A Rare Case of a Pancreatic Intraductal Oncocytic Papillary Neoplasm Associated With Invasive Adenocarcinoma Presenting as a Gastric Mass.

The World Health Organization recently recognized intraductal oncocytic papillary neoplasms of the pancreas (IOPNs) as distinct, pre-malignant pancreatic neoplasms. Due to their unique macroscopic and microscopic features, IOPNs are typically easy to diagnose and yield an indolent prognostic outcome. The diagnosis may be more complicated, and the prognosis may differ if an associated invasive carcinoma is present. Owing to the rarity of this entity, the available data is severely limited. Herein, we report a diagnostically challenging case of an IOPN associated with invasive carcinoma, initially presenting as a gastric mass with distinctive radiological and histopathological features.

Robotic-guided placement of cervical pedicle screws: feasibility and accuracy.

INTRODUCTION: It has been shown that pedicle screw instrumentation in the cervical spine has superior biomechanical pullout strength and stability. However, due to the complex and variable anatomy of the cervical pedicles and the risk of catastrophic complications, cervical pedicle screw placement is not widely utilized. STUDY DESIGN: A retrospective, consecutive patient review. OBJECTIVE: To review and report our experience with robotic guided cervical pedicle screw placement. METHODS: We retrospectively reviewed preoperative and postoperative CT scans of 12 consecutive patients who underwent cervical pedicle screw fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed using the robotic system's planning software by fusing the preoperative CT (with the planned cervical pedicle screws) to the post-op CT. This process was carried out by manually aligning the anatomical landmarks on the two CTs. Once a satisfactory fusion was achieved, the software's measurement tool was used manually to compare the planned vs. actual screw placements in the axial, sagittal and coronal planes within the instrumented pedicle in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications. RESULTS: Eighty-eight cervical pedicle screws were reviewed in 12 patients; mean age = 65 years, M:F = 2:1, and mean BMI = 27.99. No intra-operative complications related to the cervical pedicle screw placement were reported. Robotic guidance was successful in all 88 screws: eight in C2, 14 in C3, 16 in each of C4 and C5, 19 in C6, and 15 at C7. There were 14 pedicle screw breaches (15.9%); all were medial, less than 1 mm, and with no clinical consequences. In the axial plane, the screws deviated from the preoperative plan by 1.32 ± 1.17 mm and in the sagittal plane by 1.27 ± 1.00 mm. In the trajectory view, the overall deviation was 2.20 ± 1.17 mm. Although differences were observed in screw deviation from the pre-op plan between the right and left sides, they were not statistically significant (p > 0.05). CONCLUSION: This study indicates that robotic-guided cervical pedicle screw placement is feasible and safe. The medial breaches did not result in any clinical consequences.

The predictive accuracy of surgical planning using pre-op planning software and a robotic guidance system.

BACKGROUND: Navigation and robotic-guided systems are being used more often to facilitate efficient and accurate placement of hardware during spinal surgeries. Preoperative surgical planning is a key step in the safe use of these tools. No studies have yet investigated the predictive accuracy of surgical planning using a robotic guidance system. METHODS: Data were prospectively collected from patients in whom Mazor X-Align ™ [Medtronic Inc., Minneapolis, MN., USA] robotic guidance system software was used to plan their spinal instrumentation in order to achieve the best possible correction and the plans executed intraoperatively under robotic guidance. RESULTS: A total of 33 patients (26 females, 7 males) were included. Their mean age was 51 years (12-79), and their mean BMI was 23.90 (15.55-35.91). Their primary diagnoses were scoliosis (20), kyphosis (5), spondylolisthesis (4), adjacent segment degeneration (3), and metastatic tumor (1). Preoperatively, the patients' mean coronal Cobb Angle (CA) was 36.5 ± 14.4°, and their mean sagittal CA was 27.7 ± 20.0°. The mean planned correction coronal CA was 0.2 ± 1.2°, and the mean planned correction sagittal CA was 28.4 ± 16.7°. Postoperatively, the patients' mean coronal CA that was achieved was 5.8 ± 7.4°, and their mean sagittal CA was 31.0 ± 18.3°. The mean difference between the planned and achieved angles was 5.5 ± 7.4° for the coronal, and 9.03 ± 9.01° for the sagittal CA. For the thoracic kyphosis and lumbar lordosis, the mean difference between the planned and postoperatively measured values was 15.3 ± 10.8 and 12.8 ± 9.6, respectively. CONCLUSION: This study indicates that the predictive accuracy of the use of preoperative planning software and robotic guidance to facilitate the surgical plan is within 6° and 9° in the coronal and sagittal planes, respectively.

