Electromyography stimulation compared with intraoperative O-arm imaging for evaluating pedicle screw breaches in lumbar spine surgery: a prospective analysis of 1006 screws in 164 patients.

BACKGROUND CONTEXT: Lumbar pedicle screw placement can be technically challenging. Malpositioned screws occur in up to 15% of patients and could result in radiculopathy or instrumentation failure. PURPOSE: To compare intraoperative electromyography (EMG) and image guidance using an O-arm for identifying pedicle breach during elective lumbar fusion. STUDY DESIGN: Prospective observational study. PATIENT SAMPLE: All adult patients undergoing elective lumbar spinal fusion operations for degenerative spine disorders (including adjacent segment degeneration, degenerative scoliosis, and symptomatic spondylosis and spondylolisthesis) at a single institution from July 1, 2014, to December 1, 2015, were prospectively tracked. OUTCOME MEASURES: Pedicle breach. METHODS: Pedicle screws from L2-S1 were placed using C-arm assisted freehand technique. All screws were stimulated with EMG and evaluated using the O-arm intraoperative imaging system. Electromyography data were compared with intraoperative images to assess the accuracy of identifying pedicle breaches. No funding was received for this work. RESULTS: One thousand six lumbar pedicles screws were placed from L2 to S1 in 164 consecutive cases. The mean patient age was 59.2 years. Thirty-five breaches (15 lateral and 20 medial) were visualized with O-arm imaging and confirmed by palpation (3.5% of screws placed). Of the breaches, 14 screws stimulated below the 12-mA threshold, nine screws stimulated between 12 and 20 mA, and 12 screws did not generate an EMG response. Forty screws stimulated below a 12-mA threshold but showed no breach on imaging. Using the 12-mA threshold, the sensitivity of EMG was 40%, specificity was 96%, positive predictive value was 26%, and negative predictive value was 98%. All 35 breached screws were corrected during surgery. There were no postoperative symptoms caused by breached screws and no patients required reoperation. CONCLUSIONS: Our findings indicate that EMG may not be a highly reliable tool in determining an anatomical breach during placement of lumbar pedicle screws. O-arm may be better for detecting either medial or lateral breaches than EMG stimulation if there are concerns about screw placement or for confirmation of placement before leaving the operating room.

The Role of a Miniopen Thoracoscopic-assisted Approach in the Management of Burst Fractures Involving the Thoracolumbar Junction.

Thoracoscopic spinal surgery is a minimally invasive open endoscopic approach to the anterior thoracolumbar spine for decompression and stabilization. It offers an alternative to open thoracotomy for thoracolumbar burst fractures, anterior spinal cord decompression, and spinal reconstruction with interbody and anterolateral plate instrumentation for restoration of biomechanical stability and alignment. Posterior instrumentation may not sufficiently stabilize a significantly disrupted anterior load-bearing spinal column, and the high access morbidity of open procedures is of significant concern. The adoption by spine surgeons of minimally invasive thoracoscopic techniques used by thoracic surgeons has expanded to include treatment of most anterior thoracolumbar disorders.

The role of the mini-open thoracoscopic-assisted approach in the management of metastatic spine disease at the thoracolumbar junction.

