Early Experience With New Generation Deep Brain Stimulation Leads in Parkinson's Disease and Essential Tremor Patients.

BACKGROUND: Newer generation deep brain stimulation (DBS) systems have recently become available in the United States. Data on real-life experience are limited. We present our initial experience incorporating newer generation DBS with Parkinson's disease (PD) and essential tremor (ET) patients. Newer systems allow for smart energy delivery and more intuitive programming and hardware modifications including constant current and directional segmented contacts. METHODS: We compared six-month outcomes between 42 newer generation and legacy leads implanted in 28 patients. Two cohorts each included 7 PD patients with bilateral subthalamic nucleus (STN) stimulation and 7 ET patients with unilateral ventral intermediate nucleus (VIM) stimulation of the thalamus. All directional leads included 6172 Infinity 8-Channel Directional leads and Infinity internal pulse generators (Abbott Neuromodulation, Plano, TX, USA) and nondirectional leads included lead 3389 with Activa SC for VIM and PC for STN (Medtronic, Minneapolis, MN, USA). RESULTS: Six-month outcomes for medication reduction and motor score improvements between new and legacy DBS systems in PD and ET patients were similar. Directionality was employed in 1/3 of patients. Therapeutic window (difference between amplitude when initial symptom relief was obtained and when intolerable side effects appeared with the contact being used) was significantly greater in new DBS systems in both PD (p = 0.005) and ET (p = 0.035) patients. The windows for new and legacy systems were 3.60 V ± 0.42 and 2.00 V ± 0.32 for STN and 3.06 V ± 0.44 and 1.85 V ± 0.28 for VIM, respectively. DISCUSSION: The therapeutic window of newer systems, whether or not directionality was used, was significantly greater than that of the legacy system, which suggests increased benefit and programming options. Improvements in hardware and programming interfaces in the newer systems may also contribute to wider therapeutic windows. We expect that as we alter workflow associated with newer technology, more patients will use directionality, and amplitudes will become lower.

Use of Functional Magnetic Resonance Imaging to Assess How Motor Phenotypes of Parkinson's Disease Respond to Deep Brain Stimulation.

BACKGROUND: Deep brain stimulation (DBS) is a well-accepted treatment of Parkinson's disease (PD). Motor phenotypes include tremor-dominant (TD), akinesia-rigidity (AR), and postural instability gait disorder (PIGD). The mechanism of action in how DBS modulates motor symptom relief remains unknown. OBJECTIVE: Blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) was used to determine whether the functional activity varies in response to DBS depending on PD phenotypes. MATERIALS AND METHODS: Subjects underwent an fMRI scan with DBS cycling ON and OFF. The effects of DBS cycling on BOLD activation in each phenotype were documented through voxel-wise analysis. For each region of interest, ANOVAs were performed using T-values and covariate analyses were conducted. Further, a correlation analysis was performed comparing stimulation settings to T-values. Lastly, T-values of subjects with motor improvement were compared to those who worsened. RESULTS: As a group, BOLD activation with DBS-ON resulted in activation in the motor thalamus (p < 0.01) and globus pallidus externa (p < 0.01). AR patients had more activation in the supplementary motor area (SMA) compared to PIGD (p < 0.01) and TD cohorts (p < 0.01). Further, the AR cohort had more activation in primary motor cortex (MI) compared to the TD cohort (p = 0.02). Implanted nuclei (p = 0.01) and phenotype (p = <0.01) affected activity in MI and phenotype alone affected SMA activity (p = <0.01). A positive correlation was seen between thalamic activation and pulse-width (p = 0.03) and between caudate and total electrical energy delivered (p = 0.04). CONCLUSIONS: These data suggest that DBS modulates network activity differently based on patient motor phenotype. Improved understanding of these differences may further our knowledge about the mechanisms of DBS action on PD motor symptoms and to optimize treatment.

On the (Non-)equivalency of monopolar and bipolar settings for deep brain stimulation fMRI studies of Parkinson's disease patients.

