Clinical and Histopathologic Study of Apocrine-Type Mixed Tumor of the Skin.

ABSTRACT: Mixed tumor of the skin (MTS) is a tumor characterized by folliculosebaceous-apocrine differentiation. Because of the wide range of histological variations, understanding the unique features of MTS can help improve diagnosis. This study describes the histopathological characteristics of MTS, mainly apocrine-type MTS (AMT), using 166 cases of AMT. We found that nodular aggregates of myoepithelial cells, mucinous changes in the stroma, and follicular differentiation were standard characteristic features of MTS. Among the cases studied, 67% showed prominent follicular germinative cells and 40% showed prominent lipomatous metaplasia in the stroma. These cases often pose difficulties for the diagnosis of AMT because of insufficient evidence of sweat glands or myoepithelial cell differentiation. This is the first study to examine how the histological features of AMT change as the tumor extends deeper into the dermis. We found that the proportion of AMT with folliculosebaceous differentiation and large lumina increased as it got deeper into the dermis. Histopathological diagnosis of MTS is vital because the clinical symptoms lack specificity. This study enhances our understanding of the histopathological characteristics of MTS.

Development of Postsurgical Pyoderma Gangrenosum with New Keloid after Keloid Resection.

ABSTRACT: Keloids are a dermal fibroproliferative disorder and can arise from trauma, acne, vaccination, and herpes zoster. Pyoderma gangrenosum (PG) is a painful ulcerative skin disorder that is associated with neutrophilic dysfunction. However, the pathophysiologies of keloids and PG are not fully understood. The authors encountered an unusual case of a 24-year-old woman who presented with an anterior chest keloid that bore an ulcer. The keloid was resected along with the ulcer, and histology revealed the ulcer to be a neutrophilic PG ulcer. A year after surgery, another ulcer developed in the scar. The ulcer met the PARACELSUS criteria of a postsurgical PG ulcer. After treatment with systemic prednisone and adalimumab for 250 days, the ulcer re-epithelialized. However, relapsed keloids were then observed at the PG site. Corticosteroid taping may be the safest therapy for patients with a history of PG. Conversely, if there is suspicion that a patient is prone to keloid development, diagnostic biopsies and surgical management of PG ulcers should be avoided or conducted with care.

Laterality of lumbar disc herniation.

BACKGROUND: Lumbar disc herniation (LDH) is most common in men aged 20-40 at the L4/5 level; however, left-right differences have not been reported. Improving our understanding of left- and right-side LDH may facilitate the estimation of mechanical load on intervertebral discs. Here, we assessed left-right differences in LDH via a retrospective analysis of LDH cases. METHODS: Among 10,972 surgical cases of LDH identified in the Nagoya Spine Group database, 2899 in which right- and left-LDH sides were observable in a single vertebral segment were identified (mean age 46.3 ± 16.6 years, 2028 males). The following characteristics of patients with right- and left-LDH were compared: age, LDH level, surgical technique, operative time, blood loss, length of hospital stay, preoperative Japan Orthopaedic Association (JOA) score, and JOA recovery rate. RESULTS: LDH occurred on the right and left sides in 1358 and 1541 patients, respectively, with patients with right-side LDH significantly older than those with left (47.9 ± 16.6 versus 45.0 ± 16.5, respectively; p < 0.001). No between-group differences in sex, age, LDH level, surgical technique, operative time, blood loss, length of hospital stay, preoperative JOA score, or JOA recovery rate were observed. The occurrence of right-side LDH increased with age, occurring in 42.7%, 45.1%, 49.9%, and 54.7% of patients aged 10-29, 30-49, 50-69, and 70-89 years, respectively. CONCLUSION: Left-side LDH was observed more frequently than right; however, right-side LDH incidence increased with age. No significant between-group differences regarding symptoms, treatments, or outcomes were observed.

Folliculosebaceous Cystic Hamartoma Arising in Miescher-Type Melanocytic Nevi.