Objective: Treatment advances have resulted in improved survival for many cancer types, and this, in turn, has led to an increased incidence of metastatic disease, specifically to the vertebral column. Surgical decompression and stabilization prior to radiation therapy have been shown to improve functional outcomes, but anterior access to the thoracolumbar junction may involve open thoracotomy, which can cause significant morbidity. The authors describe the treatment of 12 patients in whom a mini-open thoracoscopic-assisted approach (mini-open TAA) to the thoracolumbar junction was used to treat metastatic disease, with an analysis of outcomes. Methods: The authors reviewed a retrospective cohort of patients treated for thoracolumbar junction metastatic disease with mini-open TAA between 2004 and 2016. Data collection included operative time, estimated blood loss, length of stay, follow-up duration, and pre- and postoperative visual analog scale scores and Frankel grades. Results: Twelve patients underwent a mini-open TAA procedure for metastatic disease at the thoracolumbar junction. The mean age of patients was 59 years (range 53-77 years), mean estimated blood loss was 613 ml, and the mean duration of the mini-open TAA procedure was 234 minutes (3.8 hours). The median length of stay in the hospital was 7.5 days (range 5-21 days). All 12 patients had significant improvement in their postoperative pain scores in comparison with their preoperative pain scores (p < 0.001). No patients suffered from worsening neurological function after surgery, and of 7 patients who presented with neurological dysfunction, 6 (86%) had an improvement in their Frankel grade after surgery. No patients experienced delayed hardware failure requiring reoperation over a mean follow-up of 10 months (range 1-45 months). Conclusions: The mini-open TAA to the thoracolumbar junction for metastatic disease is a durable procedure that has a reduced morbidity rate compared with traditional open thoracotomy for ventral decompression and fusion. It compares well with traditional and novel posterior approaches to the thoracolumbar junction. The authors found a significant improvement in preoperative pain and neurological symptoms that supports greater use of the mini-open TAA for the treatment of complex metastatic disease at the thoracolumbar junction.

Three-Dimensional Versus Two-Dimensional Neuroendoscopy: A Preclinical Laboratory Study.

BACKGROUND: Use of traditional two-dimensional (2-D) neuroendoscopy is limited by lack of depth perception. The advent of next-generation three-dimensional (3-D) endoscopes potentially compensates for this limitation. The aim of this study was to objectively compare the 2 modalities in a controlled laboratory environment. METHODS: Using 2-D and 3-D endoscopes, 8 participants performed simple and complex motor tasks. Participants were divided into 3 groups: novice (n = 3), beginner (n = 4), and expert (n = 1), based on prior neuroendoscopy training. Efficiency of completing simple motor tasks in an allocated time and time to complete complex motor tasks were recorded for both visualization methods with demerits for inaccuracy. RESULTS: Inaccuracy was reduced with increasing experience in the use of the 3-D endoscope for simple motor tasks such as spiral drawing (P = 0.04), but there was no statistical difference in completion time for complex motor tasks pertaining to depth perception among the groups (P > 0.05) or within groups for simple or complex tasks. To assess the impact on the learning curve, we analyzed the performance improvement in use of the other endoscope based on which endoscope each participant used first. There was marked improvement in accuracy and efficiency of 2-D scope use in the "3-D first" group for performing simple motor tasks such as dotted-line drawing (P = 0.002), but no benefit was observed for complex motor tasks. CONCLUSIONS: Our data do not support the superiority of the 3-D endoscope over its conventional 2-D congener, although its use may shorten the learning curve associated with neuroendoscopy, regardless of subjects' prior experience with neuroendoscopy.

Genetic drivers of metastatic dissemination in sonic hedgehog medulloblastoma.

Leptomeningeal dissemination (LMD), the metastatic spread of tumor cells via the cerebrospinal fluid to the brain and spinal cord, is an ominous prognostic sign for patients with the pediatric brain tumor medulloblastoma. The need to reduce the risk of LMD has driven the development of aggressive treatment regimens, which cause disabling neurotoxic side effects in long-term survivors. Transposon-mediated mutagenesis studies in mice have revealed numerous candidate metastasis genes. Understanding how these genes drive LMD will require functional assessment using in vivo and cell culture models of medulloblastoma. We analyzed two genes that were sites of frequent transposon insertion and highly expressed in human medulloblastomas: Arnt (aryl hydrocarbon receptor nuclear translocator) and Gdi2 (GDP dissociation inhibitor 2). Here we show that ectopic expression of Arnt and Gdi2 promoted LMD in mice bearing Sonic hedgehog (Shh)-induced medulloblastomas. We overexpressed Arnt and Gdi2 in a human medulloblastoma cell line (DAOY) and an immortalized, nontransformed cell line derived from mouse granule neuron precursors (SHH-NPD) and quantified migration, invasiveness, and anchorage-independent growth, cell traits that are associated with metastatic competence in carcinomas. In SHH-NPD cells. Arnt and Gdi2 stimulated all three traits. In DAOY cells, Arnt had the same effects, but Gdi2 stimulated invasiveness only. These results support a mechanism whereby Arnt and Gdi2 cause cells to detach from the primary tumor mass by increasing cell motility and invasiveness. By conferring to tumor cells the ability to proliferate without surface attachment, Arnt and Gdi2 favor the formation of stable colonies of cells capable of seeding the leptomeninges.

