Scott P. Leary

Toward the Emergence of Nanoneurosurgery: Part III—Nanomedicine: Targeted Nanotherapy, Nanosurgery, and Progress Toward the Realization of Nanoneurosurgery

THE NOTION OF nanotechnology has evolved since its inception as a fantastic conceptual idea to its current position as a mainstream research initiative with broad applications among all divisions of science. In the first part of this series, we reviewed the structures and principles that comprise the main body of knowledge of nanoscience and nanotechnology. In the second part, we discussed applications of nanotechnology to the emerging field of nanomedicine, with specific attention on medical diagnostics and imaging. This article further explores the applications of nanotechnology to nanomedicine. Specific attention is given to developments in therapeutic modalities, including advanced drug delivery systems and targeted nanotherapy, which will form the basis for the treatment arm of mature nanomedicine. A variety of modalities are discussed, including polymeric nanoparticles, micelles, liposomes, dendrimers, fullerenes, hydrogels, nanoshells, and smart surfaces. Applications of nanotechnology to nanosurgery and nanoneurosurgery are presented. Femtosecond laser systems, nanoneedles, and nanotweezers are presented as technologies that are operational at the nanoscale level and have the potential to revolutionize the practice of neurosurgery in a profound and momentous way.

Toward the emergence of nanoneurosurgery: Part II-Nanomedicine : Diagnostics and imaging at the nanoscale level

THE NOTION OF nanotechnology has evolved since its inception as a fantastic conceptual idea to its current position as a mainstream research initiative with broad applications among all divisions of science. In the first part of this series, we reviewed the structures and principles that comprise the main body of knowledge of nanoscience and nanotechnology (58). This article reviews and discusses the applications of nanotechnology to biological systems that will undoubtedly transform the foundations of disease diagnosis, treatment, and prevention in the future. Specific attention is given to developments in diagnostics and imaging at the nanoscale level. The use of nanoparticles and nanomaterials as biodetection agents for deoxyribonucleic acid and proteins is presented. In addition, nanodevices, such as nanowires, nanotubes, and nanocantilevers, can be combined with nanoarrays and nanofluidics to create integrated and automated nanodetection platforms. Molecular imaging modalities based on quantum dots and magnetic nanoparticles are also discussed. This technology has been extended to the imaging of intracranial neoplasms. Further innovation within these disciplines will form the basis for the development of mature nanomedicine. The final article of the series will focus on additional advancements in nanomedicine, namely nanotherapy and nanosurgery, and will cover the innovations that will lead to the eventual realization of nanoneurosurgery.

Revision and explantation strategies involving the CHARITÉ lumbar artificial disc replacement

Study Design. A large case series of anterior revision surgery in patients who had complications following lumbar total disc replacement with the CHARITÉ artificial disc. Objectives. To analyze and discuss the etiology of implant-related complications and to present a strategy that can be applied to lumbar intervertebral disc prostheses in cases where anterior revision surgery is necessary. Summary of Background Data. This report represents the largest single-site, consecutive case series reported in the literature of anterior revision surgery following lumbar disc arthroplasty. Methods. A total of 18 patients are included in this study. All patients required an anterior revision procedure for repositioning or removal of the prosthesis. The mean time to revision was 6 months (range, 9 days to 4 years). Results. In 17 of 20 cases, implant removal was required and the patient was converted to a fusion. In 3 cases, primary revision of the CHARITÉ artificial disc was performed. Six revision cases were performed within the early postoperative period, defined as 7 to 14 days. All early cases were approached via reexploration of the original anterior midline retroperitoneal incision. Late revision was required in 14 cases, ranging from 3 weeks to 4 years following initial arthroplasty. A variety of surgical approaches were used in late revisions, including the lateral transpsoas approach at L3–L4 or L4–L5 (n = 5), expanded ipsilateral left retroperitoneal approach at L4–L5 (n = 2), contralateral right retroperitoneal approach at L5–S1 (n = 6), and transperitoneal approach (n = 1). Following 20 consecutive, anterior revision procedures, implant revision was successfully achieved in all cases. Conclusions. Total disc replacement implant revisions occur largely as a result of technical errors in positioning and sizing of the implant. In addition, adherence to strict patient selection criteria will eliminate many cases of implant failure. When necessary, anterior revision surgery can be performed safely when a strategic approach is used.

Toward the Emergence of Nanoneurosurgery: Part I—Progress in Nanoscience, Nanotechnology, and the Comprehension of Events in the Mesoscale Realm

Since its original conception in 1959, the notion of nanotechnology and its potential ramifications have not only created fascination, but also intense scientific effort and scrutiny. Currently, research activities are being principally conducted in mesoscale, the realm between nanoscale and macroscale, with the rudiments of nanoscience being defined in realities and principles that will determine activities and discoveries in the future. This paper reviews and discusses the evolution of nanoscience, its contemporary status, and the discoveries that currently constitute the main components of the body of knowledge from a neurosurgical perspective. Specific attention is given to the developments in imaging, fabrication, nanostructures, nanoelectromechanical systems, molecular manufacturing, nanocomputation, and emerging physical and chemical concepts in mesoscale, as they will establish foundations for the realization of nanomedicine and nanoneurosurgery.

