Takayuki Kitahara, Masatoshi Morimoto, Naoto Ono, Takafumi Ohshima, Yuji Nagao, Saori Soeda, Kosuke Sugiura, Hiroaki Manabe, Fumitake Tezuka, Hiroshi Kageyama, Junzo Fujitani, Kazuta Yamashita and Koichi Sairyo : Maximal facet tropism of 10.8° as a quantitative cutoff for predicting lumbar disk herniation in young elite athletes: a retrospective case-control study in Japan., Asian Spine Journal, 2026.
(Summary)
Retrospective case-control study.To determine whether maximal facet tropism (FT) is an independent risk factor for lumbar disk herniation (LDH) in young athletes and establish a data-driven, quantitative cutoff value.The role of FT in LDH remains debated because previous studies have focused on level-specific prevalence without defining a clinically significant threshold for maximal asymmetry, particularly in athletes.Axial magnetic resonance images from L3 to S1 in 43 athletes were compared with LDH and 11 symptomatic nonherniated athletes. The primary variable was maximal FT, the single greatest asymmetry across the measured levels. Risk was assessed using multivariable logistic regression, and a cutoff was determined by receiver-operating characteristic (ROC) curve analysis.The LDH group exhibited significantly greater maximal FT (11.8°±5.9° vs. 7.6°±3.0°, p=0.028) and was confirmed to be an independent predictor of LDH (with odds ratio of 1.23 per increment of 1°; p=0.041). ROC curve analysis identified an optimal 10.8° cutoff (area under the ROC curve, 0.727), yielding 55.8% sensitivity and 90.9% specificity. Although severe FT (>10°) was most prevalent at L5/S1 in the LDH group (p=0.024), maximal FT values were not significantly different between the L4/5 and L5/S1 groups (p=0.353) in an analysis stratified by herniation level.Maximal FT is an independent risk factor for LDH in young athletes. The magnitude of maximal asymmetry in the lower lumbar spine, rather than its specific spinal level, appears to be the primary contributor to this risk, and an angle >10.8° serves as a preliminary threshold for identifying high-risk athletes.
Hiroshi Kageyama, Ryota Mio, Fumiaki Makiyama, Takayuki Kitahara, Takafumi Ohshima, Naoto Ono, Yuji Nagao, Saori Soeda, Makoto Takeuchi, Kosuke Sugiura, Masatoshi Morimoto, Hiroaki Manabe, Fumitake Tezuka, Kazuta Yamashita, Junzo Fujitani and Koichi Sairyo : Sequential Full-Endoscopic Decompression under Local Anesthesia for Concurrent L4/5 Lateral Recess and L5/S1 Foraminal Stenosis Due to Stable Isthmic Spondylolisthesis: A Case Report., NMC Case Report Journal, 12, 547-552, 2025.
(Summary)
Isthmic spondylolisthesis at the L5-S1 level frequently leads to foraminal stenosis, while degenerative changes often cause lumbar spinal canal stenosis at L4-5. When both conditions coexist, accurate identification of the symptomatic lesion is challenging. Conventional surgical strategies typically involve combined decompression and interbody fusion under general anesthesia, which may not be suitable for elderly or high-risk patients. Recent advances in full-endoscopic spine surgery performed under local anesthesia provide a minimally invasive alternative. In this report, we present the case of a 75-year-old man with L5 radiculopathy in whom magnetic resonance imaging demonstrated right-sided lateral recess stenosis at L4-5 and right-sided foraminal stenosis at L5-S1 due to stable isthmic spondylolisthesis. Two-stage full-endoscopic spine surgery was performed under local anesthesia. The first procedure involved transforaminal pars crisscross decompression at L5-S1. Although foraminal decompression was achieved, symptoms persisted. A second-stage full-endoscopic ventral facetectomy at L4-5 resulted in immediate resolution of his symptoms. The patient remained asymptomatic at the 3-month follow-up. This case highlights the feasibility and efficacy of sequential full-endoscopic decompression under local anesthesia for multilevel lumbar stenosis associated with L5 radiculopathy. This approach may serve as a safe, less invasive alternative to fusion surgery in elderly patients and those with significant comorbidities.
