Feasibility and performance of a frameless stereotactic system for targeting subcortical nuclei in nonhuman primates.

OBJECTIVE: Deep brain stimulation (DBS) is an effective therapy for different neurological diseases, despite the lack of comprehension of its mechanism of action. The use of nonhuman primates (NHPs) has been historically important in advancing this field and presents a unique opportunity to uncover the therapeutic mechanisms of DBS, opening the way for optimization of current applications and the development of new ones. To be informative, research using NHPs should make use of appropriate electrode implantation tools. In the present work, the authors report on the feasibility and accuracy of targeting different deep brain regions in NHPs using a commercially available frameless stereotactic system (microTargeting platform). METHODS: Seven NHPs were implanted with DBS electrodes, either in the subthalamic nucleus or in the cerebellar dentate nucleus. A microTargeting platform was designed for each animal and used to guide implantation of the electrode. Imaging studies were acquired preoperatively for each animal, and were subsequently analyzed by two independent evaluators to estimate the electrode placement error (EPE). The interobserver variability was assessed as well. RESULTS: The radial and vector components of the EPE were estimated separately. The magnitude of the vector of EPE was 1.29 ± 0.41 mm and the mean radial EPE was 0.96 ± 0.63 mm. The interobserver variability was considered negligible. CONCLUSIONS: These results reveal the suitability of this commercial system to enhance the surgical insertion of DBS leads in the primate brain, in comparison to rigid traditional frames. Furthermore, our results open up the possibility of performing frameless stereotaxy in primates without the necessity of relying on expensive methods based on intraoperative imaging.

Kinematic Metrics from a Wireless Stylus Quantify Tremor and Bradykinesia in Parkinson's Disease.

A fundamental challenge in the clinical care of Parkinson disease (PD) is the current dependence on subjective evaluations of tremor and bradykinesia. New technologies offer the ability to evaluate motor deficits using purely objective measures. The aim of this study was to develop and evaluate the efficacy of a wireless stylus (Cleveland Clinic Stylus) with an embedded motion sensor to quantitatively assess tremor and bradykinesia in patients with PD with subthalamic nucleus (STN) deep brain stimulation (DBS). Twenty-one subjects were tested in various on and off DBS conditions while holding the Cleveland Clinic Stylus while at rest, maintaining a postural hold, and during a movement task. Kinematic metrics were calculated from the motion sensor data, including 3D angular velocity and 3D acceleration data, and were compared between the on and off conditions. Generalized estimating equations (GEEs) were used to determine the relationship between kinematic metrics and MDS-Unified Parkinson's Disease Rating Scale Motor III (UPDRS-III) subscores. Kinematic metrics from the rest and postural tasks were significantly related to the UPDRS-III subscores of tremor (p < 0.001 for all metrics), and kinematic metrics from the movement task were significantly related to the UPDRS-III subscore of bradykinesia (p < 0.001 for 3/7 metrics). Kinematic metrics (7/9) showed a significant effect of stimulation setting (range: p < 0.03- < 0.0001) across the three tasks, indicating significant improvements from DBS in these measures. The Cleveland Clinic Stylus provided quantitative kinematic measures of tremor and bradykinesia severity and detected significant improvements in these measures from medication and DBS therapy. This low-cost, easy-to-use tool can provide objective measures that will improve clinical care of PD patients by providing a more reliable and objective evaluation of movement symptoms, disease progression, and effects of therapy in and outside the clinical setting.

The Role of Additional Spine Surgery in the Management of Failed Back Surgery Syndrome, Complex Regional Pain Syndrome, and Intractable Pain in the Setting of Previous or Concurrent Spinal Cord Stimulation: Indications and Outcomes.

OBJECTIVE: Spinal cord stimulation (SCS) is both relatively safe and reversible. Although SCS is generally regarded as a last resort, some of these patients will undergo additional spinal surgery after the device has been implanted or after its removal. We present a descriptive study of subsequent spinal surgery after SCS implantation. METHODS: A retrospective review of patients who had undergone percutaneous or paddle SCS lead placement at our institution from 2009 to 2016 was performed. Patients who had only undergone trials or who had not undergone spine surgery after SCS implantation were excluded. RESULTS: We identified 22 patients (5.7%) who had undergone spine surgery during the course of SCS treatment or after SCS removal, or both, of a total 383 patients who had undergone paddle and/or percutaneous SCS implantation. The most common additional spine interventions included lumbosacral decompression and fusion (n = 15; 42%). Of 36 surgeries, the most frequent indications for subsequent intervention were stenosis or restenosis (n = 16; 73%) and spine deformity (n = 6; 27%). The median EuroQol-5D index was 0.397 preoperatively and 0.678 postoperatively. CONCLUSIONS: To the best of our knowledge, the present study is the first to describe spine surgery in the setting of SCS implantation. Our results have indicated that spine surgery subsequent to, or concurrent with, SCS implantation appears to occur in few patients. Our study results suggest a modest improvement in quality of life outcomes. Therefore, clinicians should remember that patients might require further spine surgery despite the use of SCS implantation and, thus, might require reevaluation by the spine team.

