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Satoshi Kato, Hideki Murakami, Satoru Demura, Katsuhito Yoshioka, Hiroyuki Hayashi, Noriaki Yokogawa, Xiang Fang and Hiroyuki Tsuchiya


Several surgical procedures have been developed to treat thoracic OPLL (ossification of the posterior longitudinal ligament). However, favorable surgical results are not always achieved, and consistent protocols and procedures for surgical treatment of OPLL in this region have not been established. Beak-type OPLL in the thoracic spine is known to be the most complicated form of OPLL to treat surgically. In this study, the authors examine the clinical outcomes after anterior decompression via a posterolateral approach for beak-type OPLL in the thoracic spine and address the gradual spinal cord decompression caused by migration of the floated plaques after surgery.


Between 2011 and 2013, a total of 12 patients with thoracic myelopathy due to OPLL were surgically treated at the authors’ institute. The study group for this paper comprises 6 of those 12 patients. These 6 patients, who had beak-type OPLL, underwent with anterior decompression and instrumented fusion via the authors’ posterolateral approach-based surgical technique. The other 6 patients, who exhibited other types of OPLL, underwent posterior decompression and instrumented fusion. In the study group (the 6 patients with beak-type OPLL), half of the patients (the 3 patients who were treated first) were treated with removal of the ossified ligament. These patients are referred to as the removal group. The other 3 patients were treated by means of “floating” the OPLL plaques and are referred to as the floating group. Clinical and radiographic outcomes were evaluated in these 6 cases.


The recovery rates were 52.4% in the removal group and 60.0% in the floating group. Two patients in the removal group had operative complications, including a dural tear and temporary neurological deterioration. No operative complications were encountered in the floating group. In all 3 cases in the floating group, floating of the ossified ligament was completely achieved, and the floated plaque gradually migrated into the ventral bone resection areas. The mean migration distances of the floated plaque were 2.4 mm, 4.3 mm, 4.7 mm, and 4.8 mm at 1, 3, 6, and 12 months after surgery.


Treatment of beak-type OPLL in the thoracic spine via the posterolateral approach-based floating plaque technique was safe and effective in this small case series. Gradual migration of the floated plaques provided additional spinal cord decompression during the postoperative course.

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Satoshi Kato, Hideki Murakami, Satoru Demura, Katsuhito Yoshioka, Hiroyuki Hayashi and Hiroyuki Tsuchiya

Several surgical procedures have been developed to treat thoracic ossification of the posterior longitudinal ligament (OPLL). However, favorable surgical results are not always achieved, and consistent protocols and procedures for surgical treatment of thoracic OPLL have not been established. This technical note describes a novel technique to achieve anterior decompression via a single posterior approach. Three patients with a beak-type thoracic OPLL underwent surgery in which the authors' technique was used. Complete removal of the ossified PLL was achieved in all cases. With the patient in the prone position, the authors performed total resection of the posterior elements at the anterior decompression levels. This maneuver included not only laminectomies but also removal of the transverse processes and pedicles, which allowed space to be created bilaterally at the sides of the dural sac for the subsequent anterior decompression. The thoracic nerves at the levels of anterior decompression were ligated bilaterally and lifted up to manipulate the ossified ligament and the dural sac. An anterior decompression was then performed posteriorly. The PLL was floated without any difficulty. After exfoliation of the adhesions between the ossified ligament and the ventral aspect of the dural sac, the ossified PLL was removed. In every step of the anterior decompression, the space created in the bilateral sides of the dural sac allowed the surgeons to see the OPLL and anterolateral aspect of the dural sac directly and easily. After removal of the ossified PLL, posterior instrumented fusion was performed. This surgical procedure allows the surgeon to perform, safely and effectively, anterior decompression via a posterior approach for thoracic OPLL.

