Faculty Profiles - SAITO Ryuta

Papers - SAITO Ryuta

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Phase II single-arm, multi-center, physician-initiated clinical trial of convection-enhanced delivery of nimustine hydrochloride (ACNU) against diffuse intrinsic pontine gliomas

Ryuta Saito, Masayuki Kanamori, Yohei Mineharu, Yoshiki Arakawa, Kentaro Chiba, Yasuo Aihara, Ichiyo Shibahara, Toshihiro Kumabe, Kenichiro Matsuda, Yukihiko Sonoda, Fumiaki Takahashi, Teiji Tominaga

JOURNAL OF CLINICAL ONCOLOGY Vol. 40 ( 16 ) 2022.6

Quick and simple dural threading technique for transsphenoidal surgery - dural tenting, haemostasis and skull base reconstruction. International journal

Kazuhito Takeuchi, Yuichi Nagata, Kuniaki Tanahashi, Ryuta Saito

Acta neurochirurgica Vol. 164 ( 6 ) page： 1619 - 1622 2022.6

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: Dural suturing is one of the most robust reconstruction methods in transsphenoidal surgery; however, the technique is considered difficult, primarily due to the restricted range of needle movement. METHOD: We performed dural threading during transsphenoidal surgery by holding the needle with forceps as a hook and moving the needle in a distal to proximal direction. CONCLUSION: Our dural suturing technique is simple and quick. It can be used not only for dural closure but also for other procedures, such as controlling haemostasis from the intercavernous sinus and dural tenting.

DOI： 10.1007/s00701-022-05227-5

Evaluation of the differences in pressure applied to the vessel wall by different types of balloon remodeling microcatheters in an experimental model. International journal Open Access

Mizuka Ikezawa, Takashi Izumi, Masahiro Nishihori, Tetsuya Tsukada, Yosuke Tamari, Yoshio Araki, Kinya Yokoyama, Kenji Uda, Shunsaku Goto, Asuka E Kropp, Takafumi Otsuka, Naoki Kato, Mizuki Nakano, Ryuta Saito

Interventional neuroradiology : journal of peritherapeutic neuroradiology, surgical procedures and related neurosciences Vol. 28 ( 3 ) page： 323 - 331 2022.6

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: We examined compliance differences among balloon remodeling microcatheters, which have not been established previously. METHODS: Straight and 120° angulated vascular models were created in a 3 mm diameter tube with 3 mm hole (vascular model A), a tube with a 4 mm hole (vascular model B), and a 4 mm diameter tube (vascular model C). We compared the pressure exerted when each balloon was herniated 1 or 2 mm between three compliant balloons (SHOURYU SR, TransForm C, and Scepter C) and four super-compliant balloons (HyperForm, SHOURYU HR, TransForm SC, and Scepter XC). RESULTS: In vascular model A, there was a significant difference in the pressure exerted by compliant balloons and super-compliant balloons in both the straight and angulated models. In the straight model (1 and 2 mm), the lowest pressure was exerted by HyperForm (super-compliant balloons group) and SHOURYU SR (compliant balloons group). The lowest pressure was exerted in the angulated model by HyperForm (super-compliant balloons group) and Scepter C (compliant balloons group). The Scepter balloon exerted higher pressure in the straight model than other balloon remodeling microcatheters but less in the angulated model. In vascular model B, the pressure decreased in all balloons compared with model A. In vascular model C, the pressure increased in all balloons compared with model A. CONCLUSIONS: Pressure differed across balloon remodeling microcatheters. In addition, vessel shape and diameter, and hole size, affected the results. Our findings can help select balloon remodeling microcatheters.

DOI： 10.1177/15910199211031765

Changes in cerebral blood flow in the postoperative chronic phase after combined cerebral revascularization for moyamoya disease with ischaemic onset. International journal

Yoshio Araki, Takashi Mamiya, Naotoshi Fujita, Kenji Uda, Kinya Yokoyama, Fumiaki Kanamori, Kai Takayanagi, Kazuki Ishii, Masahiro Nishihori, Kazuhito Takeuch, Kuniaki Tanahashi, Yuichi Nagata, Yusuke Nishimura, Takafumi Tanei, Masaki Sumitomo, Sho Okamoto, Takashi Izumi, Katsuhiko Kato, Ryuta Saito

Neurosurgical review Vol. 45 ( 3 ) page： 2471 - 2480 2022.6

Language：English Publishing type：Research paper (scientific journal)