Surgical fidelity: comparing the microscope and the endoscope.

BACKGROUND: Both the microscope and the endoscope are widely used as visualization tools in neurosurgery; however, surgical dexterity when operating with each may differ. The aim of this study was to compare the surgical fidelity when using each of these visualization tools. METHODS: Junior residents and expert surgeons performed standardized motor tasks under microscopic and endoscopic visualization. Demerits for inaccuracy and time needed to complete the tasks were used to compare the surgeons' performance with the microscope and the endoscope. The participants also performed a motor task under direct vision using different instruments to evaluate whether the shape of the instrument had any impact on the surgical fidelity. RESULTS: For the junior residents, the number of demerits accrued was lower with the microscope than with the endoscope, and the time needed to complete the tasks was also lower with the microscope. There was no difference in the number of demerits between the microscopic and the endoscopic experts, but the microscopic expert completed the task in a shorter time. There was no difference in demerits or performance time when comparing a short, straight instrument and a longer, bayoneted one. CONCLUSIONS: For junior residents, surgical fidelity is higher with the microscope than with the endoscope. This difference vanishes with experience, but a slower speed of execution is observed with endoscopic visualization, both in junior and expert surgeons.

An assessment of academic productivity in pediatric neurosurgery.

OBJECT: Various bibliometric indices are now commonly used to assess academic productivity in medicine. Some evidence suggests that these measures are specific to subspecialty areas. The authors' goal was to measure the h index of academic pediatric neurosurgeons and compare it with previously reported results for academic neurosurgeons in general. METHODS: Programs with an Accreditation Council for Pediatric Neurosurgery Fellowships-approved fellowship were identified, and the h and g indices of each of their surgeons were calculated. These were correlated with academic rank and compared with published literature on academic neurosurgical departments. RESULTS: Seventy-two pediatric neurosurgeons had a mean h index of 16.6 and a mean g index of 29.5. Both indices increased with progressive academic rank. The rank-specific mean index for academic pediatric neurosurgeons was similar to that of neurosurgeons from academic departments in general. CONCLUSIONS: Overall, the authors conclude that the h index metric is a reasonable measure of academic productivity in the pediatric neurosurgery arena that provides a robust measure of an individual's contribution to the pediatric neurosurgery literature. Like its counterpart in neurosurgery in general, the h index for pediatric neurosurgeons correlates with institutional rank. The h index calculation also reveals the productivity of the pediatric neurosurgeons to be on par with the productivity of neurosurgeons in general.

Posterior plagiocephaly.

INTRODUCTION: Asymmetrical cranial vaults resulting from external forces on an infant's head can be caused by abnormal sutural development (synostotic plagiocephaly) or abnormal external forces acting on an intrinsically normal, developing cranium (deformational plagiocephaly). DISCUSSION: The incidence of posterior plagiocephaly has increased dramatically since the initiation of the "Back to Sleep" campaign against sudden infant death syndrome. The majority of cases are due to deformational plagiocephaly, but rigorous diagnostic evaluation including physical examination and radiological imaging must be undertaken to rule out lambdoid synostosis in extreme or refractory cases. CONCLUSION: Unique clinical features and radiological examination using computed tomography technology are helpful in confirming the correct cause of posterior plagiocephaly. Plagiocephaly is considered a benign condition, but with the recent increase in cases, new studies have revealed developmental problems associated with cranial vault asymmetries. Treatment of positional/deformational plagiocephaly includes conservative measures, primarily behavior modification, and, in some cases, helmet therapy, whereas lambdoid synostotic plagiocephaly requires surgical intervention, making differentiation of the cause of the asymmetry critical.