Clinical Outcomes of Idiopathic Scoliosis Surgery: Is There a Difference Between Young Adult Patients and Adolescent Patients?

Background Surgical outcomes of adolescent idiopathic scoliosis (AIS) patients have been well studied. However, few studies have examined the surgical outcomes of young adult idiopathic scoliosis (YAdIS) patients. This study analyzed and compared the surgical outcomes of young adult (19-30 years) and adolescent (10-18 years) idiopathic scoliosis patients. Methods This is a retrospective, comparative two-center study. Reviewed data of consecutive AIS and YAdIS patients who had undergone posterior spinal deformity surgery (n=56) by two spine surgeons from 2010 to 2014. Inclusion criteria were age between 10 to 30 years and preoperative coronal Cobb angle >40o. We excluded patients with previous correction surgery. Demographic data (age at time of surgery, gender, body mass index (BMI)), surgical data (preoperative diagnosis, number of levels fused, blood loss, duration of surgery, peri- and postoperative complications, duration of surgery, length of stay, revision surgery, and final follow-up) and radiographic data collected, reviewed, and analyzed. The groups were divided as AIS (n=29) and YAdIS (n=27). Results Patients' gender, BMI, average preoperative main coronal curve (YAdIS 53o vs. AIS 570), and follow-up intervals were not statistically different between groups. Statistically significant for YAdIS patients were more levels fused (10.6 vs. 8.9, p=0.02) and more intraoperative blood loss (872 ml vs. 564 ml, p=0.02) were statistically significant. Not significant between the groups were duration of surgery (p>0.05), perioperative complications (p=0.14), and length of stay (p=0.11). At mean 21 months follow-up, patients in both groups had a significant correction of their main coronal curve (YAdIS 21o vs. 53o, p<0.001, and AIS, 19o vs. 57o, p<0.01). YAdIS had a lower percentage correction of their curves (61% vs. 68%, p=0.03). Three YAdIS (11.1%) and no AIS (0%) patients had additional surgery, p=0.07. YAdIS had more distal fusion levels at L4 or below. Conclusions YAdIS patients had a greater number of levels fused, higher blood losses, and lower major Cobb correction versus AIS patients.

The Correlation of Spinopelvic Parameters With Biomechanical Parameters Measured by Gait and Balance Analyses in Patients With Adult Degenerative Scoliosis.

STUDY DESIGN: A prospective cohort study. OBJECTIVE: The objective of this study was to establish the correlation between radiographic spinopelvic parameters with objective biomechanical measures of function in patients with adult degenerative scoliosis (ADS). SUMMARY OF BACKGROUND DATA: Gait and balance analyses can provide an objective measure of function. Patients with ADS demonstrate altered gait and balance patterns. Spinopelvic parameters are commonly used by clinicians to evaluate patients with ADS. However, to the best of our knowledge, no studies have examined the correlation between patients' radiographic spinopelvic parameters and biomechanical gait and balance parameters. PATIENT SAMPLE: Forty-four patients with symptomatic ADS who have been deemed, appropriate surgical candidates. METHODS: Radiographic spinopelvic parameters (CVA: central vertical axis, SVA: sagittal vertical axis, Cobb angle, PI-LL mismatch: pelvic incidence lumbar lordosis mismatch, and T1PA: T1 pelvic angle) were obtained the week before surgery. Then, gait and functional balance analyses (spatiotemporal parameters, center of mass, and head sway parameters) were performed on the same day. Correlations were determined between the radiographic spinopelvic parameters and biomechanical gait and balance parameters using Pearson product correlation. RESULTS: Our results show that patients with higher Cobb angle and CVA tend to walk slower (r=-0.494, P<0.05). Furthermore, the higher the Cobb angle (r=0.396), CVA (r=0.412), SVA (r=0.440), and PI-LL mismatch (r=0.493), the more time ADS patients spend with their feet planted during single and double support phases of gait (P<0.05). In addition, patients with a higher Cobb angle, CVA, SVA, PI-LL mismatch, and T1PA, exhibited more trunk sway, increased lower extremity neuromuscular activity, and decreased spine neuromuscular activity (0.331

