Seiei Torazawa

The University of Tokyo

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i-10 index

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Co-Authors

Shotaro Ogawa

The University of Tokyo

Nobuhito Saito

The University of Tokyo

Satoru Miyawaki

The University of Tokyo

Daisuke Sato

University of Tokyo Hospital

Hideaki Ono

University of Tokyo Hospital

Takahiro Ota

Tokyo Metropolitan Tama Medical Center

Hiroki Hongo

The University of Tokyo

Shogo Dofuku

The University of Tokyo

Yudai Hirano

The University of Tokyo

Hideaki Imai

Tokyo Yamate Medical Center

Cooperative Institutions

The University of Tokyo

University of Tokyo Hospital

Neurological Surgery

Tokyo Medical and Dental University

Tokyo Metropolitan Tama Medical Center

University of California, Los Angeles

Icahn School of Medicine at Mount Sinai

Hospital de Sant Pau

Yale University

Kyoto University

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Research Field

Advantages and Clinical Outcomes of CEA Utilizing Early Identification of the Posterior Belly of the Digastric Muscle

Surgery for Cerebral Stroke (2023)

Seiei Torazawa Daisuke Sato Shotaro Ogawa Shogo Dofuku Masayuki Sato

当院では頚動脈内膜剝離術（carotid endarterectomy：CEA）において，内頚動脈（internal carotid artery：ICA）の遠位を剝離・確保するための手技として「顎二腹筋後腹早期同定法」の有用性を提唱している．顎二腹筋後腹を早期に同定し，その周囲のスペースを広く利用する本法では，ICAの遠位を展開していく際に特に損傷しやすい顔面神経下顎縁枝と舌下神経の損傷を回避し，また高位病変でも対応可能な，ICA遠位の広いworking spaceを確保するのに有用と考えている．当院で本法にて施行したCEA連続191例の検討から，顔面神経下顎縁枝と舌下神経の障害出現率はともに0.5％と，文献的報告と比較して低く抑えられていた．また，高位病変であっても術後30日以内の同側脳梗塞の出現率を上げることなく対応可能であったことが示された．本法は上記神経障害を回避しつつICA遠位までの安全かつ迅速な展開操作を習得するのに有用な手法となり得ると考えている．

Digastric muscle

Identification

10.2335/scs.51.390

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Current molecular understanding of central nervous system schwannomas

Acta Neuropathologica Communications (2025)

Takahiro Tsuchiya Satoru Miyawaki Yu Teranishi Kenta Ohara Yudai Hirano

Schwannomas are tumors that originate from myelinating Schwann cells and can occur in cranial, spinal, and peripheral nerves. Although our understanding of the molecular biology underlying schwannomas remains incomplete, numerous studies have identified various molecular findings and biomarkers associated with schwannomas of the central nervous system (CNS). The development of these tumors is primarily linked to mutations in the NF2 gene. Merlin, the protein encoded by NF2, is integral to several signaling pathways, including Ras/Raf/MEK/ERK, PI3K/Akt/mTORC1, Wnt/β-catenin, and the Hippo pathway. Recent research has also uncovered novel genetic alterations, such as the SH3PXD2A::HTRA1 fusion gene, VGLL-fusions in intraparenchymal CNS schwannomas, and the SOX10 mutation particularly in non-vestibular cranial nerve schwannomas. In addition to genetic alterations, research is also being conducted on gene expression and epigenetic regulation, with a focus on NF2 methylation and post-transcriptional silencing by micro RNA. Furthermore, the advent of advanced techniques like single-cell sequencing and multi-omics analysis has facilitated rapid discoveries related to the tumor microenvironment and tumor heterogeneity in schwannomas. A deeper exploration of these molecular findings could clarify the mechanisms of schwannoma tumorigenesis and progression, ultimately guiding the development of new therapeutic targets. This review offers a comprehensive overview of the current molecular understanding of CNS schwannomas, emphasizing the insights gained from previous research, while addressing existing controversies and outlining future research and treatment perspectives.