Endocrinological outcome after pituitary transposition (hypophysopexy) and adjuvant radiotherapy for tumors involving the cavernous sinus.

OBJECT: Stereotactic radiosurgery and fractionated stereotactic radiotherapy are commonly used in the treatment of residual or recurrent benign tumors of the skull base and cavernous sinus. A major risk associated with radiosurgical or radiotherapy treatment of residual or recurrent tumors adjacent to normal functional pituitary gland is radiation of the pituitary, which frequently leads to the development of hypopituitarism. The authors have used a technique of pituitary transposition to reduce the radiation dose to the normal pituitary gland in cases of planned radiosurgical treatment of residual tumor within the cavernous sinus. Here, the authors analyze the long-term endocrinological outcomes in patients with residual and recurrent tumors who undergo hypophysopexy and adjuvant radiosurgical or conformal fractionated radiotherapy treatment. METHODS: Pituitary transposition involves placement of a fat graft between the normal pituitary gland and residual tumor in the cavernous sinus. A sellar exploration for tumor resection is performed, the pituitary gland is transposed from the region of the cavernous sinus, and the graft is interposed between the pituitary gland and the residual tumor. The residual tumor may then be treated with stereotactic radiosurgery or conformal fractionated radiation therapy. The authors evaluated endocrinological outcome, safety of the procedure, and postoperative complications in patients who underwent this procedure during a 7-year period. RESULTS: Hypophysopexy has been used in 34 patients with nonfunctioning pituitary adenomas (19), functional pituitary adenomas (8), chordomas (2), meningiomas (2), chondrosarcoma (1), hemangiopericytoma (1), or hemangioma (1) involving the sella and cavernous sinus. Follow-up (radiographic and endocrinological) has been performed yearly in all patients. Two patients experienced postoperative endocrine deficits before radiosurgery (1 transient), but none of the patients developed new hypopituitarism during the median 4-year follow-up (range 1-8 years) after radiosurgery or fractionated stereotactic radiotherapy. CONCLUSIONS: The increased distance between the normal pituitary gland and the residual tumor facilitates treatment of the tumor with radiosurgery or radiotherapy and effectively reduces the incidence of radiation injury to the normal pituitary gland when compared with historical controls.

The in vivo antitumoral effects of lipopolysaccharide against glioblastoma multiforme are mediated in part by Toll-like receptor 4.

OBJECTIVE: Toll-like receptor 4 (Tlr-4) mediates many biological effects of lipopolysaccharide (LPS), which has antitumoral effects on glioblastoma both in vivo and in vitro. However, the precise role of Tlr-4 in these antitumoral effects remains unknown. METHODS: The role of Tlr-4 in the antitumoral effect of LPS on glioblastomas was assessed in wild-type BALB/c mice and in Tlr-4 knockout (KO) BALB/c mice. Mice were implanted with DBT glioblastoma cells intracranially or subcutaneously, were treated with intratumoral LPS, and were assessed by histopathological examination for degrees of tumor progression and inflammation. Flow cytometry and Western blotting with antibodies to the Tlr-4 receptor and flow cytometry to the related CD14 moiety were performed to quantitate the expression levels of these two receptors by glioblastoma cells. RESULTS: For subcutaneous tumors, LPS caused near complete tumor elimination in wild-type mice, but only a 50% reduction in Tlr-4 KO mice. For mice implanted with intracranial glioblastomas, LPS increased survival times modestly in wild-type mice, but showed no benefit in the Tlr-4 KO mice. There were no histological differences among wild-type and Tlr-4 KO mice, except for tumor size. In both models, an early neutrophilic and later macrophage-rich inflammatory infiltrate were seen after LPS administration. Quantitative flow cytometry and Western blotting showed no Tlr-4 receptor or CD14 expression in murine and human glioblastoma cells in vitro, and Western blotting suggested that Tlr-4 effects are mediated by nontumoral elements such as microglia and inflammatory cells. CONCLUSION: LPS-induced antitumoral effects on glioblastoma multiforme are mediated, in part, by the Tlr-4 receptor. Further understanding of this process may lead to novel treatment strategies for this uniformly fatal disease.