Evaluation of Decompression and Interlaminar Stabilization Compared with Decompression and Fusion for the Treatment of Lumbar Spinal Stenosis: 5-year Follow-up of a Prospective, Randomized, Controlled Trial

Introduction If nonoperative treatment for lumbar stenosis fails, surgery may be considered. This traditionally includes decompression often combined with fusion. Desire for less extensive surgery led to developing new techniques and implants, including an interlaminar device designed with the goal of providing segmental stability without fusion, following decompression. The purpose of this study was to investigate 5-year outcomes associated with an interlaminar device. Methods This prospective, randomized, controlled trial was conducted at 21 centers. Patients with moderate to severe lumbar stenosis at one or two contiguous levels and up to Grade I spondylolisthesis were randomized (2:1 ratio) to decompression and interlaminar stabilization (D+ILS; n=215) using the coflex® Interlaminar Stabilization® device (Paradigm Spine, LLC) or decompression and fusion with pedicle screws (D+PS; n=107). Clinical evaluations were made preoperatively and at 6 weeks and 3, 6, 12, 18, 24, 36, 48, and 60 months postoperatively. Overall Food and Drug Administration success criteria required that a patient meet 4 criteria: 1) >15 point improvement in Oswestry Disability Index (ODI) score; 2) no reoperation, revision, removal, or supplemental fixation; 3) no major device-related complication; and 4) no epidural steroid injection after surgery. Results At 5 years, 50.3% of D+ILS vs. 44% of D+PS patients (p>0.35) met the composite success criteria. Reoperation/revision rates were similar in the two groups (16.3% vs. 17.8%; p >0.90). Both groups had statistically significant improvement through 60 months in ODI scores with 80.6% of D+ILS patients and 73.2% of D+PS patients demonstrating >15 point improvement (p>0.30). VAS, SF-12, and ZCQ scores followed a similar pattern of maintained significant improvement throughout follow-up. On the SF-12 and ZCQ, D+ILS group scores were statistically significantly better during early follow-up compared to D+PS. In the D+ILS group, foraminal height, disc space height, and range of motion at the index level were maintained through 5 years. Conclusion Both treatment groups achieved and maintained statistically significant improvements on multiple outcome assessments throughout 5-year follow-up. On some clinical measures, there were statistically significant differences during early follow-up favoring D+ILS. At no point were there significant differences favoring D+PS. Results of this 5-year follow-up study demonstrate that decompression and interlaminar stabilization with coflex is a viable alternative to traditional decompression and fusion in the treatment of patients with moderate to severe stenosis at one or two lumbar levels. Level of Evidence and Ethical Statements This is a Level I study. Institutional approval was received at each of the sites participating in the trial. Each patient gave informed consent to participate in the trial.

Therapeutic sustainability and durability of coflex interlaminar stabilization after decompression for lumbar spinal stenosis: a four year assessment

Background Approved treatment modalities for the surgical management of lumbar spinal stenosis encompass a variety of direct and indirect methods of decompression, though all have varying degrees of limitations and morbidity which potentially limit the efficacy and durability of the treatment. The coflex® interlaminar stabilization implant (Paradigm Spine, New York, NY), examined under a United States Food and Drug Administration (US FDA) Investigational Device Exemption (IDE) clinical trial, is shown to have durable outcomes when compared to posterolateral fusion in the setting of post-decompression stabilization for stenotic patients. Other clinical and radiographic parameters, more indicative of durability, were also evaluated. The data collected from these parameters were used to expand the FDA composite clinical success (CCS) endpoint; thus, creating a more stringent Therapeutic Sustainability Endpoint (TSE). The TSE allows more precise calculation of the durability of interlaminar stabilization (ILS) when compared to the fusion control group. Methods A retrospective analysis of data generated from a prospective, randomized, level-1 trial that was conducted at 21 US sites was carried out. Three hundred forty-four per-protocol subjects were enrolled and randomized to ILS or fusion after decompression for lumbar stenosis with up to grade 1 degenerative spondylolisthesis. Clinical, safety, and radiographic data were collected and analyzed in both groups. Four-year outcomes were assessed, and the TSE was calculated for both cohorts. The clinical and radiographic factors thought to be associated with therapeutic sustainability were added to the CCS endpoints which were used for premarket approval (PMA). Results Success rate, comprised of no second intervention and an ODI improvement of ≥ 15 points, was 57.6% of ILS and 46.7% of fusion patients (p = 0.095). Adding lack of fusion in the ILS cohort and successful fusion in the fusion cohort showed a CCS of 42.7% and 33.3%, respectively. Finally, adding adjacent level success to both cohorts and maintenance of foraminal height in the coflex cohort showed a CCS of 36.6% and 25.6%, respectively. With additional follow-up to five years in the U.S. PMA study, these trends are expected to continue to show the superior therapeutic sustainability of ILS compared to posterolateral fusion after decompression for spinal stenosis. Conclusion There are clear differences in both therapeutic sustainability and intended clinical effect of ILS compared to posterolateral fusion with pedicle screw fixation after decompression for spinal stenosis. There are CCS differences between coflex and fusion cohorts noted at four years post-op similar to the trends revealed in the two year data used for PMA approval. When therapeutic sustainability outcomes are added to the CCS, ILS is proven to be a sustainable treatment for stabilization of the vertebral motion segment after decompression for lumbar spinal stenosis.