The purpose of this study was to examine the effects of combined revascularization for ischaemic-onset moyamoya disease (MMD) on cerebral haemodynamics by comparing cerebral blood flow (CBF) during the postoperative chronic phase with preoperative CBF. A retrospective cohort of 24 MMD patients (representing 31 surgeries) who received single photon emission computed tomography (SPECT) before and more than 6 months after surgery was investigated. The CBF value of each vascular territory was extracted from SPECT data, and the value relative to the ipsilateral cerebellar value (relative CBF, or RCBF) was calculated. The correlation between the revascularization effect and the proportional change in RCBF before and after surgery (calculated as post-RCBF/pre-RCBF ("post/pre-RCBF")) was analysed. Furthermore, the relationships between changes in neurological symptoms and post/pre-RCBF were investigated. Preoperative and postoperative mean RCBF values were 0.92 ± 0.15 and 0.96 ± 0.13 (p = 0.619) in the anterior cerebral artery territory, 0.99 ± 0.17 and 1.01 ± 0.17 (p = 0.598) in the middle cerebral artery territory and 1.15 ± 0.22 and 1.14 ± 0.19 (p = 0.062) in the posterior cerebral artery territory, respectively. No significant correlation was found between the revascularization score and post/pre-RCBF. The revascularization score and post/pre-RCBF were not significant predictors of worsening neurological symptoms postoperatively. No significant change in RCBF was observed in any vascular territory in the chronic phase after revascularization. Combined revascularization may assist in the redirection of blood flow from the internal to the external carotid system and contribute to CBF maintenance.

DOI： 10.1007/s10143-022-01774-8

Recent Molecular and Genetic Findings in Intramedullary Spinal Cord Tumors. International journal Open Access

Yoshitaka Nagashima, Yusuke Nishimura, Kaoru Eguchi, Junya Yamaguchi, Shoichi Haimoto, Fumiharu Ohka, Masakazu Takayasu, Ryuta Saito

Neurospine Vol. 19 ( 2 ) page： 262 - 271 2022.6

Language：English Publishing type：Research paper (scientific journal)

The study of genetic alterations and molecular biology in central nervous system (CNS) tumors has improved the accuracy of estimations of patient prognosis and tumor categorization. Therefore, the updated 2021 World Health Organization (WHO) classification includes various diagnostic genes, molecules, and pathways for diagnosis, as well as histological findings. These findings are expected both to have diagnostic applications and to facilitate new targeted therapies that target tumor-specific genetic changes and molecular biology. Intramedullary spinal cord tumors (IMSCTs) are rare CNS tumors that are difficult to treat because they occur in eloquent areas. Although the genetic underpinnings of IMSCTs remain unclear compared to their intracranial counterparts, the genetic characteristics of these tumors are gradually being revealed. Here, we describe the major changes in the new 2021 WHO classification and review the major types of IMSCTs, with an emphasis on their clinical features and genetic alterations.

DOI： 10.14245/ns.2244168.084

Supratotal Resection of Gliomas With Awake Brain Mapping: Maximal Tumor Resection Preserving Motor, Language, and Neurocognitive Functions. International journal Open Access

Kazuya Motomura, Fumiharu Ohka, Kosuke Aoki, Ryuta Saito

Frontiers in neurology Vol. 13 page： 874826 - 874826 2022.5

Language：English Publishing type：Research paper (scientific journal)

Gliomas are a category of infiltrating glial neoplasms that are often located within or near the eloquent areas involved in motor, language, and neurocognitive functions. Surgical resection being the first-line treatment for gliomas, plays a crucial role in patient outcome. The role of the extent of resection (EOR) was evaluated, and we reported significant correlations between a higher EOR and better clinical prognosis of gliomas. However, recurrence is inevitable, even after aggressive tumor removal. Thus, efforts have been made to achieve extended tumor resection beyond contrast-enhanced mass lesions in magnetic resonance imaging (MRI)-defined areas, a process known as supratotal resection. Since it has been reported that tumor cells invade beyond regions visible as abnormal areas on MRI, imaging underestimates the true spatial extent of tumors. Furthermore, tumor cells have the potential to spread 10-20 mm away from the MRI-verified tumor boundary. The primary goal of supratotal resection is to maximize EOR and prolong the progression-free and overall survival of patients with gliomas. The available data, as well as our own work, clearly show that supratotal resection of gliomas is a feasible technique that has improved with the aid of awake functional mapping using intraoperative direct electrical stimulation. Awake brain mapping has enabled neurosurgeons achieve supratotal resection with favorable motor, language, and neurocognitive outcomes, ensuring a better quality of life in patients with gliomas.

