Vacuum phenomenon as a predictor of kyphosis after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture: a single-center retrospective study.

BACKGROUND: Posterior pedicle screw fixation without fusion has been commonly applied for thoracolumbar burst fracture. Implant removal is performed secondarily after bone union. However, the occurrence of secondary kyphosis has recently attracted attention. Secondary kyphosis results in poor clinical outcomes. The purpose of this was to determine predictors of kyphosis after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture. METHODS: This retrospective study reviewed 59 consecutive patients with thoracolumbar burst fracture who underwent implant removal following posterior pedicle screw fixation without fusion. Inclusion criteria were non-osteoporotic fracture and T11-L3 burst fracture. Old age, sex, initial severe wedge deformity, initial severe kyphosis, and vacuum phenomenon were examined as factors potentially associated with final kyphotic deformity (defined as kyphotic angle greater than 25°) or loss of correction. Logistic regression analysis was performed using propensity score matching. RESULTS: Among the 31 female and 28 male patients (mean age 38 years), final kyphotic deformity was found in 17 cases (29%). Multivariate analysis showed a significant association with the vacuum phenomenon. Loss of correction was found in 35 cases (59%) and showed a significant association with the vacuum phenomenon. There were no significant associations with other factors. CONCLUSIONS: The findings of this study suggest that the vacuum phenomenon before implant removal may be a predictor of secondary kyphosis of greater than 25° after implant removal following posterior pedicle screw fixation without fusion for thoracolumbar burst fracture, but that old age, sex, initial severe kyphosis, and initial severe wedge deformity may not be predictors.

Development and Achievement of Cervical Laminoplasty and Related Studies on Cervical Myelopathy.

Cervical laminoplasty (CL) is one of the surgical methods via the posterior approach for treating patients with multilevel affected cervical myelopathy (CM). The main purpose of CL is to decompress the cervical spinal cord by widening the narrowed spinal canal, combined with preserving the posterior anatomical structures to the degree possible and preserving the widened space stably. During the development and improvement of spine surgeries including CL, various studies on CM have progressed and useful achievements have been obtained: (1) posterior cervical spine fixation systems that can be used in combination with CL simultaneously have been developed; (2) various materials to stably maintain the enlarged spinal canal have been developed; (3) the main influential factors on the surgical results are the inner factors of the patients, such as the patient's age and the disease duration; (4) various surgical methods to preserve the function of the posterior cervical muscles have been tried to avoid postoperative kyphotic changes of the cervical spine; (5) postoperative complications, such as C5 palsy and axial pain, have been examined, and the countermeasures have been tried; (6) K-line on lateral X-ray films has been applied to evaluate the indication of CL in patients with CM due to ossification of the posterior longitudinal ligament (OPLL) preoperatively; and (7) the method and idea of CL have been adapted to surgeries at the thoracic and lumbar spine. However, some issues remain to be resolved, such as the deterioration of neurological findings, especially in patients with continuous or mixed-type OPLL, the postoperative kyphotic-directional alignment change of the cervical spine, C5 palsy, and axial pain.

Postoperative C5 Palsy: Conjectured Causes and Effective Countermeasures.

Postoperative C5 palsy (C5 palsy) is defined as de novo or aggravating muscle weakness mainly at the C5 region with slight or no sensory disturbance after cervical spine surgery. The features of C5 palsy are as follows: 1) one-half of patients are accompanied by sensory disturbance or intolerable pain at the C5 region; 2) 92% of patients have hemilateral palsy; 3) almost all palsy occurs within a week after surgery; 4) the incidence is almost the same between the anterior and posterior approaches to the cervical spine; 5) the prognosis is relatively good even in patients with severe muscle weakness. Even now, the precise causes of C5 palsy have not yet been revealed. From the viewpoint of the kinds of nerve tissue involved, the uncertain causes of C5 palsy are divided into two theories: 1) the segmental spinal cord disorder theory and 2) the nerve root injury theory. In the former, the segmental spinal cord, particularly the anterior horn cells, is thought to be chemically damaged because of preoperative ischemia and/or the aggression of reactive oxygen during postoperative reperfusion. By contrast, in the latter, the anterior rootlet and/or nerve root are believed to be mechanically damaged because of compression force and/or distraction force. In this theory, the features of C5 palsy can be well explained from anatomical viewpoints. Additionally, various countermeasures have been proposed, such as the intermittent relaxation of the tension of the hooks to the multifidus muscles during surgery; prophylactic foraminotomy to decompress C5 nerve root; prevention of excessive posterior shift of the spinal cord, which may cause the tethering effect of the nerve root; and prevention of excessive postoperative lordotic alignment of the cervical spine. These countermeasures have been proved effective, and may support the nerve root injury theory as the main conjectured theory on the causes of C5 palsy.

