Are T1-Weighted Three-Dimensional Magnetic Resonance Images Inferior to T2-Weighted Images for Diagnosing Lumbar Foraminal Stenosis in the Fifth Lumbar Nerve Root? A Prospective, Comparative Study in Identical Patients.

Introduction: Imaging analysis of foraminal stenosis in the fifth lumbar (L5) nerve root remains to be a challenge because of the anatomical complexity of the lumbosacral transition. T2-weighted three-dimensional (3D) magnetic resonance images (MRI) have been dominantly used for diagnosis of lumbar foraminal stenosis, while the reliability of T1-weighted images (WI) has also been proven. In this study, we aim to compare the reliability and reproducibility of T1- and T2-weighted 3D MRI in diagnosing lumbar foraminal stenosis (LFS) of the L5 nerve root. Methods: In this study, 39 patients with unilateral L5 radiculopathy (20 had L4-L5 intracanal stenosis; 19 had L5-S foraminal stenosis) were enrolled, prospectively. T1- and T2-weighted 3D lumbar MRI were obtained from each patient. T1WI and T2WI were blinded and then separately reviewed twice by four examiners randomly. The examiners were instructed to answer the side of LFS or absence of LFS. The correct answer rate, sensitivity, specificity, and area under the curve were analyzed and compared between T1WI and T2WI. Also, intra- and interobserver agreements were calculated using kappa (κ)-statistics and compared in the same manner. Results: The average correct answer rate, sensitivity, specificity, and area under the curve of the T1WI/T2WI were 84.6%/80.1%, 82.9%/80.3%, 86.3%/81.3%, and 0.846/0.801, respectively. The intraobserver κ-values of the four examiners ranged from 0.692 to 0.916 (average: 0.762) and from 0.669 to 0.801 (average: 0.720) for T1WI and T2WI, respectively. The interobserver κ-values calculated in a round-robin manner (24 combinations in total) ranged from 0.544 to 0.790 (average: 0.657) and from 0.524 to 0.828 (average: 0.652), respectively. Conclusions: As per our findings, T1- and T2-weighted 3D MRI were determined to have nearly equivalent reliability and reproducibility in terms of diagnosing LFS of the L5 nerve root.

Surgical management of facet cysts in the thoracic spine: Radiological manifestations and results of fenestration.

BACKGROUND: Facet cysts in the thoracic spine are a rare cause of thoracic myelopathy. We aimed to investigate the clinical/radiological features and surgical results of these lesions. METHODS: Nine thoracic facet cysts in eight patients (seven men, one woman) were diagnosed based on magnetic resonance imaging (MRI) and computed tomography (CT) with facet arthrography findings and surgically treated. The mean patient age was 71 (59-83) years. The cysts were distributed as follows: one each at T8-9 and T9-10, two each at T1-2 and T11-12, and three at T10-11. The mean follow-up period was 1.8 (1-5) years. Clinical and radiological features were retrospectively investigated, and surgical outcomes were evaluated according to modified Japanese Orthopaedic Association (JOA) scores for thoracic myelopathy (full score: 11). RESULTS: Neurological examination revealed progressive thoracic transverse myelopathy in all patients with a mean disease duration of 1.2 months (2 weeks-2 months). MRI revealed a total of nine cysts across the eight patients: four in the median region and five in the paramedian portion of the spinal canal. CT revealed degeneration in all involved facet joints. All the cysts were in communication with the neighboring facet joint confirmed by CT facet arthrography. All patients underwent bilateral fenestration, and the cysts were resected with the ligamentum flavum. The mean preoperative and postoperative modified JOA scores were 4.5 and 8.8, respectively. The mean recovery rate was 67.5%. Differences in the degree of local kyphosis were 2° or less between before and after surgery. On histopathology, synovial lining cells were not noted in any case. CONCLUSIONS: Decompression surgery is recommended for treating progressive myelopathy in patients with cystic lesions. Our study suggests that thoracic facet cyst resection with satisfactory surgical outcomes would be possible through fenestration.

Y-27632, a ROCK inhibitor, improved laser-induced shock wave (LISW)-induced cochlear synaptopathy in mice.

