Reoperation for Proximal Adjacent Segment Pathology in Posterior Cervical Fusion Constructs that Fuse to C2 vs C3.

BACKGROUND: Few studies have described rates of proximal clinical adjacent segment pathology (CASP) after posterior cervical decompression and fusion (PCDF). OBJECTIVE: To investigate rates of proximal CASP at C2 vs C3 in PCDFs for degenerative spine disease. METHODS: A retrospective review of 380 cases of PCDF for degenerative disease with proximal constructs ending at C2 vs C3 was performed. Minimum follow-up was 12 mo. The primary outcome was proximal CASP requiring reoperation. Variable analysis included demographic, operative, and complication data. RESULTS: There were 119 patients in the C2 group and 261 in the C3 group with no significant differences in age, gender, comorbidities, presenting symptoms, or complications. Vertebral artery injury rates were 0.8% in the C2 group and 0.0% in the C3 group (P = .12). No patients in the C2 group had reoperation for proximal CASP, while 5.0% of patients in the C3 group did (P = .01). Patients with arthrodesis up to C3 had an increased risk of proximal failure when the fusion construct crossed the cervicothoracic junction (P = .03). Multivariate logistic regression analysis showed no factors that were independently associated with re-instrumentation for proximal CASP. CONCLUSION: Instrumenting to the C2 level reduces the risk for proximal CASP compared to fusion only up to C3. The type of instrumentation used at these 2 levels, form of ASP disease at C1-C2, and natural motion of the relevant proximal adjacent joint may contribute to this difference. Furthermore, within the C3 cohort, fusion across the cervicothoracic junction increased the risk for proximal CASP.

Use of Recombinant Human Bone Morphogenetic Protein-2 at the C1-C2 Lateral Articulation without Posterior Structural Bone Graft in Posterior Atlantoaxial Fusion in Adult Patients.

BACKGROUND: Posterior atlantoaxial fusion is an important armamentarium for neurosurgeons to treat several pathologies involving the craniovertebral junction. Although the potential advantages of recombinant human bone morphogenetic protein-2 (rhBMP-2) are well documented in the lumbar spine, its indication for C1-C2 fusion has not been well characterized. In our institution, we apply rhBMP-2 to the C1-C2 joint either alone or with hydroxyapatite, locally harvested autograft chips, and/or morselized allogenic bone graft for selected cases-without conventional posterior structural bone graft. We report the clinical outcomes of the surgical technique to elucidate its feasibility. METHODS: We performed a single-center, retrospective review of data from 2008 to 2016 and identified 69 patients who had undergone posterior atlantoaxial fusion with rhBMP-2. The clinical records of these patients were reviewed, and the baseline characteristics, operative data, and postoperative complications were collected and statistically analyzed. RESULTS: The average age of the 69 patients was 60.8 ± 4.5 years, and 55.1% were women. With an average follow-up period of 21.1 ± 4.2 months, the C1-C2 fusion rate was 94.3% (65 of 69), and the average time to fusion was 11.4 ± 2.6 months (range, 5-23). The overall reoperation rate was 10.1% (7 of 69), with instrumentation failure in 7 patients (10.1%), adjacent segment disease in 2 (2.9%), and postoperative dysphagia and dyspnea in 2 patients (2.9%). No ectopic bone formation or soft tissue edema developed. CONCLUSIONS: Although retrospective and from a single center, our study has shown that rhBMP-2 usage at the C1-C2 joint without posterior structural bone grafting is a safe and reasonable surgical option.

Lumbar disc reherniation after transforaminal lumbar endoscopic discectomy.