Gene Expression Profile Signature of Aggressive Waldenström Macroglobulinemia with Chromosome 6q Deletion.

BACKGROUND: Waldenström macroglobulinemia (WM) is a rare, indolent B-cell lymphoma. Clinically, chromosome 6q deletion (6q del) including loss of the B lymphocyte-induced maturation protein 1 gene (BLIMP-1) is reported to be associated with poor prognosis. However, it remains unclear how the underlying biological mechanism contributes to the aggressiveness of WM with 6q del. METHODS: Here, we conducted oligonucleotide microarray analysis to clarify the differences in gene expression between WM with and without 6q del. Gene ontology (GO) analysis was performed to identify the main pathways underlying differences in gene expression. Eight bone marrow formalin-fixed paraffin-embedded samples of WM were processed for interphase fluorescence in situ hybridization analysis, and three were shown to have 6q del. RESULTS: GO analysis revealed significant terms including "lymphocyte activation" (corrected p value=6.68E-11), which included 31 probes. Moreover, IL21R and JAK3 expression upregulation and activation of the B-cell receptor signaling (BCR) pathway including CD79a, SYK, BLNK, PLCγ2, and CARD11 were detected in WM with 6q del compared with WM without 6q del. CONCLUSION: The present study suggested that the BCR signaling pathway and IL21R expression are activated in WM with 6q del. Moreover, FOXP1 and CBLB appear to act as positive regulators of the BCR signaling pathway. These findings might be attributed to the aggressiveness of the WM with 6q del expression signature.

Impact of rituximab and half-dose CHOP as primary therapy for untreated symptomatic Waldenström Macroglobulinemia: review of a combined regimen of rituximab with an alkylating agent.

BACKGROUND: Waldenström Macroglobulinemia (WM) is a rare subtype of indolent B-cell lymphoma, and prospective randomized studies on WM are scarce. The R-CHOP therapy [rituximab (R), cyclophosphamide, hydroxy-doxorubicin, vincristine, and prednisone] is a popular and recommended regimen for primary therapy, prescribed by several treatment guidelines for WM. However, treatment with R-CHOP is accompanied by severe myelosuppression and high rates of peripheral neuropathy. Therefore, we retrospectively evaluated the efficacy and toxicity of half-dose CHOP combined with R as a primary therapy for WM. METHODS: Patients with untreated symptomatic WM, treated at the Disaster Medical Center between April 2011 and September 2016, were retrospectively analyzed after administration of 6 cycles of half-dose R-CHOP for every 3 weeks. The response, median time to response, best response, progression-free survival, overall survival, and toxicities were evaluated. RESULTS: Of the 20 WM patients analyzed, 16 (80%) received half-dose R-CHOP without vincristine, and 13 (65%) responded to the treatment. With a median follow-up duration of 26.3 months, the 2-year progression-free survival and 2-year overall survival rates were 70 and 93.3%, respectively. The median time to response and best response were 6 and 9.9 weeks, respectively. Grade 3/4 leukocytopenia, neutropenia, febrile neutropenia, and Grade 1 peripheral neuropathy developed in 32, 37, 0, and 21% of patients, respectively. CONCLUSION: The half-dose R-CHOP is an effective and well-tolerated primary therapy for WM. To the best of our knowledge, this is the first study reporting the use of a reduced-dose R-CHOP regimen for the primary treatment of WM.

Surgical Treatment for Ossification of the Posterior Longitudinal Ligament (OPLL) at the Thoracic Spine: Usefulness of the Posterior Approach.

