Kun Woo Park

Pulmonary Cement Embolism after Percutaneous Vertebroplasty in Osteoporotic Vertebral Compression Fractures: Incidence, Characteristics, and Risk Factors

PURPOSE To prospectively evaluate the incidence of, characteristics of, and risk factors for pulmonary cement embolism after percutaneous vertebroplasty (PVP) in osteoporotic vertebral compression fractures (VCFs). MATERIALS AND METHODS Institutional review board approval and written informed consent were obtained. From June 2006 to September 2007, 75 patients (57 women, 18 men; mean age, 74.78 years; range, 48-93 years) who underwent 78 PVP sessions at 119 levels for osteoporotic VCFs were prospectively enrolled in this study. Computed tomographic (CT) scans of the chest and treated vertebrae were obtained after PVP. The presence, location, involved pulmonary arteries, number, and size of each pulmonary cement embolus were analyzed at CT. Possible risk factors were analyzed as follows: Age, injected cement volumes, and numbers of treated vertebrae were analyzed by using the Mann-Whitney U test; operators (radiologist or nonradiologist), level of treated vertebrae, guidance equipment, approach (uni- or bipedicular), presence of intravertebral vacuum clefts, and presence of paravertebral venous leakage were analyzed by using Pearson chi(2) and Fisher exact tests. RESULTS Pulmonary cement emboli developed in 18 (23%) of 78 PVP sessions and were detected in the distal to third-order pulmonary arteries. Only cement leakage into the inferior vena cava showed a statistically significant relationship to pulmonary cement embolism (P = .03). A higher frequency of pulmonary cement embolism was noted for the absence of intravertebral vacuum clefts, for the bipedicular approach, and for a nonradiologist operator with C-arm fluoroscopy (P > .05). CONCLUSION In osteoporotic VCFs, pulmonary cement embolism was detected in 23% of PVP sessions, developed in the distal to third-order pulmonary arteries, and was related to leakage into the inferior vena cava.

Value of Diagnostic Lumbar Selective Nerve Root Block: A Prospective Controlled Study

BACKGROUND AND PURPOSE: Although diagnostic lumbar selective nerve root blocks are often used to confirm the pain-generating nerve root level, the reported accuracy of these blocks has been variable and their usefulness is controversial. The purpose of this study was to evaluate the accuracy of diagnostic lumbar selective nerve root blocks to analyze potential causes of false results in a prospective, controlled, single-blinded manner. Materials and METHODS: A total of 105 block anesthetics were performed under fluoroscopic guidance in 47 consecutive patients with pure radiculopathy from a single confirmed level: 47 blocks were performed at the symptomatic level, and 58 were performed at the adjacent asymptomatic “control” level. Contrast and local anesthetics were injected, and spot radiographs were taken in all cases. We calculated the diagnostic value of the block anesthetics using concordance with the injected level. We analyzed the potential causes of false results using spot radiographs. RESULTS: On the basis of a definition of a positive block as 70% pain relief, determined by receiver-operator characteristic (ROC) analysis, diagnostic lumbar selective nerve root block anesthetics had a sensitivity of 57%, a specificity of 86%, an accuracy of 73%, a positive predictive value of 77%, and a negative predictive value of 71%. False-negatives were due to the following causes identifiable on spot radiographs: insufficient infiltration, insufficient passage of the injectate, and intraepineural injections. On the other hand, false-positives resulted from overflow of the injectate from the injected asymptomatic level into either the epidural space or symptomatic level. CONCLUSION: The accuracy of diagnostic lumbar selective nerve root blocks is only moderate. To improve the accuracy, great care should be taken to avoid inadequate blocks and overflow, and to precisely interpret spot radiographs.