Recently, a pathological condition called cochlear synaptopathy has been clarified, and as a disorder of the auditory nerve synapses that occurs prior to failure of hair cells, it has been recognized as a major cause of sensorineural hearing loss. However, cochlear synaptopathy is untreatable. Inhibition of rho-associated coiled-coil containing protein kinase (ROCK), a serine-threonine protein kinase, has been reported to have neuroprotective and regenerative effects on synaptic pathways in the nervous system, including those in the inner ear. We previously demonstrated the regenerative effect of the ROCK inhibitor, Y-27632, on an excitotoxic cochlear nerve damage model in vitro. In this study, we aimed to validate the effect of ROCK inhibition on mice with cochlear synaptopathy induced by laser-induced shock wave (LISW) in vivo. After the elevation of ROCK1/2 expression in the damaged cochlea was confirmed, we administered Y-27632 locally via the middle ear. The amplitude of wave I in the auditory brainstem response and the number of synapses in the Y-27632-treated cochlea increased significantly. These results clearly demonstrate that ROCK inhibition has a promising clinical application in the treatment of cochlear synaptopathy, which is the major pathology of sensorineural hearing loss.

Consistent removal of hair cells in vestibular end organs by time-dependent transtympanic administration of gentamicin in guinea pigs.

BACKGROUND: Vestibular hair cell loss and its role in balance disorders are not yet completely understood due largely to the lack of precise hair cell damage protocols. NEW METHOD: Our damage protocol aims to selectively remove type I hair cells in a way that produces consistent and predictable lesions that can be used for reliable inter-animal and inter-group comparison in balance research. This objective is achieved by transtympanic injection of gentamicin on both the round window membrane and oval window over a fixed time period followed by thorough washing. RESULTS: We achieved nearly total and consistent loss of type I hair cells at 94 % for the crista ampullaris of the lateral semicircular canal (LSC) and 86 % for the utricular macula with negligible loss of type II hair cells at 4% for the crista ampullaris of the LSC and 6% for the utricular macula. While the vestibular function was compromised in the relevant study group, this group had a zero mortality rate with no significant suppression of body weight gain. COMPARISON WITH EXISTING METHODS: Gentamicin is typically administered via intraperitoneal systemic injection or, more recently, transtympanic injection. The intraperitoneal method is simple, but mortality rate is high. The transtympanic injection method produces ototoxic damage but with inconsistent lesion size. This inconsistency prevents reliable comparisons among animals. CONCLUSIONS: This protocol employs a transtympanic injection method which selectively targets type I hair cells for removal in the vestibular epithelia in a time-dependent manner, uniformly damages vestibular function, and causes uniform hair cell loss.

Regenerative Effect of a ROCK Inhibitor, Y-27632, on Excitotoxic Trauma in an Organotypic Culture of the Cochlea.

In the past, most inner ear diseases were thought to start with the impairment of the sensory epithelium of the cochlea before subsequently progressing to secondary neural degeneration. However, recent studies show that loss of primary synapses accompanied by excitotoxic degeneration of peripheral axons is likely to be the underlying pathology in sensorineural hearing loss. Rho-associated coiled-coil containing protein kinase (ROCK) inhibition has been reported to have neuroprotective and regenerative effects on synaptic pathways. Therefore, we analyzed the effect of ROCK inhibition using Y-27632 in a model of peripheral axonal damage in the spiral ganglion neurons created using the glutamate agonists, N-methyl-D-aspartate (NMDA) and kainic acid, to induce excitotoxic trauma in the explanted cochlea. The number of axons projecting to hair cells in the cochlea treated with Y-27632 was significantly greater than those in the cochlea treated only with NMDA + kainic acid. Furthermore, there was a significant increase in synapses between the spiral ganglion and the inner hair cells in the cochlea treated with Y-27632. The findings of this study suggest that ROCK inhibition could be a potential strategy for the regeneration of peripheral axons in the spiral ganglion and synapse formation in the inner hair cells of a cochlea that has sustained excitotoxic injury, which is one of the primary etiologies of inner ear disease.

Rate of spinal surgery in a rapidly aging society: the 27-year changes in Miyagi prefecture, Japan.