DOI： 10.3389/fneur.2022.874826

Blood flow stagnation after treatment of a giant internal carotid artery aneurysm: a computed fluid dynamics analysis. International journal Open Access

Shinsuke Muraoka, Reiya Takagi, Yoshio Araki, Kenji Uda, Masaki Sumitomo, Sho Okamoto, Masahiro Nishihori, Takashi Izumi, Masanori Nakamura, Ryuta Saito

Scientific reports Vol. 12 ( 1 ) page： 7283 - 7283 2022.5

Language：English Publishing type：Research paper (scientific journal)

Balloon test occlusion (BTO) is an angiographic test to evaluate ischemic tolerance after permanent occlusion of an internal carotid artery (ICA). BTO can simulate ischemia caused by parent artery occlusion and can be used to select a suitable bypass surgery using specific criteria. On the other hand, a postoperative thrombus can form despite proper case selection, optimal radiological evaluation, and an appropriate surgical strategy. Postoperative ischemic complications related to perforating branches are clinically significant. This simulation study aimed to analyze postoperative flow characteristics and elucidate the cause of ischemic complications related to the perforating branch using computational fluid dynamics (CFD). An unexpected postoperative thrombus formation related to the perforating branch occurred after treating a giant aneurysm in the cavernous portion of the ICA in a patient. Three-dimensional digital subtraction angiography was used to acquire flow data and set up the CFD simulation. The flow simulations were performed at various bypass flow rates. The CFD analysis indicated flow stagnation in the ICA only when surgical treatment using a low-flow bypass graft was performed. Thrombus formation may lead to ischemic complications related to the perforating branch, such as the anterior choroidal artery. BTO did not reflect the influence of bypass blood flow. Therefore, recognizing that blood flow stagnation may occur and comprehensively deciding on the surgical strategy by CFD analysis can be helpful to prevent ischemic complications in patients with giant aneurysms.

DOI： 10.1038/s41598-022-11321-6

脳腫瘍研究のcutting edge-先端画像、実験/分子病理、デジタル病理- 神経膠腫の術中迅速遺伝子変異解析を目指した高速リアルタイムPCR法の確立

前田紗知, 大岡史治, 北野詳太郎, 本村和也, 青木恒介, 西川知秀, 山口純矢, 木部祐士, 齋藤竜太

Brain Tumor Pathology Vol. 39 ( Suppl. ) page： 069 - 069 2022.5

術中所見はラトケ嚢胞、されど病理は頭蓋咽頭腫

永田雄一, 竹内和人, 棚橋邦明, 佐々木博勇, 原田英幸, 井下尚子, 齋藤竜太

Brain Tumor Pathology Vol. 39 ( Suppl. ) page： 110 - 110 2022.5

Angiographic characteristics of improper watershed shift after STA-MCA bypass in a patient with moyamoya disease: illustrative case. International journal Open Access

Fumiaki Kanamori, Yoshio Araki, Kinya Yokoyama, Kenji Uda, Takashi Mamiya, Shota Nohira, Kai Takayanagi, Kazuki Ishii, Masahiro Nishihori, Takashi Izumi, Ryuta Saito

Journal of neurosurgery. Case lessons Vol. 3 ( 16 ) 2022.4

Language：English Publishing type：Research paper (scientific journal)

BACKGROUND: In patients with moyamoya disease (MMD) who receive superficial temporal artery (STA) to middle cerebral artery (MCA) bypass, hypoperfusion remote from the anastomosis site rarely occurs. Watershed shift due to direct bypass has been proposed as the mechanism; however, no report has confirmed this phenomenon using angiography. OBSERVATIONS: A 48-year-old man presented with transient weakness in his left arm. Angiography revealed severe bilateral stenosis of the MCAs and moyamoya vessels. The right anterior cerebral artery (ACA) had short stenosis at A2 but ample blood supply to the cortical area of the right ACA and MCA regions. The patient was diagnosed with MMD and received a single STA-MCA bypass. The next day, he had difficulty communicating, and a cerebral infarction away from the anastomosis site was identified. Perfusion examination revealed hyperperfusion around the direct bypass and hypoperfusion away from the anastomosis site. Angiography revealed bypass patency; however, the original anterograde flow of the right ACA decreased significantly at the stenosed point, indicating an improper watershed shift. LESSONS: STA-MCA bypass for patients with MMD can cause an improper watershed shift decreasing cerebral flow. Donor flow should be prepared based on each angiographic characteristic, and the risk of the improper watershed shift should be considered.