BACKGROUND: The majority of Parkinson's disease patients with deep brain stimulation (DBS) use a monopolar configuration, which presents challenges for EEG and MRI studies. The literature reports algorithms to convert monopolar to bipolar settings. PURPOSE/HYPOTHESIS: To assess brain responses of Parkinson's disease patients implanted with DBS during fMRI studies using their clinical and presumed equivalent settings using a published conversion recipe. STUDY TYPE: Prospective. SUBJECTS: Thirteen DBS patients. FIELD STRENGTH/SEQUENCE: 1.5T and 3T, fMRI using gradient echo-planar imaging. ASSESSMENT: Patients underwent 30/30sec ON/OFF DBS fMRI scans using monopolar and bipolar settings. To convert to a bipolar setting, the negative contact used for the monopolar configuration remained constant and the adjacent dorsal contact was rendered positive, while increasing the voltage by 30%. fMRI activation/deactivation maps and motor Unified Parkinson's Disease Rating Scale (UPDRS-III) scores were compared for patients in both configurations. STATISTICAL TESTS: T-tests were used to compare UPDRS scores and volumes of tissue activated (VTA) diameters in monopolar and bipolar configurations. RESULTS: The patterns of fMRI activation in the monopolar and bipolar configurations were generally different. The thalamus, pallidum, and visual cortices exhibited higher activation using the patient's clinical settings than the presumed equivalent settings. VTA diameters were lower (7 mm vs. 6.3 mm, P = 0.047) and UPDRS scores were generally higher in the bipolar (33.2 ± 16) than in the monopolar configuration (28.3 ± 17.4), without reaching statistical significance (P > 0.05). DATA CONCLUSION: Monopolar and bipolar configurations result in different patterns of brain activation while using a previously published monopolar-bipolar conversion algorithm. Clinical benefits may be achieved with varying patterns of brain responses. Blind conversion from one to the other should be avoided for purposes of understanding the mechanisms of DBS. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018.

A Novel Approach to Avoid Baclofen Withdrawal When Faced With Infected Baclofen Pumps.

BACKGROUND: Intrathecal (IT) Baclofen is beneficial for spasticity, but if pumps become infected necessitating removal, baclofen withdrawal is difficult to manage and life-threatening. Furthermore there is no consistency between dosing and severity of withdrawal. Case reports detail full baclofen withdrawal at dosages of 260 µg/day. OBJECTIVE: To demonstrate that in patients on stable IT baclofen for prolonged periods, externalizing a patient's original IT pump is a safe, effective way to wean IT doses. METHODS: Here, we describe a technique of continuing IT baclofen when urgent pump removal is needed. Specifically, we remove the infected pump. Then using a new or existing lumbar drain based on extent of infection, we reconnect the pump after cleaning with betadine and administer therapy externally during IT weaning. RESULTS: Hundred forty seven baclofen pumps were implanted or replaced within four years. Infections occurred in seven patients. We utilized this technique in five of seven patients. Mean IT dose at time of explant was 400.5 ± 285.3 µg/day. We titrated the dose by 20-50% per day based on clinical response over a mean of 6.2 ± 1.3 days. The catheter was removed at bedside once weaning was complete. No patients had any signs of withdrawal, excluding minimal spasticity increases while optimizing oral treatment. CONCLUSION: Here, we show preliminary evidence that an externalized IT pump is an effective means of weaning IT baclofen when infection of the pump occurs. This treatment strategy warrants further investigation, but appears to be a safe and effective. CONFLICT OF INTEREST: Dr. Pilitsis is a consultant for Medtronic, Boston Scientific, Nevro, Jazz Pharmaceuticals, Neurobridge Therapeutics, and Abbott and receives grant support from Medtronic, Boston Scientific, Abbott, Nevro, Jazz Pharmaceuticals, GE Global Research and NIH 1R01CA166379. She is medical advisor for Centauri and Karuna and has stock equity. Dr. Sukul receives consultant fees from Medtronic. Julia Prusik receives grant support from Jazz Pharmaceuticals.

Duloxetine Improves Spinal Cord Stimulation Outcomes for Chronic Pain.