BACKGROUND: Japan has had a rapidly aging population during the past 30 years. This study aimed to investigate longitudinal changes in the surgical rate for spinal disorders in Miyagi Prefecture (2.35 million inhabitants) with a similar population composition to Japan. METHODS: Data of spinal surgeries were collected using the spine registry by Tohoku University Spine Society. Data on the annual number of spinal surgeries between 1988 and 2014 of all populations, in those aged ≥65 years old, in those aged ≥75 years old, and for each pathology were collected. The annual surgical rate per 100,000 inhabitants was calculated. RESULTS: The surgical rate in 2010-2014 in total, at ≥65 years old, and at ≥75 years old showed 3.2-, 3.8- and 7.1-fold increases, respectively, compared with that in 1988-1989. Degenerative spinal disorders, spinal trauma and pyogenic spondylitis markedly increased, while metastatic spinal tumor and tuberculous spondylitis decreased over time. The surgical rate at ≥75 years with lumbar spinal stenosis showed a 12.6-time increase. CONCLUSIONS: During a rapid period of aging, the rate of spinal surgeries has markedly increased, particularly, that for degenerative disorders. This is the first report on the long-term longitudinal changes in the rate of spinal surgery.

Reoperation Rates after Laminoplasty for Cervical Disorders: A 26-Year Period Survival Function Method Analysis.

INTRODUCTION: Laminoplasty is a common surgery for cervical myelopathy. Previous studies have analyzed the reoperation rates in posterior decompression surgeries of the cervical spine. However, few studies have solely focused on midline-splitting laminoplasty (MSL) using a large number of patients. This aims to analyze the reoperation rates after MSL using the survival function method. METHODS: Between 1988 and 2013, 4,208 MSLs were performed as a primary operation for cervical myelopathy and enrolled in our spinal surgery registration system. The Kaplan-Meier survival function method was used to analyze the rates of reoperation. RESULTS: Of 4,208 patients with primary MSL, 40 underwent reoperation for neurological complications. The overall reoperation rate was 0.26%, 0.64%, 0.83%, 0.93%, and 0.95% at 1, 5, 10, 20, and >20 years, respectively. The causes of reoperation were postoperative cervical radiculopathy in 10 patients, stenosis at an adjacent level in 8, stenosis due to failed "open-door" lamina in 6, instability of the cervical spine in 4, cervical disc herniation in 3, elongation of ossification of the posterior longitudinal ligament in 3, spinal cord injury in 1, fracture of the cervical spine in 1, postoperative scar formation in 1, ossification of anterior longitudinal ligament in 1, and unknown in 2. The number of patients with surgical site infection (SSI) who needed surgical debridement was 34 (0.81%). CONCLUSIONS: Excluding reoperations for SSI, the reoperation rate of MSL was approximately 1.0% at the maximum of 26 years after surgery. MSL was determined to be a reliable surgical procedure regarding postoperative complications requiring additional surgeries.

An increase in the degree of olisthesis during axial loading reduces the dural sac size and worsens clinical symptoms in patients with degenerative spondylolisthesis.

BACKGROUND CONTEXT: Previous studies have shown that axial loading during magnetic resonance imaging (MRI) significantly reduces the size of the dural sac compared with conventional MRI in patients with degenerative lumbar disease. In our previous study, axial-loaded MRI showed a significantly larger degree of olisthesis than conventional MRI in patients with degenerative spondylolisthesis (DS). Furthermore, the degree of olisthesis on axial-loaded MRI correlated more strongly with that observed on X-ray in the upright position. However, no study has investigated whether or not the increase in the degree of olisthesis during axial loading correlates with the reduction in the dural sac size and affects the severity of clinical symptoms in patients with DS. PURPOSE: The objective of this study was to determine whether or not the increase in the degree of olisthesis correlates with the reduction of the dural sac cross-sectional area (DCSA) detected on axial-loaded MRI and worsens the severity of clinical symptoms in patients with DS. STUDY DESIGN/SETTING: This is an imaging cohort study. PATIENT SAMPLE: A total of 41 consecutive patients with DS were prospectively evaluated in this study. OUTCOME MEASURES: The outcome measures include the degree of olisthesis, the DCSA, the Pearson correlation coefficient, and the severity of clinical symptoms. MATERIALS AND METHODS: The differences in the degree of olisthesis and the DCSA between conventional and axial-loaded MRIs were determined. The Pearson correlation coefficient of the increase in the degree of olisthesis with the reduction in the DCSA during axial loading was calculated. The reduction in the DCSA and the severity of clinical symptoms in patients exhibiting a ≥2-mm increase in the degree of olisthesis were compared with those in patients exhibiting a <2-mm increase. RESULTS: The increase in the degree of olisthesis was significantly correlated with the reduction in the DCSA during axial loading (Pearson correlation coefficient=0.63, p<.001). The reduction in the DCSA during axial loading in patients with a ≥2-mm increase in the degree of olisthesis (26±3 mm2) was significantly greater than in those with a <2-mm increase (13±2 mm2) (p<.01). Clinical symptoms such as walking distance and activity of daily living evaluated using the Japanese Orthopaedic Association score were significantly worse in patients with a ≥2-mm increase in the degree of olisthesis (117±19 m and 6.7±0.5 points, respectively) than in those with a <2-mm increase (236±36 m and 8.4±0.4 points, respectively) (p<.05). CONCLUSIONS: The present study demonstrated that the increase in the degree of olisthesis was significantly correlated with the reduction in the dural sac size detected on axial-loaded MRI and worsened the severity of clinical symptoms in patients with DS. These results suggest that axial-loaded MRI may be a useful imaging study for detecting dynamic changes in the degree of olisthesis during axial loading to the lumbar spine related to the narrowing of the spinal canal and the severity of clinical symptoms in the assessment of patients with DS.