DOI： 10.3171/CASE22104

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Risk Factors for Cerebral Infarction Early After Revascularization in Children Younger than 5 Years with Moyamoya Disease. International journal

Yoshio Araki, Kenji Uda, Kinya Yokoyama, Fumiaki Kanamori, Michihiro Kurimoto, Yoshiki Shiba, Takashi Mamiya, Masahiro Nishihori, Kazuhito Takeuchi, Kuniaki Tanahashi, Yuichi Nagata, Yusuke Nishimura, Sho Okamoto, Masaki Sumitomo, Takashi Izumi, Ryuta Saito

World neurosurgery Vol. 160 page： E220 - E226 2022.4

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: Cerebral revascularization is necessary for pediatric patients younger than 5 years with moyamoya disease (MMD). However, they have a high risk of developing cerebral infarction early after surgery. This study aimed to analyze the risk factors for developing cerebral infarction among these patients. METHODS: The charts of 21 consecutive patients with MMD (39 surgeries) younger than 5 years who had undergone revascularization at our hospital were retrospectively analyzed. Because cerebral infarction occurring within 1 month after surgery was the primary end point, other clinical information was evaluated, including each surgical procedure. Multivariate analysis of the risk factors for postoperative cerebral infarction was performed. RESULTS: Cerebral infarction occurred after 7 of 39 surgeries (17.9%). Of the 39 surgeries, 23 (59%) included direct and indirect combined revascularization. The incidence of cerebral infarction did not differ significantly between the combined (21.7%) and indirect (12.5%) groups (P = 0.46). Logistic regression showed no association between the revascularization procedure and the occurrence of cerebral infarction after surgery (P = 0.3). However, younger age at surgery was correlated with a higher risk of developing cerebral infarction in the early postoperative period (P = 0.05). CONCLUSIONS: No differences were found in the risk of developing cerebral infarction early after surgery as a result of surgical procedures. However, younger patients had higher postoperative risk. Further multicenter research should examine this issue for young pediatric patients with moyamoya at high risk of developing cerebral infarction.

DOI： 10.1016/j.wneu.2021.12.115

Modified Shoelace Dural Closure with Collagen Matrix in Extended Transsphenoidal Surgery. Open Access

Yuichi Nagata, Kazuhito Takeuchi, Hiroo Sasaki, Akihiro Mizuno, Hideyuki Harada, Kuniaki Tanahashi, Yoshio Araki, Ryuta Saito

Neurologia medico-chirurgica Vol. 62 ( 4 ) page： 203 - 208 2022.4

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Neurosurgical Society

Extended endonasal transsphenoidal surgery (eTSS) offers a wide surgical field for various parasellar lesions; however, intraoperative high-flow cerebrospinal fluid (CSF) leakage is inevitable. Therefore, secure sellar reconstruction methods are essential to prevent postoperative CSF leakage. Although collagen matrix has been applied for dural reconstruction in neurosurgery, its suitability for application in extended eTSS remains unclear. Eighteen patients underwent modified shoelace dural closure using collagen matrix after lesionectomy via extended eTSS. In this technique, a collagen matrix, which was placed subdurally (inlay graft), was continuously sutured with both open dural edges like a shoelace. Then, another collagen matrix was placed epidurally (onlay graft), and rigid reconstruction was performed using the septal bone and a resorbable fixation mesh. Postoperative CSF leakage did not occur in 17 patients but did occur in 1 patient with tuberculum sellae meningioma. In this case, the CSF leakage point was detected just around the area between the coagulated dura and the adjacent collagen matrix. The collagen matrix harvested from this area was pathologically examined; neovascularization and fibroblastic infiltration into the collagen matrix were not detected. On the other hand, neovascularization and fibroblast infiltration into the collagen matrix were apparent on the surface of the collagen matrix harvested from the non-CSF leakage area. Our novel dural closure technique using collagen matrix could be an effective option for sellar reconstruction in extended eTSS; however, it should be applied in patients in whom normal dural edges are preserved.

DOI： 10.2176/jns-nmc.2021-0355

Challenging direct bypass surgery for very young children with moyamoya disease: technical notes. International journal

Neurosurgical review Vol. 45 ( 2 ) page： 1799 - 1807 2022.4

Language：English Publishing type：Research paper (scientific journal)

Cerebral revascularization for moyamoya disease (MMD) is an effective treatment for improving cerebral ischaemia and preventing rebleeding. Although direct bypass surgery is commonly performed on older children and adults, it is challenging in very young children due to the high difficulty level of the procedure. The subjects were MMD patients under 3 years of age on whom surgery was performed by a single surgeon (Y.A.). Preoperative clinical findings, information related to direct bypass surgery, bypass patency, and the incidence of postoperative stroke were investigated. Combined revascularization, including direct bypass surgery, was performed on 3 MMD patients (3 sides) under 3 years of age. The average diameter of the grafts used in direct bypass was 0.8 mm. The average recipient diameter was 0.8 ± 0.17 (range 0.6-1) mm. In all cases, the anastomotic procedure was completed using 11-0 monofilament nylon thread, and patency was confirmed. Direct bypass for MMD patients under 3 years old is technically challenging. However, despite the anatomical differences between very young children and elderly individuals, direct bypass surgery could certainly be completed. In addition, a rapid recovery from cerebral blood flow insufficiency could yield a promising neurological outcome.