Cost and Clinical Outcome of Adolescent Idiopathic Scoliosis Surgeries-Experience From a Nonprofit Community Hospital.

BACKGROUND: Recognition of the variables that drive the cost of adolescent idiopathic scoliosis (AIS) surgeries will help physicians and hospitals to initiate cost-effective measures. The purpose of this study is to analyze the hospital costs and clinical outcome for AIS surgeries. METHODS: A total of 6417 individual hospital costs and charges for 42 consecutive AIS surgeries were reviewed. The patients' demographic, surgical, and radiographic data were recorded. The costs were categorized. The relationships between total costs, categorized costs, and the independent variables were analyzed. Perioperative and postoperative complications were reviewed. Back pain, leg pain, and Oswestry Disability Index scores were obtained. RESULTS: The patients' mean age was 15 years, and 37 patients were female. Their mean main curve measured 55°. A total of 39 patients had posterior-only procedures, and 3 patients had anterior/posterior procedures. The average number of levels fused was 8. The mean hospital charge was $126,284 (range, $76,171-$215,516). The mean hospital cost was $44,126 (range, $23,205-$74,302). The average hospital stay was 5 days, with an average cost per day of $8825. The largest contributors to the overall hospital cost were spinal implants (31%), and surgery department labor cost (23%). Other categoric cost contributors included medical/surgical bed (19%), central supply/operating room supplies (9%), intensive care unit (6%), bone graft (3%), and others. No complications or revision surgeries occurred in these patients. For patients who had back and/or leg pain preoperatively, their back pain visual analog scale scores improved 1.8 points (4.5 versus 2.7 points, P < .05) and their leg pain visual analog scale scores improved 1.5 points (2.1 versus 0.6 points, P < .05). Their Oswestry Disability Index scores improved 6.1 points (17.3 versus 11.2 points, P > 0.05). CONCLUSIONS: The hospital cost for AIS surgeries is significant, with spinal implants and surgery department labor being the largest contributors. These are also areas for potential cost-effective measures.

Giant cell tumor of the thoracic spine in a 30-year-old woman.

Giant cell tumor (GCT) of the spine is a rare, benign tumor. Patients typically present with pain and also may experience neurologic deficits from spinal cord and/or nerve root compression. This article describes a patient who presented with acute mid-back pain, was diagnosed with spinal GCT through biopsy, and was treated successfully with surgical resection and instrumentation.

Sagittal Spinal and Pelvic Parameters in Patients With Scheuermann's Disease: A Preliminary Study.

BACKGROUND: Sagittal spinopelvic parameters remain poorly defined in patients with Scheuermann disease (SD). For example, although pelvic incidence (PI) should approximate lumbar lordosis (LL) by 10°, this is not true in patients with SD. This retrospective radiographic study was conducted to propose a new mathematical relationship between sagittal spinopelvic parameters in skeletally mature patients with SD. METHODS: The following formula (Δ) was proposed [(thoracic kyphosis - 45°) + (thoracolumbar kyphosis - 0°) + (PI - LL) = ± 10°] and validated with standard spino pelvic parameters in patients with skeletally mature SD without prior spine surgery at 2 centers between 2006 and 2015. The T1 pelvic angle (TPA) was used as a measure of global balance with normal maximum of 15°. Subgroup analysis was performed to compare Δ between balanced (TPA ≤ 15°) and unbalanced (TPA > 15°) patients with SD. RESULTS: In patients with SD (n = 30), half were female (n = 15), the average age was 39 years, and the average Δ was 2.4°. A significant correlation was discovered between Δ and both TPA (R 2 = 0.75) and PI (R 2 = 0.69). At TPA of 15°, average Δ was 9.2°. There was also a significant difference between balanced and unbalanced patients (-8.7° ± 11.6° versus 28.2° ± 19.7°, P = .0003). CONCLUSIONS: This study of a new formula (Δ) to evaluate global sagittal balance in patients with SD found that accounting for the kyphosis maintained Δ within ± 10°. Further study is planned to determine whether maintaining and/or restoring a normal Δ is associated with improved outcomes in patients with SD after surgery.