Increasing Incidence of Degenerative Spinal Diseases in Japan during 25 Years: The Registration System of Spinal Surgery in Tohoku University Spine Society.

Spinal disorders affect mainly older people and cause pain, paralysis and/or deformities of the trunk and/or extremities, which could eventually disturb locomotive functions. For ensuring safe and high-quality treatment of spinal disorders, in 1987, the Tohoku University Spine Society (TUSS) was established by orthopedic departments in Tohoku University School of Medicine and its affiliated hospitals in and around Miyagi Prefecture. All spine surgeries have been enrolled in the TUSS Spine Registry since 1988. Using the data from this registration system between 1988 and 2012, we demonstrate here the longitudinal changes in surgical trends for spinal disorders in Japan that has rushed into the most advanced "aging society" in the world. In total, data on 56,744 surgeries were retrieved. The number of spinal surgeries has annually increased approximately 4-fold. There was a particular increase among patients aged ≥ 70 years and those aged ≥ 80 years, with a 20- to 90-fold increase. Nearly 90% of the spinal operations were performed for degenerative disorders, with their number increasing approximately 5-fold from 705 to 3,448. The most common disease for surgery was lumbar spinal stenosis (LSS) (35.9%), followed by lumbar disc herniation (27.7%) and cervical myelopathy (19.8%). In 2012, approximately half of the patients with LSS and cervical myelopathy were ≥ 70 years of age. In conclusion, the number of spinal operations markedly increased during the 25-year period, particularly among older patients. As Japan has a notably aged population, the present study could provide a near-future model for countries with aging population.

Changes in lumbar spondylolisthesis on axial-loaded MRI: do they reproduce the positional changes in the degree of olisthesis observed on X-ray images in the standing position?

BACKGROUND CONTEXT: Axial-loaded magnetic resonance imaging (MRI) can partially simulate the lumbar spine in patients in a standing position and potentially provides additional imaging findings that cannot be obtained with conventional MRI in the clinical assessment of patients with degenerative lumbar disease. Previous studies have shown that axial-loaded MRI demonstrates a significant reduction in the size of the dural sac compared with conventional MRI. However, there has been no study to compare the degree of olisthesis among conventional MRI, axial-loaded MRI, and upright X-ray imaging in patients with degenerative spondylolisthesis (DS). PURPOSE: The purpose of the study is to determine whether axial-loaded MRI can demonstrate similar positional changes in lumbar olisthesis as those detected on upright lateral X-ray in patients with DS. STUDY DESIGN: This is an imaging cohort study. PATIENT SAMPLE: A total of 43 consecutive patients with DS exhibiting olisthesis of 3 mm or more on X-ray images in the standing position were prospectively evaluated in this study. OUTCOME MEASURES: The degree of olisthesis, intraclass correlation coefficient (ICC), and percentage of patients exhibiting olisthesis of 3 mm or more on MRI. METHODS: The degree of olisthesis was measured on conventional MRI, axial-loaded MRI, and lateral X-ray imaging performed in the upright position. The degree of olisthesis was compared among the three imaging techniques. The ICC values for the measurements of olisthesis between X-ray studies and conventional and axial-loaded MRI were calculated and compared. The percentage of patients exhibiting olisthesis of 3 mm or more was compared between conventional MRI and axial-loaded MRI. RESULTS: The degree of olisthesis on axial-loaded MRI (5.9±2.5 mm) was significantly greater than that observed on conventional MRI (4.4±2.4 mm) (p<.05) although the degrees on conventional and axial-loaded MRI were significantly smaller than that on upright X-ray images (7.1±2.8 mm) (p<.05). The ICC between axial-loaded MRI and X-ray imaging (0.75, 95% confidence interval: 0.58-0.85) was considerably greater than that observed between conventional MRI and X-ray imaging (0.40, 95% confidence interval: 0.11-0.62). The percentage of patients exhibiting olisthesis of 3 mm or more was significantly higher on axial-loaded MRI (91%) than on conventional MRI (63%) (p<.01). CONCLUSIONS: Axial-loaded MRI demonstrates a significantly larger degree of olisthesis than conventional MRI. In addition, the degree of olisthesis on axial-loaded MRI was found to be more strongly correlated with that observed on X-ray studies in the upright position. Furthermore, the use of axial-loaded MRI significantly reduced the misdiagnosis of olisthesis of 3 mm or more that was detected on X-ray imaging. These results suggest that axial-loaded MRI may be superior to identify the olisthesis of the lumbar spine and show the degrees of olisthesis correlated to those detected on upright X-ray imaging. Further studies should be needed to clarify the actual value of these findings on axial-loaded MRI and provide the evidence to support its clinical significance in the assessment of patients with DS.