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Yuki Yamamuro, Satoru Demura, Hideki Murakami, Satoshi Kato, Noritaka Yonezawa, Noriaki Yokogawa and Hiroyuki Tsuchiya

Acute progressive adolescent idiopathic cervical kyphosis (AICK) is rare, and its treatment strategy is controversial. The authors present a case of AICK successfully treated with preoperative halo-gravity traction, followed by combined anterior-posterior surgery. A 15-year-old girl with no relevant past or family history presented with axial neck pain without any cause. A few months after the development of cervical myelopathy, cervical kyphosis progressed to 71° despite conservative treatment. CT scanning demonstrated osteophyte formation at the anterior aspect of the vertebral body. MRI showed a forward migration of the spinal cord with a ratio (C/M ratio) between the anteroposterior diameter of the medulla-pons junction and the spinal cord at the apex of the kyphosis of 0.27. After 2 weeks of preoperative halo-gravity traction, anterior release and posterior fusion was performed. After surgery, cervical kyphosis was corrected to 0°, and cervical myelopathy improved. One year after surgery, the patient was neurologically intact, and bony union and improved cervical alignment were observed. Preoperative halo-gravity traction followed by combined anterior-posterior surgery led to safe and effective correction. Osteophyte formation at the anterior aspect of the vertebral body and the C/M ratio were useful in predicting the progression of AICK.

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Yoshihisa Nishiyama, Hiroyuki Kinouchi, Nobuo Senbokuya, Tatsuya Kato, Kazuya Kanemaru, Hideyuki Yoshioka and Toru Horikoshi

Recently, intraoperative fluorescence video angiography using indocyanine green (ICG) has been widely used in aneurysm surgery. This is a simple and useful method to confirm complete occlusion of the aneurysm lumen and preservation of blood flow in the arteries around the aneurysm. However, the observation field of ICG video angiography is limited under a microscope, making it difficult to confirm the flow in the arteries behind the parent arteries or aneurysm. The authors developed a new technique of intraoperative endoscopic ICG video angiography to assess the blood flow in perforating arteries hidden by the parent arteries or aneurysm. The endoscope emits excitation light with a wavelength of approximately 800 nm, and video images were obtained through a cut filter. The authors used this ICG fluorescence endoscope in treating 3 patients with unruptured cerebral aneurysms. During clip placement, the endoscope was inserted to confirm aneurysm occlusion. Then, ICG was intravenously administered, and the fluorescence in the vessels was observed via the endoscope as well as under the microscope. The blood flow in the perforating arteries was clearly identified, and no procedural complication occurred. The authors conclude that the technique is very useful and facilitates intraoperative real-time assessment of the patency of perforating arteries behind parent arteries or aneurysms.

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Tomoyuki Kawataki, Eiji Sato, Tatsuya Kato, Takashi Sato, Toru Horikoshi and Hiroyuki Kinouchi

In this report, a rare case of dysembryoplastic neuroepithelial tumor (DNET) initially presented as a small white matter lesion with calcification adjacent to the lateral ventricle and extending to the frontal cortex after 7 years. This 1-year-old boy initially suffered from partial seizures. Initial CT revealed a small, low-density area surrounding a tiny calcified mass in the deep white matter of the left frontal lobe. Seven years later, his seizures had become intractable to antiepileptic agents, and MR imaging demonstrated a relatively large mass extending from the calcified lesion up to the adjacent cortical surface. He underwent surgery and the tumor was subtotally removed. Histological examination of the tumor verified it as a DNET consisting of clusters of small oligodendrocytes with floating neurons in the mucoid background. The pattern of the tumor progression in this case suggests that a DNET in the cortex originates from the subependymal germinal layer near the ventricle.

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Satoru Demura, Norio Kawahara, Hideki Murakami, Mohamed E. Abdel-Wanis, Satoshi Kato, Katsuhito Yoshioka, Katsuro Tomita and Hiroyuki Tsuchiya


Thyroid carcinoma generally has a favorable prognosis, and patients rarely present with distant metastases. Authors of several studies have proposed piecemeal resection for spinal metastases in thyroid carcinoma; however, few have analyzed the impact of local curative surgery such as total en bloc spondylectomy (TES) for thyroid carcinoma. The purposes of the present study are to determine the strategy of surgical treatment for spinal metastases of thyroid carcinoma and to evaluate the surgical results of and the prognosis associated with TES.