10.1186/s40478-025-01937-w

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Acute Thrombectomy for Contralateral Internal Carotid Artery Occlusion after Revascularization Surgery for Quasi-moyamoya Disease: A Case Report

NMC Case Report Journal (2021)

Shotaro Ogawa Daisuke Sato Seiei Torazawa Takahiro Ota

Ischemic complications can occur after revascularization surgery for moyamoya disease, but acute contralateral internal carotid artery (ICA) occlusion is an extremely rare complication. The patient was a 51-year-old woman with no medical history. Left frontal lobe infarction and bilateral ICA terminal stenosis were identified by repeated transient right paresis and aphasia. We diagnosed her with quasi-moyamoya disease associated with hyperthyroidism and performed revascularization surgery for the symptomatic left side. Although neurological symptoms did not worsen immediately after the surgery, disturbance of consciousness, right conjugate deviation, and left paresis appeared 4 hr after the surgery. New infarction appeared in the right frontal lobe, and the blood signal beyond the right middle cerebral artery (MCA) disappeared on MRI and MRA. Mechanical thrombectomy (MT) using a suction catheter improved antegrade blood flow in the MCA. The left paresis remained at discharge (modified Rankin Scale score = 4), but she was able to walk independently 3 months after the operation and was independent at home. Acute contralateral ICA occlusion after revascularization for moyamoya disease is an extremely rare complication, but the symptoms can be severe and treatment should be considered. To the best of our knowledge, there have been no reports of MT for postoperative acute contralateral ICA occlusion. Since the results of endovascular treatment such as percutaneous transluminal angioplasty and stent placement for patients with moyamoya disease are poor, MT using an aspiration catheter could be a good treatment option.

Moyamoya Disease

Paresis

Bypass surgery

10.2176/nmccrj.cr.2021-0089

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Intentional staged clipping following previous coil embolization of ruptured aneurysm with a branch arising from the neck: technical note

Turkish Neurosurgery (2022)

Seiei Torazawa Daisuke Sato Shotaro Ogawa Shogo Dofuku Masayuki Sato

AIM:To present a substitute strategy for clipping: coil embolization of the ruptured aneurysm followed by intentional, staged clipping. CASE DESCRIPTION:We treated five cases of ruptured intracranial aneurysms with branches arising from the neck.The mean aneurysm diameter was 4.4 mm.In the acute rupture phase, coiling was performed without adjunctive endovascular techniques with intentional preservation of the neck in all cases.To treat recurrence during follow-up, the previously coiled aneurysm was clipped, which did not occasion any complications.Postoperative imaging showed completely obliterated aneurysms and preserved branches.No rebleeding occurred during the interval between coiling and clipping, and no rebleeding or recurrence occurred after clipping.No treatment-related complications occurred after coiling and clipping. CONCLUSION:This two-stage strategy may be effective for hemostasis and branch preservation for small-and medium-sized ruptured aneurysms with a branch arising from the neck.This intentional two-stage strategy can be a substitute strategy for clipping in the acute rupture phase with an acceptable outcome if the patient cannot undergo clipping as the first-line treatment.

Clipping (morphology)

Endovascular coiling

10.5137/1019-5149.jtn.36970-21.3

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Extradural Middle Fossa and Transcavernous Approach for Resection of Trigeminal Neurinoma at Lateral Cavernous Sinus

Journal of Neurological Surgery Part B Skull Base (2021)

Hideaki Ono Seiei Torazawa T Tanishima Akira Tamura Isamu Saito

We present a 52-year-old male case of right trigeminal neurinoma at lateral cavernous sinus. The tumor was 40 mm in maximum diameter, obviously compressed temporal lobe and encased internal carotid artery. Extradural middle fossa and transcavernous approach was applied and the tumor was resected via Parkinson's triangle. This approach enabled safe and effective tumor resection, sufficient visualization, and operative field ( Figs. 1 and 2 ). We performed dissection of the tumor from trigeminal nerve, tentorium, and middle fossa and resect the tumor around internal carotid artery sufficiently. Postoperative course was good without any new neurological deficit. This surgical method is considered safe and effective for the resection of the tumor at lateral cavernous sinus. The link to the video can be found at: https://youtu.be/2ekuILIgEuo.