[Residual pesticide concentrations after processing various types of tea and tea infusions].

The effects of processing to produce various types of tea or infusion on the levels of pesticide residues in tea were investigated for three insecticides (chlorfenapyr, pyrimiphos-methyl, and clothianidin). Tea plants were sprayed with one of the three pesticides and cultivated under cover. The levels of pesticide residues in tea decreased after processing according to the time and temperature of heating, as well as fermentation. Although significant differences were not observed among the three pesticides in the ratio of decreased of pesticide concentration after processing to green tea, clothianidin, which is a neonicotinoid insecticide and has a lower log Pow value, tended to be transferred more than the other two insecticides into infusions. However, no significant difference in the ratios of clothianidin transferred to infusions was observed among green tea with three different leaf sizes.

Dynamic change of dural sac cross-sectional area in axial loaded magnetic resonance imaging correlates with the severity of clinical symptoms in patients with lumbar spinal canal stenosis.

STUDY DESIGN: Cross-sectional registry and imaging cohort study. OBJECTIVE.: To examine whether the dural sac cross-sectional area (DCSA) in axial loaded magnetic resonance imaging (MRI) correlates with the severity of clinical symptoms in patients with lumbar spinal canal stenosis (LSCS). SUMMARY OF BACKGROUND DATA: Many studies have analyzed the relationship between DCSA on conventional MRI and the severity of symptoms in LSCS, but the link is still uncertain. Recently, axial loaded MRI, which can stimulate the spinal canal of patients in the upright position, has been developed. Axial loaded MRI demonstrates significant reduction of DCSA and provides valuable radiologic findings in the assessment of LSCS. However, there has been no study of the correlation between DCSA in axial loaded MRI and the severity of symptoms in LSCS. METHODS: In 88 patients with LSCS, DCSA in conventional MRI, axial loaded MRI, and changes in the DCSA were determined at the single most constricted intervertebral level. The severity of symptoms was evaluated on the basis of the duration of symptoms, walking distance, visual analogue scale of leg pain/numbness, and Japanese Orthopaedic Association score. Spearman correlations of the DCSA in conventional MRI, axial loaded MRI, and changes in the DCSA with the severity of symptoms were analyzed. In addition, the severity of symptoms and DCSA in conventional and axial loaded MRI were compared, respectively, between patients with and without significant (>15 mm) changes in the DCSA. RESULTS: The DCSA in axial loaded MRI had good correlations with walking distance and Japanese Orthopaedic Association score (rs = 0.46 and 0.45, respectively; P < 0.001). In addition, the change in the DCSA significantly correlated to walking distance, visual analogue scale of leg numbness, and Japanese Orthopaedic Association score (rs = 0.59, 0.44, and 0.54, respectively; P < 0.001). Furthermore, the symptoms were significantly worse in patients with more than 15 mm change in the DCSA (P < 0.001). Axial loaded MRI, but not conventional MRI, showed a significantly smaller DCSA in patients with more than 15 mm change in the DCSA (P < 0.05). CONCLUSION: DCSA in axial loaded MRI significantly correlated with the severity of symptoms. Axial loaded MRI demonstrated that changes in the DCSA significantly correlated with the severity of symptoms, which conventional MRI could not detect. Thus, MRI with axial loading provides more valuable information than the conventional MRI for assessing patients with LSCS.

