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Morbidity has been reported as a sequelae of crystalline steroid epidural steroid injections (ESIs), and particulate steroid size, aggregation, and embolization in brain and spinal cord may be the mechanism related to these neurologic effects. The objective of the study was to examine the aggregation properties of triamcinolone acetonide in commonly used local anesthetics with and without human serum. This study was conducted in an academic tertiary care center. Triamcinolone acetonide shows different aggregation characteristics in serum compared to a non-physiologic solution. Triamcinolone acetonide was mixed with lidocaine 1% (first group) and bupivacaine 0.5% (second group) in a 1:1 ratio and then mixed with either distilled water (control group) or serum ex vivo. A pathologist blinded to our hypothesis inspected all solutions under light microscopy with 100× and 400× magnifications. Total number of particulate steroid aggregates and the number of particles forming each aggregate (recorded as single,1 double,2 triple,3 quadruple,4 or large [>4} crystals) were counted. Particle size and aggregate size were measured (in μm). The ratios of quadruple to total aggregates, large to total, and quadruple with large to total aggregates were calculated. Steroid-serum solutions and steroid-sterile water were then compared. Triamcinolone aggregates showed an increased crystal and aggregate size when compared with other steroids. Within the triamcinolone subgroup, the mixture of lidocaine 1% and serum resulted in the largest crystal aggregates. Whole blood analysis may have provided a more physiologically accurate model but was not chosen due to poor microscopic analysis. Serum donor variability may also have affected particle characteristics. Fewer large triamcinolone aggregates were noted in the presence of serum when compared to the non-serum control groups. However, when compared to previously studied particulate steroids, it had the largest aggregates when added to serum.

Contraction is a well‐documented phenomenon occurring within two months of mesh implantation. Its etiology is unknown, but it is suggested to occur as a result of inadequate tissue ingrowth into the mesh and has been associated with hernia recurrence. In continuation of our previous studies, we compared tissue ingrowth characteristics of large patches of polyester (PE) and heavyweight polypropylene (PP) and their effect on mesh contraction. The materials used were eight PE and eight PP meshes measuring 10 × 10 cm2. After random assignment to the implantation sites, the meshes were fixed to the abdominal wall fascia of swine using interrupted polypropylene sutures. A necropsy was performed three months after surgery for evaluation of mesh contraction/shrinkage. Using a tensiometer, tissue ingrowth was assessed by measuring the force necessary to detach the mesh from the fascia. Histologic analysis included inflammatory and fibroblastic reactions, scored on a 0–4 point scale. One swine developed a severe wound infection that involved two PP meshes and was therefore excluded from the study. The mean area covered by the PE meshes (87 ± 7 cm2) was significantly larger than the area covered by the PP meshes (67 ± 14 cm2) (p = 0.006). Tissue ingrowth force of the PE meshes (194 ± 37 N) had a trend toward being higher than that of the PP meshes (159 ± 43 N), although it did not reach statistical significance. There was no difference in histologic inflammatory and fibroblastic reactions between mesh types. There was a significant correlation between tissue ingrowth force and mesh size (p = 0.03, 95% CI: 0.05–0.84). Our results confirm those from previous studies in that mesh materials undergo significant contraction after suture fixation to the fascia. PE resulted in less contraction than polypropylene. A strong integration of the mesh into the tissue helps prevent this phenomenon, which is evidenced by a significant correlation between tissue ingrowth force and mesh size.

Loss of depth cues is a major challenge facing surgeons performing video-assisted surgery (VAS). Whether the degradation of image quality from a video-displayed image plays a direct role in performance of VAS has not been studied. Twenty-four volunteer novice subjects were randomized to binocular direct-vision (BDV), monocular direct-vision (MDV), or video-imaging (VI) conditions. Each subject completed ten trials of a simple cutting task in a box trainer using standard laparoscopic instruments. VI subjects made significantly fewer correct incisions than both of the other groups for all trials. Differences between the BDV and MDV groups did not reach statistical significance. Improvement in performance was more rapid in the BDV group than in either the MDV or VI groups. The degradation of image quality with VI has a detrimental influence on VAS performance above and beyond the loss of binocular vision.