Hiroshi Kageyama, Yukoh Ohara, Hirohiko Arimoto, Toru Maeda and Koichi Sairyo : Surgical Management of Cervical Myelopathy Due to Congenital Synostosis at the Craniovertebral Junction: Vertebral Artery Anomalies and Full-Endoscopic Retropharyngeal Odontoidectomy in a Case Series of Five Patients., Curēus, 17, 11, 2025.
(Summary)
Congenital synostosis at the craniovertebral junction (CVJ), including C1 assimilation and C2-C3 fusion, can lead to cervical myelopathy due to adjacent segment stenosis or instability. These anomalies are rare and frequently associated with vertebral artery (VA) variations, which complicate surgical planning and instrumentation. This case report describes five patients who developed cervical myelopathy associated with congenital CVJ synostosis and were surgically treated at our institution between 2019 and 2023. Preoperative imaging, including computed tomography (CT), magnetic resonance imaging (MRI), and CT angiography, was used to evaluate bony anomalies and VA morphology. Posterior decompression and fusion were performed under navigation guidance, with screw selection tailored to the individual anatomy. Among the five patients (mean age, 74.8 years), three had C1 assimilation, four had C2-C3 fusion, and two had both. VA anomalies, such as high-riding VA and unilateral hypoplasia, were present in all patients with C2-C3 fusion, requiring modified screw trajectories to prevent vascular injury. Three patients underwent full-endoscopic retropharyngeal odontoidectomy for persistent ventral compression after posterior fixation. All patients showed postoperative neurological improvement, and no VA injury or screw malposition occurred. Imaging confirmed sufficient decompression and appropriate fixation. Congenital CVJ synostosis with associated VA anomalies presents unique surgical challenges. Preoperative vascular imaging and intraoperative navigation are essential for safe fixation, and full-endoscopic retropharyngeal odontoidectomy offers a minimally invasive and effective option for anterior decompression in selected cases.
Takayuki Kitahara, Takafumi Ohshima, Naoto Ono, Yuji Nagao, Saori Soeda, Kosuke Sugiura, Masatoshi Morimoto, Hiroaki Manabe, Fumitake Tezuka, Hiroshi Kageyama, Junzo Fujitani, Kazuta Yamashita and Koichi Sairyo : Transforaminal Full-Endoscopic Lumbar Foraminotomy Under Local Anesthesia for L5/S1 Adjacent Segment Foraminal Stenosis., Journal of visualized experiments : JoVE, 224, 2025.
(Summary)
Foraminal stenosis in patients with L5/S1 adjacent segment disease (ASD) presents a significant clinical challenge, as conventional treatment often requires fusion extension surgery. This approach sacrifices spinal mobility and is associated with considerable surgical morbidity. This video article describes a motion-preserving surgical alternative, namely, transforaminal full-endoscopic foraminotomy performed under local anesthesia, detailing a step-by-step protocol to navigate the challenges of these revision cases. The technique utilizes a posterolateral corridor, avoiding prior surgical scarring. Key procedural steps include meticulous preoperative trajectory planning, foraminoplasty via resection of the superior articular process (SAP), and partial resection of the inferior articular process to fully expose the ligamentum flavum (LF). A specific "detach" technique is then demonstrated, involving undercutting the ventral rim of the S1 SAP to release the LF before its removal. Representative results demonstrate successful osseous decompression confirmed by postoperative computed tomography. The procedure resulted in immediate improvement in radicular pain and motor weakness, with the patient's visual analog scale score decreasing from 9/10 to 1/10 at the one-month follow-up. This minimally invasive technique provides effective neural decompression and facilitates rapid recovery, offering a valuable alternative to more extensive surgery for this challenging patient population.