Axial loading during magnetic resonance imaging in patients with lumbar spinal canal stenosis: does it reproduce the positional change of the dural sac detected by upright myelography?

STUDY DESIGN: We compared the sizes of the dural sac among conventional magnetic resonance imaging (MRI), axial loaded MRI, and upright myelography in patients with lumbar spinal canal stenosis (LSCS). OBJECTIVE: To determine whether axial loaded MRI can demonstrate similar positional changes of the dural sac size as were detected by upright myelography in LSCS. SUMMARY OF BACKGROUND DATA: In patients with LSCS, constriction of the dural sac is worsened and symptoms are aggravated during standing or walking. To disclose such positional changes, upright myelography has been widely used. Recently, axial loaded MRI, which can simulate a standing position, has been developed. However, there has been no study to compare the dural sac size between axial loaded MRI and upright myelography. METHODS: Forty-four patients underwent conventional MRI, axial loaded MRI, and myelography. Transverse and anteroposterior diameters and the cross-sectional areas of the dural sac from L2-L3 to L5-S1 were compared. Pearson correlations of the diameters between the MRIs and the myelograms were analyzed. On the basis of the myelograms, all disc levels were divided into severe and nonsevere constriction groups. In each group, the diameters and the cross-sectional areas were compared. Sensitivity and specificity to detect severe constriction were calculated for the conventional and axial loaded MRI. RESULTS: Transverse and anteroposterior diameters at L4-L5 in the axial loaded MRI and myelogram were significantly smaller than those observed in the conventional MRI (P < 0.001). Cross-sectional areas in the axial loaded MRI were significantly smaller than those in the conventional MRI at L2-L3, L3-L4, and L4-L5 (P < 0.001). Between the axial loaded MRI and the myelography, Pearson correlation coefficients of the transverse and anteroposterior diameters were 0.85 and 0.87, respectively (P < 0.001), which were higher than those for conventional MRI. Reductions of the dural sac sizes in the axial loaded MRI were more evident in the severe constriction group. The axial loaded MRI detected severe constriction with a higher sensitivity (96.4%) and specificity (98.2%) than the conventional MRI. CONCLUSION: The axial loaded MRI demonstrated a significant reduction in the dural sac size and significant correlations of the dural sac diameters with the upright myelogram. Furthermore, the axial loaded MRI had higher sensitivity and specificity than the conventional MRI for detecting the severe constriction observed in the myelogram. Therefore, the axial loaded MRI can be used to represent positional changes of the dural sac size detected by the upright myelography in patients with LSCS.

Reoperation for recurrent lumbar disc herniation: a study over a 20-year period in a Japanese population.

BACKGROUND: Many studies have been reported on recurrent lumbar disc herniations covering several pathological conditions. In those studies, reoperation rate of revised disc excisions was calculated by simple division between the number of reoperations and that of the total primary disc excisions. To determine the real reoperation rate, strict definition of pathologies, a large number of patients, a long observation period, and survival function method are necessary. METHODS: Between 1988 and 2007, 5,626 patients with disc excision were enrolled by the spine registration system of the Department of Orthopaedic Surgery, Tohoku University, Japan. Among them, 192 had revised disc surgery, and we obtained data of 186 patients whose clinical features were assessed and reoperation rates analyzed using the Kaplan-Meier method. RESULTS: In total, 205 disc herniations were excised in the revision surgery (including contralateral herniation at the same level and new herniation at a different level), and 101 were real recurrent herniations (recurrence at the same level and side as the primary herniation). The kappa coefficient of the spinal level and side between the primary and revision surgeries was 0.41, indicting moderate correlations. Real recurrent herniations showed shorter intervals between primary and revision surgeries. Male patients with surgery at a younger age carried a higher risk of reoperation. In the revision surgery, transligamentous extrusion was significantly more common than other types of herniation. On Kaplan-Meier analysis, the reoperation rate of overall revised excisions was 0.62% at 1 year, 2.4% at 5 years, 4.4% at 10 years, and 5.9% after 17 years. That of real recurrent herniations was 0.5%, 1.4%, and 2.1%, respectively, and 2.8% after 15.7 years. CONCLUSION: Reoperation rate of real recurrent herniations calculated using survival function method gradually increased year by year, from 0.5% at 1 year after primary surgery to 2.8% at 15.7 years.