BACKGROUND: Transforaminal lumbar endoscopic discectomy is a minimally invasive surgical procedure that can be performed in awake patients through an incision less than 1 cm. The procedure requires very little bony removal to access the herniated disc material because the approach is through the foramen, and only a small amount of the superior articulating process is removed to access Kambin's triangle. This study describes our experience with transforaminal endoscopic lumbar decompression (TELD) for the treatment of lumbar disc herniation. We evaluate the risk for reherniation in the first year after surgery and the characteristics of the patients who experience reherniation. METHODS: We describe the technique for the transforaminal endoscopic approach to treat lumbar disc herniations. Retrospectively, a series of 141 consecutive patients, who were operated on with lumbar radiculopathy, was analyzed. We excluded patients who had previous surgery at the lumbar level, surgeries done for disease adjacent to a fusion, and surgeries done for spondylolisthesis. A total of 84 consecutive patients were included who had single level lumbar non-revision surgery and at least 1-year follow up. RESULTS: A series of 46 consecutive male and 38 female patients with an average age of 57.4 years (range, 28-87 years old) who underwent transforaminal endoscopic treatment for lumbar disc herniations between 2014 and 2016 is presented. Four patients required microdiscectomy due to reherniation at 5 months, 8 months, 9 months, and 10 months postoperatively. All the patients in the series improved immediately following their endoscopic procedures, and no patients presented with symptoms suggestive of reherniation until 5 months after their initial endoscopic surgery. Patients with reherniation tended to be young: 31, 45, 48, and 49 years of age: all less than the average patient age who underwent endoscopic surgery. CONCLUSIONS: Transforaminal endoscopic surgical access to lumbar disc herniations is an ultra-minimally invasive approach for the treatment lumbar degenerative disc disease. It allows for neural decompression by removing disc and foraminal pathology with minimal bone removal. This minimal bone removal prevents iatrogenic destabilization. However, the 1-year reherniation rate presented here is 4.7%. This suggests that the benefit of this technique may be that it is ultra-minimally invasive, but it may only be equal, not superior to microdiscectomy in its rate of reherniation.

Intraoperative Computed Tomography Navigational Assistance for Transforaminal Endoscopic Decompression of Heterotopic Foraminal Bone Formation After Oblique Lumbar Interbody Fusion.

Transforaminal endoscopic spine surgery is an emerging technique in spine surgery, but it offers 2 distinct challenges to spine surgeons looking to adopt it: 1) targeting spine pathology and 2) understanding the endoscopic anatomy visualized through the endoscope. Intraoperative computed tomography (CT)-guided navigation is also an emerging technique in spine surgery that is becoming widely adopted for its benefits in assisting surgeons in localizing pathology and guided spine instrumentation placement. In this technical note, we describe a technique that uses intraoperative CT-guided navigation concomitantly with a transforaminal endoscopic approach to decompress a L4-L5 foraminal heterotopic bone formation after an oblique lumbar interbody fusion. The addition of intraoperative CT-guided navigation proved beneficial in targeting the pathology during the procedure and ensuring that the pathology was resolved by offering postoperative CT visualization of the decompressed neural foramen.

Comparison Between S2-Alar-Iliac Screw Fixation and Iliac Screw Fixation in Adult Deformity Surgery: Reoperation Rates and Spinopelvic Parameters.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The S2-alar-iliac (S2AI) technique has been described as an alternative method for pelvic fixation in place of iliac screws (ISs) in spinal deformity surgery. The objective of this study was to analyze the impact of S2AI screws on radiographical outcomes, including spinopelvic parameters. METHODS: A retrospective review of 17 patients receiving ISs and 46 patients receiving S2AI screws for correction of adult spinal deformity between 2010 and 2015 with minimum 1-year follow-up was conducted. Patient data on postoperative complications, including reoperation rates and proximal junctional kyphosis (PJK), and radiographical parameters was collected and statistically analyzed. RESULTS: With mean follow-up of 21.1 months, the overall reoperation rate was significantly lower in the S2AI group than in the IS group (21.7% vs 58.8%, P = .01), but the incidence of PJK was similar (32.6% vs 35.3%, P > .99). Moreover, the time to reoperation in the IS group was significantly shorter than in the S2AI group (P = .001), and the S2AI group trended toward a longer time to reoperation due to PJK (P = .08). There was a significantly higher change in pelvic incidence (PI) in the S2AI group (-6.0°) compared with the IS group (P = .001). CONCLUSIONS: Compared with the IS technique, the S2AI technique demonstrated a lower rate of overall reoperation, a similar rate of PJK, longer time to reoperation, and possible reduction in PI. Future studies may be warranted to clarify the mechanism of these results and how they can be translated into improved patient care.