OBJECTIVE: Spinal cord stimulation (SCS) has been shown to be effective in treating chronic pain in patients with varying etiologies. However, the impact of pharmacological treatment on augmenting response to SCS has not been previously studied. METHODS: We enrolled 108 patients who had undergone SCS surgery and documented their pain preoperatively and at 12 months postoperatively using the Numeric Rating Scale (NRS), McGill Pain Questionnaire (MPQ), Beck Depression Inventory (BDI), Oswestry Disability Index (ODI), Pain Catastrophizing Scale (PCS), and Global Impression of Change (GIC). Pain outcomes were compared between patients receiving SCS alone and in addition to duloxetine. RESULTS: At 1-year follow-up, patients receiving duloxetine and SCS (n = 41) had better pain relief in the affective component of MPQ (p < 0.05) than those receiving SCS alone (n = 71). Patients on duloxetine with SCS also were significantly more willing to receive SCS again (p < 0.01). This willingness appeared to be duloxetine dose dependent (p < 0.05). Patients receiving pregabalin or gabapentin with SCS did not have significantly more pain relief than patients receiving SCS alone. CONCLUSION: This study shows the combination therapy to be an effective strategy to provide more holistic pain relief and further improve the quality of life of SCS patients.

Use of a Psychological Evaluation Tool as a Predictor of Spinal Cord Stimulation Outcomes.

INTRODUCTION: Preoperative work-up for spinal cord stimulation (SCS) includes a psychological assessment; however, no one psychological factor has correlated with poor outcomes across studies. We developed a Psychological Evaluation Tool for Spinal Cord Stimulation Candidacy (PETSCSC), which includes all factors in the literature found to correlate with outcomes. In this study, we examine whether PETSCSC correlates with postoperative outcomes. METHODS: Patients undergoing SCS were prospectively enrolled in this study. PETSCSC scores were obtained preoperatively. Numeric rating scale (NRS), global impression of change (GIC), pain catastrophizing scale (PCS), McGill pain questionnaire (MPQ), Oswestry disability index (ODI), and Beck Depression Inventory were assessed preoperatively and postoperatively. Outcomes were correlated with PETSCSC scores. RESULTS: Thirty-four SCS patients had a mean follow-up of 9.88 ± 2.91 months. At latest follow-up, we observed significant improvement in NRS, PCS, MPQ, and ODI. Total PETSCSC score exhibited significant correlation with GIC (p = 0.026, r = 0.380) and improvement in PCS total (p = 0.041, r = 0.351), and MPQ affective (p = 0.002, r = 0.517) scores. The PETSCSC emotive subset significantly correlated with GIC (p = 0.020, r = 0.395). The PETSCSC depression subset significantly correlated with improvement in PCS rumination (p = 0.009, r = 0.439), PCS helplessness (p = 0.021, r = 0.393), PCS total (p = 0.021, r = 0.394), and MPQ affective (p = 0.002, r = 0.501). The PETSCSC therapy subset significantly correlated with improvement in MPQ sensory (p = 0.026, r = -0.381) and MPQ affective (p < 0.001, r = 0.583). DISCUSSION: PETSCSC scores and subscores demonstrate significant correlation with pain outcomes used in assessment of SCS efficacy. Higher PETSCSC scores correlate with greater improvement in GIC, MPQ affective, and PCS scores. Stratification of these patients based on PETSCSC total and subset scores could help with prognostication.

EKG-based detection of deep brain stimulation in fMRI studies.

PURPOSE: To assess the impact of synchronization errors between the assumed functional MRI paradigm timing and the deep brain stimulation (DBS) on/off cycling using a custom electrocardiogram-based triggering system METHODS: A detector for measuring and predicting the on/off state of cycling deep brain stimulation was developed and tested in six patients in office visits. Three-electrode electrocardiogram measurements, amplified by a commercial bio-amplifier, were used as input for a custom electronics box (e-box). The e-box transformed the deep brain stimulation waveforms into transistor-transistor logic pulses, recorded their timing, and propagated it in time. The e-box was used to trigger task-based deep brain stimulation functional MRI scans in 5 additional subjects; the impact of timing accuracy on t-test values was investigated in a simulation study using the functional MRI data. RESULTS: Following locking to each patient's individual waveform, the e-box was shown to predict stimulation onset with an average absolute error of 112 ± 148 ms, 30 min after disconnecting from the patients. The subsecond accuracy of the e-box in predicting timing onset is more than adequate for our slow varying, 30-/30-s on/off stimulation paradigm. Conversely, the experimental deep brain stimulation onset prediction accuracy in the absence of the e-box, which could be off by as much as 4 to 6 s, could significantly decrease activation strength. CONCLUSIONS: Using this detector, stimulation can be accurately synchronized to functional MRI acquisitions, without adding any additional hardware in the MRI environment. Magn Reson Med 79:2432-2439, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Efficacy of Alternating Conventional Stimulation and High Frequency Stimulation in Improving Spinal Cord Stimulation Outcomes: A Pilot Study.