Outcomes following deep brain stimulation lead revision or reimplantation for Parkinson's disease.

OBJECTIVEThe number of patients who benefit from deep brain stimulation (DBS) for Parkinson's disease (PD) has increased significantly since the therapy was first approved by the FDA. Suboptimal outcomes, infection, or device failure are risks of the procedure and may require lead removal or repositioning. The authors present here the results of their series of revision and reimplantation surgeries.METHODSThe data were reviewed from all DBS intracranial lead removals, revisions, or reimplantations among patients with PD over a 6-year period at the authors' institution. The indications for these procedures were categorized as infection, suboptimal outcome, and device failure. Motor outcomes as well as lead location were analyzed before removal and after reimplant or revision.RESULTSThe final sample included 25 patients who underwent 34 lead removals. Thirteen patients had 18 leads reimplanted after removal. There was significant improvement in the motor scores after revision surgery among the patients who had the lead revised for a suboptimal outcome (p = 0.025). The mean vector distance of the new lead location compared to the previous location was 2.16 mm (SD 1.17), measured on an axial plane 3.5 mm below the anterior commissure-posterior commissure line. When these leads were analyzed by subgroup, the mean distance was 1.67 mm (SD 0.83 mm) among patients treated for infection and 2.73 mm (SD 1.31 mm) for those with suboptimal outcomes.CONCLUSIONSPatients with PD who undergo reimplantation surgery due to suboptimal outcome may experience significant benefits. Reimplantation after surgical infection seems feasible and overall safe.

Disseminated cerebral toxoplasmosis in a patient with chronic lymphocytic leukemia.

Infections are one of the most common causes of mortality in immunocompromised patients. In patients diagnosed with hematologic malignancies, treatment with stem cell transplants (SCT) or T-cell suppressing chemotherapy increases the risk of central nervous system (CNS) infections, of which toxoplasmosis is the most common. We report the case of a 63 year-old woman with chronic lymphocytic leukemia (CLL) that presented with gait instability and visual changes. Intracranial lesions were noted on initial neuro-imaging. A rapid decline in the patient's mental status warranted an urgent biopsy of the lesions that revealed tachyzoites consistent with toxoplasmosis. In the presence of diffuse brain lesions that lack a metastatic pattern or contrast enhancement, a common approach is to perform biopsy only after a battery of non-invasive testing. This diagnostic delay may take several days, exposing the patient to a rapidly fatal infection. This report illustrates the utility of early brain biopsy in high-risk patients with hematologic malignancies and CNS lesions.

Rate of Complications Following Spinal Cord Stimulation Paddle Electrode Removal.

OBJECTIVE: Spinal cord stimulation (SCS) is a safe, reversible surgical treatment for complex regional pain syndrome and failed back surgery syndrome refractory to conventional medical management. Paddle electrodes are routinely used for the permanent implant because of the reduced risk of migration, lower energy requirements, and expanded coverage options. The risks associated with paddle lead removal are not well defined in the literature. METHODS: We retrospectively reviewed the outcomes of all patients at the Cleveland Clinic who underwent removal of SCS paddle electrodes between 2009 and 2016. RESULTS: We identified 68 patients during this interval who had a paddle electrode removed. The most common reason for removal was loss of coverage or effect (75%), followed by infection (13.24%), and the need for magnetic resonance imaging for diagnostic purposes (8.82%). Postoperative complications occurred in eight patients (11.75%), two of which were classified as major (2.94%). One of these patients developed a postoperative cerebrospinal fluid leak, and another suffered a large suprafascial hematoma. Both patients underwent reoperation. Minor complications were reported in six patients (8.82%) and included wound dehiscence, infection, and prolonged ileus in one case. On average, patients who developed complications lost 20 mL more blood during surgery than those who did not develop complications (p = 0.006). CONCLUSION: One of the benefits of SCS therapy is the reversibility of the procedure. However, removal is not without some risk though the overall risk of minor or major complication is low. Patients who are considering removal should be counseled appropriately. Prophylactic removal is not recommended. However, when removal is needed, surgeons and pain specialists must be familiar with these complications and their management.