Ryota Mio, Fumiaki Makiyama, Hiroshi Kageyama, Saori Soeda, Yuij Nagao, Naoto Ono, Masatoshi Morimoto, Hiroaki Manabe, Fumitake Tezuka, Kazuta Yamashita and Koichi Sairyo : Impact of Extended Endoscopic Lumbar Foraminotomy on Postoperative Surgical Outcomes: Is Greater Decompression Beneficial?, International Journal of Spine Surgery, 19, 4, 418-425, 2025.
(Summary)
The transforaminal (TF) approach in full endoscopic spine surgery (FESS) is the least invasive spinal surgery, as it can be performed under local anesthesia with only an 8-mm skin incision. Transforaminal FESS-based foraminotomy was first performed in the early 2000s for the decompression of foraminal stenosis. The technique has improved year by year over the past 2 decades. In our hospital, full endoscopic lumbar foraminotomy (FELF) has been performed since 2015. Since our development of the FESS undercutting laminectomy procedures in 2019, the size of the decompressed area achieved by FELF has increased.To estimate the technical alteration of FELF over time by comparing the pre- and postoperative osseous foraminal areas (FAs) between traditional and advanced FELF techniques.Fifty-two cases were retrospectively reviewed. In the early phase of FELF before 2019, partial or total resection of the superior articular process (SAP) was performed. Twenty-six of the patients were treated using the traditional FELF procedure (SAP-ectomy group). The remaining 26 underwent advanced FELF procedures, including SAP-ectomy, undercutting laminectomy, and removal of the ligamentum flavum (advanced FELF group). Clinical outcomes were assessed using the modified MacNab score. Pre- and postoperative osseous FAs were measured on sagittal computed tomography, and data were compared between the SAP-ectomy and advanced FELF groups. Paired and unpaired t tests were used for statistical analysis.By the modified MacNab score, the excellent/good rate was 82.6% in the SAP-ectomy group and 95.5% in the advanced FELF group. The improvement was greater in advanced FELF but not significantly. FA prior to surgery was 87.5 ± 27.0 mm2 in the SAP-ectomy group and 95.7 ± 34.3 mm2 in the advanced FELF group, with postoperative increases to 151.4 ± 45.5 mm2 and 195.3 ± 39.1 mm2, respectively (P < 0.05). FA increased by 63.9% and 99.6% in the SAP-ectomy and advanced FELF groups, respectively.Full endoscopic foraminotomy techniques have evolved over time. The recently developed advanced FELF technique appears to safely and effectively achieve better clinical outcomes by significantly enlarging FA.The advanced FELF technique contributes to improved decompression of the exiting nerve root.
Hiroshi Kageyama : Spinal malignant melanotic nerve sheath tumor with atypical magnetic resonance imaging findings: A case report, Surgical Neurology International, 15, 250, 2024.
(Summary)
Malignant melanotic nerve sheath tumors (MMNSTs) are relatively rare, comprising <1% of all neoplastic peripheral nerve lesions. Here, we describe a 79-year-old male who presented with atypical magnetic resonance imaging (MRI) findings of an MMNST. A 79-year-old male presented with lower back pain, paraparesis, and bladder/bowel dysfunction. The MRI showed an intradural extramedullary (IE) lesion at the T9-T10 level with low-signal intensity on T1-weighted images (WI) and high intensity on T2-WI, which markedly enhanced with contrast. The IE nerve root involved with the tumor was completely removed surgically. The lesion was confirmed to be an MMNST. In the absence of metastases, adjuvant therapy was deemed unnecessary. One year later, the lesion has not recurred. A 79-year-old male patient presented with a T9-T10 MR intradural lesion that was pathologically proved to be an MMNST, which was treated with gross total surgical resection (i.e., removal of the involved nerve root alone).