INTRODUCTION: Spinal cord stimulation (SCS) is an established, effective method of treating chronic pain. High frequency stimulation (HFS) is an alternative SCS waveform that has been shown to alleviate pain but also necessitates more frequent recharging. The purpose of this pilot study is to evaluate efficacy of alternating conventional stimulation and HFS (termed "shuffle" stimulation) in improving SCS outcomes. METHODS: Shuffle stimulation was designed to deliver conventional stimulation in upright positions with relative HFS in lying positions, automated through accelerometer technology. In this 13-week cross-over study, patients were randomized to receiving conventional and shuffle stimulation in four-week blocks. Pain outcomes and sensory testing were compared from preoperative baseline and at the conclusion of each study period. RESULTS: Twelve patients completed this study. Two patients showed no change from baseline visual analogue scale (VAS) with either type of stimulation and were excluded from statistical analysis of pain outcomes. Mean numerical rating scale (NRS) scores assessing current pain were significantly lower in shuffle stimulation (4.0 ± 1.6) compared to conventional stimulation (5.8 ± 2.3) (p = 0.024). In the total cohort, 7 of 11 patients preferred shuffle over conventional stimulation. CONCLUSIONS: This study generated preliminary evidence showing improved NRS current pain scores in shuffle stimulation compared to conventional stimulation. More patients preferred shuffle stimulation compared to conventional stimulation. Optimizing stimulation when patients are recumbent may increase patient satisfaction and pain control. The potential advantages of shuffle stimulation may warrant further investigation.

Pain Remission at One-Year Follow-Up With Spinal Cord Stimulation.

OBJECTIVES: Spinal Cord Stimulation (SCS) is an effective treatment for chronic pain. How often pain remission follows SCS has not been evaluated. This is a retrospective analysis of patients who underwent an implantation of spinal cord stimulators for various chronic pain conditions. The objective of the study was to elucidate characteristics and features of patients with pain relief greater than 80% after one year of treatment. METHODS: A total of 86 patients with thoracic SCS and 12-month follow-up data were identified. Patients were divided into a remission group (>80% improvement in Numeric Pain Rating Scale [NRS] pain scale), average responders (20-80% improvement) and a non-responder group (less than 20% improvement). These patient groups were compared via the following outcome measures: NRS, Oswestry Disability Index (ODI), Pain Catastrophizing Scale (PCS), McGill Pain Questionnaire (MPQ), and Insomnia Severity Index (ISI). Correlations with age, body mass index (BMI), tobacco and alcohol usage, patient satisfaction with SCS, disability status, and opioid usage were assessed. RESULTS: Nineteen of 86 patients (22%) were remitters at one year follow-up, including 17 patients who had an NRS = 0 at that time. Upon analyzing the three patient groups (non-responders, average responders, and remitters), remitter patients showed the greatest change over the one-year post-operative period in ODI (F(2) = 8.101, p < 0.01) and PCS (F(2) = 7.607, p < 0.01). Moreover, remission was less likely when the patients were on disability prior to implant (χ2 (2) = 6.469, p < 0.05) and on opioids pre-operatively (χ2 (2) = 17.688, p < 0.01). CONCLUSIONS: Our study demonstrates a remission rate of 22% with SCS at one-year follow with a total of 19.8% of our total patient cohort having an NRS of 0. Greater decreases in PCS and ODI correlate with remission. Further, pre-operative disability and opioid use correlate with lower likelihood of remission.

King's Parkinson's Disease Pain Scale for Assessment of Pain Relief Following Deep Brain Stimulation for Parkinson's Disease.