Revision adult spinal deformity surgery: Does the number of previous operations have a negative impact on outcome?

PURPOSE: To study the effect of the number of previous operations on the outcome of revision adult spinal deformity (ASD) surgery. METHODS: One hundred and thirty-seven consecutive patients who underwent revision ASD surgery were classified as follows: those who had one previous operation (group 1), had two previous operations (group 2) and had three or more previous operations (group 3). Perioperative complications and additional surgeries were reviewed. Back pain, leg pain, ODI scores and radiographic measurements were obtained. RESULTS: Preoperatively, the patients in group 3 had worse ODI (60.0 vs. 48.1 and 47.9, p < 0.01) but not back pain or leg pain. Group 2 and group 3 had worse coronal plumb line (38.4 and 35.8 mm vs. 18.2 mm, p < 0.05) and SVA (99.7 and 153.9 mm vs. 67.8 mm, p < 0.05). Group 3 had worse PI-LL mismatch (40.1° vs. 25.3° and 26.2°, p = 0.08). Minor and major perioperative complication rates were 27.5% in group 1, 31.1% in group 2 and 39.0% in group 3 (p > 0.05). At mean 30-month follow-up, the additional surgery rates were 7.8, 17.8 and 22.0%, respectively (p = 0.07). The patients in all groups had improved back pain, leg pain and ODI scores. The net improvements on back pain, leg pain and ODI were not statistically different between the groups. CONCLUSIONS: Revision ASD patients who had two or more previous operations present with more coronal and sagittal imbalance and worse functional status. Patients who had three or more previous operations have relatively higher reoperation rate but similar perioperative complication rate and similar clinic improvements. These slides can be retrieved under Electronic Supplementary Material.

Prevalence and Factors Affecting Cervical Deformity in Adolescent Idiopathic Scoliosis Patients: A Single-Center Retrospective Radiological Study.

BACKGROUND: It has been reported that adult spinal deformity patients have a high prevalence of cervical kyphosis (CK) and cervical positive sagittal malalignment (CPSM). However, the prevalence and possible factors affecting CK and CPSM in patients with adolescent idiopathic scoliosis (AIS) are less clear. METHODS: We retrospectively analyzed a consecutive series of AIS patients from a single center. Radiographic measurements included the Cobb angle, C2-C7 sagittal vertical axis (C2-C7SVA), and C2-C7 lordosis. Cervical deformity was defined as loss of lordotic or neutral cervical angle (CK) or C2-C7SVA more than 4 cm (CPSM). Patients were stratified by the degree of thoracic kyphosis and coronal thoracic curve. RESULTS: A total of 99 patients were included in this study. The patients' mean age was 14 years (range, 10-18 years). Mean cervical lordosis and C2-C7SVA were 1.5° and 30.4 mm, respectively. The CK and CPSM prevalence were 49% and 16%, respectively, and prevalence of CK and/or CPSM was 59%. CK was present in 32% of the patients who had >20° thoracic kyphosis, and it was present in 75% of the patients who had ≤20° thoracic kyphosis (P = .003). No association between CPSM and thoracic kyphosis was found. The patients who had >20° coronal thoracic curve had higher CK prevalence (64% versus 37%, P = .05), but no CPSM association was found. CONCLUSIONS: Cervical deformity is highly prevalent in AIS patients. There is a significant correlation between the loss of thoracic kyphosis and the development of CK but not the development of CPSM. High coronal thoracic curve is associated with CK prevalence, but it is not associated with CPSM prevalence.

