Bone flap necrosis after decompressive hemicraniectomy for malignant middle cerebral artery infarction.

BACKGROUND: Autologous bone flap reinsertion follows as a second surgical intervention after decompressive craniectomy in patients with malignant middle cerebral artery (MCA) infarction. In addition to surgery-related short-term complications, aseptic resorption of the reimplanted bone flap is a possible long-term problem which has not yet been sufficiently elucidated in these patients. METHODS: A total of 109 patients who had undergone decompressive hemicraniectomy for malignant MCA infarction in our institution between September 1994 and December 2011 were included in the study. Clinical and radiological findings were retrieved retrospectively. Aseptic bone necrosis was classified into two categories based on computer tomographic features. RESULTS: A total of 76 patients received their own cryoconserved bone flap (mean age 54.34 ± 10.73 years; 49 males). The overall short-term complication rate was 9.2 %. Bone flap necrosis occurred in 26 patients (22.8 %) with 7 flaps showing signs of surgically relevant type II necrosis after a median time of 14 months (interquartile range [IQR] 4-22). CONCLUSIONS: There is a noticeable complication rate in patients undergoing bone flap reinsertion after hemicraniectomy due to malignant MCA infarction. Aseptic bone necrosis represents a significant complication during long-term follow-up. The pathophysiological mechanisms remain unclear and more efforts should be undertaken to understand and possibly prevent this complication in these patients.

Expandable titanium cages for anterior column cervical reconstruction and their effect on sagittal profile: a review of 48 cases.

BACKGROUND: Expandable cervical cages have been utilised successfully to reconstruct the cervical spine for various conditions. However, to date there are only limited data on their influence on cervical sagittal profile. In this retrospective study, we present our experience with performing anterior cervical corpectomy in one or two levels using expandable titanium cages in order to achieve stable reconstruction and restoration of cervical lordosis. METHODS: A case series of data from 48 consecutive patients (20 men, 28 women; mean age 61 years) operated upon in a 5-year-period is retrospectively reviewed. Standard anterior single- or two-level cervical corpectomy, fusion and spinal reconstruction were performed, including placement of an expandable titanium cage and an anterior cervical plate. The mean follow-up was 23 months (range, 8-42 months). Outcome was measured by clinical examinations and visual analogue scale (VAS) scale; myelopathy was classified according the Nurick grading system. Radiographic analysis comprised several parameters, including segmental Cobb angle, cervical lordosis, subsidence ratio and sagittal cage angle. Computed tomography was done 1 and 2 years after surgery; cervical spine radiographs were obtained 3, 6, 12 and 24 months after surgery. RESULTS: In 38 patients (79 %) osseous fusion or stability of construct could be demonstrated in the 2-year follow up examination. The mean restoration of segmental Cobb angle as well as cervical lordosis amounted to 7.6° and 5.4° respectively, both being statistically significant. Furthermore, a profound correction (10° or more) of the sagittal cervical curve was shown in 15 patients. CONCLUSION: Regarding the restoration of the physiological sagittal cervical profile, expandable cervical cages seem to be efficient and easy to use for cervical spine reconstruction after anterior corpectomy. Donor-site-related complications are avoided, fast and strong reconstruction of the anterior column is provided, resulting in satisfactory fusion rates after 2 years.

Anterior cervical intercorporal fusion in patients with osteoporotic or tumorous fractures using a cement augmented cervical plate system: first results of a prospective single-center study.

STUDY DESIGN: Prospective observational clinical study. OBJECTIVE: The aim of this study is to evaluate the technical feasibility and the safety of additional cement augmentation of anterior cervical implants in patients with poor bone quality because of osteoporosis or tumor infiltration. SUMMARY OF BACKGROUND DATA: With an increasing number of elderly patients in spinal surgery the problem of implant dislocation after cervical instrumentation will become a more and more important problem. Whereas in the thoracolumbar area cement augmented screws have become widely accepted to ensure a rigid fixation in patients with reduced bone quality there are no data concerning an additional intravertebral cement augmentation after cervical plating. METHODS: Nine patients (4 males, 5 females, mean age 62.8 y) with newly diagnosed fractures of 1 or 2 cervical vertebrae because of tumor infiltration (6 cases) or osteoporosis (3 cases) were included in our study. A standard 1-level or 2-level cervical corpectomy with vertebral body replacement by an in situ expandable titanium cage and additional anterior plating was carried out. After this, additional cement augmentation was performed as a vertebroplasty of the anterior two thirds of the cranial and caudal adjacent vertebra by a new anterior hole. The cement should enclose the screws and stabilize the endplates of the adjacent vertebrae. Follow-up comprised clinical examinations, SF-36 questionnaire and visual analog scale 3, 6, and 12 months after surgery. Cervical spine radiographs were obtained 3 and 6 months after surgery and computed tomography scans 6 and 12 months after surgery. RESULTS: The median follow-up was 10 months with a range of 4-18 months. There was no intraoperative cement leakage into the spinal canal. The visual analog scale decreased from 8.2 to 4.2 at 6 months, physical and mental component summaries of SF-36 increased significantly from 27.7 to 36.1 and 31.5 to 48.6 at 6 months, respectively. Loosening of screws or plates was not detected throughout the whole observation period. There was 1 subsidence of a titanium cage into an adjacent vertebra without any clinical consequences. There was no adjacent fracture during the follow-up period and other surgical interventions or revisions were not necessary in any patient. CONCLUSIONS: In patients with severe osteoporosis or in patients with advanced tumor disease, excellent surgical, clinical, and radiologic results are possible following our method. In our opinion, a second-step posterior approach can be avoided by this technique.