OBJECTIVE: Pain is a prevalent and debilitating nonmotor symptom of Parkinson's disease (PD) that is often inadequately managed. Deep brain stimulation (DBS) has been shown to relieve pain in PD but an effective method of identifying which types of PD pain respond to DBS has not been established. We examine the effects of DBS on different types of PD pain using the King's Parkinson's disease pain scale (KPDPS), the only validated scale of PD pain. METHODS: We prospectively followed 18 PD patients undergoing subthalamic nucleus (STN) or Globus pallidus interna (GPi) DBS. Subjects completed the KPDPS, low back disability index (LBDI), and McGill pain questionnaire (MPQ), preoperatively and at six months postoperatively. Subjects underwent the unified Parkinson's disease rating scale-III (UPDRS-III) with preoperative scores ON medication and postoperative scores ON medication/DBS stimulation. RESULTS: Of the 18 patients, a total of 12 subjects had STN DBS and 6 had GPi DBS. As a group, subjects showed improvement in total KPDPS score at six-month postoperative follow-up (p = 0.004). Fluctuation and nocturnal pain were most significantly improved (p = 0.006, 0.01, respectively). Significant improvements were found in fluctuation-related pain domain following GPi DBS. CONCLUSIONS: In this pilot study, we are the first group to employ KPDPS to monitor pain relief following DBS in PD patients. We demonstrate that fluctuation-related pain and nocturnal pain significantly improve with DBS. Use of the KPDPS in the future will allow better understanding of how STN and GPi DBS treat PD pain over time.

Use of Low Dose Ziconotide as First-Line Intrathecal Monotherapy.

BACKGROUND: Ziconotide use in intrathecal drug therapy (IDT) has been limited by dosing related side effects. We examine our experience with ziconotide as a first line IDT monotherapy in patients with chronic pain and present our low and slow dosing algorithm aimed at reducing these patient experienced side effects while adequately managing pain. METHODS: We retrospectively reviewed demographics, dosing, and outcomes of 15 consecutive patients with complete three-month data sets implanted with intrathecal pain pumps more than three years utilizing ziconotide as a first-line monotherapy. RESULTS: Ziconotide response was assessed at visit 5 (69 ± 10 days) and responders were characterized by having 30% or greater improvement in numerical rating scale scores (n = 7), or activities of daily living (ADL) (n = 7). Eight of our patients had a response in at least one measure (53%). In our eight responders, NRS score decreased from 8.4 ± 0.7 at baseline (consult visit) to 2.4 ± 1.0 at 2.6 months and 4.0 ± 1.3 at most recent follow-up, mean of 12.9 months after implant. We noted that our responders tended to have neuropathic pain with an objective etiology. Initial dosing in 12 patients was 1.2 mcg/day (range for the other three patients was 0.6-1.4). Following initial dosing, visits were at 2-4 week intervals with mean titration doses between 1.1 and 2.8 mcg/day. Slight dizziness in two patients and transient urinary retention in one patient occurred, all resolving with dose reduction. No patients had discontinued use at three-month follow-up. DISCUSSION: We present our experience with low and slow ziconotide IDT as a first-line monotherapy, which showed no side effects resulting in discontinuation of the medication at three-month follow-up. Using a conservative dosing strategy, we were able to effectively treat 53% of patients.

BMI as a Predictor of Spinal Cord Stimulation Success in Chronic Pain Patients.

BACKGROUND: Spinal cord stimulation (SCS) is an effective method of treating chronic pain. Obese patients are overrepresented in chronic pain cases. We examine the effect of body mass index (BMI) on SCS success. METHODS: We prospectively follow outcome measures including visual analog score, Beck Depression Inventory (BDI), McGill Pain Questionnaire, Oswestry Disability Index (ODI), Pain Catastrophizing Scale (PCS), and the Insomnia Severity Index at baseline, six months, and one year postoperatively. Retrospectively, we examined whether our patients with a BMI above the 75th percentile (BMI ≥36.5) had worse outcomes. RESULTS: Our analysis included thoracic and cervical SCS patients-19 with a BMI ≥36.5 and 58 with a BMI <36.5. High BMI patients experienced less BDI improvement at 6 months (T(df) 2.257(36); p = 0.030; 95% CI [4.7%, 87.4%]) and one year (2.74(28); p = 0.011; 95% CI [18.1%, 125.0%]) post-SCS. High BMI patients had less improvement in pain as measured by the PCS at one year (U = 79.5; p = 0.045; 95% CI [-116.0%, 0.0%]). DISCUSSION: Each group experienced successful surgical outcomes. High BMI patients had less BDI improvement at six months and one year and less PCS improvement at one year. These data aid us in counseling our patients preoperatively.

A Single Center Prospective Observational Study of Outcomes With Tonic Cervical Spinal Cord Stimulation.