Revision spine surgery in patients without clinical signs of infection: How often are there occult infections in removed hardware?

PURPOSE: To examine the incidence of occult infection in revision spine surgeries and its correlation with preoperative inflammatory markers. METHODS: We retrospectively reviewed all patients who underwent revision spine surgery and hardware removal between 2010 and 2016. Patients who had preoperative clinical signs of infection were excluded. The hardware and surrounding tissue culture results were obtained. The patients' diagnosis and preoperative inflammatory marker (ESR, CRP, and procalcitonin) levels were recorded. RESULTS: A total of 162 consecutive patients were included in this study. The patients' mean age was 61 years (range 14-88). One hundred and three patients (63.6%) were female. Seventy-two patients (44.4%) had loose hardware and 88 patients (54.3%) had pseudarthrosis. Postoperatively, the hardware and/or surrounding tissue culture was positive in 15 patients (9.3%). The most commonly identified organisms were Propionibacterium acnes (7/15, 46.7%) and Staphylococcus (6/15, 40.0%). The other identified organisms were Pseudomonas aeruginosa (1/15, 6.7%) and Serratia marcescens (1/15, 6.7%). Only four patients with positive cultures had elevated preoperative ESR and CRP levels. Only two patients with positive cultures had elevated preoperative procalcitonin levels. There is no correlation between the patients' preoperative ESR, CRP, procalcitonin levels, and positive culture results (p > 0.05). CONCLUSIONS: Our study shows that occult infections are present in 9.3% of patients who underwent revision spine surgery and hardware removal although they did not have clinical signs of infection. Those commonly used preoperative inflammatory markers such as ESR, CRP, and procalcitonin may not be sensitive enough to detect occult infections in these patients. These slides can be retrieved under Electronic Supplementary Material.

Robotic-guided sacro-pelvic fixation using S2 alar-iliac screws: feasibility and accuracy.

PURPOSE: To review our experience with robotic guided S2-alar iliac (S2AI) screw placement. METHODS: We retrospectively reviewed patients who underwent S2AI fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed by fusing preoperative CT (with the planned S2AI screws) to postoperative CT. The software's measurement tool was used to compare the planned vs. actual screw placements in axial and lateral views, at entry point to the S2 pedicle and at a 30 mm depth at the screws' mid-shaft, in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications. RESULTS: 35 S2AI screws were reviewed in 18 patients. The patients' mean age was 60 years. No intra-operative complications that related to the placement of S2AI screws were reported and robotic guidance was successful in all 35 screws. Post-operative CT scans showed that all trajectories were accurate. No violations of the iliac cortex or breaches of the anterior sacrum were noted. At the entry point, the screw deviated from the pre-operative plan by 3.0 ± 2.2 mm in the axial plane and 1.8 ± 1.6 mm in the lateral plane. At 30 mm depth, the screw deviated from the pre-operative plan by 2.1 ± 1.3 mm in the axial plane and 1.2 ± 1.1 mm in the lateral plane. CONCLUSIONS: Robotic guided S2AI screw placement is feasible and accurate. No screw malpositions or complications that related to the placement of S2AI screws occurred in this series. Larger studies are needed to assess the long-term clinical outcomes of robotic guided sacral-pelvic fixation.

Biomechanical behavior of novel composite PMMA-CaP bone cements in an anatomically accurate cadaveric vertebroplasty model.