The objective of this study was to determine whether the GI Mentor II virtual reality simulator can distinguish the psychomotor skills of intermediately experienced endoscopists from those of novices, and do so with a high level of consistency and reliability. A total of five intermediate and nine novice endoscopists were evaluated using the EndoBubble abstract psychomotor task. Each subject performed three repetitions of the task. Performance and error data were recorded for each trial. The intermediate group performed better than the novice group in each trial. The differences were significant in trial 1 for balloons popped ( P = .001), completion time ( P = .04), and errors ( P = .03). Trial 2 showed significance only for balloons popped ( P = .002). Trial 3 showed significance for balloons popped ( P = .004) and errors ( P = .008). The novice group showed significant improvement between trials 1 and 3 ( P<0.05). No improvement was noted in the intermediate group. Measures of consistency and reliability were greater than 0.8 in both groups with the exception of novice completion time where test-retest reliability was 0.74. The GI Mentor II simulator can distinguish between novice and intermediate endoscopists. The simulator assesses skills with levels of consistency and reliability required for high-stakes assessment.

We present the case of a 24 yr old male who was diagnosed with gluteal compartment syndrome and was subsequently found to have developed lumbosacral radiculoplexopathy and complex regional pain syndrome. The patient's gluteal compartment syndrome was diagnosed within 24 h of presentation to the emergency room, and he underwent emergent compartment release. While recovering postoperatively, persistent weakness was noted in the right lower limb. Results of electrodiagnostic testing were consistent with a lumbosacral radiculoplexopathy. After admission to inpatient rehabilitation, the patient complained of pain, burning sensation, and numbness in the distal right lower limb. Based on clinical findings, he was diagnosed with complex regional pain syndrome type II, or causalgia, and was referred for a lumbar sympathetic block under fluoroscopic guidance. Sympathetic block resulted in relief of the patient's symptoms. He was discharged home with good pain control on oral medications.

Background: Headache (HA) is a significant cause of morbidity globally. Despite many available treatment options, HAs that are refractory to conservative management can be challenging to treat. Third occipital nerve (TON) and greater occipital nerve (GON) irritation are potential etiologic agents of primary and cervicogenic HAs that can be targeted using minimally invasive treatment options such as nerve blocks or radiofrequency ablation. However, a substantial number of patients that undergo radiofrequency ablation do not experience pain relief despite a positive diagnostic medial branch block (MBB). Objective: In this study, we investigate the underlying cause for the high rate of false positives associated with MBBs by evaluating injectate spread in cadaveric subjects. Study Design: Cadaveric study. Setting: Academic medical center. Methods: After obtaining exemption status from our Institutional Review Board, TON injections were performed on 5 preserved cadavers, a total of 10 TONs, using anatomic landmarks, partial dissection, and palpation to guide needle placement. Cadaveric dissections were performed to evaluate the location, vertical spread, and grossly observed injectate coating of the TON and GON for each quantity of methylene blue injectate, 0.3 mL and 0.5 mL, administered. Results: The average distance between the TON and GON at their respective foraminal exit points was 1.81 cm. The average vertical spread for 0.3 mL and 0.5 mL of methylene blue injectate was 2.02 + 0.35 cm and 3.26 + 0.48 cm when performing a TON block. When using 0.3 mL injectate, both the TON and GON were simultaneously coated 60% of the time. After increasing the injectate volume to 0.5 mL, both the TON and GON were simultaneously coated 100% of the time. Limitations: The cadaveric design of this study presents limitations when translating cadaveric findings to the clinical setting. Also, the small sample size limits its power and generalizability. Lastly, the potential for researcher bias exists as the investigators were not blinded. Conclusions: This study demonstrates that currently recommended injectate volumes for TON blocks may result in concomitant coating of the GON. Conventional radiofrequency ablation (RFA) of these nerves may not lesion both the TON and GON given its restrictive circumferential lesioning diameter of 5 – 7 mm. As such, interventionalists should consider performing radiofrequency ablation to both the TON and GON after a positive TON block. Key Words: Chronic pain, cervicogenic headache, third occipital nerve, greater occipital nerve, injectate spread, radiofrequency ablation