BACKGROUND: Spinal cord stimulation (SCS) has been a valuable resource for the treatment of chronic, nonmalignant pain that persists in the face of maximal medical management. A recent study demonstrated efficacy of cervical SCS in a multicenter registry. Here, in our single center study, we are able to delve into patient specifics, explore outcomes with percutaneous vs. paddle implants, and examine impact of patient symptomatology. METHODS: We prospectively collected data on subjects who underwent cervical SCS via numeric rating scale (NRS), McGill Pain Questionnaire, Oswestry Disability Index (ODI), and Beck Depression Inventory. Subjects completed this battery pre-operatively, at six months and at one year. Data were analyzed via repeated measures ANOVA, bivariate correlation analysis, and paired t-tests. RESULTS: In 30 consecutive subjects, 24 had a complete data set. The diagnosis was failed neck surgery syndrome (13%), Complex regional pain syndrome (29%), and neuropathic pain (58%). Compared with baseline, NRS score significantly improved at six months (p = 0.021) and one year (p = 0.047). ODI score also improved at one year (p = 0.009). At both six months and one year, subjects with percutaneous implants reported significantly less disability on ODI (p = 0.016 and 0.034, respectively), as compared with those who received paddle implants. There was no difference in NRS score or any other outcome measure based on type of implant. Diagnosis or region of pain did not correlate with any measure of outcome. DISCUSSION: We demonstrate that neck and arm pain can be improved with cervical SCS at six month and one-year follow-ups. Both percutaneous and paddle implants have benefit. We tend to place percutaneous implants for radicular pain and retrograde C1-2 paddles for axial pain that is ineffectively treated during the trial.

Prospective Study of the Use of Intraoperative Neuromonitoring in Determining Post-Operative Energy Requirements and Physiologic Midline in Spinal Cord Stimulation.

BACKGROUND: Intraoperative neuromonitoring (IONM) through electromyography (EMG) studies has been shown to be a safe, effective way to determine the laterality of the spinal cord and guide electrode placement during spinal cord stimulation (SCS). However, the use of IONM to predict post-operative energy requirements and midline has not been examined and offers a new avenue to streamline programming and device selection. Further, the impact of cerebrospinal fluid (CSF) thickness on intraoperative and post-operative amplitudes is understood but has not been explicitly characterized. METHODS: A total of 24 patients undergoing SCS implantation for chronic pain had intraoperative EMG studies performed to determine physiologic midline. The intraoperative midline was compared to the midline determined on post-operative day 1 based on paresthesia patterns during programming. For patients who had thoracic leads placed, the amplitudes needed to induce abdominal and extremity lateralization during SCS placement were compared with the intensities needed to induce therapy at post-operative day 1. Additionally, we examined whether CSF thickness, body mass index, diabetes, drug use, and smoking correlated with intraoperative and post-operative amplitudes. RESULTS: Intraoperative EMG was able to predict post-operative paresthesia-based midline in 70.83% of patients. There was a statistically significant relationship between the intraoperative intensity needed to induce extremity lateralization with the post-operative intensity to induce therapy (p = 0.009) as well as the intraoperative intensity needed to stimulate abdominals with the post-operative intensity (p = 0.033). There was also a relationship seen between CSF thickness and the post-operative energy requirements in patients (p = 0.039). DISCUSSION: EMG accurately predicts post-operative energy requirements and midline in SCS patients. While 29.17% of patients did not have a match between their intraoperative and post-operative midlines, EMG testing was still valuable in guiding electrode placement and providing information to predict post-operative intensities. Additionally, CSF thickness correlated with amplitude settings on the first post-operative day.

Evaluation of Quantitative Measurement Techniques for Head Tremor With Thalamic Deep Brain Stimulation.

BACKGROUND: Ventralis intermedius thalamic deep brain stimulation (VIM DBS) has shown to be safe and effective for medically refractory essential tremor (ET). We evaluate the use of quantitative tremor measurement methods for head tremor in ET using a "smart" hat and a smartphone application. METHODS: We enrolled 13 ET patients who previously underwent VIM DBS. Head and arm tremor was measured ON and OFF stimulation using the clinical gold standard Fahn-Tolosa-Marin Tremor Rating Scale (TRS). Results were then compared to two quantitative measurement techniques: Lift Pulse (smartphone application) and modified Nizet (adapted laser point measurement from Nizet et al.). Spearman's rank correlation was used to compare tremor severity and improvement on stimulation using TRS and quantitative methods to measure tremor. RESULTS: Lift Pulse tremor severity measurement significantly correlated with TRS for head (ρ = 0.53, p < 0.01) and arm tremor (ρ = 0.49, p < 0.01). Modified Nizet tremor severity measurement significantly correlated with TRS for head (ρ = 0.83, p < 0.001) and arm tremor (ρ = 0.50, p < 0.01). Inter-method correlation for head tremor severity was significant (ρ = 0.45, p < 0.05). Lift Pulse tremor improvement measurement significantly correlated with TRS for arm tremor (ρ = 0.56, p < 0.05). Modified Nizet tremor improvement measurement significantly correlated with TRS for head tremor (ρ = 0.53, p < 0.01). DISCUSSION: Our results show that Lift Pulse and modified Nizet are both effective techniques to quantitatively measure head and arm tremor severity. We also show the utility of a "smart" hat to measure head tremor. Modified Nizet technique is more effective for measuring head tremor, while Lift Pulse is an effective measure of tremor severity, especially arm tremor improvement.