Use of S2-Alar-iliac Screws Associated With Less Complications Than Iliac Screws in Adult Lumbosacropelvic Fixation.

STUDY DESIGN: Retrospective comparative study. OBJECTIVE: To compare clinical and radiographic outcomes between the S2-alar-iliac (S2AI) and the iliac screw (IS) techniques in the adult population and clarify the clinical strength of S2AI screws. SUMMARY OF BACKGROUND DATA: S2AI screws have been described as an alternative method for lumbosacropelvic fixation in place of ISs. The S2AI technique has several advantages with lower prominence, increased ability to directly connect to proximal instrumentation, less extensive dissection of tissue, and enhanced biomechanical strength over the IS technique. However, the clinical significance of these advantages remains unclear. METHODS: A single-center retrospective review of patients who underwent lumbosacropelvic fixation yielded 25 IS group patients and 65 S2AI group patients. Baseline demographic information, postoperative complications, pain and functional outcomes, and screw-related outcomes were collected. RESULTS: The S2AI group had lower rates of reoperation (8.8% vs. 48.0%, P < 0.001), surgical site infection (SSI) (1.5% vs. 44.0%, P < 0.001), wound dehiscence (1.5% vs. 36.0%, P < 0.001), and symptomatic screw prominence (0.0% vs. 12.0%, P = 0.02) than the IS group, whereas rates of L5-S1 pseudarthrosis, proximal junctional failure, and sacroiliac joint pain were similar in both groups. Statistically significant pain relief and functional recovery were achieved in both groups without any significant intergroup differences. On multivariate analyses, age [odds ratio (OR) = 0.91, P = 0.004] and S2AI instrumentation (OR = 0.08, P < 0.001) were protective of reoperation, whereas diabetes mellitus (OR = 10.9, P = 0.03) and preoperative diagnosis of tumor (OR = 12.3, P = 0.04) were associated with SSI, and S2AI instrumentation (OR = 0.09, P < 0.001) was protective of SSI. CONCLUSION: The use of the S2AI technique over the IS technique was an independent predictor of preventing reoperation and SSI, while achieving similar clinical and functional outcomes. LEVEL OF EVIDENCE: 4.

Surgical Management of Osteoblastoma of the Spine: Case Series and Review of the Literature.

AIM: To describe the demographics, clinical and radiologic presentation, surgical considerations, and clinical outcomes associated with spinal osteoblastoma. MATERIAL AND METHODS: A spinal tumor database of 522 patients treated surgically at a single institution between January 2002 and June 2012 was analyzed and five patients with spinal osteoblastoma were identified and included in this study. Basic demographic and epidemiological data were recorded. Tumor characteristics, surgical parameters, and clinical follow-up data were noted. RESULTS: The mean follow-up was 21.9 months. There were four males and one female, and the mean age at diagnosis was 28.4 years. There was a mean reported symptom length of 26.4 months prior to diagnosis. There were three cervical lesions, one lumbar lesion, and one sacrococcygeal lesion. One patient was Enneking stage III and four patients were Enneking stage II. Based on spinal instability neoplastic score criteria, two patients were stable and three patients were potentially unstable. Four patients had intralesional gross total resections and one patient had an en bloc marginal resection. All patients remained neurologically stable or improved postoperatively. A single patient had recurrence of a previously resected osteoid osteoma with progression to osteoblastoma. CONCLUSION: Aggressive surgical resection of spinal osteoblastoma is suggested to minimize the risk of tumor recurrence, although this may still occur even with en bloc resection. Patients rarely present with preoperative spinal instability, but surgical fusion is often required due to removal of structural elements of the spine during resection. Of note, osteoid osteoma may progress to osteoblastoma in the spine despite prior resection.

S2-Alar-Iliac Screws are Associated with Lower Rate of Symptomatic Screw Prominence than Iliac Screws: Radiographic Analysis of Minimal Distance from Screw Head to Skin.