ABSTRACT: Folliculosebaceous cystic hamartoma (FSCH) is a rare cutaneous hamartoma consisting of dilated folliculosebaceous units associated with mesenchymal elements. Ansai et al reported that distinctive features of Miescher-type melanocytic nevi (MMCNs) accompanied 4.6% of FSCH; however, there have been no data about how often FSCH features accompany MMCNs. In this study, we used 7829 cases that had been histopathologically diagnosed as MMCNs of the face, neck, and scalp at the Department of Dermatopathology, Nippon Medical School Musashi Kosugi Hospital and observed whether features of FSCH accompanied them. Of the resected MMCNs, 274 of 7829 (3%) were accompanied by features of FSCH. The nose was the most common resection site, followed by the eyebrow area, ear, and cheek. The coexistence rate for the nevi on the nose and features of FSCH was as high as 10%-20%, and its rate increased with age. We found that FSCH appears mostly in seborrheic areas, such as the nose and cheek, which are rich in normal sebaceous glands. This suggests that nevi, especially on and around the nose, may induce FSCH or similar lesions.

Primary cervical decompression surgery may improve lumbar symptoms in patients with tandem spinal stenosis.

PURPOSE: Tandem spinal stenosis (TSS) refers to coexisting lumbar and cervical canal stenosis. Evidence regarding whether cervical decompression improves lumbar symptoms in TSS is insufficient. Therefore, we determined the effectiveness of cervical decompression surgery for patients with lumbar spinal stenosis (LSS) and cervical spinal stenosis. METHODS: The records of 64 patients with TSS experiencing lumbar symptoms who underwent cervical decompression surgery between April 2013 and July 2017 at a single institution were retrospectively reviewed. We categorized patients into the Non-improved (n = 20), Relapsed (n = 30), and Maintained-improvement (n = 14) groups according to the presence or absence of improvement and relapse in lower limb symptoms in TSS following cervical decompression surgeries. RESULTS: Of 64 patients, 44 (69%) showed improved lower limb or low back symptoms, with 14 (22%) patients maintaining improvement. The preoperative cervical myelopathy-Japanese Orthopedic Association score and the preoperative number of steps determined using the 10-s step test were significantly lower in the Non-improved group than in the Maintained-improvement group. Receiver operating characteristic curve of preoperative 10-s step test results revealed 12 steps as a predictor for maintained improvement. CONCLUSION: The improvement of LSS symptoms following cervical decompression surgeries may be associated with the severity of cervical myelopathy as determined in clinical findings rather than in imaging findings. Patients with TSS having a 10-s step test result of < 12 steps were more likely to experience a relapse of lower limb symptoms following cervical decompression surgeries.

Age-related changes in upper and lower cervical alignment and range of motion: normative data of 600 asymptomatic individuals.

PURPOSE: To identify age-related changes and the relationship between upper and lower cervical sagittal alignment and the range of motion (ROM). METHODS: A total of 600 asymptomatic volunteers were enrolled. There were 50 males and 50 females in each decade of life between the third and the eighth. The O-C2 angle and the C2-7 angle were measured using the neutral radiographs of the cervical spine. ROM was assessed by measuring the difference in alignment in the neutral, flexion, and extension positions. RESULTS: The mean O-C2 angle in the neutral position was 14.0° lordotic. The mean ROM of the O-C2 angle was 23.1°. The mean C2-7 angle in the neutral position was 14.3° lordotic. The mean ROM of the C2-7 angle was 56.0°. The O-C2 angle was 16.1° in the third decade and gradually decreased to 11.4° in the eighth decade. There were no significant age-related changes in the ROM of the O-C2 angle. The C2-7 angle was 7.2° in the third decade and gradually increased to 20.8° in the eighth decade, and the ROM gradually decreased with increasing age. Significant negative correlation was observed between O-C2 angle and C2-7 angle. CONCLUSION: The O-C2 angle gradually decreased and the C2-7 angle increased with age. The ROM of the O-C2 angle did not change, but the ROM of the C2-7 angle decreased with age. The upper and lower cervical spine showed different age-related changes.