Twenty-four cases of spinal metastases were retrospectively reviewed. The patients included 16 women and 8 men, with a mean age of 60.7 years. Histological examination showed follicular carcinoma in 15 cases, papillary carcinoma in 8, and medullary carcinoma in 1. Total en bloc spondylectomy was performed in 10 cases; debulking surgery, such as piecemeal excision or eggshell curettage, was performed in 14. The average follow-up time was 55 months (12–180 months).


Four patients had no evidence of disease, 8 were alive with the disease, and 12 had died of the disease. The overall survival rate from the time of surgery was 74% at 5 years. Patients with visceral metastases had a significant, higher risk of death. The survival rate of patients following TES was 90% at 5 years, which was higher than the rate in patients who underwent debulking surgery (63%). However, no significant difference was observed between the 2 types of surgery. There was a local recurrence after debulking surgery in 8 (57%) of 14 cases. Because of the recurrences, reoperation was required after a mean of 41 months. In contrast, there was a local recurrence after TES in only 1 (10%) of 10 cases. The difference between debulking surgery and TES regarding local recurrence was statistically significant.


Total en bloc spondylectomy with enough of a margin provided favorable local control of spinal metastases of thyroid carcinoma during a patient's lifetime.

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Hiroyuki Kayaba, Tatsuzo Hebiguchi, Yasunobu Itoh, Hiroaki Yoshino, Masaru Mizuno, Mayako Morii, Tetsuya Adachi, Junichi Chihara and Tetsuo Kato

Object. Disturbance in anorectal function is a major factor restricting the activities of daily living in patients with spinal cord disorders. To detect changes in anorectal motilities due to a tethered spinal cord, anorectal functions were evaluated using a saline enema test and fecoflowmetry before and after patients underwent untethering surgery.

Methods. The bowel functions in five patients with a tethered cord syndrome (TCS) were evaluated by performing a saline enema test and fecoflowmetry. The contractile activity of the rectum, the volume of infused saline tolerated in the rectum, anal canal pressure, and the ability to evacuate rectal content were examined.

The characteristic findings in anorectal motility studies conducted in patients with TCS were a hyperactive rectum, diminished rectal saline-retention ability, and diminished maximal flow in saline evacuation. A hyperactive rectum was considered to be a major contributing factor to fecal incontinence. In one asymptomatic patient diminished anal squeezing pressure was exhibited and was incontinent to liquid preoperatively, but recovered after surgery. Two patients who underwent surgery for myeloschisis as infants complained of progressive fecal incontinence when they became adolescents. In one patient fecal incontinence improved but in another patient no improvement was observed after untethering surgery.

Conclusions. Fecodynamic studies allow the detection of neurogenic disturbances of the anorectum in symptomatic and also in asymptomatic patients with TCS. More attention should be paid to the anorectal functions of patients with TCS.

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Satoru Egawa, Toshitaka Yoshii, Kyohei Sakaki, Hiroyuki Inose, Tsuyoshi Kato, Shigenori Kawabata, Shoji Tomizawa and Atsushi Okawa

Superficial siderosis (SS) of the CNS is a rare disease caused by repeated hemorrhages in the subarachnoid space. The subsequent deposition of hemosiderin in the brain and spinal cord leads to the progression of neurological deficits. The causes of bleeding include prior intradural surgery, carcinoma, arteriovenous malformation, nerve root avulsion, and dural abnormality. Recently, surgical treatment of SS associated with dural defect has been reported. The authors of the present report describe 2 surgically treated SS cases and review the literature on surgically treated SS. The patients had dural defects with fluid-filled collections in the spinal canal. In both cases, the dural defects were successfully closed, and the fluid collection was resolved postoperatively. In one case, the neurological symptoms did not progress postoperatively. In the other case, the patient had long history of SS, and the clinical manifestations partially deteriorated after surgery, despite the successful dural closure.

In previously reported surgically treated cases, the dural defects were closed by sutures, patches, fibrin glue, or muscle/fat grafting. Regardless of the closing method, dural defect closure has been shown to stop CSF leakage and subarachnoid hemorrhaging. Successfully repairing the defect can halt the disease progression in most cases and may improve the symptoms that are associated with CSF hypovolemia. However, the effect of the dural closure may be limited in patients with long histories of SS because of the irreversibility of the neural tissue damage caused by hemosiderin deposition. In patients with SS, it is important to diagnose and repair the dural defect early to minimize the neurological impairments that are associated with dural defects.