BACKGROUND: In sacropelvic fixation, the iliac screw technique offers biomechanically strong constructs, but its disadvantages include screw prominence, wound dehiscence, and postoperative pain secondary to the high profile nature. To overcome this drawback, S2-alar-iliac (S2AI) screws were developed as an alternative technique for sacropelvic fixation. This study aimed to compare the S2AI screw technique with the iliac screw technique in terms of postoperative symptomatic screw prominence. METHODS: A retrospective review of the records of sacropelvic fusion procedures performed at a single institution between October 2010 and January 2015 identified 32 patients with 72 iliac screws and 68 patients with 148 S2AI screws, and clinical and radiographic data were collected. If a patient had wound dehiscence and/or tenderness in the buttock immediately overlying a pelvic screw head postoperatively, it was defined as symptomatic screw prominence. The minimal distance from screw head to skin (MDSS) on postoperative computed tomography scans was measured for each patient to clarify the relationship between symptomatic screw prominence and MDSS. RESULTS: Mean follow-up period was 22.0 months. There was significantly more symptomatic pelvic screw prominence in the iliac screw group (11.1% vs. 1.4%, P = 0.002). MDSS ≤23 mm was the strongest predictor of symptomatic pelvic screw prominence, which yielded sensitivity of 100%, specificity of 94.1%, positive predictive value of 47.6%, and negative predictive value of 100%. CONCLUSIONS: The use of the S2AI screw technique resulted in a reduced rate of symptomatic screw prominence. MDSS ≤23 mm was the strongest predictor of symptomatic screw prominence.

Surgical Outcomes in Patients with High Spinal Instability Neoplasm Score Secondary to Spinal Giant Cell Tumors.

Study Design Retrospective review. Objective To describe the surgical outcomes in patients with high preoperative Spinal Instability Neoplastic Score (SINS) secondary to spinal giant cell tumors (GCT) and evaluate the impact of en bloc versus intralesional resection and preoperative embolization on postoperative outcomes. Methods A retrospective analysis was performed on 14 patients with GCTs of the spine who underwent surgical treatment prior to the use of denosumab. A univariate analysis was performed comparing the patient demographics, perioperative characteristics, and surgical outcomes between patients who underwent en bloc marginal (n = 6) compared with those who had intralesional (n = 8) resection. Results Six patients underwent en bloc resections and eight underwent intralesional resection. Preoperative embolization was performed in eight patients. All patients were alive at last follow-up, with a mean follow-up length of 43 months. Patients who underwent en bloc resection had longer average operative times (p = 0.0251), higher rates of early (p = 0.0182) and late (p = 0.0389) complications, and a higher rate of surgical revision (p = 0.0120). There was a 25% (2/8 patients) local recurrence rate for intralesional resection and a 0% (0/6 patients) local recurrence rate for en bloc resection (p = 0.0929). Conclusions Surgical excision of spinal GCTs causing significant instability, assessed by SINS, is associated with high intraoperative blood loss despite embolization and independent of resection method. En bloc resection requires a longer operative duration and is associated with a higher risk of complications when compared with intralesional resection. However, the increased morbidity associated with en bloc resection may be justified as it may minimize the risk of local recurrence.

A systematic review of the use of expandable cages in the cervical spine.

Expandable vertebral body replacement cages (VBRs) have been widely used for reconstruction of the thoracolumbar spine following corpectomy. However, their use in the cervical spine is less common, and currently, no expandable cages on the market are cleared or approved by the US Food and Drug Administration for use in the cervical spine. The objective of this study was to perform a systematic review on the use of expandable cages in the treatment of cervical spine pathology with a focus on fusion rates, deformity correction, complications, and indications. A comprehensive Medline search was performed, and 24 applicable articles were identified and included in this review. The advantages of expandable cages include greater ease of implantation with less risk of damage to the end plate, less intraoperative manipulation of the device, and potentially greater control over lordosis. They may be particularly advantageous in cases with poor bone quality, such as patients with osteoporosis or metastatic tumors that have been radiated. However, there is a potential risk of overdistraction, which is increased in the cervical spine, their minimum height limits their use in cases with collapsed vertebra, and the amount of hardware in the expansion mechanism may limit the surface area available for fusion. The use of expandable VBRs are a valuable tool in the armamentarium for reconstruction of the anterior column of the cervical spine with an acceptable safety profile. Although expandable cervical cages are clearly beneficial in certain clinical situations, widespread use following all corpectomies is not justified due to their significantly greater cost compared to structural bone grafts or non-expandable VBRs, which can be utilized to achieve similar clinical outcomes.