Vertebral compression fractures are caused by many factors including trauma and osteoporosis. Osteoporosis induced fractures are a result of loss in bone mass and quality that weaken the vertebral body. Vertebroplasty and kyphoplasty, involving cement augmentation of fractured vertebrae, show promise in restoring vertebral mechanical properties. Some complications however, are reported due to the performance characteristics of commercially available bone cements. In this study, the biomechanical performance characteristics of two novel composite (PMMA-CaP) bone cements were studied using an anatomically accurate human cadaveric vertebroplasty model. The study involves mechanical testing on two functional cadaveric spinal unit (2FSU) segments which include monotonic compression and cyclical fatigue tests, treatment by direct cement injection, and microscopic visualization of sectioned vertebrae. The 2FSU segments were fractured, treated, and mechanically tested to investigate the stability provided by two novel bone cements; using readily available commercial acrylic cement as a control. Segment height and stiffness were tracked during the study to establish biomechanical performance. The 2FSU segments were successfully stabilized with all three cement groups. Stiffness values were restored to initial levels following fatigue loading. Cement interdigitation was observed with all cement groups. This study demonstrates efficient reinforcement of the fractured vertebrae through stiffness restoration. The pre-mixed composite cements were comparable to the commercial cement in their performance and interdigitative ability, thus holding promise for future clinical use. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2067-2074, 2017.

Light-Driven Processes Control Both Rhodopsin Maturation and Recycling in Mosquito Photoreceptors.

Many invertebrates carry out a daily cycle of shedding and rebuilding of the photoreceptor's photosensitive rhabdomeric membranes. The mosquito Aedes aegypti shows a robust response, losing nearly all Aaop1 rhodopsin from the rhabdomeric membranes during the shedding process at dawn. Here, we made use of Aaop1 antibodies capable of distinguishing newly synthesized, glycosylated rhodopsin from mature nonglycosylated rhodopsin to characterize the fate of Aaop1 during the shedding and rebuilding processes. The rhabdomeric rhodopsin is moved into large cytoplasmic vesicles at dawn and is subsequently degraded during the standard 12 h daytime period. The endocytosed rhodopsin is trafficked back to the photosensitive membranes if animals are shifted back to dark conditions during the morning hours. During the daytime period, small vesicles containing newly synthesized and glycosylated Aaop1 rhodopsin accumulate within the cytoplasm. At dusk, these vesicles are lost as the newly synthesized Aaop1 is converted to the nonglycosylated form and deposited in the rhabdomeres. We demonstrate that light acts though a novel signaling pathway to block rhodopsin maturation, thus inhibiting the deglycosylation and rhabdomeric targeting of newly synthesized Aaop1 rhodopsin. Therefore, light controls two cellular processes responsible for the daily renewal of rhodopsin: rhodopsin endocytosis at dawn and inhibition of rhodopsin maturation until dusk. SIGNIFICANCE STATEMENT: Organisms use multiple strategies to maximize visual capabilities in different light conditions. Many invertebrates show a daily cycle of shedding the photoreceptor's rhabdomeric membranes at dawn and rebuilding these during the following night. We show here that the Aedes aegypti mosquito possesses two distinct light-driven cellular signaling processes for modulating rhodopsin content during this cycle. One of these, endocytosis of rhabdomeric rhodopsin, has been described previously. The second, a light-activated cellular pathway acting to inhibit the anterograde movement of newly synthesized rhodopsin, is revealed here for the first time. The discovery of this cellular signaling pathway controlling a G-protein-coupled receptor is of broad interest due to the prominent role of this receptor family across all areas of neuroscience.

Two novel high performing composite PMMA-CaP cements for vertebroplasty: An ex vivo animal study.

There is a growing body of the literature on new cement formulations that address the shortcomings of PMMA bone cements approved for use in vertebroplasty (VP) and balloon kyphoplasty (BKP). The present study is a contribution to these efforts by further characterization of two pre-mixed CaP filler-reinforced PMMA bone cements intended for VP; namely, PMMA-HA and PMMA-brushite cements. Each of these cements showed acceptable levels of various properties determined in porcine vertebral bodies. These properties included radiographic contrast, maximum exotherm temperature setting time, cement extravasation, stiffness change after fatigue loading, change of VB height after fracture following fatigue loading, and interdigitation. Each property value was comparable to or better than that for a PMMA bone cement approved for use in BKP. Thus, the results for the composite bone cements are promising.

Spinal Myeloid Sarcoma "Chloroma" Presenting as Cervical Radiculopathy: Case Report.

