Post-Operative Localization of Deep Brain Stimulation Electrodes in the Subthalamus Using Transcranial Sonography.

OBJECTIVES: The correct positioning of deep brain stimulation electrodes determines the success of surgery. In this study, we attempt to validate transcranial sonography (TCS) as a method for early postoperative confirmation of electrode location in the subthalamic nucleus (STN). MATERIALS AND METHODS: Nineteen patients diagnosed with Parkinson's disease were enrolled in the study. Postoperative TCS was applied to measure the distance between the implanted electrodes and the third ventricle in the axial plane. Whether the electrodes were positioned within or outside the substantia nigra (SN) was evaluated through measurements in the coronal plane. The obtained metrics through TCS were compared with those from postoperative computed tomography (CT) and magnetic resonance imaging (MRI). RESULTS: A statistically significant correlation between distances from electrode to third ventricle by TCS and CT/MRI (r = 0.75, p < 0.01) was observed. Distances from third ventricle to electrodes tips were different when sonographically they showed to be inside or outside the SN (p < 0.01). A cut-off value of 8.85mm in these distances was the most sensitive (100%) and specific (90.5%) to predict if electrodes were positioned inside the SN (CI 95% 0.81-10.30, p = 0.001). CONCLUSIONS: Transcranial sonography is a useful technique to reliably identify targeted positioning of deep brain stimulation electrodes in or out of the SN.

Relevant Anatomy, Morphology, and Implantation Techniques of the Dorsal Root Ganglia at the Lumbar Levels.

OBJECTIVES: While dorsal root ganglion (DRG) stimulation has been available in Europe and Australia for the past five years and in the United States for the past year, there are no published details concerning the optimal procedures for DRG lead implantation. MATERIALS AND METHODS: We describe several techniques that can be applied to implant cylindrical leads over the DRG, highlighting some tips and tricks according to our experiences. Focus is mainly shifted toward implantations in the lumbar area. We furthermore give some insights in the results we experienced in Spain as well as some worldwide numbers. IMPLANT TECHNIQUES AND RESULTS: A 14-gauge needle is placed using a "2-Level Technique (2-LT)" or exceptionally a "1-Level Technique (1-LT)" or a "Primary- or Secondary Technique" at the level of L5. The delivery sheath, loaded with the lead, is advanced toward the targeted neural foramen. The lead is placed over the dorsal aspect of the DRG. A strain relief loop is created in the epidural space. Sheath and needle are retracted and the lead is secured using an anchor or anchorless technique. In Spain, 87.2% (N = 78) of the selected patients have been successfully implanted. Seven (8.9%) had a negative trial and three (4.2%) were explanted. Average VAS score decreased from 8.8 to 3.3 and on average 94.5% of the pain area was covered. In our center's subjects (N = 47 patients, 60.3% of all implanted patients in Spain), VAS scores decreased from an average of 8.8-1.7 and pain coverage averaged 96.4%. We used an average of 1.8 electrodes. Worldwide more than 4000 permanent cases have been successfully performed. CONCLUSIONS: We present implantation techniques whereby a percutaneous lead is placed over the DRG through the use of a special designed delivery sheath. Further investigation of the safety, efficacy, and sustainability of clinical outcomes using these devices is warranted.

Spinal cord stimulation for the treatment of chronic back pain patients: 500-Hz vs. 1000-Hz burst stimulation.