Postoperative survival and functional outcomes for patients with metastatic gynecological cancer to the spine: case series and review of the literature.

OBJECTIVE: Spinal metastases from gynecological cancers are rare, with few cases reported in the literature. In this study, the authors examine a series of patients with spinal metastases from gynecological cancer and review the literature. METHODS: The cases of 6 consecutive patients who underwent spine surgery for metastatic gynecological cancer between 2007 and 2012 at a single institution were retrospectively reviewed. The recorded demographic, operative, and postoperative factors were reviewed, and the functional outcomes were determined by change in Karnofsky Performance Scale and the American Spine Injury Association (ASIA) score during follow-up. A systematic review of the literature was also performed to evaluate outcomes for patients with similar gynecological metastases to the spine. RESULTS: In this series, details regarding metastatic gynecological cancers to the spine are as follows: 2 patients with cervical cancer (both presented at age 46 years, mean postoperative survival of 32 months), 2 patients with endometrial cancer (mean age of 40 years, mean postoperative survival of 26 months), and 2 patients with leiomyosarcoma (mean age of 44 years, mean postoperative survival of 20 months). All patients presented with pain, and no complications were noted following surgery. All patients with known follow-up had stable or improved neurological outcomes, performance status, and improved pain, without local recurrence of tumor. Overall median survival after diagnosis of metastatic spine lesions for all cases in the literature as well as those treated by the authors was 15 months. When categorized by type, median survival of patients with cervical cancer (n = 2), endometrial cancer (n = 26), and leiomyosarcoma (n = 16) was 32, 10, and 22.5 months, respectively. CONCLUSIONS: Gynecological cancers metastasizing to the spine are rare. In this series, overall survival following diagnosis of spinal metastasis and surgery was 27 months, with cervical cancer, endometrial cancer, and leiomyosarcoma survival being 32, 26, and 20 months, respectively. Combined with literature cases, survival differs depending on primary histology, with decreasing survival from cervical cancer (32 months) to leiomyosarcoma (22.5 months) to endometrial cancer (10 months). Integrating such information with other patient factors may more accurately guide decision making regarding management of such spinal lesions.

Successful anterior fusion following posterior cervical fusion for revision of anterior cervical discectomy and fusion pseudarthrosis.

Pseudarthrosis occurs after approximately 2-20% of anterior cervical discectomy and fusion (ACDF) procedures; it is unclear if posterior or anterior revision should be pursued. In this study, we retrospectively evaluate the outcomes in 22 patients with pseudarthrosis following ACDF and revision via posterior cervical fusion (PCF). Baseline demographics, preoperative symptoms, operative data, time to fusion failure, symptoms of pseudarthrosis, and revision method were assessed. Fusion outcome and clinical outcome were determined at last follow-up (LFU). Thirteen females (59%) and 9 (41%) males experienced pseudarthrosis at a median of 11 (range: 3-151)months after ACDF. Median age at index surgery was 51 (range: 33-67)years. All patients with pseudarthrosis presented with progressive neck pain, with median visual analog scale (VAS) score of 8 (range: 0-10), and/or myeloradiculopathy. Patients with pseudarthrosis <12 months compared to >12 months after index surgery were older (p=0.013), had more frequent preoperative neurological deficits (p=0.064), and lower baseline VAS scores (p=0.006). Fusion was successful after PCF in all patients, with median time to fusion of 10 (range: 2-14)months. Eighteen patients fused both anteriorly and posteriorly, two patients fused anteriorly only, and two patients fused posteriorly only. Median VAS neck score at LFU significantly improved from the time of pseudarthrosis (p=0.012). While uncommon, pseudarthrosis may occur after ACDF. All patients achieved successful fusion after subsequent posterior cervical fusion, with 91% fusing a previous anterior pseudarthrosis after posterior stabilization. Neck pain significantly improved by LFU in the majority of patients in this study.