CT-navigation versus fluoroscopy-guided placement of pedicle screws at the thoracolumbar spine: single center experience of 4,500 screws.

PURPOSE: Single center evaluation of the placement accuracy of thoracolumbar pedicle screws implanted either with fluoroscopy or under CT-navigation using 3D-reconstruction and intraoperative computed tomography control of the screw position. There is in fact a huge variation in the reported placement accuracy of pedicle screws, especially concerning the screw placement under conventional fluoroscopy most notably due to the lack of the definition of screw misplacement, combined with a potpourri of postinstrumentation evaluation methods. METHODS: The operation data of 1,006 patients operated on in our clinic between 1995 and 2005 is analyzed retrospectively. There were 2,422 screws placed with the help of CT-navigation compared to 2,002 screws placed under fluoroscopy. The postoperative computed tomography images were reviewed by a radiologist and an independent spine surgeon. RESULTS: In the lumbar spine, the placement accuracy was 96.4 % for CT-navigated screws and 93.9 % for pedicle screws placed under fluoroscopy, respectively. This difference in accuracy was statistically significant (Fishers Exact Test, p = 0.001). The difference in accuracy became more impressing in the thoracic spine, with a placement accuracy of 95.5 % in the CT-navigation group, compared to 79.0 % accuracy in the fluoroscopy group (p < 0.001). CONCLUSION: This study underlines the relevance of CT-navigation-guided pedicle screw placement, especially when instrumentation of the middle and upper thoracic spine is carried out.

Neural cell adhesion molecule isoform 140 declines with rise of WHO grade in human gliomas and serves as indicator for the invasion zone of multiform glioblastomas and brain metastases.

PURPOSE: Gliomas are highly invasive neuroepithelial tumors with a propensity of malignant transformation and very restricted treatment options. The neural cell adhesion molecule (NCAM) modulates cellular migration, proliferation, and synaptic plasticity by homophilic and heterophilic interactions. Hereby, we investigated its relevance as a glioma tissue marker for the biological aggressiveness of these tumors and compared these features with the carcinoma brain metastasis invasion zone. MATERIALS AND METHODS: We analyzed 194 human brain samples. Human tumor-free brain specimens served as control for the white and gray matter. In addition to that, we used human glioblastomas from nude rats. All tissues were investigated immunohistochemically for the expression of the NCAM isoform 140. Additionally, the multiplanar MRI-CT fusion neuronavigation-guided serial stereotactic biopsy was performed and completed by histopathological workup. RESULTS: Human gliomas loose NCAM-140 with the rise of their WHO grade. Meningiomas are NCAM-140 negative. As the most striking feature, human brain metastases and the majority of human glioblastomas of our patients and of nude rats were totally NCAM-140 negative. This NCAM negativity led us to the conclusion of three different main glioblastoma invasion patterns. Surprisingly, the majority of brain metastasis samples that contained surrounding brain parenchyma demonstrated invasive tumor cell nests beyond the sharply demarcated metastasis border. We also found invasive metastatic cell nests outside the contrast enhancing tumor zone by means of the MRI-CT fusion neuronavigation-guided serial stereotactic biopsy. CONCLUSION: The expression of NCAM-140 inversely correlates with the WHO grade of human gliomas. The lost expression of NCAM-140 in human glioblastomas and in brain metastases enables the investigation of the brain-tumor interface and the definition of glioblastoma invasion patterns and shows that brain metastases are more invasive than ever thought.