Citations

The arteriovenous fistula (AVF) is the preferred hemodialysis vascular access, but it is complicated by high failure rates and attendant morbidity. This study provides the first description of a murine AVF model that recapitulates two salient features of hemodialysis AVFs, namely, anastomosis of end-vein to side-artery to create the AVF and the presence of chronic kidney disease (CKD). CKD reduced AVF blood flow, observed as early as 3 days after AVF creation, and increased neointimal hyperplasia, venous wall thickness, thrombus formation, and vasculopathic gene expression in the AVF. These adverse effects of CKD could not be ascribed to preexisting alterations in blood pressure or vascular reactivity in this CKD model. In addition to vasculopathic genes, CKD induced potentially vasoprotective genes in the AVF such as heme oxygenase-1 (HO-1) and HO-2. To determine whether prior HO-1 upregulation may protect in this model, we upregulated HO-1 by adeno-associated viral gene delivery, achieving marked venous induction of the HO-1 protein and HO activity. Such HO-1 upregulation improved AVF blood flow and decreased venous wall thickness in the AVF. Finally, we demonstrate that the administration of carbon monoxide, a product of HO, acutely increased AVF blood flow. This study thus demonstrates: 1) the feasibility of a clinically relevant murine AVF model created in the presence of CKD and involving an end-vein to side-artery anastomosis; 2) the exacerbatory effect of CKD on clinically relevant features of this model; and 3) the beneficial effects in this model conferred by HO-1 upregulation by adeno-associated viral gene delivery.

Immobilization causes loss of muscle by decreasing its protein synthesis and response to feeding.

Study Design. Laboratory/animal-based proof of principle study. Objective. To validate the accuracy of a magnetic resonance imaging (MRI)-guided stereotactic system for intraspinal electrode targeting and demonstrate the feasibility of such a system for controlling implantation of intraspinal electrodes. Summary of Background Data. Intraspinal microstimulation (ISMS) is an emerging preclinical therapy, which has shown promise for the restoration of motor function following spinal cord injury. However, targeting inaccuracy associated with existing electrode implantation techniques remains a major barrier preventing clinical translation of ISMS. Methods. System accuracy was evaluated using a test phantom comprised of nine target locations. Targeting accuracy was determined by calculating the root mean square error between MRI-generated coordinates and actual frame coordinates required to reach the target positions. System performance was further validated in an anesthetized pig model by performing MRI-guided intraspinal electrode implantation and stimulation followed by computed tomography of electrode location. Finally, system compatibility with a commercially available microelectrode array was demonstrated by implanting the array and applying a selection of stimulation amplitudes that evoked hind limb responses. Results. The root mean square error between actual frame coordinates and software coordinates, both acquired using the test phantom, was 1.09 ± 0.20 mm. Postoperative computed tomography in the anesthetized pig confirmed spatially accurate electrode placement relative to preoperative MRI. Additionally, MRI-guided delivery of a microwire electrode followed by ISMS evoked repeatable electromyography responses in the biceps femoris muscle. Finally, delivery of a microelectrode array produced repeatable and graded hind limb evoked movements. Conclusion. We present a novel frame-based stereotactic system for targeting and delivery of intraspinal instrumentation. This system utilizes MRI guidance to account for variations in anatomy between subjects, thereby improving upon existing ISMS electrode implantation techniques. Level of Evidence: N/A

Abstract The myocardium is known to be an anisotropic medium where the muscle fiber orientation changes through the thickness of the wall. Shear wave elastography methods use propagating waves which are measured by ultrasound or magnetic resonance imaging (MRI) techniques to characterize the mechanical properties of various tissues. Ultrasound- or MR-based methods have been used and the excitation frequency ranges for these various methods cover a large range from 24–500 Hz. Some of the ultrasound-based methods have been shown to be able to estimate the fiber direction. We constructed a model with layers of elastic, transversely isotropic materials that were oriented at different angles to simulate the heart wall in systole and diastole. We investigated the effect of frequency on the wave propagation and the estimation of fiber direction and wave speeds in the different layers of the assembled models. We found that waves propagating at low frequencies such as 30 or 50 Hz showed low sensitivity to the fiber direction but also had substantial bias in estimating the wave speeds in the layers. Using waves with higher frequency content (>200 Hz) allowed for more accurate fiber direction and wave speed estimation. These results have particular relevance for MR- and ultrasound-based elastography applications in the heart.

Abstract Background Cervical dystonia is thought to result in high disease burden, but limited information exists on its impact on employment and work productivity. We utilized data from the Cervical Dystonia Patient Registry for the Observation of OnabotulinumtoxinA Efficacy (ClinicalTrials.gov identifier: NCT 00836017) to assess the impact of cervical dystonia on employment and work productivity and examine the effect of onabotulinumtoxinA treatments on work productivity. Methods Subjects completed a questionnaire on employment status and work productivity at baseline and final visit. Baseline data were examined by severity of cervical dystonia, predominant subtype, presence of pain, prior exposure to botulinum toxin, and/or utility of a sensory trick. Work productivity results at baseline and final visit were compared in subjects who were toxin‐naïve at baseline and received three onabotulinumtoxinA treatments. Results Of 1,038 subjects, 42.8% were employed full‐ or part‐time, 6.1% unemployed, 32.7% retired, and 11.8% disabled. Of those currently employed, cervical dystonia affected work status of 26.0%, caused 29.8% to miss work in the past month (mean, 5.1 ± 6.4 days), and 57.8% reported decreased productivity. Half of those unemployed were employed when symptoms began, and 38.5% attributed lost employment to cervical dystonia. Pain, increasing severity, and anterocollis/retrocollis had the largest effects on work status/productivity. Preliminary analyses showed that absenteeism and presenteeism were significantly decreased following onabotulinumtoxinA treatments in the subpopulation that was toxin‐naïve at baseline. Conclusions This analysis confirms the substantial negative impact of cervical dystonia on employment, with cervical dystonia‐associated pain being a particularly important driver. OnabotulinumtoxinA treatment appears to improve work productivity.

