Akira Nakamura

Short-Term Clinical Result of Cortical Bone Trajectory Technique for the Treatment of Degenerative Lumbar Spondylolisthesis with More than 1-Year Follow-Up

Study Design Retrospective follow-up study on the result of surgical treatment for patients with degenerative lumbar spondylolisthesis (DLS) using cortical bone trajectory (CBT) technique. Purpose To evaluate the capability of CBT to manage patients with DLS. Overview of Literature CBT is a recently advocated, novel, less-invasive technique of lumbar pedicle screw, which provides enhanced screw purchase by maximizing the thread contact with higher density bone surface. Despite the frequent use of CBT technique in the lumbar spine surgery, little is known of the capability of this technique to manage patients with DLS. Methods Thirty two consecutive patients (5 males, 27 females) surgically treated with single-level DLS in our institute using CBT were included. All patients were followed up at least 12 months (mean 24 months). Their clinical and radiological features were measured. Results Good leg pain relief was achieved in all patients. The mean postoperative percentage slip demonstrated significant reduction with significant neurological recovery when compared with preoperative percentage slip, and it was maintained until the latest follow-up. Loss of correction of more than 3 mm during the follow-up period was observed in 3 cases. Surgical site infection was observed in one case; however, pull-out of PSs or neurological deterioration was not found. No patient needed additional surgery during the follow-up period. Conclusions These preliminary results confirmed that CBT is useful for the treatment for patients with DLS. This technique allows good reduction of spondylolisthesis and neurological improvement.

Prevalence of thoracic diffuse idiopathic skeletal hyperostosis (DISH) in Japanese: Results of chest CT-based cross-sectional study

BACKGROUNDnThe epidemiology and etiology of diffuse idiopathic skeletal hyperostosis (DISH) remain obscure. To date, to the best of our knowledge, there is no study that precisely evaluated the prevalence of thoracic DISH based on computed tomography (CT) data in large number of non-operated cohort with wide age distribution.nnnMETHODSnThe participants of this study were the consecutive patients who have undergone chest CT for the examination of pulmonary diseases in our institute. The patients with previous thoracic spine surgery and younger than 15 years old were excluded. Chest CT data were reconstructed in the condition suitable for bone evaluation by the software application. Definitive diagnosis of DISH was determined according to the criteria established by Resnick and Niwayama. Prevalence and distribution of thoracic DISH were reviewed and the data was statistically analyzed.nnnRESULTSnTotal 3013 patients (1261 females and 1752 males) with the mean age of 65 years were recruited. The CT-based evidence of thoracic DISH was noted in 261 individuals (31 females and 230 males) (8.7%), and their mean age was 73 years. Statistical analyses revealed that thoracic DISH had a significant male preponderance. The mean age of thoracic DISH positive individuals was significantly higher than that of thoracic DISH negative individuals. There was significant difference of bone mass index (BMI) between thoracic DISH positive and negative individuals. Thoracic DISH was noted after the age of 40s with the highest distribution found at the age of 70s. No thoracic DISH localizes only higher thoracic region was found.nnnCONCLUSIONSnThe CT-based prevalence of thoracic DISH in Japanese was 8.7%. Thoracic DISH has a significant predisposition to elderly male with high BMI.

Plexiform schwannoma arising from cauda equina.

A 61-year-old woman with rheumatoid arthritis (RA) presented with unprecedented progressive low back and bilateral lower leg dull-pain. She has a 10-year and 7year history of methotrexate and etanercept treatment for RA, respectively. Physical examination revealed the absence of neurologic compromise. There was no evidence of any skin pigmentation and familial history of neurogenic tumors. Plain radiographs of the lumbar spine revealed degenerative changes, especially at L2/L3 level (Fig. 1). The plain magnetic resonance imaging (MRI) revealed intradural low-intensity lesion on both T1and T2-weighted images (Fig. 2, Left and Middle); however, which may have been overlooked without gadoliniumenhanced MRI (Gd-MRI). The succeeding Gd-MRI of lumbar spine clearly revealed a homogeneously enhanced intradural lesion that extended from L2 to L4 (Fig. 2, Right). Computed tomography revealed neither calcification of the lesion nor bone scalloping (data not shown). Taking all these findings including being under treatment

Aortic pulsation prevents the development of ossification of anterior longitudinal ligament toward the aorta in patients with diffuse idiopathic skeletal hyperostosis (DISH) in Japanese: Results of chest CT-based cross-sectional study