Prospective Evaluation of Patient Usage of Above and Below Threshold Waveforms With Traditional Spinal Cord Stimulation Devices.

OBJECTIVES: Spinal cord stimulation (SCS) is an efficacious therapy used to treat chronic pain. The type of SCS programming is important in improving patients' quality of life and overall satisfaction. In this study, 19 patients who underwent SCS with traditional devices were given between 4 and 6 programs including programs with stimulation below sensory threshold and above sensory threshold. Usage patterns and preferences were assessed. METHODS: SCS patients were given 4-6 programs, some above sensory threshold and some below threshold immediately postoperatively after permanent implantation. Usage patterns of different programs were documented, including percent of time that the settings were used and preference for above threshold vs. below threshold settings during sleeping, walking, sitting, and vigorous activity. Improvements at three months in Oswestry disability index (ODI), numeric rating scale (NRS), Beck depression inventory (BDI), McGill pain questionnaire (MPQ), pain catastrophizing scale (PCS), insomnia severity index (ISI), and Epworth sleepiness scale (ESS) were evaluated. RESULTS: Patients were all trialed on above sensory threshold programs. Six weeks after implantation, most patients preferred above threshold stimulation (74%) vs. below threshold waveforms (21%). Patient diagnosis, type/location of lead or recharging burden played no role in patient preference. Above threshold patients had significantly better improvement in BDI scores than did below threshold patients (p < 0.05) at three-month follow-up but also had worse ESS scores (p < 0.05). Above threshold stimulation was preferred for walking and sitting (p < 0.05). CONCLUSIONS: Results indicate that when given the option between waveforms inducing paresthesias and those that do not, SCS patients tend to prefer waveforms that induce paresthesias. Among users of above threshold waveforms, there was preference for these settings during walking and sitting. There was a trend for below threshold preference in vigorous activity and sleeping.

Evolving Concepts in Posterior Subthalamic Area Deep Brain Stimulation for Treatment of Tremor: Surgical Neuroanatomy and Practical Considerations.

BACKGROUND: Although thalamic deep brain stimulation (DBS) has been established as an effective therapy for refractory tremor in Parkinson's disease and essential tremor, reports investigating the efficacy of posterior subthalamic area (PSA) DBS for severe, debilitating tremors continue to emerge. However, questions regarding the optimal anatomical target, surgical approach, programming paradigms and effectiveness compared to other targets remain. OBJECTIVES: In this report, we aimed to review the current literature to assess different stereotactic techniques, anatomical considerations, adverse effects and stimulation settings in PSA DBS. METHODS: A comprehensive literature review was performed searching for articles discussing tremors and PSA stimulation. We performed a quantitative analysis comparing different DBS tremor targets. RESULTS: Tremor improvement is consistently documented in most reports with an average reduction in tremor of 79% depending on the specific tremor syndrome. Tremor benefit in patients with multiple sclerosis (MS) tremor was significantly higher than for other stimulation targets. Transient paresthesias, imbalance, dizziness and dysarthria are the most common side effects with PSA DBS. CONCLUSIONS: PSA DBS is an effective and safe treatment for tremor control and should be considered in patients with refractory tremors with associated cerebellar or dystonic features, proximal tremors and MS tremor.

MRI Conditionality in Patients with Spinal Cord Stimulation Devices.

