The Presence of Biofilms in Instrumented Spinal Fusions.

Study Design: Prospective observational cohort study. Objective: To determine whether biofilms exist on spinal instrumentation recovered during revision surgery in which microbial cultures were negative. Background: Biofilm bacteria are extremely difficult to detect by conventional culture methods used in the standard hospital setting. Chronic infections in which bacteria form biofilms have been demonstrated to slow healing and prevent bony fusion. These slime encased microbial communities serve to isolate the bacteria from the body's immune responses, while simultaneously providing metabolic resistance to antimicrobial therapy. Methods: Traditional debridement wound cultures were taken from each specimen and sent for microbiological analyses. Bacterial DNA testing was performed using polymerase chain reaction (PCR) electrospray ionization-mass spectrometry (ESI-MS). Based on the PCR/ESI-MS results, specific crossed immune electrophoresis was used to detect the bacterial species within biofilms observed on the removed instrumentation. In addition, fluorescent in situ hybridization (FISH) probes corresponding to the bacterial species identified by PCR/ESI-MS were used with confocal microscopy to visualize and confirm the infecting bacteria. Results: Fifteen patients presented for surgical revision of thoracolumbar spinal implantation: four for clinical suspicion of infection, six for adjacent segment disease (ASD), one with ASD and pseudoarthrosis (PA), three with PA, and one for pain. Infections were confirmed with PCR/ESI-MS for all four patients who presented with clinical infection, and for five of the patients for whom infection was not clinically suspected. Of the presumed non-infected implants, 50% demonstrated the presence of infectious biofilms. Half of the revisions due to pseudoarthrosis were shown to harbour biofilms. The revisions that were performed for pain demonstrated robust biofilms but did not grow bacteria on traditional culture media. Conclusions: Culture is inadequate as a diagnostic modality to detect indolent/subclinical biofilm infections of spinal instrumentation. The PCR/ESI-MS results for bacterial detection were confirmed using species-specific microscopic techniques for both bacterial nucleic acids and antigens. Biofilms may contribute to pseudoarthrosis and back pain in postoperative wounds otherwise considered sterile.

Vagal Nerve Stimulation: Indications for Revision in Adult Refractory Epilepsy.

OBJECTIVE: The goal of this study was to assess the indications of revision for vagal nerve stimulation at a single institution in an adult population with drug-resistant epilepsy. METHODS: This was a retrospective review of a prospectively collected database who underwent vagal nerve stimulator implantation for drug-resistant epilepsy during 1992-2017. Patients receiving vagal nerve stimulation (VNS) implants were monitored throughout their perioperative and postoperative course and were classified according to type of seizure at the time of diagnosis and indications for VNS revision. In addition, response to dysfunctional VNS devices or adverse effects were noted. RESULTS: Most patients receiving VNS implants were given a diagnosis of complex partial seizures (CPSs) before implantation (95.1%). Other epileptic conditions identified requiring implantation included generalized seizures, generalized-atonic seizures, Lennox-Gastaut syndrome, CPS or generalized seizures, and tuberous sclerosis (with generalized characteristics). High lead impedance was the most common indication for revision (5.6%), whereas device ineffectiveness leading to continued seizures was the most common indication for removal (2.3%). Infection, lead fracture, and dual- to single-pin lead battery changes occurred at an incidence of 1.9%, requiring either implant removal or revision. Other events that occurred, albeit rarely, included skin extrusion (0.5%), postoperative hematoma (0.5%), and implant rejection (0.5%) necessitating removal. CONCLUSIONS: VNS implantation in adults was shown to be a well-tolerated procedure. In addition, indications for revision or removal of the VNS device was low in this population with lead fracture rates lower than the incidence reported in pediatric population literature.

Spinal Cord Stimulator Explantation: Motives for Removal of Surgically Placed Paddle Systems.

BACKGROUND: Despite requiring successful trials prior to implantation, spinal cord stimulation (SCS) systems for pain are often later removed. Removing surgically implanted hardware subjects patients to the risks and discomfort of a second surgery, threatens the cost-effectiveness of SCS, and limits the perceived durability of SCS technology for pain problems. OBJECTIVE: To investigate patterns of reasons given among patients who underwent SCS explant surgery (SCSES). METHODS: Retrospective review of SCSES cases over 17 years at Allegheny General Hospital, Pittsburgh, PA. RESULTS: 165 patients underwent SCSES between 1997 and 2014. The top 3 reasons for explantation were inadequate pain control (IPC; 73%), hardware discomfort (22%), and need for magnetic resonance imaging (MRI) (10%). Other less frequent reasons were infection (9%), painful dysesthesias (9%), electrical arcing (4%), resolution of inciting symptoms (4%), weakness (2%), pseudomeningocele (1%) and muscle spasms (1%). CONCLUSION: Inadequate pain control is the most common reason for SCSES. Advances in technology are needed to improve the quality and duration of pain control, as well as to design improvements to make the hardware more comfortable. A significant number of implants are removed due to need for MRI, a fact obviating the need for MRI-compatible systems. Patients considering SCS paddle lead placement should be counseled on the most common reasons for later explantation.