Tentorium

Middle cranial fossa

Trigeminal Nerve

10.1055/s-0041-1736630

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Endoscopic Transnasal Resection of Solitary Fibrous Tumor in the Optic Canal

World Neurosurgery (2018)

Seiei Torazawa Masahiro Shin Hirotaka Hasegawa Ryohei Otani Keisuke Ueki

Optic canal

Endoscopic endonasal surgery

Solitary Fibrous Tumor

Endoscope

10.1016/j.wneu.2018.05.050

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Trapping, dome puncture, and direct suction decompression in conjunction with assistant superficial temporal artery- middle cerebral artery bypass to clip giant internal carotid artery bifurcation aneurysm

Surgical Neurology International (2019)

Seiei Torazawa Hideaki Ono Tomohiro Inoue T Tanishima Akira Tamura

Very large and giant aneurysms (≥20 mm) of the internal carotid artery (ICA) bifurcation (ICAbif) are definitely rare, and optimal treatment is not established. Endovascular treatments are reported as suboptimal due to difficulties of complete occlusion and tendencies to recanalization. Therefore, direct surgery remains an effective strategy if the clipping can be performed safely and reliably, although very difficult.Two cases of ICAbif aneurysms (>20 mm) were treated. Prior assistant superficial temporal artery (STA)-middle cerebral artery (MCA) bypass was performed to avoid ischemic complications during prolonged temporary occlusion of the arteries in both cases. In Case 1 (22-mm aneurysm), the dome was inadvertently torn in applying the clip because trapping had resulted in insufficient decompression. Therefore, in Case 2 (28-mm aneurysm), almost complete trapping of the aneurysm and subsequent dome puncture was performed, and the aneurysm was totally deflated by suction from the incision. This complete aneurysm decompression allowed safe dissection and successful clipping.Trapping, deliberate aneurysm dome puncture, and suction decompression from the incision in conjunction with assistant STA-MCA bypass can achieve complete aneurysm deflation, and these techniques enable safe dissection of the aneurysm and direct clipping of the aneurysm neck. Direct clipping with this technique for very large and giant ICAbif aneurysms may be the optimal treatment choice with the acceptable outcome if endovascular treatment remains suboptimal.

Clipping (morphology)

Superficial temporal artery

10.25259/sni_462_2019

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Basic Techniques for the Clipping of Middle Cerebral Aneurysms: Gaining Expertise with Limited Surgical Experience

Surgery for Cerebral Stroke (2022)

Seiei Torazawa Hideaki Ono Toshiya Aono Masafumi Segawa T Tanishima

中大脳動脈瘤クリッピング術は,脳動脈瘤クリッピング術の基本として位置づけられる.当院では若手術者が限られた症例数の中で手術手技を習得できるように,手術の細部にいたるまでコンセプトを明確にし統一徹底している.sylvian fissureの展開に関しては,安全で精確なretractionとsharp dissectionを用いて必要十分な広範囲の展開を,動脈瘤へのアプローチに関しては動脈瘤非癒着側からの剝離手順を,それぞれ徹底している.今回これらのコンセプトを紹介するとともに,実際に若手術者が執刀した63症例の成績を検証した.結果は,手術操作に関連した虚血性合併症を2例(3.2%)に認めたがいずれも無症候性であり,術後modified Rankin Scaleが悪化した症例は認めなかった.当院の手術コンセプトは安全確実に中大脳動脈瘤クリッピング術を遂行できるものであり,また,このような汎用性の高い手技を統一徹底することは若手術者の教育に有用であると考える.

Clipping (morphology)

10.2335/scs.50.107

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Genetic analysis of foramen magnum meningiomas reveals AKT1 mutations uncomplicated by TRAF7 mutations

Acta Neuropathologica Communications (2024)

Yudai Hirano Satoru Miyawaki Yu Sakai Yu Teranishi Atsushi Okano

Foramen magnum

10.1186/s40478-024-01835-7

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Long-Term Patency of Posterior Auricular Artery—Middle Cerebral Artery Bypass for Adult-Onset Moyamoya Disease: Case Report and Review of Literature