented with headache, unsteady gait, blurred vision, and progressive hearing loss. Brain magnetic resonance (MR) imaging with gadolinium revealed a well enhanced, intraventricular mass in the anterior part of the third ventricle. T2*-weighted gradient echo (GE) MR imaging revealed a hypointense rim around the brain particularly marked within the depth of the sulci. Superficial siderosis was diagnosed based on these findings. The tumor was diffusely hypointense on T2*-weighted GE imaging, indicating intratumoral hemorrhage. The lateral ventricles were dilated, suggesting hydrocephalus. [(18)F]fluorodeoxyglucose positron emission tomography revealed increased uptake in the tumor. The whole brain surface appeared dark ocher at surgery. Histological examination showed the hemorrhagic tumor was papillary craniopharyngioma. His hearing loss progressed after removal of the tumor. T2*-weighted GE MR imaging demonstrated not only superficial siderosis but also diffuse intratumoral hemorrhage in the tumor. Superficial siderosis and its related symptoms, including hearing loss, should be considered in patients with hemorrhagic tumor related to the CSF space. Purely third ventricle craniopharyngioma rarely has hemorrhagic character, which could cause superficial siderosis and progressive hearing loss.

1 November 2021 in World Neurosurgery
Verified
Journal Article
Closed access
MTMasahiko Tosaka
Masahiko Tosaka
DPDaniel M Prevedello
Daniel M Prevedello
RYRei Yamaguchi
Rei Yamaguchi
NFNoriaki Fukuhara
Noriaki Fukuhara
TMTakaaki Miyagishima
Takaaki Miyagishima
YYYuhei Yoshimoto
Yuhei Yoshimoto

12 August 2019 in Acta Neurochirurgica
Verified
Journal Article
Closed access
PDF file
TMTakaaki Miyagishima
Takaaki Miyagishima
MTMasahiko Tosaka
Masahiko Tosaka
RYRei Yamaguchi
Rei Yamaguchi
TNTomohito Nagaki
Tomohito Nagaki
NINobukazu Ishii
Nobukazu Ishii
YYYuhei Yoshimoto
Yuhei Yoshimoto

1 January 2021 in Journal of Neurosurgery
Verified
Journal Article
Closed access
PDF file
RYRei Yamaguchi
Rei Yamaguchi
MTMasahiko Tosaka
Masahiko Tosaka
TMTakaaki Miyagishima
Takaaki Miyagishima
TOTadashi Osawa
Tadashi Osawa
KHKeishi Horiguchi
Keishi Horiguchi
YYYuhei Yoshimoto
Yuhei Yoshimoto
OBJECTIVE: Visual acuity impairment due to sellar and suprasellar tumors is not fully understood. The relationship between these tumors and disturbance of visual function was examined using preoperative MRI. METHODS: This study reviewed 93 consecutive patients with sellar and suprasellar tumors. Best-corrected visual acuity (BCVA) and visual impairment score (VIS) were used for estimation of visual impairments. Preoperative MR images were examined to obtain several values for estimation of chiasmatic compression. Additionally, the optic nerve–canal bending angle (ONCBA) was newly defined as the external angle formed by the optic nerve in the optic canal and the optic nerve in the intracranial subarachnoid space at the junction, using preoperative sagittal T2-weighted MR images. RESULTS: The mean ONCBA was about the same on the right (44° ± 25°) and the left (44° ± 24°). Sagittal ONCBA was defined as large (> 45°) and moderate (≤ 45°) on each side. Preoperative VIS was found to be significantly worse if the right or left ONCBA (or both) was large (right side: ONCBA large [median 20, IQR 8–30] > ONCBA moderate [median 10, IQR 3–17], p = 0.003, Mann-Whitney U-test; left side: ONCBA large [median 22, IQR 9–30] > ONCBA moderate [median 10, IQR 2–16], p = 0.001). A large ONCBA showed a significant relationship with unfavorable ipsilateral BCVA (> logMAR, 0; right side, p = 0.001, left side, p = 0.001, chi-square test). The ONCBA had a positive correlation with ipsilateral BCVA (right: r = 0.297, p = 0.031; left: r = 0.451, p = 0.000, Pearson’s correlation coefficient). Preoperative BCVA was significantly lower on the same side in the large ONCBA group compared with the moderate ONCBA group (right side: large ONCBA 0.169 ± 0.333 [logMAR, mean ± standard deviation] vs moderate ONCBA 0.045 ± 0.359, p = 0.026, Student t-test; left side: large ONCBA 0.245 ± 0.346 vs moderate ONCBA 0.025 ± 0.333, p = 0.000). This visual acuity impairment improved after resection of the tumors. CONCLUSIONS: Sagittal bending of the optic nerve at the entrance from the intracranial subarachnoid space to the optic canal may be related to ipsilateral deterioration of visual acuity in sellar and suprasellar lesions. Sagittal T2-weighted MRI is recommended for preoperative estimation of the optic nerve bending.