BACKGROUNDnThe development and etiology of diffuse idiopathic skeletal hyperostosis (DISH) were far from complete understanding. Even the precise mechanism of the development of its typical right-sided ossification of the anterior longitudinal ligament (OALL) frequently compared to flowing candle wax, a hallmark of DISH, remains unknown.nnnMETHODSnThe participants of this study were 261 individuals (31 females and 230 males) diagnosed as DISH according to the criteria established by Resnick and Niwayama extracted from a consecutive 3013 patients who have undergone chest CT for the examination of pulmonary diseases in our institute. The patients with previous thoracic spine surgery and younger than 15 years old were excluded. Chest CT data were converted to the condition suitable for bone evaluation by the software application. The positional relationship between thoracic aorta and OALL, the morphology of the OALL adjacent to the aorta and the presence of calcification of the aortic wall adjacent to the OALL were studied.nnnRESULTSnOf 261 individuals with DISH, we found that thoracic aorta was localized adjacent to the OALL (AD-group) in 123 cases (47%), whereas 138 cases (53%) were not (NAD-group). All OALL in AD-group was localized between T6 and T12. The shape of the OALL adjacent to the aorta was either flat or concave except for one. No case showed obvious calcification of the aortic wall adjacent to the OALL in AD-group.nnnCONCLUSIONSnThe aortic pulsation might play an important role in inhibit the development of the OALL toward the aorta in DISH. It is likely that establishment of the optimal condition of the pulsation stress simulating aortic pulsation and its delivery system can achieve arresting, slowing the progression and/or changing the morphology of the ossified lesions.

Wnt signaling pathway correlates with ossification of the spinal ligament: A microRNA array and immunohistochemical study

BACKGROUNDnOssification of the posterior longitudinal ligament or the ligamentum flavum parallels endochondral ossification. Cell differentiation at the ossification front is known to be important during this process, although the factors regulating its initiation and progression are still unclear. The purpose of this study was to identify factors important for the regulation of chondrocyte/osteoblast differentiation during spinal ossification.nnnMETHODSnLigamentum flavum tissue was isolated from 25 patients who underwent decompressive surgery for cervical ossification of the posterior longitudinal ligament. Tissue sections were used for inxa0vitro culture to obtain primary cells through migration methods. To identify microRNAs associated with ossification of the posterior longitudinal ligament, cultured cells were prepared from the ligamentous tissue (nxa0=xa04; continuous type) or from control ligamentous samples harvested from patients with cervical spondylosis without spinal ossification, and analyzed using a microRNA array. The ligamentous sections were also examined by immunohistochemistry for the expression of candidate microRNA target genes.nnnRESULTSnThe microRNA array identified 177 factors; 12 of which were expressed at significantly different levels in patients with ossification of the posterior longitudinal ligament compared to those in control patients. The hsa-miR-487b-3p was down-regulated in patients with ossification of the posterior longitudinal ligament, which met the false discovery rate of <0.05. This microRNA was predicted to regulate the expression of genes involved in Wnt signaling. Furthermore, immunohistochemistry of Wnt signaling proteins, including Wnt 3a, LRP5/6, and beta-catenin, revealed positive expression in mesenchymal cells and/or premature chondrocytes at the ossification front.nnnCONCLUSIONnOur results suggested that down-regulation of miR-487b-3p plays an important role in the initiation of Wnt signaling during the ossification process. Wnt signaling may regulate both chondrocyte and osteoblast differentiation and the specification of endochondral ossification in the pathogenesis of ossification of the posterior longitudinal ligament or the ligamentum flavum.

Novel Landmark for Cervical Pedicle Screw Insertion Point from Computed Tomography-Based Study

Study Design Cross-sectional study. Purpose The purpose of this study was to evaluate a novel landmark for the cervical pedicle screw insertion point. Overview of Literature To improve the accuracy of pedicle screw placement, several studies have employed the lateral mass, lateral vertical notch, and/or inferior articular process as landmarks; however, we often encounter patients in whom we cannot identify accurate insertion points for pedicle screws using these landmarks because of degenerative changes in the facet joints. The superomedial edge of the lamina is less affected by degenerative changes, and we hypothesized that it could be a new landmark for identifying an accurate cervical pedicle screw insertion point. Methods A total of 327 consecutive patients, who had undergone neck computed tomographic scanning for determination of neck disease in our institute, were included in the study. At first, the line was drawn parallel to the superior border of the pedicle in the sagittal plane and parallel to the vertical body in the coronal plane. The line was moved downward in 1-mm increments to the inferior border of the pedicle. We determined whether the line passing through the superomedial edge of the lamina (termed the “N-line”) was located between the superior and inferior borders of the pedicle in the sagittal plane. Results The percentages of N-lines located between the superior and inferior borders of the pedicle were 100% at C3, 100% at C4, 99% at C5, 96% at C6, and 97% at C7. The lower cervical spine has the higher N-line location. Conclusions The N-line was frequently located at the level of the pedicle of each cervical spine in the sagittal plane. The superomedial edge of the lamina could be a new landmark for the insertion point of the cervical pedicle screw.

