Long-term clinical and radiological postoperative outcomes after an interspinous microdecompression of degenerative lumbar spinal stenosis.

STUDY DESIGN: A retrospective study to evaluate the clinical outcome and the risk of postoperative instability 5 years after microsurgical management of lumbar spinal stenosis using the interspinous approach. OBJECTIVE: To evaluate the long-term outcome and the risk of postoperative instability after the microsurgical interspinous decompression of lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: The interspinous approach involves partial resection of the supraspinous ligament followed by resection of the interspinous ligament, partial resection of the caudal aspect of the superior spinous process and resection of the ligamentum flavum, producing a central fenestration through which the decompression of the cauda equina and the nerve roots can be effected with an undercutting technique, with tailored partial resection of the lamina and the medial aspects of the facet joints. In this article, we investigated the long-term clinical outcome and the long-term risk for instability after using this approach. METHODS: One hundred and 6 patients undergoing decompressive surgery for lumbar spinal stenosis using the interspinous approach, including cases with spondylolisthesis without instability, were included in this study. The long-term outcome was evaluated in a follow-up study, 5 years after surgery. The clinical long-term outcome was evaluated retrospectively using self-rating questionnaires: the Oswestry Disability Index, visual analogue scale (0-10), walking capacity (1-5), progress in walking capacity and global activity, and level of satisfaction. The risk of postoperative instability was evaluated on the basis of dynamic radiographs of the lumbar spine. RESULTS: The Oswestry Disability Index showed a mean improvement in symptoms from 58.20% to 21.61%, and the visual analogue scale showed that the intensity of leg and back pain decreased from 8.62 and 8.69 points to 2.33 and 3.48 points, respectively. Walking capacity increased from 3.37 (severely restricted) to 1.81 (slightly restricted), and 93.23% of cases indicated that they were moderately satisfied or very satisfied. Dynamic radiographs revealed no postoperative instability after decompression using the interspinous approach. CONCLUSION: The clinical outcome 5 years postoperatively after using the interspinous approach for lumbar spinal stenosis showed a favorable maintenance of improvement in symptoms. Radiological data showed that this approach does not alter the stability of the spine. LEVEL OF EVIDENCE: 4.

Vesicular localization of the rat ATP-binding cassette half-transporter rAbcb6.

The clarification of subcellular localization represents an important basis toward characterization of ATP-binding cassette (ABC) transporters and resolution of their roles in cellular physiology. Rat Abcb6 (rAbcb6) is a membrane-situated half-transporter belonging to the ABC protein superfamily. To investigate rAbcb6 subcellular distribution, the human colon adenocarcinoma line LoVo, which we found to be devoid of endogenous human ABCB6 mRNA, was employed for heterologous expression of rAbcb6 bearing a COOH-terminal epitope tag (rAbcb6-V5). Following subcellular fractionation, rAbcb6-V5 was observed as an N-glycosylated protein in fractions enriched with lysosomal/endosomal membrane proteins. Indirect immunofluorescence analyses of rAbcb6-V5 using antibodies against a rAbcb6-specific peptide or against the V5-tag revealed a punctate pattern that was colocalized with lysosome-associated membrane protein 1 (LAMP1), a marker of lysosomes/late endosomes. Substantial colocalization of tagged rAbcb6 with lysosomal/late endosomal marker was confirmed with living, unfixed LoVo cells coexpressing rAbcb6 fused to enhanced green fluorescent protein. Vesicular distribution in LoVo cells was consistent with localization of endogenous rAbcb6 expressed in rat primary hepatocyte cultures or in liver sections, as revealed by overlap of rat Lamp1 with rAbcb6 in double immunofluorescence analyses. Since several Abcb6-related half-transporters confer heavy metal tolerance, we investigated whether rAbcb6 expression in LoVo cells might affect sensitivity toward transition metal toxicity. Applying MTT viability assays, we found that expression of either rAbcb6-V5 or untagged rAbcb6 conferred tolerance toward copper, but not to cobalt or zinc. In summary, these results demonstrate that rAbcb6 is a glycosylated protein targeted to intracellular vesicular membranes and suggest involvement of rAbcb6 in transition metal homeostasis.

Delayed presentation of pulmonary polymethylmethacrylate emboli after percutaneous vertebroplasty.

STUDY DESIGN: Literature review concerning pulmonary embolism of polymethylmethacrylate (PMMA) material following percutaneous vertebroplasty and a report on 2 new cases. OBJECTIVE: To inform clinicians about delayed clinical manifestation of pulmonary embolism of polymethylmethacrylate material after percutaneous vertebroplasty, pathophysiology, precautions, and therapeutic management of this complication. SUMMARY OF BACKGROUND DATA: Percutaneous vertebroplasty is a minimal invasive intervention used to treat vertebral fractures, which yields good therapeutic results and rarely produces complications. Nevertheless, serious complications may occur. Pulmonary PMMA embolism, which has been recently reported in some cases, is one of these. METHODS AND RESULTS: We report on 2 cases of pulmonary embolism of PMMA material after percutaneous vertebroplasty. In the case of a 45-year-old female patient, symptoms of pulmonary embolism arose with a delay of 3 days following percutaneous vertebroplasty. A therapy with low-molecular-weight heparin, Enoxaparin, enabled recovery from pulmonary failure. The second case occurred without detection of any cement leakage into the paravertebral venous system, neither intraoperatively nor perioperatively. The existence of PMMA in pulmonary vessels was detected 1 year later and remained asymptomatic. CONCLUSION: These 2 cases allow us to conclude that the risk of pulmonary embolism of PMMA might be underestimated. We propose routine chest radiograph following every vertebroplasty, in order to detect pulmonary PMMA embolism and thereby prevent serious delayed cardiopulmonary failures.