The Safety and Efficacy of Using the O-Arm Intraoperative Imaging System for Deep Brain Stimulation Lead Implantation.

INTRODUCTION: Accurate electrode implantation is a major goal of deep brain stimulation (DBS) surgery. Intraoperative physiology with microelectrode recording (MER) is routinely used to refine stereotactic accuracy during awake electrode implantation. Recently, portable imaging systems such as the O-arm have become widely available and can be used in isolation or in association with MER to guide DBS lead placement. The aim of this study was to evaluate how the routine use of the O-arm affected DBS surgery safety, efficiency, and outcomes. METHODS: Two cohorts of patients with Parkinson's disease who underwent MER-guided awake subthalamic DBS lead implantation with and without O-arm were compared. We examined the total number of microelectrode and macroeletrode passes during each surgery, procedure duration, surgical complications, lead revisions, and motor outcomes. RESULTS: A total of 50 procedures in 41 unique patients were analyzed, of which 26 were performed without O-arm and 24 performed without the O-arm. The mean number of microelectrode passes was 2.46 (SD = 0.99) in the group without O-arm utilization, compared to 1.29 (SD = 0.75) in the group with O-arm usage (p < 0.001). A significant reduction was also found in procedure duration (p = 0.016). No differences were found in motor outcomes between groups. CONCLUSION: The use of the O-arm during DBS lead implantation was associated with significantly fewer brain cannulations for microelectrode recording as well as reduced surgical time.

Subsequent Pulse Generator Replacement Surgery Does Not Increase the Infection Rate in Patients With Deep Brain Stimulator Systems: A Review of 1537 Unique Implants at a Single Center.

INTRODUCTION: Deep brain stimulation (DBS) is a well-recognized treatment for patients with movement disorders and other neurological diseases. The implantable pulse generator (IPG) is a fundamental component of the DBS system. Although IPG implantation and replacement surgeries are comparatively minor procedures relative to the brain lead insertion, patients often require multiple IPG replacements during their lifetime with each operation carrying a small but possibly cumulative risk of complications. To better educate our patients and improve surgical outcomes, we reviewed our series of patients at our institution. METHODS: Using electronic health record data, we retrospectively reviewed all initial and subsequent IPG surgeries from patients who underwent at least one IPG surgery between the years of 2010 and 2015 at the Cleveland Clinic main campus. We calculated infection rates for initial IPG implantation surgeries and the infection rate for subsequent replacements. Fisher's exact tests were used to evaluate the chance of an infection between the initial implantation and replacement. Fisher's exact tests and simple logistic regression analyses were used to determine the predictive ability of selected demographic and clinical variables RESULTS: Our final sample included 697 patients and 1537 surgeries. For all patients, the infection rate at the first surgery was 2.01%; at the second surgery, it was 0.44%; and at the third surgery, it was 1.83%. When considering only patients that underwent at least three replacement surgeries (n = 114) the infection rate did not change in a significant manner with subsequent interventions compared to the first replacement. No other variable of interest was a significant predictor of infection. CONCLUSION: We did not find increasing rates of infection with subsequent IPG replacement procedures.

Polyetheretherketone (PEEK) intervertebral cage as a cause of chronic systemic allergy: a case report.

BACKGROUND CONTEXT: Polyetheretherketone (PEEK) is an organic polymer thermoplastic with strong mechanical and chemical resistance properties. It has been used in industry to fabricate items for demanding applications such as bearings, piston parts, compressor plate valves, and cable insulation. Since the early 1980s, polyetheretherketone polymers have been increasingly used in orthopedic and spinal surgery applications. Numerous studies and years of clinical experience have confirmed the biocompatibility of this material. PURPOSE: The purpose of the study was to report a case of chronic systemic allergy after anterior cervical decompression and fusion (ACDF) and implantation of an intervertebral PEEK cage, with resolution of symptoms after removal of PEEK cage. STUDY DESIGN/SETTING: This study is a case report with clinical evidence for allergy to PEEK. METHODS: The methods involve clinical findings and review of current literature. RESULTS: After ACDF and implantation of an intervertebral PEEK cage, the patient had developed an angioedema-like picture marked by severe redness, itching, swelling of his tongue, and skin thickening. A skin patch test was positive for PEEK. Removal of the implant resulted in the resolution of his allergy symptoms shortly after surgery. CONCLUSIONS: Tissue reactions to PEEK are extremely rare. Herein, we present the first report of a chronic allergic response to interbody PEEK material.