Various methods via anterior or posterior approach with or without spinal stabilization have been performed in accordance with the level and configuration of ossification of the posterior longitudinal ligament (OPLL) as the decompression surgery for thoracic myelopathy due to OPLL. Among them, anterior decompression at the middle thoracic level (T4/T5-T7/T8) is especially difficult to perform because of the special anatomical structures, where the spinal alignment is kyphotic and the thoracic cage containing circulatory-respiratory organs exist nearby. Of the anterior decompression procedures at this level, the posterior approach has various advantages compared to the anterior one. In the anterior approach, the procedure is complicated and the effect of decompression of the spinal cord can be obtained only by direct resection or anterior floating of the OPLL. However, complications such as spinal cord injury and dural tear are most likely to occur at that time. On the contrary, in the posterior approach, the procedure is simple, and various options to obtain decompression can be selected from, these are, laminectomy, laminoplasty, dekyphosis surgery, staged decompression surgery (Tsuzuki's method), circumferential decompression via posterior approach alone (Ohtsuka's method), and circumferential decompression via combined posterior and anterior approaches (Tomita's method). Among them, in laminectomy, laminoplasty, and dekyphosis surgery, anterior decompression can be obtained to some extent without performing direct procedure on the OPLL. In Ohtsuka's method, complete decompression can be obtained via posterior approach alone, although it is somewhat technically demanding. It is preferable to drop the shaved down and separated OPLL anteriorly instead of trying to remove it completely to avoid complications, especially in patients with severe adhesion between the dura mater and OPLL.

Orotate phosphoribosyltransferase is overexpressed in malignant pleural mesothelioma: Dramatically responds one case in high OPRT expression.

OBJECTIVE: Malignant pleural mesothelioma (MPM) is a rare and aggressive, treatment-resistant cancer. Pemetrexed, an inhibitor of thymidylate synthase (TS), is used worldwide for MPM as a first-line chemotherapy regimen. However, there is little consensus for a second-line chemotherapy. S-1, a highly effective dihydropyrimidine dehydrogenase (DPD)-inhibitory fluoropyrimidine, mainly acts via a TS inhibitory mechanism similar to pemetrexed. Orotate phosphoribosyltransferase (OPRT) is a key enzyme related to the first step activation of 5-fluorouracil (5-FU) for inhibiting RNA synthesis. We investigated 5-FU related-metabolism proteins, especially focusing on OPRT expression, in MPM Methods and Patients: Fifteen MPM patients who were diagnosed between July 2004 and December 2013 were enrolled. We examined the protein levels of 5-FU metabolism-related enzymes (TS, DPD, OPRT, and thymidine phosphorylase [TP]) in 14 cases RESULTS: High TS, DPD, OPRT, and TP expressions were seen in 28.6%, 71.4%, 85.7%, and 35.7% of patients, respectively. We found that OPRT expression was extremely high in MPM tissue. We experienced one remarkable case of highly effective S-1 combined therapy for pemetrexed refractory MPM. This case also showed high OPRT protein expression Conclusion: The present study suggests that OPRT expression is high in MPM tumors. Although pemetrexed is mainly used for MPM chemotherapy as a TS inhibitor, S-1 has potential as an anticancer drug not only as a TS inhibitor but also inhibiting RNA synthesis through the OPRT pathway. This is the first report investigating OPRT protein expressions in MPM.

Pulmonary Neoplasms in Patients with Birt-Hogg-Dubé Syndrome: Histopathological Features and Genetic and Somatic Events.

Birt-Hogg-Dubé syndrome (BHD) is an inherited disorder caused by genetic mutations in the folliculin (FLCN) gene. Individuals with BHD have multiple pulmonary cysts and are at a high risk for developing renal cell carcinomas (RCCs). Currently, little information is available about whether pulmonary cysts are absolutely benign or if the lungs are at an increased risk for developing neoplasms. Herein, we describe 14 pulmonary neoplastic lesions in 7 patients with BHD. All patients were confirmed to have germline FLCN mutations. Neoplasm histologies included adenocarcinoma in situ (n = 2), minimally invasive adenocarcinoma (n = 1), papillary adenocarcinoma (n = 1), micropapillary adenocarcinoma (n = 1), atypical adenomatous hyperplasia (n = 8), and micronodular pneumocyte hyperplasia (MPH)-like lesion (n = 1). Five of the six adenocarcinoma/MPH-like lesions (83.3%) demonstrated a loss of heterozygosity (LOH) of FLCN. All of these lesions lacked mutant alleles and preserved wild-type alleles. Three invasive adenocarcinomas possessed additional somatic events: 2 had a somatic mutation in the epidermal growth factor receptor gene (EGFR) and another had a somatic mutation in KRAS. Immunohistochemical analysis revealed that most of the lesions were immunostained for phospho-mammalian target of rapamycin (p-mTOR) and phospho-S6. Collective data indicated that pulmonary neoplasms of peripheral adenocarcinomatous lineage in BHD patients frequently exhibit LOH of FLCN with mTOR pathway signaling. Additional driver gene mutations were detected only in invasive cases, suggesting that FLCN LOH may be an underlying abnormality that cooperates with major driver gene mutations in the progression of pulmonary adenocarcinomas in BHD patients.