Background: Case reports of catastrophic neurological sequelae during ESIs have questioned the safety of this procedure. A proposed mechanism is particulate steroid embolization resulting in neuralischemia. Previous reports have described steroid clumping in common epidural injection mixtures. We demonstrate that physiologic medium can also modify aggregation. Objective: To inspect and compare aggregative properties of steroid preparations with and without human serum. Setting: Academic tertiary care center. Hypothesis: Particulate steroids display different aggregation characteristics in serum compared to non-physiologic solutions. Design: Solutions were inspected under light microscopy: betamethasone sodium phosphate/ betamethasone acetate, methylprednisolone, and dexamethasone were each mixed in lidocaine 1%, bupivacaine 0.5%, or sterile water in a 1:1 ratio. All preparations were inspected under light microscopy with 100x and 400x magnifications by a pathologist blinded to our expectations and hypothesis. Five random viewing fields were selected within each slide and the number of aggregates per field and the number of particles per aggregate was evaluated. Results: The addition of serum had a significant effect on steroid particle aggregation and number of particles per aggregate. Limitations: This study was limited by sample size as only 2 sets of human serum samples were tested with each preparation against one non-serum control. Additionally, as steroid preparations were evaluated under light microscopy, the ex vivo setting must be considered in the interpretation of results. Finally, mixing preparations with human serum as opposed to whole blood was necessary to allow for improved visibility on light microscopy despite the fact that whole blood may be necessary to more closely emulate in vivo coagulation setting. Conclusions: Overall, the presence of serum resulted in fewer large steroid particle aggregates when compared to non-serum control samples. Amongst particulate steroids, betamethasone with bupivacaine 0.5% demonstrated the fewest and smallest particle aggregates, suggesting that preparation may reduce the risk of embolic infarction. Methylprednisolone formed significantly larger particles in bupivicaine 0.5% with serum compared to non-serum controls. Key words: Corticosteroid, particulate aggregate, epidural injection, embolic infarction, serum

The ability to return to work (RTW) postinjury is one of the primary goals of rehabilitation. The modified Rankin Scale (mRS) is a validated simple scale used to assess the functional status of stroke patients during rehabilitation. We sought to determine the applicability of mRS in predicting RTW postinjury in a general trauma population. The trauma registry was queried for patients, aged 18 to 65 years, discharged from 2012 to 2013. A telephone interview for each patient included questions about employment status and physical ability to determine the mRS. Patients who had RTW postinjury were compared with those who had not (nRTW). Two hundred and thirty-four patients met the inclusion criteria. Of these, 171 (72.5%) patients RTW and 63 (26.7%) did nRTW. Patients who did nRTW were significantly older, had longer length of stay and higher rates of in-hospital complications. Multivariate analysis revealed that older patients were less likely to RTW (odds ratio = 0.961, P = 0.011) and patients with a modified Rankin score ≤2 were 15 times more likely to RTW (odds ratio = 14.932, P < 0.001). In conclusion, an mRS ≤2 was independently associated with a high likelihood of returning to work postinjury. This is the first study that shows applicability of the mRS for predicting RTW postinjury in a trauma population.

The objective of this study was to determine whether the GI Mentor II virtual reality simulator can distinguish the psychomotor skills of intermediately experienced endoscopists from those of novices, and do so with a high level of consistency and reliability. A total of five intermediate and nine novice endoscopists were evaluated using the EndoBubble abstract psychomotor task. Each subject performed three repetitions of the task. Performance and error data were recorded for each trial. The intermediate group performed better than the novice group in each trial. The differences were significant in trial 1 for balloons popped (P=.001), completion time (P=.04), and errors (P=.03). Trial 2 showed significance only for balloons popped (P=.002). Trial 3 showed significance for balloons popped (P=.004) and errors (P=.008). The novice group showed significant improvement between trials 1 and 3 (P<0.05). No improvement was noted in the intermediate group. Measures of consistency and reliability were greater than 0.8 in both groups with the exception of novice completion time where test-retest reliability was 0.74. The GI Mentor II simulator can distinguish between novice and intermediate endoscopists. The simulator assesses skills with levels of consistency and reliability required for high-stakes assessment.

DNA methylation changes have been implicated in many common chronic diseases leading to the hypothesis that environmental and age-related DNA methylation changes within individuals are involved in disease etiology. Few studies have examined DNA methylation changes within an individual over time and all of these studies have been conducted in adults. Here, we aim to characterize how global DNA methylation changes from birth to age three within a longitudinal birth cohort study and to determine whether there are consistent predictors of DNA methylation levels measured three years apart. We measured global DNA methylation in the same children at birth (cord blood) and again at three years of age among 165 children, using an immunoassay. We found that on average, DNA methylation was significantly higher in blood at age 3-years than in cord blood (p<0.01). However, for any individual child, the difference was less than would be expected by chance. We found that pre-pregnancy BMI was negatively predictive of both cord and three-year DNA methylation, even after statistical adjustment to account for the correlation between cord blood and three-year DNA methylation. The biologic implications of small changes in global DNA methylation are unknown. However, the observation that global DNA methylation levels persist within an individual from birth to age three supports the belief that factors that influence global DNA methylation, including pre-pregnancy BMI, may confer long-term effects.