Giant balloon-like presacral schwannoma

A 69-year-old female patient visited a gynecologist because of lower abdominal discomfort. Magnetic resonance (MR) imaging was conducted, and the patient was referred to our institute because a presacral abnormal lesion was found. Physical examination revealed absence of neurologic compromise. Plain MR imaging revealed presacral single balloon-like cyst, which was homogenously low intensity on T1-weighted images and high intensity on T2-weighted images (Fig. 1A–C). The succeeding gadolinium-enhanced MR imaging revealed ring enhancement of the lesion (Fig. 1D, E). The initial differential diagnosis of the lesion includes schwannoma, abscess, chordoma, and perineural cyst. We, together with the gynecologists, conducted a laparoscopic excisional biopsy of the lesion. After the aspiration of liquid in the cyst, total extirpation of the lesion was successfully performed. Histologic examination revealed spindle-shaped cells arranged in short bundles with foci of nuclear palisading. Neither nuclear atypia nor mitotic figures were observed. These findings were consistent with benign schwannoma. At the time of the latest follow-up, 2 years after the surgery, the patient was free of symptoms without evidence of regrowth of the lesion (Fig. 2, Left and Right). Sacral schwannomas have a very rare etiology, comprising less than 1% to 5% of all spinal schwannomas, and only around 50 cases have been reported in the literature [1]. Schwannomas can develop degenerative changes with cystic formations; however, purely cystic change is by far a rare finding in the spinal schwannoma, and only few cases of giant sacral schwannoma with significant cystic component have been reported in the literature [2]. Even though the lesion presents significant cystic component, most of the lesions present heterogeneous multilobulated mass. To the best of our knowledge, the single-lobulated giant presacral schwannoma is an extremely rare condition. We advocate that uneven thickness of the cystic wall is one of the factors distinguishing tumors from other simple cystic lesions like perineural cyst.

Atraumatic Occult Odontoid Fracture in Patients with Osteoporosis-Associated Thoracic Kyphotic Deformity: Report of a Case and Review of the Literature.

Anderson type II odontoid fractures are reported to be the most common injury of the odontoid process in patients over the age of 65. However, atraumatic occult Anderson type III odontoid fractures have been rarely described and remain a diagnostic challenge. In the present report, we illustrate a 78-year-old female with osteoporosis-associated marked thoracic kyphotic deformity who developed atraumatic Anderson type III occult odontoid fracture and raise awareness of this condition. Anteroposterior and lateral standard radiographs of cervical spine failed to disclose odontoid fracture. Magnetic resonance imaging demonstrated intensity changes of the axis. Subsequent computed tomography clearly demonstrated Anderson type III odontoid fracture. Conservative treatment achieved complete bone union without neurological deteriorations. At 3-year follow-up, the patient was doing well without neurological and radiological deteriorations. Even if the patients have no traumatic event, we have to keep odontoid fractures in our mind as one of the differential diagnoses when we encounter elderly patients with neck pain, especially in patients with osteoporosis-associated marked thoracic kyphotic deformity.

Tumor-Induced Osteomalacia Caused by a Bone Tumor in the Ulna

Hypophosphatemic osteomalacia induced by overproduction of fibroblast growth factor 23 (FGF23) by a tumor is a relatively rare paraneoplastic syndrome that recently has been recognized. During the course of the disease, termed “tumor-induced osteomalacia” (TIO), the level of phosphorus in the blood becomes reduced as a result of accelerated diuresis due to excessive FGF23 production by the tumor, resulting in bone calcification dysfunction in the entire body, which leads to osteomalacia1-4. TIO most commonly develops in middle-aged adults, with no differences between men and women. Clinically, it is characterized by general bone pain, muscular weakness, and pathological fractures. A TIO-like syndrome can also be seen in association with other diseases such as prostate cancer, small-cell carcinoma (oat cell cancer), hematologic malignancies, neurofibromatosis, epidermal nevus syndrome, and polyostotic fibrous dysplasia of bone5-15.nnWe describe a tumor resection and ulnar bone reconstruction in a patient with an ulnar tumor that caused TIO. The patient was informed that data concerning the case would be submitted for publication, and he provided consent.nnA forty-nine-year-old left-handed man presented to our department with pain in the left forearm. There was no appreciable family or previous medical history. He worked as a delivery person. Plain radiographic findings revealed a cystic lesion of the bone and a pathological fracture in the diaphysis of the left ulna. Moreover, a Looser zone, which is a lucent band adjacent to the periosteum representing an unhealed insufficiency-type stress fracture commonly associated with osteomalacia, was seen in the diaphysis of the left radius (Fig. 1). Systemic bone disease was suspected. The patient initially had noticed bone pain throughout the entire body about two years prior, but did not seek treatment.nnnnFig. 1 nAnteroposterior (top) and lateral (bottom) radiographs show a cystic lesion and pathological fracture in the …