Gamma Heavy Chain Disease with T-cell Large Granular Lymphocytic Leukemia: A Case Report and Review of the Literature.

Gamma heavy chain disease (gHCD) is a rare lymphoproliferative disorder characterized by the production of a truncated immunoglobulin heavy chain. Although some cases of gHCD are concurrent with other lymphoid neoplasms, few have been reported. We herein present the case of a 73-year-old woman with gHCD and T-cell large granular lymphocytic leukemia. A multiparameter flow cytometry analysis revealed neoplastic cells that were positive for CD28, a marker of T-cell activation, the anti-apoptotic antigen of neoplastic plasma cells, CD38 and CD45. The results of this multiparameter flow cytometry analysis may contribute to furthering the understanding of the clinicopathological features of gHCD.

Pseudomesotheliomatous carcinoma due to pleural metastasis from renal pelvic cancer.

A 78-year-old man was referred to our department with a one-week history of dyspnea and coughing. A chest X-ray showed massive left pleural effusion. Computed tomography revealed diffuse irregular thickening of the left pleura similar to malignant mesothelioma and multiple nodules in both lungs. The patient died of respiratory failure nine days after hospitalization. An autopsy revealed metastasis to the pleura and lungs from urothelial carcinoma of the left kidney.

Accelerated Versus Traditional Rehabilitation After Anterior Talofibular Ligament Reconstruction for Chronic Lateral Instability of the Ankle in Athletes.

BACKGROUND: Although several reconstruction procedures for chronic lateral ankle instability using autografts have been reported, all have recommended postoperative immobilization and a nonweightbearing period. HYPOTHESIS: Reconstructive surgery with a gracilis autograft using an interference fit anchoring system for chronic lateral ankle instability enables early accelerated rehabilitation and recovery with a return to activity without requiring immobilization. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 33 patients (33 feet) who underwent reconstruction of the anterior talofibular ligament with a gracilis autograft using interference screws were included; 15 were followed for 4 weeks with postoperative cast immobilization (group I), while 18 were followed with accelerated rehabilitation without immobilization (group A). Clinical and radiological results were evaluated based on the Karlsson and Peterson score, talar tilt angle, anterior displacement of the talus on stress radiography, and time between surgery and return to full athletic activity. RESULTS: The mean Karlsson and Peterson scores before and 2 years after surgery were the following: for group I: 62.3 ± 4.7 (range, 54-72) and 94.4 ± 7.1 (range, 76-100), respectively (P < .001), and for group A: 64.1 ± 4.8 (range, 57-70) and 91.7 ± 7.7 (range, 74-100), respectively (P < .001). The mean difference in the talar tilt angle compared with the contralateral side and mean displacement of the talus on stress radiography before and 2 years after surgery were the following: for group I: 8.7° ± 2.6° and 7.7 ± 1.8 mm and 3.8° ± 1.5° and 4.0 ± 1.6 mm, respectively, and for group A: 10.5° ± 3.4° and 8.7 ± 2.1 mm and 4.3° ± 1.8° and 4.3 ± 1.2 mm, respectively. Radiography revealed significantly improved postoperative outcomes in both groups (P < .0001). No significant differences in the score and any parameters on stress radiography were evident at 2 years after surgery between the groups. The mean time between surgery and return to full athletic activity was significantly higher in group I (18.5 ± 3.5 weeks) than in group A (13.4 ± 2.2 weeks) (P < .0001). No cases of reinjury were reported, and no differences in athletic performance ability were observed between the groups. CONCLUSION: Patients in group A returned to full athletic activity 5 weeks earlier than those in group I, demonstrating the advantage of accelerated rehabilitation after surgery.

Impact of C-Myc gene-related aberrations in newly diagnosed myeloma with bortezomib/dexamethasone therapy.