BACKGROUND: Because of the commonality of diagnostic magnetic resonance imaging (MRI), MRI conditional technology has increased throughout the device industry. It is often difficult to be aware of MRI specifications for each device. OBJECTIVES: We provide a review of the clinical experience with MRI and spinal cord stimulation (SCS) devices and develop a general reference of current device/MRI specifications. METHODS: We reviewed the available literature on the clinical experience with SCS devices and examined its specifications. RESULTS: We developed a user-friendly table of the specific compatibility of SCS devices in the USA and the European Union, and examined the existing literature on the clinical experience with MRI and SCS devices. We share our experience with obtaining spine MRI with MRI conditional SCS leads. CONCLUSION: By describing SCS device specifications and reviewing the literature, we provide a guide to implanting and treating physicians on obtaining MRIs in patients who have SCS devices.

Pedometry as an External Measure of Spinal Cord Stimulation Patient Outcomes.

BACKGROUND: Chronic pain is a debilitating biologic and psychologic condition which affects nearly one third of the American population with an annual cost of $560 to $635 billion from associated health care costs and lost productivity. Treatment of chronic pain is difficult to objectively evaluate as it relies on subjective measure. An objective measure would be beneficial in assessing treatment efficacy and towards developing a closed loop system. We assess the efficacy of pedometry as an objective measure of treatment efficacy in spinal cord stimulation (SCS). METHODS: Participants who had back and/or leg pain and were scheduled for permanent thoracic SCS implantation were offered inclusion. Preoperatively and at three months post-operatively, patients underwent a battery of tests including the Oswestry Disability Index (ODI), Pain Catastrophization Scale (PCS), McGill Pain Questionnaire-Short Form (MPQ), Likert Pain Scale, Visual Analog Scale (VAS), Insomnia Severity Scale (ISS), and Epworth Sleepiness Scale (ESS). They also wore a pedometer for 48 hours prior to SCS implantation and for 48 hours at three months. Walking distance, step count, and steps per hour were documented. Additionally, patients were asked to record their activity level in hours per day. RESULTS: Eight patients completed three month follow-up. All measurements of disability and pain decreased significantly: ODI (p = 0.004), PCS (p = 0.01), MPQ (p = 0.02), VAS (p = 0.001), ISS (p = 0.002), and ESS (p = 0.041). All pain and disability measurements decreased independent of activity measures, except lowest levels of pain at the patient's best. A positive correlation was found between improvement in participant's active time and improvement in ESS score, suggesting decreased daytime sleepiness with increased time spent active (r = 0.844, N = 7, p = 0.017). CONCLUSIONS: We demonstrate a mean improvement of more than 50% in distance walked, steps per hour, and total steps. Interestingly, total activity (number of hours spent active per day) was not dramatically improved. Our data suggests that as a group our patients' ambulation increased dramatically after successful SCS. The use of pedometry in conjunction with self-reporting can lend both quantitative and qualitative validity to pain, as well as allow objective assessment of efficacy of SCS in patients suffering from chronic low back and/or leg pain. Further, external sensors tracking these data may be a means of creating a closed loop system with SCS.

The Impact of Spinal Cord Stimulation on Sleep Patterns.

BACKGROUND: Studies of chronic pain show sleep disturbances to be a prevalent symptom in 50-88% of patients and studies show improved pain to correspond with improved sleep. The impact of spinal cord stimulation (SCS) on sleep in failed back surgery syndrome, complex regional pain syndrome, and neuropathic pain patients has not been studied prospectively. OBJECTIVES: We prospectively assess the impact of SCS on sleep quality using the Insomnia Severity Index (ISI) and Epworth Sleepiness Scale (ESS). Further we examine the correlations between sleep and pain. METHODS: Patients who underwent permanent SCS implantation completed six validated questionnaires to compare sleep patterns, pain intensity, and quality of life at baseline and six months postoperatively. Results were analyzed via paired samples t-tests and bivariate analysis. RESULTS: Data from 27 patients were collected. We saw a significant decrease in ISI scores (n = 23, t(df)=2.9(22), p = 0.008), and noted a trend in the percentage improvement between ISI and ESS (n = 12, t(df)=2.0(10), p = 0.078). We did not see any significant improvement in ESS. However, improvements in insomnia correlated with pain intensity as measured through visual analog scale score and McGill Pain Questionnaire (R = 0.546, p = 0.007 and R = 0.559, p = 0.006, respectively). DISCUSSION: We demonstrate that insomnia scores on ISI improve with SCS at six-month follow-up. Further, we find that improvements in pain correlate with these ISI improvements.