Yu Otake, Fumitake Tezuka, Kazuta Yamashita, Masatoshi Morimoto, Kosuke Sugiura, Makoto Takeuchi, Shunsuke Tamaki, Junzo Fujitani, Hiroshi Kageyama and Koichi Sairyo : Full-Endoscopic Foraminal Decompression for Foraminal Stenosis Following Osteoporotic Vertebral Fracture in an Elderly Woman Under Local Anesthesia:A Case Report., The Journal of Medical Investigation : JMI, 71, 1.2, 179-183, 2024.
(Summary)
Osteoporotic vertebral fracture (OVF) is common in the elderly population. In this report, we describe a case with radiculopathy due to foraminal stenosis caused by OVF in a very elderly patient that was treated successfully by full-endoscopic foraminotomy under local anesthesia. The patient was an 89-year-old woman who presented with a chief complaint of left leg pain for 5 years. She visited a couple of hospitals and finally consulted us to determine the exact cause of the pain. Computed tomography scans were obtained and selective nerve root block at L3 was performed. The diagnosis was radiculopathy at L3 due to foraminal stenosis following OVF. The patient had severe heart disease, so we decided to avoid surgery under general anesthesia and planned full-endoscopic spine surgery under local anesthesia. We performed transforaminal full-endoscopic lumbar foraminotomy at L3-L4 to decompress the L3 nerve root. The leg pain disappeared completely immediately after surgery. Postoperative computed tomography confirmed appropriate bone resection. The leg pain did not recur during a year of postoperative follow-up. OVF may cause lumbar radiculopathy as a result of foraminal stenosis, and transforaminal full-endoscopic lumbar foraminotomy under local anesthesia would be the best option in an elderly patient with poor general condition. J. Med. Invest. 71 : 179-183, February, 2024.
(Keyword)
Humans / Female / Aged, 80 and over / Anesthesia, Local / Spinal Fractures / Spinal Stenosis / Decompression, Surgical / Endoscopy / Osteoporotic Fractures / Lumbar Vertebrae / Radiculopathy
Koichi Sairyo, Yutaro Kanda, Kozaburo Mizutani, Masashi Kumon, Saori Soeda, Fumiaki Makiyama, Ryota Mio, Masatoshi Morimoto, Shunsuke Tamaki, Keisuke Nishidono, Kosuke Sugiura, Makoto Takeuchi, Hiroaki Manabe, Fumitake Tezuka, Kazuta Yamashita, Hiroshi Kageyama and Junzo Fujitani : Transforaminal full-endoscopic decompression under local anesthesia for foraminal stenosis due to stable L5 isthmic spondylolisthesis, a technical note and review:Pars crisscross decompression., The Journal of Medical Investigation : JMI, 71, 3.4, 191-196, 2024.
(Summary)
Foraminal stenosis is one of the types of lumbar spinal stenosis. The pathology can be treated minimally invasively by full-endoscopic spine surgery (FESS). The final challenge in transforaminal FESS is foraminal stenosis in patients with stable isthmic spondylolisthesis at L5. This article provides a step-by-step explanation of how to achieve complete decompression. A cannula of 8 mm in diameter is docked at the base of the superior articular process of the sacrum. The pars crisscross that consists of the superior articular process at S1, the floating lamina, the inferior articular process at L4, and the pars ragged edge is then clearly seen endoscopically. Visualization of the pars crisscross is key to successful decompression. Starting with the superior articular process at S1, followed by partial removal of the floating lamina. Next, the tip of the inferior articular process at L4 is removed. The pars ragged edge is then carefully shaved. Finally, decompression of the exiting nerve root at L5 is confirmed. This report provides the first step-by step description of full-endoscopic decompression of foraminal stenosis under local anesthesia in patients with stable L5 isthmic spondylolisthesis, which we have named "full-endoscopic pars crisscross decompression". J. Med. Invest. 71 : 191-196, August, 2024.