Recent studies have suggested that c-Myc over-expression may be a factor indicating poor prognosis in multiple myeloma (MM), although c-Myc gene-related abnormalities, including translocation and gene amplification, have not been fully investigated in the novel agent era. Additional chromosome 8 may be considered as aggressive disease in the 1990s. To clarify the impact of these aberrations, we retrospectively analyzed newly diagnosed MM (NDMM) and relapsed/refractory MM (RRMM) with bortezomib and dexamethasone induction therapy. In the present study, the high-risk group was defined as having at least one of the following present: non-hyperdiploidy, IgH/FGFR3, and del p53. Forty NDMM cases were analyzed. At the median follow-up duration of 14.1 months, 14 RRMM were recognized. The proportions of patients in the high-risk, c-Myc gene-related aberrations, and additional chromosome 8 groups at diagnosis were 45.5, 22.5, and 10 %, respectively. The proportions of patients who developed RRMM in the high-risk, c-Myc gene-related aberrations, and additional chromosome 8 groups were 41.7, 77.7, and 50 %, respectively. Furthermore, patients with c-Myc gene-related abnormalities tended to exhibit inferior progression-free survival (PFS), and those with c-Myc gene-related abnormalities and/or additional chromosome 8 showed statistically shorter PFS. Therefore, c-Myc gene-related abnormalities and additional chromosome 8 may be related to a poorer prognosis.

Extramedullary hematopoietic pleural effusion accompanied by follicular lymphoma.

Extramedullary hematopoietic effusion (EHE) is recognized to be an unusual phenomenon accompanied by hematologic disorders. Only a few reports are available of EHE occurring in patients with lymphoma. We herein report the case of a 54-year-old man with follicular lymphoma. Bone marrow aspirates and biopsied specimens showed diffuse invasion of small cleaved atypical lymphoid cells that were positive for CD10, 20, bcl2, immunoglobulin lambda and Bcl-2-IgH rearrangement. The pleural effusion aspirates and a biopsied specimen obtained via thoracoscopy revealed megakaryocytes and immature myeloid cells in addition to lymphoma cells. To the best of our knowledge, this is the first report of EHE accompanied by lymphoma according to the World Health Organization classification.

Histopathologic profiles of coronary atherosclerosis by myocardial bridge underlying myocardial infarction.

OBJECTIVE: Anatomic properties of myocardial bridge (MB) are sometimes responsible for myocardial infarction (MI) through the changes in the atherosclerosis distribution in the left ascending coronary artery (LAD). The purpose of this study was to investigate histopathologic profiles of atherosclerotic lesions resulting from the MB presence in the LAD in the MI cases. METHODS: In 150 consecutive autopsied MI hearts either with MBs [MI(+)MB(+); n = 67] or without MBs [MI(+)MB(-); n = 83] and 100 normal hearts with MBs [MI(-)MB(+)], LADs were consecutively cross-sectioned at 5-mm intervals. The most advanced intimal lesion and unstable plaque-related lesion characteristics (UPLCs) in each section were histopathologically evaluated in conjunction with the anatomic properties of the MB, such as its thickness, length, location, and MB muscle volume burden (MMV: the total volume of MB thickness multiplied by MB length). RESULTS: The MB showed a significantly greater thickness (P = 0.0090), length (P = 0.0300), and MMV (P = 0.0019) in MI(+)MB(+) than in MI(-)MB(+). Mean age of acute MI cases was significantly younger (P = 0.0227) in MI(+)MB(+) than in MI(+)MB(-). Frequency of plaque fissure/rupture in the proximal LAD was significantly higher in acute MI cases of MI(+)MB(+) than in MI(+)MB(-). UPLCs tended to be located proximally in MI(+)MB(+) and frequent 2.0 cm or more proximal to the MB entrance in MI(+)MB(+). CONCLUSION: In MI(+)MB(+), UPLCs tend to be located more proximally, and a plaque in the LAD proximal to the MB is prone to rupture, resulting in MI at younger age.

Reconstructive surgery using interference screw fixation for painful accessory navicular in adult athletes.