Factors Associated with Life Expectancy in Patients with Metastatic Spine Disease from Adenocarcinoma of the Lung.

Study Design Retrospective study. Objective Our objective was to identify preoperative prognostic factors associated with survival in patients with spinal metastasis from lung carcinoma. Methods A retrospective analysis of 26 patients diagnosed with lung carcinoma metastatic to the spinal column was performed to determine factors associated with survival. We used 3 months survival as the clinical cutoff for whether surgical intervention should be performed. We analyzed patients who survived less than 3 months compared with those who survived more than 3 months. Demographic, preoperative, operative, and postoperative factors including functional scores were collected for analysis. Results The median survival for all patients in our study was 3.5 months. We found a statistically significant difference between the group that survived less than 3 months and the group that survived greater than 3 months in terms of extrathoracic metastasis, visceral metastasis, and average postoperative modified Rankin score. Conclusion Determining which patients with lung cancer spinal metastases will benefit from surgical intervention is often dictated by the patient's predicted life expectancy. Factors associated with poorer prognosis include age, functional status, visceral metastases, and extrathoracic metastases. Although the prognosis for patients with lung cancer spinal metastases is poor, some patients may experience long-term benefit from surgical intervention.

Regression of an atlantoaxial rheumatoid pannus following posterior instrumented fusion.

OBJECTIVE: Rheumatoid patients may develop a retrodental lesion (atlantoaxial rheumatoid pannus) that may cause cervical instability and/or neurological compromise. The objective is to characterize clinical and radiographic outcomes after posterior instrumented fusion for atlantoaxial rheumatoid pannus. METHODS: We retrospectively reviewed all patients who underwent posterior fusions for an atlantoaxial rheumatoid pannus at a single institution. Both preoperative and postoperative imaging was available for all patients. Anterior or circumferential operations, non-atlantoaxial panni, or prior C1-C2 operations were excluded. Primary outcome measures included Nurick score, Ranawat score (neurologic status in patients with rheumatoid arthritis), pannus regression, and reoperation. Pannus volume was determined with axial and sagittal views on both preoperative and postoperative radiological images. RESULTS: Thirty patients surgically managed for an atlantoaxial rheumatoid pannus were followed for a mean of 24.43 months. Nine patients underwent posterior instrumented fusion alone, while 21 patients underwent posterior decompression and instrumented fusion. Following a posterior instrumented fusion in all 30 patients, the pannus statistically significantly regressed by 44.44%, from a mean volume of 1.26cm(3) to 0.70cm(3) (p<0.001), over 8.02 months. The Nurick score significantly improved from 2.40 to 0.60 (p<0.001), but the marginal improvement of 0.20 in the Ranawat score did not reach significance (p=0.312). Six patients (20%) required reoperations over a mean of 13.18 months. Reoperations were indicated for C1 instrumentation failure in four patients and pseudoarthrosis in two patients. CONCLUSION: Following posterior instrumented fusion, the pannus radiographically regressed by 44.44% over a mean of 8.02 months, and patients clinically improved per the Nurick score. The Ranawat score did not improve, and 20% of patients required reoperation over a mean of 13.18 months. The annualized reoperation rate was approximately 13.62%.

A systematic assessment of the use of platelet-rich plasma in spinal fusion.

Spinal fusion is one of the most commonly performed procedures for the treatment of spinal instability caused by a multitude of pathologies. However, despite significant advances in spinal instrumentation, failed fusion, or pseudoarthrosis, remains a significant challenge. Therefore, other additives such as bone graft extenders and growth factors have been explored as a method to augment fusion rates. Platelet-rich plasma (PRP) represents an additional approach, as it has shown some promise in bone regeneration. While the general use of PRP in orthopedic applications has been reviewed previously, its use in spinal fusion has not been systematically analyzed. The objective of this review is to systematically discuss the role of PRP in augmentation of bone regeneration for the purpose of spinal fusion. Background information on PRP, including a discussion of its preparation, activation, and growth factors, is included. Additionally, data from in vitro studies utilizing PRP in bone tissue engineering strategies is analyzed, and the available animal and clinical studies are systematically reviewed in order to provide guidance on future research pathways as well as the potential role of PRP in spinal fusion surgery.