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Naoko Araya, Hiroyuki Inose, Tsuyoshi Kato, Masanori Saito, Satoshi Sumiya, Tsuyoshi Yamada, Toshitaka Yoshii, Shigenori Kawabata and Atsushi Okawa

Hyperimmunoglobulin E syndrome (HIES) is a rare primary immunodeficiency syndrome characterized by recurrent staphylococcal infections in the skin and lungs, with an incidence of less than one case per million persons. Skeletal and connective tissue abnormalities, such as scoliosis, osteoporosis, pathological fractures, and hyperextensive joints, are other manifestations of HIES. However, only one report documents the use of implants to treat spinal deformity caused by HIES, which was discovered following corrective surgery resulting in postoperative infection. In this case report, the authors describe a 16-year-old male with low-back pain and infections of the soft tissue. Radiological findings showed deteriorated kyphotic deformity due to the pathological compression fracture of T-11 with intensive conservative treatment. Anterior and posterior fixation surgery was performed. Thereafter, the patient showed no signs of infection. An investigation was conducted to avoid any postoperative infection.

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Hiroki Oba, Jun Takahashi, Sho Kobayashi, Tetsuro Ohba, Shota Ikegami, Shugo Kuraishi, Masashi Uehara, Takashi Takizawa, Ryo Munakata, Terue Hatakenaka, Michihiko Koseki, Shigeto Ebata, Hirotaka Haro, Yukihiro Matsuyama and Hiroyuki Kato


Unfused main thoracic (MT) curvatures occasionally increase after selective thoracolumbar/lumbar (TL/L) fusion. This study sought to identify the predictors of an unacceptable increase in MT curve (UIMT) after selective posterior fusion (SPF) of the TL/L curve in patients with Lenke type 5C adolescent idiopathic scoliosis (AIS).


Forty-eight consecutive patients (44 females and 4 males, mean age 15.7 ± 2.5 years, range 13–24 years) with Lenke type 5C AIS who underwent SPF of the TL/L curve were analyzed. The novel “Shinshu line” (S-line) was defined as a line connecting the centers of the concave-side pedicles of the upper instrumented vertebra (UIV) and lowest instrumented vertebra (LIV) on preoperative radiographs. The authors established an S-line tilt to the right as S-line positive (S-line+, i.e., the UIV being to the right of the LIV) and compared S-line+ and S-line− groups for thoracic apical vertebral translation (T-AVT) and MT Cobb angle preoperatively, early postoperatively, and at final follow-up. The predictors for T-AVT > 20 mm at final follow-up were evaluated as well. T-AVT > 20 mm was defined as a UIMT.


Among the 48 consecutively treated patients, 26 were S-line+ and 22 were S-line−. At preoperative, early postoperative, and final follow-up a minimum of 2 years later, the mean T-AVT was 12.8 mm (range −9.3 to 32.8 mm), 19.6 mm (range −13.0 to 41.0 mm), and 22.8 mm (range −1.9 to 68.7 mm) in the S-line+ group, and 10.8 mm (range −5.1 to 27.3 mm), 16.2 mm (range −11.7 to 42.1 mm), and 11.0 mm (range −6.3 to 26.9 mm) in the S-line− group, respectively. T-AVT in S-line+ patients was significantly larger than that in S-line− patients at the final follow-up. Multivariate analysis revealed S-line+ (odds ratio [OR] 23.8, p = 0.003) and preoperative MT Cobb angle (OR 7.9, p = 0.001) to be predictors of a UIMT.


S-line+ was defined as the UIV being to the right of the LIV. T-AVT in the S-line+ group was significantly larger than in the S-line− group at the final follow-up. S-line+ status and larger preoperative MT Cobb angle were independent predictors of a UIMT after SPF for the TL/L curve in patients with Lenke type 5C AIS. Surgeons should consider changing the UIV and/or LIV in patients exhibiting S-line+ during preoperative planning to avoid a possible increase in MT curve and revision surgery.