Comparison of MR Imaging Findings between Extraligamentous and Subligamentous Disk Herniations in the Lumbar Spine

Extra- and subligamentous lumbar disk herniations are treated differently. These authors utilized 10 criteria in an attempt to establish the exact location of disk herniations with respect to the posterior longitudinal ligament. Extraligamentous herniations showed: 1) spinal canal compromise of more than half its diameter, 2) internal signal difference in the disk, 3) ill-defined disk margins, 4) disruption of the continuous low-signal-intensity line covering the disk, and 5) presence of an internal dark line in the herniated disk. When combined these 5 yield sensitivity, specificity, accuracy, and an odds ratio of 77.3%, 74.5%, 76.1%, and 9.93, respectively. BACKGROUND AND PURPOSE: The method of treating an HIVD in the lumbar spine may depend on the integrity of the PLL. The purpose of this study was to analyze and compare the MR imaging findings of extraligamentous and subligamentous HIVDs in the lumbar spine. MATERIAL AND METHODS: One hundred seventeen patients (M/F = 71:46; mean age, 47 years; age range, 15–79 years) underwent lumbar spine MR imaging and disk surgery (extraligamentous/subligamentous = 66:51) from May 2003 to November 2006. Two radiologists in consensus retrospectively reviewed all MR images, focusing on 10 criteria. RESULTS: The following 5 criteria are suggestive of extraligamentous HIVD in the lumbar spine: 1) spinal canal compromised for more than half its dimension, 2) internal signal difference in the HIVD, 3) an ill-defined margin of the HIVD, 4) disruption of the continuous low-signal-intensity line covering the HIVD, and 5) the presence of an internal dark line in the HIVD (P < .05). When we combined these 5 MR imaging criteria, the sensitivity, specificity, accuracy, and odds ratio were 77.3%, 74.5%, 76.1%, and 9.93 (P < .0001). CONCLUSIONS: Our proposed 5 MR imaging criteria will be helpful in differentiating extraligamentous and subligamentous HIVDs in the lumbar spine.

Herniation of cartilaginous endplates in the lumbar spine: MRI findings.

OBJECTIVE The purpose of this study was to determine reliable MRI findings suggesting disk herniation with cartilage endplate herniation in the lumbar spine. MATERIALS AND METHODS The records of 73 patients who underwent lumbar spinal MRI and lumbar microdiskectomy between March 2005 and January 2009 were searched to find those with the diagnosis of disk herniation with cartilage endplate herniation confirmed during surgery. The following morphologic features were assessed: posterior corners (posterior marginal nodes, dorsal corner defects, Modic changes, and posterior osteophytes), mid endplates (endplate irregularities, Modic changes), and heterogeneous low signal intensity of extruded material. The chi-square test and multiple logistic regression analysis with age, body mass index, and sex as covariates were used for the analysis. The ROC curve was obtained with scores of the statistically significant MRI findings. RESULTS Posterior marginal nodes, posterior osteophytes, Modic changes in posterior corners, mid endplate irregularities, Modic changes in mid endplates, and heterogeneous low signal intensity of extruded material were significantly more frequent in patients with disk herniation with cartilage endplate herniation (0.000 < p < 0.009). The AUC for diagnosing disk herniation with cartilage endplate herniation with our scoring system of the six MRI findings (0-6) was 0.888. CONCLUSION The presence of disk herniation with cartilage endplate herniation could be ascertained with the following MRI findings: posterior marginal nodes, posterior osteophytes, mid endplate irregularities, heterogeneous low signal intensity of extruded material, and Modic changes in posterior corners and mid endplates.

Atlanto-occipital Assimilation Associated with Basilar Invagination, C1-2 Instability, C2-3 Block Vertebra,and C3-4 Retrolisthesis : A Case Report

Congenital atlanto-occipital assimilation is frequently accompanied by basilar invagination and C1-2 instability. Occipitocervical fusion is required if these conditions cause neurological symptoms. Recently posterior fusion using occipitocervical screw fixation in the extension position has been introduced for the simultaneous decompression of the cervicomedullary junction compressed by basilar invagination, a reduction of atlantoaxial subluxation, and rigid fixation. However, it is a technically demanding procedure, and there is no domestic report of an experience with this procedure. We report a case of a patient with C2-3 block vertebra and C3-4 retrolisthesis in addition to congenital atlanto-occipital assimilation, basilar invagination and C1-2 instability. The patient underwent posterior fusion using occipitocervical screw fixation in the extension position.