Does CT wand guidance improve shunt placement in patients with hydrocephalus?

OBJECT: To evaluate the effectiveness of stereotactic navigation in enhancing the accuracy of ventricular shunt placement in patients with hydrocephalus. METHODS: A retrospective cohort study at a single institution by a single surgeon was performed. Consecutive patients who underwent implantation of a ventricular shunt for the management of hydrocephalus between July 2001 and December 2011 were included in the study, totaling 535 patients. Patients were classified as either having optimal or sub-optimal placement of the shunt into the ventricle. Multiple logistic regression analysis was used. RESULTS: Overall, 93.8% of patients were found to have optimal shunt placement. On multivariate analysis, navigation use was not significantly associated with improved accuracy of shunt placement (odds ratio [OR] = 0.54; 95% confidence interval [CI] = 0.19-1.54; p = 0.25). Pseudotumor cerebri diagnosis was significantly associated with increased odds of sub-optimal shunt placement (OR = 6.41; 95% CI = 1.90-21.59; p=0.003). CONCLUSIONS: CT guided navigation did not significantly improve the accuracy of ventricular shunt placement in adults with hydrocephalus for an experienced surgeon. Further studies are required to assess the utility of CT guided navigation for less experienced surgeons and patients with small or dysmorphic ventricles.

The biomechanics of pedicle screw augmentation with cement.

BACKGROUND CONTEXT: A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a promising approach. PURPOSE: The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. STUDY DESIGN/SETTING: This is a systematic literature review. METHODS: A search of Medline was performed, combining search terms of pedicle screw, augmentation, vertebroplasty, kyphoplasty, polymethylmethacrylate, calcium phosphate, or calcium sulfate. The retrieved articles and their references were reviewed, and articles dealing with biomechanical testing were included in this article. RESULTS: Polymethylmethacrylate is an effective material for enhancing pedicle screw fixation in both osteoporosis and revision spine surgery models. Several other calcium ceramics also appear promising, although further work is needed in material development. Although fenestrated screw delivery appears to have some benefits, it results in similar screw fixation to prefilling the cement with a solid screw. Some differences in screw biomechanics were noted with varying cement volume and curing time, and some benefits from a kyphoplasty approach over a vertebroplasty approach have been noted. Additionally, in cadaveric models, cemented-augmented screws were able to be removed, albeit at higher extraction torques, without catastrophic damage to the vertebral body. However, there is a risk of cement extravasation leading to potentially neurological or cardiovascular complications with cement use. A major limitation of these reviewed studies is that biomechanical tests were generally performed at screw implantation or after a limited cyclic loading cycle; thus, the results may not be entirely clinically applicable. This is particularly true in the case of the bioactive calcium ceramics, as these biomechanical studies would not have measured the effects of osseointegration. CONCLUSIONS: Polymethylmethacrylate and various calcium ceramics appear promising for the augmentation of pedicle screw fixation biomechanically in both osteoporosis and revision spine surgery models. Further translational studies should be performed, and the results summarized in this review will need to be correlated with the clinical outcomes.

Automatic localization of target vertebrae in spine surgery: clinical evaluation of the LevelCheck registration algorithm.