Remodeling capacity of malunited odontoid process fractures in kyphotic angulation in infancy: an observation up to maturity in three patients.

STUDY DESIGN: A retrospective case study. OBJECTIVE: To confirm the remodeling potential of the kyphotic malunited odontoid fracture in the pediatric spine. SUMMARY OF BACKGROUND DATA: Nonsurgical reduction and immobilization is the gold standard for the odontoid fracture in infancy. However, the reduction occasionally results in incomplete repositioning of the odontoid process. The cervical spine is subsequently immobilized until fusion in most cases in the hope of achieving remodeling with the growth of the remaining displacement and kyphotic angulation, although there are no precise data on the acceptable limit of the deformity. METHODS: Three patients (age at injury = 1 year 2 months to 3 years) with odontoid process fracture in infancy were treated conservatively and the fractures were observed on plain lateral radiographs until at least the age of 20 years. For evaluation of the angulated odontoid process, we used our original measurement method of the odontoid process tilting angle (OPTA). In addition, the OPTAs were also measured in 127 Japanese adult patients (57 male patients and 70 female patients; average age = 43 years) without a history of odontoid fracture, as normal controls. RESULTS: The OPTA in the normal controls was -21.4° ± 23.3°. The OPTAs ranged from 41° to 62° at the initial evaluation, from 12° to 30° at the time of bony union, and from -4° to -14° at the final follow-up at more than 20 years of age, which were all within one standard deviation of the mean in the normal adult controls. CONCLUSION: Angulated odontoid fractures with the OPTA around 30° at the time of bony union in infants younger than 3 years of age could have the capacity for remodeling to the normal morphology. No surgical reduction might be needed to recommend complete apposition of the odontoid process in the absence of severe or deteriorating neural impairment.

Lumbar radiculopathy caused by foraminal stenosis in rheumatoid arthritis.

STUDY DESIGN: Case-series study. OBJECTIVE: To describe the clinical presentation, characteristic findings of imaging studies, and treatment of lumbar radiculopathy caused by foraminal stenosis in rheumatoid arthritis. BACKGROUND. Lumbar lesions in rheumatoid arthritis are relatively rare, with a limited number of systemic reports. METHODS: Six patients with lumbar radiculopathy caused by foraminal stenosis in rheumatoid arthritis were treated. The patients were all women with a mean age of 69 years and mean rheumatoid arthritis duration of 15 years. The medical records and imaging studies of all patients were reviewed. RESULTS: The affected nerve roots were L4 in four patients and L3 in two patients. Foraminal stenosis was not demonstrated in magnetic resonance images in four of the six patients. Selective radiculography with nerve root block reproduced pain, manifested blocking effect, and demonstrated compression of the nerve root by the superior articular process of the lower vertebra in all patients. Conservative treatment was performed on one patient, and surgery was conducted for the rest of the five patients; radiculopathy was improved in all patients. CONCLUSIONS: Lumbar foraminal stenosis is a characteristic pathology of rheumatoid arthritis, and should be kept in mind in the diagnosis of lumbar radiculopathy. Selective radiculography is useful in the diagnosis of affected nerve roots.

Specification of cell fate along the proximal-distal axis in the developing chick limb bud.

Pattern formation along the proximal-distal (PD) axis in the developing limb bud serves as a good model for learning how cell fate and regionalization of domains, which are essential processes in morphogenesis during development, are specified by positional information. In the present study, detailed fate maps for the limb bud of the chick embryo were constructed in order to gain insights into how cell fate for future structures along the PD axis is specified and subdivided. Our fate map revealed that there is a large overlap between the prospective autopod and zeugopod in the distal limb bud at an early stage (stage 19), whereas a limb bud at this stage has already regionalized the proximal compartments for the prospective stylopod and zeugopod. A clearer boundary of cell fate specifying the prospective autopod and zeugopod could be seen at stage 23, but cell mixing was still detectable inside the prospective autopod region at this stage. Detailed analysis of HOXA11 AND HOXA13 expression at single cell resolution suggested that the cell mixing is not due to separation of some different cell populations existing in a mosaic. Our findings suggest that a mixable unregionalized cell population is maintained in the distal area of the limb bud, while the proximal region starts to be regionalized at the early stage of limb development.