OBJECTIVE: To examine the effectiveness of a new technique for reattaching the posterior tibial tendon (PTT) using a bone tunnel and interference screw after resection of the accessory navicular for painful accessory navicular (type II) in adult athletes. METHODS: Ten adult athletes (7 male, 3 female; mean age 30 years, range 23-45) underwent reconstruction using a bone tunnel with an interference screw for a painful accessory navicular. All patients complained of pain on the medial aspect of the foot after eversion sprain during sports activities and radiographs revealed type II accessory navicular. Clinical evaluation with the American Orthopaedic Foot and Ankle Society Ankle-Hindfoot Scale (AOFAS) and visual analogue scale (VAS) before surgery was compared with that at most recent follow up (mean 30 months, range 24-39). RESULTS: Mean AOFAS score improved from a preoperative 62.8 ± 2.9 points (range 61-82) to a postoperative 92.1 ± 7.0 points (range 83-100; p < 0.01). Furthermore, mean VAS score improved from a preoperative 92.5 ± 5.4 points (range 85-100) to a postoperative 4.5 ± 3.8 points (range 0-10; p < 0.01). All patients could return to full sports activity at a mean of 14 weeks (range 12-18) after surgery. CONCLUSIONS: The presented technique reconstructs the bone-tendon interface of the PTT at the primary navicular with sufficient fixation after resection of the accessory navicular, which preserves the strength of the PTT in adult athletes with an intractably painful accessory navicular.

Successful treatment of immunoglobulin D myeloma by bortezomib and dexamethasone therapy.

Immunoglobulin D (IgD) myeloma is a rare subtype and it is widely accepted as an aggressive disease. Here, we report a 66-year-old woman with IgD myeloma who had anemia, lumbago, multiple osteolytic lesions and hypercalcemia. The patient refused a blood transfusion because of her beliefs, so we administered bortezomib and dexamethasone (BD) after high-dose dexamethasone therapy. Marked improvement of anemia and elevated serum alkaline phosphatase levels was recognized. After 5 cycles of BD therapy, the patient achieved a stringent complete response according to International Myeloma Working Group Response Criteria. BD therapy might be a feasible and useful treatment option for IgD myeloma.

[A case of coexisting malignant mesothelioma and squamous cell carcinoma of the lung].

We experienced a case of malignant mesothelioma with squamous cell carcinoma of the lung concurrently. A 40-year-old man presented with dyspnea. A massive pleural effusion was found by X-ray in the right side of his chest. Transcutaneous pleural biopsy yielded a diagnosis of malignant mesothelioma(IMIG cT4N0M0, Stage IV ). At the same time, his chest CT revealed tumor in the right hilar lesion. Transbronchial lung biopsy yielded a diagnosis of squamous cell carcinoma of the lung (cT3N0M0, Stage III B). Our diagnosis was double cancer, malignant mesothelioma and lung cancer. Chemotherapy with carboplatin, gemcitabine and radiation therapy was performed, but the patient died from deterioration of his systemic condition. We encountered a rare case of double cancer. More attention must be paid in making a diagnosis of malignant mesothelioma and lung cancer.

Anatomic properties of myocardial bridge predisposing to myocardial infarction.

BACKGROUND: A myocardial bridge (MB) that partially covers the course of the left anterior descending coronary artery (LAD) sometimes causes myocardial ischemia, primarily because of hemodynamic deterioration, but without atherosclerosis. However, the mechanism of occurrence of myocardial infarction (MI) as a result of an MB in patients with spontaneously developing atherosclerosis is unclear. METHODS AND RESULTS: One hundred consecutive autopsied MI hearts either with MBs [MI(+)MB(+) group; n=46] or without MBs (n=54) were obtained, as were 200 normal hearts, 100 with MBs [MI(-)MB(+) group] and 100 without MBs. By microscopy on LADs that were consecutively cross-sectioned at 5-mm intervals, the extent and distribution of LAD atherosclerosis were investigated histomorphometrically in conjunction with the anatomic properties of the MB, such as its thickness, length, and location and the MB muscle index (MB thickness multiplied by MB length), according to MI and MB status. In the MI(+)MB(+) group, the MB showed a significantly greater thickness and greater MB muscle index (P<0.05) than in the MI(-)MB(+) group. The intima-media ratio (intimal area/medial area) within 1.0 cm of the left coronary ostium was also greater (P<0.05) in the MI(+)MB(+) group than in the other groups. In addition, in the MI(+)MB(+) group, the location of the segment that exhibited the greatest intima-media ratio in the LAD proximal to the MB correlated significantly (P<0.001) with the location of the MB entrance, and furthermore, atherosclerosis progression in the LAD proximal to the MB was largest at 2.0 cm from the MB entrance. CONCLUSIONS: In the proximal LAD with an MB, MB muscle index is associated with a shift of coronary disease more proximally, an effect that may increase the risk of MI.