A comparative study of two reconstruction procedures for osteoporotic vertebral fracture with lumbar spinal stenosis: Posterior lumbar interbody fusion versus posterior and anterior and combined surgery.

BACKGROUND: Optimal treatment of lumbar spinal stenosis (LSS) with neurological deficit due to osteoporotic vertebral fractures (OVFs) has been controversial. We assessed the usefulness, safety, and efficacy of posterior lumbar interbody fusion (PLIF) for LSS with neurological deficit due to OVFs and compared this procedure to posterior/anterior combined surgery (PACS). METHODS: Of 36 consecutive patients with LSS with neurological deficit due to OVFs, 15 underwent PLIF (6 males, 9 females; mean age, 74 years), and 21 underwent PACS (4 males, 17 females; mean age, 70 years). Surgical complications, clinical outcomes (operative time, blood loss, American Spinal Injury Association Impairment Scale [AIS], activities of daily living [ADLs]), and sagittal alignment were investigated. Bony fusion was assessed using plain and functional X-rays and computed tomography scans. RESULTS: There were no significant differences in age, sex, or disease or follow-up duration between the groups. Operative time was significantly shorter and intraoperative blood loss significantly less in the PLIF than in the PACS groups. AIS and ADL improved significantly postoperatively in both groups. No significant difference was observed in neurological improvement, correction angle, loss of correction, and surgical complications. No pseudarthrosis occurred, and no patient required additional surgery in the PLIF group. CONCLUSIONS: PLIF for LSS with neurological deficit due to OVFs achieves posterior rigid fixation with instrumentation, anterior column reconstruction by interbody fusion, and adequate decompression using a single posterior approach. This less invasive procedure is a useful reconstructive surgery option.

A retrospective imaging study of surgical outcomes and range of motion in patients with cervical ossification of the posterior longitudinal ligament.

PURPOSE: The K line was introduced in a previous study, but did not include the cervical range of motion (ROM) as a parameter for evaluating surgical outcomes for patients with cervical ossification of the posterior longitudinal ligament (OPLL), and few reports have used both the K line and X-ray evaluations of the cervical ROM to describe the surgical outcomes in such patients. METHODS: Double-door C2-C7 or C3-C7 laminoplasty was performed in 100 patients with cervical OPLL who were classified according to the K line [86 patients, K line (+) and 14 patients, K line (-)]. Preoperative and 1-year postoperative Japanese Orthopedic Association (JOA) scores were used to evaluate recovery rates. Preoperative and postoperative C2-C7 lordotic angles were measured using the Cobb method. In addition, preoperative and postoperative sagittal alignments in flexion and extension were studied, and the flexion values were calculated by subtracting the preoperative and postoperative flexion ROM from extension ROM. RESULTS: The mean JOA scores recovery rate were 57.3% in the K line (+) and 37.7% in the K line (-) groups (p < 0.05), and the respective corresponding mean postoperative C2-C7 lordotic angles were 9.1° and -3.4° (p < 0.001). In the K line (+) group, the JOA score recovery rate for a postoperative flexion value >0 was significantly lower than that for a postoperative flexion value ≤0 (p < 0.01), and the mean JOA score recovery rate worsened with an increased signal intensity on 1-year postoperative magnetic resonance imaging. CONCLUSIONS: K line (+) patients exhibited sufficient neurological improvement after laminoplasty. However, even patients in this group had a low JOA score recovery rate if the postoperative flexion value was >0 and the 1-year postoperative increased signal intensity grade was 2 or 3.

Enormous Hydrogen Bond Strength Enhancement through π-Conjugation Gain: Implications for Enzyme Catalysis.