Background and Purpose— The association between hemorrhagic stroke and use of nonsteroidal anti-inflammatory drugs (NSAIDs) is not well established. We conducted a systematic review and meta-analysis of observation studies to further characterize this possible association. Methods— Case–control and cohort studies that reported odds ratio, relative risk, hazard ratio, or standardized incidence ratio comparing risk of hemorrhagic stroke among NSAIDs users versus nonusers were systematically searched. Point estimates from each study were extracted. Pooled risk ratios (RR) and 95% confidence intervals (CI) for all NSAIDs and individual NSAIDs were calculated using random-effect, generic inverse variance method. Results— Ten studies were identified and included in our data analysis. As a single group, NSAIDs use was associated with a small but insignificant risk of hemorrhagic stroke with the pooled RR of 1.09 (95% CI, 0.98–1.22). Individual NSAIDs analysis revealed a significantly increased risk among diclofenac and meloxicam users (RR 1.27; 95% CI, 1.02–1.59 and RR 1.27; 95% CI, 1.08–1.50, respectively). The risk estimate for rofecoxib users was higher, but statistically nonsignificant (RR 1.35; 95% CI, 0.88–2.06). Conclusions— Overall, the use of NSAIDs is not associated with an increased risk of hemorrhagic stroke, although this risk was modestly significantly elevated in diclofenac and meloxicam users.

ObjectiveTo describe surgical outcomes and perioperative complications in patients taking antiplatelet and anticoagulation medications while undergoing cochlear implantation.Study DesignCase series with chart review.SettingTwo tertiary otologic referral center.Subjects and MethodsForty‐six adult patients (2005‐2014) who underwent cochlear implantation while on perioperative antiplatelet and/or anticoagulation therapy without interruption. Outcomes included estimated intraoperative blood loss, perception of increased difficulty secondary to bleeding, and postoperative complications attributable to continuing anticoagulation or antiplatelet therapy.ResultsThe cases of 46 patients (mean age, 69.5 years; 30.2% female) were analyzed. Of these, 39 patients were taking aspirin, 10 warfarin, and 7 clopidogrel. Aside from 3 (6.5%) patients with postoperative bruising without hematoma and 1 patient (2.2%) who reported self‐resolving oral cavity blood, no intraoperative or postoperative complications occurred in any patient that could be ascribed to antiplatelet or anticoagulant use.ConclusionThese data demonstrate that the risk of perioperative complications from continued antiplatelet or anticoagulation therapy is low. For subjects who are at risk of major complications (eg, deep venous thrombosis, pulmonary embolism, myocardial infarction, cerebrovascular accident) from temporary medication cessation, continuing antiplatelet or anticoagulation therapy through the perioperative period is an appropriate strategy.

Background Sinus computed tomography (CT) is performed for the diagnosis of paranasal sinus disease and to assess response to medical therapy. In addition, sinus CT is used for intraoperative imaging guidance. Multiple CTs increase cost and radiation exposure. Objective To determine potential cost savings and radiation dose reduction that result from the use of a single universal sinus CT protocol for diagnostic imaging and intraoperative navigation. Materials and Methods For sinus CT at the authors' institution, a single imaging protocol was begun and deemed acceptable by neuroradiologists and surgeons for diagnostic imaging and intraoperative guidance. The electronic medical record was queried over a 4-year period to determine the number of sinus CTs performed, dose-length products, referring providers' specialties, percentage of CTs used for intraoperative navigation, and the elapsed time between CT and surgery. Results A total of 6187 sinus CTs were performed by using a 64-detector scanner during the study period (2759 women and 3428 men; 53.6 ± 16.7 years [mean ± SD]), and 596 endoscopic sinus surgery cases used imaging guidance, for which all the CTs were deemed technically adequate. The mean dose-length product for the CTs was 338.4 ± 31.9 mGy-cm (mean ± SD). Of the 3702 sinus CTs ordered by nonotolaryngology providers, 167 surgeries with intraoperative navigation (4.5%) were performed. A higher percentage of CT referrals from sinus surgeons (23.9%) and other otolaryngology providers (11.4%) was used for imaging guidance (p < 0.0001). The time interval between sinus CT and surgery was greatest for nonotolaryngology providers (63.1 days, p < 0.01). Based on Medicare reimbursement, the total estimated saving was $147,628. Conclusions Adopting a single universal sinus CT protocol for diagnostic imaging and intraoperative navigation can be an effective means of decreasing cost and radiation exposure. However, successful implementation must take into account multiple practice-based considerations.