Study Design Case report. Objective Myeloid sarcoma (also known as chloroma) is a rare, extramedullary tumor composed of immature granulocytic cells. It may occur early in the course of acute or chronic leukemia or myeloproliferative disorders. Spinal cord invasion by myeloid sarcoma is rare. The authors report a rare case of spinal myeloid sarcoma presenting as cervical radiculopathy. Methods A previously healthy 43-year-old man presented with progressive neck, right shoulder, and arm pain. Cervical magnetic resonance imaging (MRI) revealed a very large enhancing extradural soft tissue mass extending from C7 through T1, with severe narrowing of the thecal sac at the T1 level. The patient underwent posterior cervical open biopsy, laminectomy, and decompression. Histologic examination of the surgical specimen confirmed the diagnosis of myeloid sarcoma. Postoperatively, a bone marrow biopsy was done, which showed myeloproliferative neoplasm with eosinophilia. The patient then received systemic chemotherapy and radiotherapy. Results At the 10-month follow-up, the patient reported complete relief of arm pain and neck pain. X-rays showed that the overall cervical alignment was intact and there was no evidence of a recurrent lesion. MRI showed no evidence of compressive or remnant lesion. Conclusions Spinal myeloid sarcoma presenting as cervical radiculopathy is rare, and it may be easily misdiagnosed. Knowledge of its clinical presentation, imaging, and histologic characterization can lead to early diagnosis and appropriate treatment.

Expression and light-triggered movement of rhodopsins in the larval visual system of mosquitoes.

During the larval stages, the visual system of the mosquito Aedes aegypti contains five stemmata, often referred to as larval ocelli, positioned laterally on each side of the larval head. Here we show that stemmata contain two photoreceptor types, distinguished by the expression of different rhodopsins. The rhodopsin Aaop3 (GPROP3) is expressed in the majority of the larval photoreceptors. There are two small clusters of photoreceptors located within the satellite and central stemmata that express the rhodopsin Aaop7 (GPROP7) instead of Aaop3. Electroretinogram analysis of transgenic Aaop7 Drosophila indicates that Aaop3 and Aaop7, both classified as long-wavelength rhodopsins, possess similar but not identical spectral properties. Light triggers an extensive translocation of Aaop3 from the photosensitive rhabdoms to the cytoplasmic compartment, whereas light-driven translocation of Aaop7 is limited. The results suggest that these photoreceptor cell types play distinct roles in larval vision. An additional component of the larval visual system is the adult compound eye, which starts to develop at the anterior face of the larval stemmata during the 1st instar stage. The photoreceptors of the developing compound eye show rhodopsin expression during the 4th larval instar stage, consistent with indications from previous reports that the adult compound eye contributes to larval and pupal visual capabilities.

Robotic assisted surgeries for the treatment of spine tumors.

BACKGROUND: Surgery plays an important role in the treatment of patients with metastatic or primary spine tumors. In recent years, various new techniques, such as robotic assisted spine surgery have been developed which has shown some promising results by improving the accuracy of spinal instrumentation and reducing potential complications. The purpose of this study was to evaluate our early experience using robotic guidance in the treatment of spinal tumors. METHODS: Data were collected from medical records for each surgery in which the robotic system was used to assist with biopsy, pedicle screw placement and/or vertebral augmentation in the treatment of spinal tumors. Patient's age, gender, diagnosis and surgical procedure were documented. The surgical time, estimated blood loss, peri-operative and post-operative complications were obtained. The visual analog scale (VAS) for back pain and leg pain were also recorded. RESULTS: A total of 9 consecutive patients (7 female, 2 male) were included in this study, beginning with the first case experience. The mean age of the patients was 60 years (range 47-69). All patients presented with thoracic or lumbar vertebral collapse and/or myelopathy. Robotic assisted posterior instrumentation was successfully performed in all patients. Robotic assisted vertebral augmentation was performed in 4 patients. The average number of levels instrumented was 5. The average surgery time (skin to skin) was 4 hours and 24 minutes and the mean blood loss was 319 ml. There were no complications perioperatively or through the latest follow-up. Seven of the 9 patients reported improved back pain and/or leg pain at the latest follow-up and the data were not available in two patients. CONCLUSIONS: The published complication rates of spinal tumor surgeries range between 5.3% and 19%. With robotic assistance, the surgical complication rate appears improved over the historical figures. Our study shows that the robotic system was safe and performed as desired in the treatment of metastatic and primary spine tumors. These results support that further evaluation in a larger series of patients.