Surprisingly large resonance-assistance effects may explain how some enzymes form extremely short, strong hydrogen bonds to stabilize reactive oxyanion intermediates and facilitate catalysis. Computational models for several enzymic residue-substrate interactions reveal that when a π-conjugated, hydrogen bond donor (XH) forms a hydrogen bond to a charged substrate (Y-), XH can become significantly more π-electron delocalized, and this "extra" stabilization may boost the [XH···Y-] hydrogen bond strength by ≥15 kcal/mol. This reciprocal relationship departs from the widespread pKa concept (i.e., the idea that short, strong hydrogen bonds form when the interacting moieties have matching pKa values), which has been the rationale for enzymic acid-base reactions. The findings presented here provide new insight into how short, strong hydrogen bonds could form in enzymes.

Structural Analysis of the Glycosylated Intact HIV-1 gp120-b12 Antibody Complex Using Hydroxyl Radical Protein Footprinting.

Glycoprotein gp120 is a surface antigen and virulence factor of human immunodeficiency virus 1. Broadly neutralizing antibodies (bNAbs) that react to gp120 from a variety of HIV isolates offer hope for the development of broadly effective immunogens for vaccination purposes, if the interactions between gp120 and bNAbs can be understood. From a structural perspective, gp120 is a particularly difficult system because of its size, the presence of multiple flexible regions, and the large amount of glycosylation, all of which are important in gp120-bNAb interactions. Here, the interaction of full-length, glycosylated gp120 with bNAb b12 is probed using high-resolution hydroxyl radical protein footprinting (HR-HRPF) by fast photochemical oxidation of proteins. HR-HRPF allows for the measurement of changes in the average solvent accessible surface area of multiple amino acids without the need for measures that might alter the protein conformation, such as mutagenesis. HR-HRPF of the gp120-b12 complex coupled with computational modeling shows a novel extensive interaction of the V1/V2 domain, probably with the light chain of b12. Our data also reveal HR-HRPF protection in the C3 domain caused by interaction of the N330 glycan with the b12 light chain. In addition to providing information about the interactions of full-length, glycosylated gp120 with b12, this work serves as a template for the structural interrogation of full-length glycosylated gp120 with other bNAbs to better characterize the interactions that drive the broad specificity of the bNAb.

Dynamic changes in the cross-sectional area of the dural sac and spinal cord in the thoracic spine.

PURPOSE: The thoracic spine is considered a rigid region because it is restricted by the rib cage. Previously, we reported functional alignments and range of motion (ROM) at all segmental levels. The purpose of this study was to investigate dynamic changes of the dural sac and spinal cord in the thoracic spine using a multidetector-row computed tomography (MDCT). METHODS: Fifty patients with cervical or lumbar spinal disease were prospectively enrolled. After preoperative myelography, MDCT was performed at maximum passive flexion and extension. The anteroposterior diameter and cross-sectional area of the dural sac and spinal cord in the axial plane were measured using Scion imaging software. We also evaluated the correlation between the change ratio of the cross-sectional area and segmental kyphotic angle and ROM. RESULTS: In flexion, the anteroposterior diameter of the dural sac was larger than in extension. The cross-sectional area in the upper and middle regions was smaller, but was larger in the lower region. The anteroposterior diameter and cross-sectional area of the spinal cord in the upper and middle regions were smaller than in extension, but these values were nearly the same in both flexion and extension in the lower region. Change ratios of the cross-sectional area were correlated with segmental kyphotic angle rather than ROM. CONCLUSIONS: The thoracic spine showed some dynamic changes of the dural sac and spinal cord in the axial plane within functional motion. Segmental kyphotic angle, rather than segmental ROM, was the more important factor affecting dimensions of the dural sac and spinal cord.

Intrathecal morphine for postoperative pain control after laminoplasty in patients with cervical spondylotic myelopathy.