Disease Stabilization of DYT1-Positive Primary Generalized Dystonia With Deep Brain Stimulation of the Globus Pallidus Interna: A 15-Year Follow-up.

BACKGROUND AND IMPORTANCE: Primary generalized dystonia (PGD) is a genetic form of dystonia that frequently displays pharmacological resistance and progresses quickly after onset. Deep brain stimulation (DBS) has been used successfully to treat refractory dystonia, specifically globus pallidus interna (GPi) DBS for DYT1-positive PGD patients. Long-term follow-up of the safety and efficacy falls short of the longevity seen in other diseases treated with DBS. CASE PRESENTATION: A male patient presented for neurosurgical evaluation with scapular winging, hand contractures, and violent truncal spasms, which forced him to be bedridden. After failing conservative therapy, the 18-yr-old patient was implanted with bilateral GPi-DBS. DBS parameter adjustments were made primarily within the first 3 yr after implantation, with nominal changes thereafter. Initial settings were contact of 3 + 0-, amplitude of 4.9 V, frequency of 185 Hz, and pulse width of 270 µsec on the left and 3 + 0-, 2.8 V, 185 Hz, and 120 µsec on the right. Current settings are 3 + 2 + 1-, 5.2 V, 130 Hz, 330 µsec on the left and 3 + 0-, 3.5 V, 185 Hz, and 180 µsec on the right and have been relatively unchanged in the past 4 yr. Unified dystonia rating scale scores reveal a significant decrease in dystonic symptoms. CONCLUSION: While prior reports have shown that GPi-DBS is effective for dystonia, this is the first with 15 yr of long-term follow-up showing disease stabilization, suggesting that stimulation is efficacious and can potentially prevent disease progression. This report reaffirms previous reports that recommend early surgical intervention before the onset of permanent musculoskeletal deficits.

Disc nucleus fortification for lumbar degenerative disc disease: a biomechanical study.

OBJECTIVE Spinal stability is attributed in part to osteoligamentous structures, including the vertebral body, facets, intervertebral discs, and posterior elements. The materials in this study provide an opportunity to augment the degenerated nucleus without removing native disc material, a procedure introduced here as "fortification." The objective of this study was to determine the effect of nucleus fortification on lumbar disc biomechanics. METHODS The authors performed in vitro analysis of human cadaveric functional spinal units (FSUs), along with characterization and quantification of movement of the units using biomechanical data in intact, disc-only, and fortified specimens. The units underwent removal of all posterior elements and annulus and were fortified by injecting a biogel into the nucleus pulposus. Each specimen was subjected to load testing, range of motion (ROM) quantification, and disc bulge measurements. Optoelectric tracking was used to quantify disc bulge. These criteria were assessed in the intact, disc-only, and fortified treatments. RESULTS Disc-only FSUs resulted in increased ROM when compared with intact and fortified conditions. Fortification of the FSU resulted in partial restoration of normal ROM in the treatment groups. Analysis of hysteresis loops showed more linear response in the fortified groups when compared with the intact and disc-only groups. CONCLUSIONS Disc nucleus fortification increases linearity and decreases ROM.

Anterior lumbar interbody fusion with integrated fixation and adjunctive posterior stabilization: A comparative biomechanical analysis.

BACKGROUND: Interbody fusion cages with integrated fixation components have become of interest due to their ability to provide enhanced post-operative stability and mitigate device migration. A recently approved anterior lumbar interbody fusion cage with integrated fixation anchors has yet to be compared in vitro to a standard polyetheretherketone cage when used in combination with an interspinous process clamp. METHODS: Twelve human cadaveric lumbar segments were implanted at L4-L5 with a Solus interbody cage (n=6) or standard polyetheretherketone cage (n=6) following Intact testing and discectomy. Each cage was subsequently evaluated in all primary modes of loading after supplementation with the following posterior constructs: interspinous process clamp, bilateral transfacet screws, unilateral transfacet screw with contralateral pedicle screws, and bilateral pedicle screws. Range of motion results were normalized to Intact, and a two-way mixed analysis of variance was utilized to detect statistical differences. FINDINGS: The Solus cage in combination with all posterior constructs provided significant fixation compared to Intact in all loading conditions. The polyetheretherketone cage also provided significant fixation when combined with all screw based treatments, however when used with the interspinous process clamp a significant reduction was not observed in lateral bending or axial torsion. INTERPRETATION: Interbody cages with integrated fixation components enhance post-operative stability within the intervertebral space, thus affording clinicians the potential to utilize less invasive methods of posterior stabilization when seeking circumferential fusion. Interspinous process clamps, in particular, may reduce peri-operative and post-operative comorbidities compared to screw based constructs. Further study is necessary to corroborate their effectiveness in vivo.

Deep brain stimulation for obesity: past, present, and future targets.

The authors review the history of deep brain stimulation (DBS) in patients for treating obesity, describe current DBS targets in the brain, and discuss potential DBS targets and nontraditional stimulation parameters that may improve the effectiveness of DBS for ameliorating obesity. Deep brain stimulation for treating obesity has been performed both in animals and in humans with intriguing preliminary results. The brain is an attractive target for addressing obesity because modulating brain activity may permit influencing both sides of the energy equation--caloric intake and energy expenditure.