Peripheral Nerve Stimulation: The Evolution in Pain Medicine

Peripheral nerve stimulation (PNS) involves the application of electrical stimulation near the proximity of peripheral nerves. Although the mechanism of action remains unknown, PNS likely modulates both the central and peripheral nervous systems to provide analgesia for a wide variety of pain disorders involving the head, extremities, and trunk. Historically, PNS was not utilized widely due to underwhelming results from earlier studies. However, significant innovations in device technologies, including improved implantation techniques, hardware miniaturization, and externalized pulse generators, have led to the resurgence of PNS in the field of pain medicine. This editorial briefly reviews the evolution of PNS in the field of pain medicine and highlights areas for future investigation.

Alternative Dorsal Root Ganglion Neuromodulation Electrode Implantation: A Report of 2 Cases with 3 Different Techniques

Background and Study Aims The traditional percutaneous placement of dorsal root ganglion (DRG) electrodes may not be eligible for every patient. In this tertiary spine surgery and interventional pain therapy center, alternative neurostimulation implantation techniques were developed and applied where standard percutaneous approaches failed or were contraindicated. Case presentation Three alternative implantation techniques can be used: (1) open surgical placement of DRG leads, (2) two-lead insertion via a lateral to medial transforaminal approach (level L3), and (3) percutaneous approach with two leads close to the spinal nerves L4 (peripheral nerve stimulation). Results The placement of the leads occurred without complications and resulted in similar expected outcomes as with the common percutaneous technique with long-term stable pain suppression at 7 months and 1 year. Conclusions In patients in whom the DRG cannot be approached by the standard percutaneous approach, at least three alternatives may be used in experienced hands resulting in stable pain suppression of similar magnitude.

Bio-Scaffolds as Cell or Exosome Carriers for Nerve Injury Repair

Central and peripheral nerve injuries can lead to permanent paralysis and organ dysfunction. In recent years, many cell and exosome implantation techniques have been developed in an attempt to restore function after nerve injury with promising but generally unsatisfactory clinical results. Clinical outcome may be enhanced by bio-scaffolds specifically fabricated to provide the appropriate three-dimensional (3D) conduit, growth-permissive substrate, and trophic factor support required for cell survival and regeneration. In rodents, these scaffolds have been shown to promote axonal regrowth and restore limb motor function following experimental spinal cord or sciatic nerve injury. Combining the appropriate cell/exosome and scaffold type may thus achieve tissue repair and regeneration with safety and efficacy sufficient for routine clinical application. In this review, we describe the efficacies of bio-scaffolds composed of various natural polysaccharides (alginate, chitin, chitosan, and hyaluronic acid), protein polymers (gelatin, collagen, silk fibroin, fibrin, and keratin), and self-assembling peptides for repair of nerve injury. In addition, we review the capacities of these constructs for supporting in vitro cell-adhesion, mechano-transduction, proliferation, and differentiation as well as the in vivo properties critical for a successful clinical outcome, including controlled degradation and re-absorption. Finally, we describe recent advances in 3D bio-printing for nerve regeneration.

Repairing Cartilage with Processed Chondrocyte Constructs: A 6-Month Study Using a Porcine Model

Objective Autologous chondrocyte implantation was the first cell-based therapy that used a tissue engineering process to repair cartilage defects. Recently improved approaches and tissue-engineered cell constructs have been developed for growing patient populations. We developed a chondrocyte construct using a collagen gel and sponge scaffold and physicochemical stimuli, implanted with a surgical adhesive. We conducted a proof-of-concept study of these improvements using a cartilage defect model in miniature swine. Design We implanted the autologous chondrocyte constructs into full-thickness chondral defects in the femoral condyle, compared those results with empty and acellular scaffold controls, and compared implantation techniques with adhesive alone and with partial adhesive with suture. Two weeks after the creation of the defects and implantation of the cellular or acellular constructs, we arthroscopically confirmed that the implanted constructs remained at the chondral defects. We evaluated the regenerated tissue macro- and microscopically 6 months after the cell constructs were implanted. The tissues were stained with Safranin-O and evaluated using Sellers’ histology grading system. Results The defects implanted with processed cell constructs and acellular scaffolds were filled with chondrocyte-like round cells and with nearly normal tissue architecture that were significantly greater degree compared to empty defect control. Even with the adhesive alone and with suture alone, the cell construct was composed of the dense cartilaginous matrix that was found in the implantation using both the sutures and the adhesive. Conclusion Implantation of cell constructs promoted regeneration and integration of articular cartilage at chondral defects in swine by 6 months.

Anatomic, Radiologic and Electrocardiographic Considerations for Conduction System Pacing

His bundle pacing and left bundle branch pacing are complementary implantation techniques that combine into conduction system pacing, which allows maintaining or recovering physiological activation of the heart. We selected cases from the electrophysiological laboratory of the University Hospital in Krakow to present theoretical and practical aspects of conduction system pacing using fluoroscopy images, ECG and EGM recordings.

Supporting IOL’S in a Deficient Capsular Environment: The Tale of No “Tails”

Purpose. To evaluate the efficacy and safety of the following three distinct surgical procedures for secondary IOL implantation without capsular support: Iris-claw lens, flanged transscleral fixated IOLs (Yamane technique), and sutureless transscleral hook IOL fixation (Carlevale IOL). Materials and Methods. In this retrospective comparative study, three different sutureless IOL implantation techniques were compared in patients without any capsular support. Visual acuity and outcomes were analyzed in 24 eyes of 23 patients (14 male and 9 female). Study included 13 iris-claw lenses (Artisan Ophtec), 6 flanged transscleral fixated IOLs (Yamane technique using a MA60MA Alcon Inc IOL), and 5 transscleral Carlevale IOLS (Carlevale IOL, Soleko, Italy). Results. logMAR mean best-corrected visual acuity (BCVA) improved from 0.49 ± 0.19 to 0.19 ± 0.10 at three months after surgery p < 0.05 . Postoperative BCVA was similar in all three groups, and no intergroup difference was noted. Three eyes (12.5%) had a raised IOP >25 mmHg, 2 eyes (8%) presented a subluxated/dislocated IOL, 4 eyes (16%) had corneal edema longer than 7 days, 3 eyes (12.5%) had irregular pupil profile, 2 eyes (8%) had vitreous hemorrhage, 7 eyes had (29%) corneal astigmatism over 3 diopters, and one patient (4%) developed cystoid macular edema (CME). Conclusions. All three surgical procedures can be considered adequate to correct aphakia in patients without capsular support with significant improvement in visual acuity and low complication.

Transcatheter Aortic Valve Replacement for Bicuspid Aortic Valve Stenosis: A Practical Operative Overview

The bicuspid aortic valve (BAV) represents a complex anatomic scenario for transcatheter aortic valve replacement (TAVR) because of its unique technical challenges. As TAVR is moving towards younger and lower-risk populations, the proportion of BAV patients undergoing TAVR is expected to rise. Initial experiences of TAVR with first-generation transcatheter heart valves in high surgical risk patients with BAV stenosis showed higher rates of device failure and periprocedural complications as compared to tricuspid anatomy. The subsequent advances in imaging techniques and understanding of BAV anatomy, new iterations of transcatheter heart valves, and growing operators’ experience yielded better outcomes. However, in the lack of randomized trials and rigorous evidence, the field of TAVR in BAV has been driven by empirical observations, with wide variability in transcatheter heart valve sizing and implantation techniques across different centers and operators. Thus, in this review article, we provide a fully illustrated overview of operative periprocedural steps for TAVR in BAV stenosis, though recognizing that it still remains anecdotal.