Restoration of Cervical Alignment is Associated with Improved Clinical Outcome after One and Two Level Anterior Cervical Discectomy and Fusion.

BACKGROUND: Anterior cervical discectomy and fusion (ACDF) remains the standard of care for patients with cervical radiculopathy who are unresponsive to conservative care. However, the maintenance and restoration of cervical alignment as a predictive factor for outcome has not yet been fully evaluated. The purpose of this study was to evaluate the impact of maintaining or restoring cervical alignment on one and two level ACDF patients' outcome. METHODS: Data were collected from 104 patients who underwent one and two level ACDF. Cervical alignment was measured preoperatively and at follow-up visits. The patients were classified into three groups based on the postoperative change of their cervical alignment. Neck pain, arm pain, and Neck Disability Index (NDI) scores were obtained preoperatively and at the latest follow-up visit. Incidences of adjacent segment degeneration (ASD) and reoperations because of ASD were recorded. RESULTS: There were 64 patients in the Maintained group, 17 patients in the Restored group and 23 patients in the Kyphotic group. Pre-operatively, the neck pain scores, arm pain scores and NDI scores were not statistically different among the three groups (p>0.05). On average at 12 months follow-up, the neck pain scores improved by 2.7, 4.2, and 2.7 points respectively in the three groups (p>0.05). The patients' arm pain scores improved by 2.1, 2.4, and 2.8 points respectively (p>0.05). NDI scores improved by 12, 31 and 13.7 points respectively (p<0.05). The incidences of ASD and reoperations because of ASD were 16%, 12% and 35% respectively (p>0.05). CONCLUSIONS: The patients with restored cervical alignment had significantly greater NDI improvement and relatively better neck pain improvement. There was a trend for patients who had unchanged cervical kyphosis to have a higher incidence of ASD. Our study suggests that restoration of cervical alignment will contribute to improved clinical outcome in the patients who have one and two level ACDF surgeries. LEVEL OF EVIDENCE: This is a level III study.

Proximal instrumented vertebral body chance fracture after pedicle screw instrumentation in a thoracic kyphosis patient with osteoporosis.

STUDY DESIGN: We present a case of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a 67-year-old woman with osteoporosis and thoracic kyphosis. OBJECTIVE: To report the rare and unique complication of proximal vertebral body chance fracture after pedicle screw instrumentation and fusion in a kyphosis patient. SUMMARY OF BACKGROUND DATA: Pedicle screw instrumentation has been associated with complications not limited to neurological or vascular injury, loss of curve correction, intraoperative pedicle fracture or loosening, dural laceration, deep infection, and pseudarthrosis. To the best of our knowledge, there are no previous reports describing a chance-type fracture generated by a pedicle screw fixation at the proximal end of a construct. METHODS: A 67-year-old woman suffered from progressive thoracic kyphosis and mid thoracic pain presented 2 weeks after pedicle screw instrumentation and correction. She developed a vertebral body fracture at the proximal end of the instrumentation construct. Surgical intervention, including removal of the screws in the fractured vertebrae and extension of the instrumented fusion across the cervicothoracic junction, effectively restored the physiological sagittal alignment. RESULTS: Postoperatively, at 12-month follow-up, the patient is doing exceptionally well with near-complete relief of back pain and an excellent maintenance of correction. CONCLUSIONS: Chance fracture in osteoporotic bone at the proximal end of a construct due to a pedicle screw is a rare complication but it may result in catastrophic consequences. Early recognition of this complication, reduction of the fraction-dislocation, and an extension of the instrumentation can be utilized for realignment and long-term stabilization.