OBJECTIVES: To examine the clinical efficacy of intrathecal morphine as postoperative analgesia for cervical laminoplasty. SUMMARY OF BACKGROUND DATA: Patients who undergo posterior cervical spinal surgery frequently experience significant postoperative pain. Postoperative pain contributes to patient morbidity because of decreasing early voluntary mobilization and delayed rehabilitation. Intrathecal morphine is known to be a simple and effective analgesia. However, the effectiveness of intrathecal morphine for cervical spinal surgery has not yet been reported. METHODS: Seventy-eight patients with cervical spondylotic myelopathy were divided into two groups prospectively, a diclofenac suppository (DS) group who received 50 mg diclofenac suppository at the end of the surgery, and an intrathecal morphine (ITM) group who were preoperatively administered 0.3 mg of morphine chloride, intrathecally, via a lumbar puncture. All patients underwent double-door laminoplasty of C3-6 or C3-7 level. Visual analog scale (VAS) of cervical pain, self-rating pain impression, supplemental analgesic usage, and complication rate were evaluated until the seventh postoperative day. RESULTS: Thirty-one patients in the DS group and 32 patients in the ITM group were finally assessed. No baseline variable differences between the two groups were observed. The VAS was significantly lower in the ITM group at 4 h and 24 h until the seventh postoperative day. Self-rating pain impression was significantly better in the ITM group. No significant difference was observed in complication rate. CONCLUSIONS: Intrathecal morphine was an effective and safe analgesic method for cervical laminoplasty in patients with cervical spondylotic myelopathy.

Functional computed tomography scanning for evaluating fusion status after anterior cervical decompression fusion.

INTRODUCTION: Nonunion is a major complication of anterior cervical fusion that causes poor outcomes and occasionally requires additional operative intervention. The purpose of this study is to evaluate the accuracy of functional computed tomography (CT) scanning for determining fusion status after anterior cervical fusion by comparing with functional radiographs. MATERIALS AND METHODS: The fusion status in 59 patients treated by anterior cervical fusion was assessed by functional radiography and functional CT scanning at 6 and 12 months after surgery. Fusion rates and clinical symptoms were evaluated. Fusion on functional radiography was defined as less than 2 mm of motion between adjacent spinous processes and a particular bony trabeculation on functional CT; fusion was defined as nonexistence of a clear zone or a gas pattern and a particular bone connection on reconstructed sagittal-view images. RESULTS: Functional radiographs demonstrated solid fusion in 83.9% at 6 months and 91.1% at 12 months postoperatively; functional CT showed solid fusion in 55.3 and 78.6%, respectively. The fusion rate detected on functional CT images was significantly lower than that on functional radiographs at each period. At 6 months postoperatively, patients with incomplete union on functional CT were more likely to have neck pain than those who had complete union on functional CT. (46.2 vs 13.3%, P < 0.05) CONCLUSION: Functional CT can detect nonunion more clearly than functional radiography. At 6 months postoperatively, patients with incomplete union on functional CT images were likely to have more neck pain. Functional CT may allow accurate detection of symptomatic nonunion after anterior cervical fusion.

Range of motion determined by multidetector-row computed tomography in patients with cervical ossification of the posterior longitudinal ligament.

The purpose of this study was to measure range of motion (ROM) in patients with cervical ossification of posterior longitudinal ligament (C-OPLL) by multidetector-row computed tomography (MDCT), and to investigate the influence of dynamic factors. The study included 101 patients with C-OPLL and 99 normal control patients. Preoperative MDCT were taken in all subjects in maximum neck flexion and extension. ROM at each disc level between C2/3 and C7/T1 in sagittal view was measured. Ossification morphology at each disc segment was divided into 6 groups: covered disc, covered vertebra, unconnected vertebra, connected vertebra (continuous), connected vertebra (localized), and others. The relationship between ROM and the group of ossification morphology was also investigated. ROM of adjacent intervertebral disc in connected vertebrae (continuous and localized) and those of others were investigated for each group. The average ROM of covered disc group was significantly higher than that of connected vertebra (continuous, localized). The average ROM of connected vertebra (continuous) group was significantly lower than that of covered disc group, others group, and normal control. There was no significant difference between ROM of adjacent intervertebral disc in connected vertebrae and others, but the average ROM of the connected vertebra group was significantly lower than that of the covered disc group and normal control group. Dynamic factor was reduced at continuous segment, but it was not increased in adjacent intervertebral disc.