STUDY DESIGN: A 3-dimensional-2-dimensional (3D-2D) image registration algorithm, "LevelCheck," was used to automatically label vertebrae in intraoperative mobile radiographs obtained during spine surgery. Accuracy, computation time, and potential failure modes were evaluated in a retrospective study of 20 patients. OBJECTIVE: To measure the performance of the LevelCheck algorithm using clinical images acquired during spine surgery. SUMMARY OF BACKGROUND DATA: In spine surgery, the potential for wrong level surgery is significant due to the difficulty of localizing target vertebrae based solely on visual impression, palpation, and fluoroscopy. To remedy this difficulty and reduce the risk of wrong-level surgery, our team introduced a program (dubbed LevelCheck) to automatically localize target vertebrae in mobile radiographs using robust 3D-2D image registration to preoperative computed tomographic (CT) scan. METHODS: Twenty consecutive patients undergoing thoracolumbar spine surgery, for whom both a preoperative CT scan and an intraoperative mobile radiograph were available, were retrospectively analyzed. A board-certified neuroradiologist determined the "true" vertebra levels in each radiograph. Registration of the preoperative CT scan to the intraoperative radiograph was calculated via LevelCheck, and projection distance errors were analyzed. Five hundred random initializations were performed for each patient, and algorithm settings (viz, the number of robust multistarts, ranging 50-200) were varied to evaluate the trade-off between registration error and computation time. Failure mode analysis was performed by individually analyzing unsuccessful registrations (>5 mm distance error) observed with 50 multistarts. RESULTS: At 200 robust multistarts (computation time of ∼26 s), the registration accuracy was 100% across all 10,000 trials. As the number of multistarts (and computation time) decreased, the registration remained fairly robust, down to 99.3% registration accuracy at 50 multistarts (computation time ∼7 s). CONCLUSION: The LevelCheck algorithm correctly identified target vertebrae in intraoperative mobile radiographs of the thoracolumbar spine, demonstrating acceptable computation time, compatibility with routinely obtained preoperative CT scans, and warranting investigation in prospective studies. LEVEL OF EVIDENCE: N/A.

Venous sinus stenting is a valuable treatment for fulminant idiopathic intracranial hypertension.

Over the past 10 years, transverse sinus stenting has grown in popularity as a treatment for idiopathic intracranial hypertension. Although promising results have been demonstrated in several reported series, the vast majority of patients in these series have been treated on an elective basis rather than in the setting of fulminant disease with acute visual deterioration. We identified four patients who presented with severe acute vision loss between 2008 and 2012 who were treated with urgent transverse sinus stenting with temporary cerebrospinal fluid (CSF) diversion with lumbar puncture or lumbar drain as a bridge to therapy. All patients presented with headache, and this was stable or had improved at last follow-up. Three patients had improvement in some or all visual parameters following stenting, whereas one patient who presented with severe acute vision loss and optic disc pallor progressed to blindness despite successful stenting. We hypothesize that she presented too late in the course of the disease for improvement to occur. Although the management of fulminant idiopathic intracranial hypertension remains challenging, we believe that transverse sinus stenting, in conjunction with temporary CSF diversion, represents a viable treatment option in the acute and appropriate setting.

The Use of an Aspirating/Resecting Device to Reduce Stoma Closure Following Endoscopic Third Ventriculostomy for Aqueductal Stenosis.

BACKGROUND: Endoscopic third ventriculostomy (ETV) is commonly used to treat obstructive hydrocephalus. Closure of the stoma can be associated with symptom recurrence and need for further surgical intervention. OBJECTIVE: To describe the use of a side-cutting aspiration device for treatment of aqueductal stenosis in patients undergoing ETV. METHODS: A retrospective review of 30 consecutive adults with aqueductal stenosis treated with ETV using an adjunct side-cutting aspiration device between 2011 and 2013 was performed. Patients included in the study ranged from 35 to 64 years of age. ETV success was determined by the absence of stoma closure (aqueductal and cisternal flow assessed by high-resolution, gradient-echo magnetic resonance imaging), post-ETV symptom recurrence, and need for subsequent surgical intervention. RESULTS: Patients treated by using a side-cutting aspirator had no observed stoma closure (0%) and a 10% (n = 3) rate of post-ETV symptom recurrence. Three patients (10%) demonstrated a need for surgical revision following initial ETV with the side-cutting aspirator. CONCLUSION: Adult patients with obstructive hydrocephalus secondary to aqueductal stenosis exhibited a low rate of stoma closure with the use of a side-cutting aspiration device, and a rate of complications comparable to the known literature. Likewise, patients treated with a side-cutting aspirator may have lower symptom recurrence post-ETV and require fewer revisions in comparison with the known literature. As such, a side-cutting aspirator may be considered as a useful adjunct to traditional ETV for the treatment of obstructive hydrocephalus secondary to aqueductal stenosis.