DOI： 10.1007/s10143-021-01685-0

Advantages of petrosectomy for superficial temporal artery to superior cerebellar artery bypass based on three-dimensional distance measurements using cadaver heads. International journal Open Access

Kenji Uda, Kuniaki Tanahashi, Takashi Mamiya, Fumiaki Kanamori, Kinya Yokoyama, Masahiro Nishihori, Takashi Izumi, Yoshio Araki, Ryuta Saito

Neurosurgical review Vol. 45 ( 2 ) page： 1617 - 1624 2022.4

Language：English Publishing type：Research paper (scientific journal)

Superficial temporal artery (STA) to superior cerebellar artery (SCA) bypass is usually performed via the subtemporal approach (StA), anterior transpetrosal approach (ApA), or combined petrosal approach (CpA), but no study has yet reported a quantitative comparison of the operative field size provided by each approach, and the optimal approach is unclear. The objective of this study is to establish evidence for selecting the approach by using cadaver heads to measure the three-dimensional distances that represent the operative field size for STA-SCA bypass. Ten sides of 10 cadaver heads were used to perform the four approaches: StA, ApA with and without zygomatic arch osteotomy (ApA-ZO- and ApA-ZO+), and CpA. For each approach, the major-axis length and the minor-axis length at the anastomosis site (La-A and Li-A), the major-axis length and the minor-axis length at the brain surface (La-B and Li-B), the depth from the brain surface to the anastomosis site (Dp), and the operating angles of the major axis and the minor axis (OAa and OAi) were measured. Shallower Dp and wider operating angle were obtained in the order CpA, ApA-ZO+, ApA-ZO-, and StA. In all parameters, ApA-ZO- extended the operative field more than StA. ApA-ZO+ extended La-B and OAa more than ApA-ZO-, whereas it did not contribute to Dp and OAi. CpA significantly decreased Dp, and widened OAa and OAi more than ApA-ZO+. ApA and CpA greatly expanded the operative field compared with StA. These results provide criteria for selecting the optimal approach for STA-SCA bypass in light of an individual surgeon's anastomosis skill level.

DOI： 10.1007/s10143-021-01686-z

A novel endoscopic ventriculocisternostomy and stenting technique with a transparent acryl puncture needle for a trapped temporal horn: a technical report and literature review

Yamamoto Taiki, Takeuchi Kazuhito, Nagata Yuichi, Mizuno Akihiro, Harada Hideyuki, Saito Ryuta

NEUROSURGICAL REVIEW Vol. 45 ( 2 ) page： 1783 - 1789 2022.4

Language：Japanese Publisher：Neurosurgical Review

Trapped temporal horn is a rare type of noncommunicating focal hydrocephalus, and no standard treatment has been established yet for trapped temporal horn. Recent studies have shown the efficacy of endoscopic ventriculocisternostomy by opening the choroidal fissure; however, some surgical complications were reported during the procedure. Thus, we aimed to report a novel endoscopic ventriculocisternostomy and stenting technique for trapped temporal horn. In this technique, a 5.8-mm transparent acryl puncture needle with a 2.7-mm 0° rigid endoscope was used to open the choroidal fissure. It can fenestrate the choroidal fissure under real-time endoscopic observation of the critical neurovascular structures over the choroidal fissure. Moreover, the dull tip of the needle is less likely to injure the critical neurovascular structures, resulting in safer ventriculocisternostomy than the previously reported technique. Then, a stent is placed along the tract to prevent future obstruction of the stoma. Six trapped temporal horns in four patients were treated using the technique. All the patients showed improved symptoms with no surgical complications. None of the patients showed recurrence of trapped temporal horn during the mean follow-up period of 39.3 months. The combination of endoscopic ventriculocisternostomy and stenting with a transparent acryl puncture needle is a safe and effective treatment option for trapped temporal horn.

DOI： 10.1007/s10143-021-01634-x

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3D培養法を用いた新規下垂体腺腫オルガノイドモデルの作成

佐々木博勇, 竹内和人, 棚橋邦明, 永田雄一, 水野晃宏, 原田英幸, 須賀英隆, 齋藤竜太

日本内分泌学会雑誌 Vol. 98 ( 1 ) page： 329 - 329 2022.4