Treatment outcomes of intradiscal steroid injection/selective nerve root block for 161 patients with cervical radiculopathy.

Patients with cervical radiculopathy (CR) were treated with intradiscal injection of steroids (IDIS) and/or selective nerve root block (SNRB) at our hospital. We retrospectively report the outcomes of these nonsurgical treatments for CR. 161 patients who were followed up for >2months were enrolled in this study. Patients' clinical manifestations were classified as arm pain, arm numbness, neck and/or scapular pain, and arm paralysis. Improvement in each manifestation was classified as "disappeared," "improved," "poor," or "worsened." Responses of "disappeared" or "improved" manifestations suggested treatment effectiveness. Final clinical outcomes were evaluated using the Odom criteria. Changes in herniated disc size were evaluated by comparing the initial and final MRI scans. On the basis of these changes, the patients were divided into regression, no-change, or progression groups. We investigated the relationship between the Odom criteria and changes observed on MRI. Effectiveness rates were 89% for arm pain, 77% for arm numbness, 82% for neck and/or scapular pain, and 76% for arm paralysis. In total, 91 patients underwent repeated MRI. In 56 patients (62%), the size of the herniated disc decreased, but 31 patients (34%) exhibited no change in disc size. The regression group showed significantly better Odom criteria results than the no-change group. In conclusion, IDIS and SNRB for CR are not widely performed. However, other extremely effective therapies that can rapidly improve neuralgia should be considered before surgery.

Grafted vertebral fracture after implant removal in a patient with spine-shortening vertebral osteotomy.

We experienced the rare complication of a vertebral fracture that was caused by implant removal after bony fusion had been achieved in a patient who underwent spine-shortening osteotomy (SSO) for tethered cord syndrome (TCS). We propose that the removal of the implant used for SSO should be contraindicated. The patient (a 27-year-old female) presented to our institution with a history of progressive severe lower back pain, gait disturbance, and urinary incontinence. As an infant, she had undergone surgery for spina bifida with lipoma. Magnetic resonance imaging of the spine revealed tethering of the spinal cord to a lipoma. We performed SSO at the level of the L1 vertebra level. After spine shortening and fixation using a posterior approach, the L1 vertebral body was completely removed anteriorly and replaced with a left iliac bone graft. The patient's symptoms improved after surgery. After bony fusion was achieved after surgery, we decided to remove the spinal implant after we explained the advantages and disadvantages of the procedure to the patient. We performed implant removal surgery safely 2 years later; however, the patient complained of severe lower back pain 10 days after the surgery without any history of trauma. Reconstruction computed tomography showed fracture of the grafted vertebra. We performed a repeat posterior fixation, which relieved the lower back pain; she has experienced no complications in the subsequent 5 years. In summary, we report a case of a rare complication of the fracture of a grafted vertebra after removal of an implant used in SSO for TCS. Spinal stability could not be maintained without the spinal posterior implant after SSO. Postoperative fracture after spinal implant removal is rare but possible, and patients must be informed of this potential risk.

Defining the structural origin of the substrate sequence independence of O-GlcNAcase using a combination of molecular docking and dynamics simulation.

Protein glycosylation with O-linked N-acetylglucosamine (O-GlcNAc) is a post-translational modification of serine/threonine residues in nucleocytoplasmic proteins. O-GlcNAc has been shown to play a role in many different cellular processes and O-GlcNAcylation is often found at sites that are also known to be phosphorylated. Unlike phosphorylation, O-GlcNAc levels are regulated by only two enzymes, O-GlcNAc transferase (OGT) and O-GlcNAc hydrolase (O-GlcNAcase or OGA). So far, no obvious consensus sequence has been found for sites of O-GlcNAcylation. Additionally, O-GlcNAcase recognizes and cleaves all O-GlcNAcylated proteins, independent of their sequence. In this work, we generate and analyze five models of O-GlcNAcylated peptides in complex with a bacterial OGA. Each of the five glycopeptides bind to OGA in a similar fashion, with OGA-peptide interactions primarily, but not exclusively, involving the peptide backbone atoms, thus explaining the lack of sensitivity to peptide sequence. Nonetheless, differences in peptide sequences, particularly at the -1 to -4 positions, lead to variations in predicted affinity, consistent with observed experimental variations in enzyme kinetics. The potential exists, therefore, to employ the present analysis to guide the development glycopeptide-specific inhibitors, or conversely, the conversion of OGA into a reagent that could target specific O-GlcNAcylated peptide sequences.

Dynamic changes in the dural sac of patients with lumbar canal stenosis evaluated by multidetector-row computed tomography after myelography.

PURPOSE: Some reported studies have evaluated the dural sac in patients with lumbar spinal stenosis (LSS) by computed tomography (CT) after conventional myelography or magnetic resonance imaging (MRI). But they have been only able to evaluate static factors. No reports have described detailed dynamic changes in the dural sac during flexion and extension observed by multidetector-row computed tomography (MDCT). The aim of this study was to elucidate or demonstrate, in detail, the influence of dynamic factors on the severity of stenosis. METHODS: One hundred patients with LSS were enrolled in this study. All underwent MDCT in both flexion and extension positions after myelography, in addition to undergoing MRI. The anteroposterior diameter (AP-distance) and cross-sectional area of the dural sac (D-area) were measured at each disc level between L1-2 and L5-S1. The dynamic change in the D-area was defined as the absolute value of the difference between flexion and extension. The rate of dynamic change (dynamic change in D-area/D-area at flexion) in the dural sac at each disc level was also calculated. RESULTS: The average AP-distance in flexion/extension (mm) was 9.2/7.4 at L3-4 and 8.3/7.4 at L4-5. The average D-area in flexion/extension (mm(2)) was 96.3/73.6 at L3-4 and 72.3/61.0 at L4-5. The values were significantly lower in extension than in flexion at all disc levels from L1-2 to L5-S1. AP-distance was narrowest and D-area smallest at L4-5 during extension. The rates of dynamic changes at L2-3 and L3-4 were higher than those at L4-5. CONCLUSIONS: MDCT clearly elucidated the dynamic changes in the lumbar dural sac. Before surgery, MDCT after myelography should be used to evaluate the dynamic change during flexion and extension, especially at L2-3, L3-4, and L4-5.

Range of motion of thoracic spine in sagittal plane.

STUDY DESIGN: Imaging study of thoracic spine. OBJECTIVE: The purpose of this study was to investigate dynamic alignment and range of motion (ROM) at all segmental levels of thoracic spine. Thoracic spine is considered to have restricted ROM because of restriction by the rib cage. However, angular movements of thoracic spine can induce thoracic compressive myelopathy in some patients. Although few previous studies have reported segmental ROM with regard to sagittal plane, these were based on cadaver specimens. No study has reported normal functional ROM of thoracic spine. METHODS: Fifty patients with cervical or lumbar spinal disease but neither thoracic spinal disease nor compression fracture were enrolled prospectively in this study (34 males, 16 females; mean age 55.4 ± 14.7 years; range 27-81 years). After preoperative myelography, multidetector-row computed tomography scanning was performed at passive maximum flexion and extension position. Total and segmental thoracic kyphotic angles were measured and ROM calculated. RESULTS: Total kyphotic angle (T1/L1) was 40.2° ± 11.4° and 8.5° ± 12.8° in flexion and extension, respectively (P < 0.0001). The apex of the kyphotic angle was at T6/7 in flexion. Total ROM (T1/L1) was 31.7° ± 11.3°. Segmental ROM decreased from T1/2 to T4/5 but increased gradually from T4/5 to T12/L1. Maximum ROM was at T12/L1 (4.2° ± 2.1°) and minimum at T4/5 (0.9° ± 3.0°). CONCLUSIONS: Thoracic spine showed ROM in sagittal plane, despite being considered a stable region. These findings offer useful information in the diagnosis and selection of surgical intervention in thoracic spinal disease.