OBJECTIVE: Spinal cord stimulation is a commonly used, safe, and effective procedure applied for medically intractable failed back surgery syndrome, as well as other neuropathic pain syndromes. Recently, a novel stimulation paradigm called burst stimulation has been developed that is paresthesia-free and has a more pronounced suppressive effect on neuropathic pain. MATERIALS AND METHODS: Fifteen patients who were being treated with burst spinal cord stimulation for failed back surgery syndrome participated in an open-label trial to verify whether their pain suppression could be further ameliorated by changing the burst pattern. Burst stimulation with packets of five electrical pulses delivered at 500 Hz with 1000-µsec pulse width 40 times per second was changed to burst mode delivering five spikes at 1000 Hz with 500-µsec pulse width 40 times a second. As the amplitudes did not differ between the two groups, the total delivery of current to the spinal cord was not different between the two modes of burst stimulation. Scores on visual analog scales for pain and paresthesia, the Pain Catastrophizing Scale, the Pain Vigilance and Awareness Questionnaire, and the Short Form 36 quality of life measurement were compared between the two modes of burst stimulation. [Correction added on 06 Feb 2015, after first online publication: this paragraph has been revised to signify the comparison of amplitudes between two groups] RESULTS: No statistically significant differences were found between the two modes of stimulation. CONCLUSION: The results suggest that increasing the frequency from 500 to 1000 Hz while keeping the pulse width constant does not add any extra benefit in suppressing pain. Further studies should verify whether increasing the frequency above 1000 Hz has a similar lack of effect.

Is preoperative pain duration important in spinal cord stimulation? A comparison between tonic and burst stimulation.

OBJECTIVE: Conflicting data have been published as to whether the success rate of spinal cord stimulation (SCS) is inversely proportional to the time interval from the initial onset of symptoms to implantation. Recently, a new stimulation design called burst stimulation has been developed that seems to exert its effect by modulating both the medial and lateral pain pathways and has a better effect than tonic stimulation on global pain, back pain, and limb pain. MATERIALS AND METHODS: We analyzed the effect of preoperative pain duration on the degree of pain suppression by both tonic and burst stimulation in a group of patients (n = 49) who underwent both tonic and burst SCS. RESULTS: Using Pearson correlation analysis and controlling for age and duration of SCS, no correlation could be found between the preoperative pain duration and the success of SCS, either for tonic or for burst SCS, as defined by a numeric rating scale for pain. Using a different analysis method, dividing patients into groups according to preoperative pain duration, the same absence of influence was found. Pain was better suppressed by burst stimulation than tonic stimulation, irrespective of the preoperative pain duration. CONCLUSIONS: These results suggest that the duration of pain is not an exclusion criterion for SCS and that similar success rates can be obtained for longstanding pain and pain of more recent onset.

Laser-Evoked Potentials in Fibromyalgia: The Influence of Greater Occipital Nerve Stimulation on Cerebral Pain Processing.

OBJECTIVE: Fibromyalgia causes widespread musculo-skeletal pain in the four quadrants of the body. Greater occipital nerve stimulation has recently shown beneficial effects in fibromyalgia patients on pain, fatigue, and mood disorders. Laser-evoked potentials (LEPs) are used for research to understand the pathophysiological mechanisms of pain and to evaluate the effects of pain treatment. In fibromyalgia patients, LEPs tend to have a higher N2 amplitude, a tendency to shorter latencies, and patients have a lower pain threshold. Greater occipital nerve stimulation might exert a modulation of the medial pain pathways processing the affective motivational components of pain (unpleasantness) as well as the descending pain inhibitory pathways (reducing pain), both of which are contributing to the N2P2 peak. MATERIALS AND METHODS: To test this hypothesis, the authors performed LEPs in a group of fibromyalgia patients with and without greater occipital nerve stimulation. RESULTS: Occipital nerve stimulation does not alter the amplitudes of the LEP recordings, although a significant difference in latencies can be seen. More specifically, latencies of the N2P2 increased in the condition after stimulation, and especially at the Pz electrode. CONCLUSION: Our results suggest Occipital Nerve Stimulation (ONS) induces a modification of the balance between antinociceptive pain inhibitory pathways and pain-provoking pathways.

Long-term outcomes of spinal cord stimulation with percutaneously introduced paddle leads in the treatment of failed back surgery syndrome and lumboischialgia.

OBJECTIVE: The study aims to evaluate the long-term clinical and technical efficacy of recently developed percutaneously introducible plate electrodes for spinal cord stimulation. METHODS: Twenty-one patients diagnosed with failed back surgery syndrome (FBSS) or lumboischialgia were implanted with a small profile plate-type electrode. Patients were followed-up long term and were asked at baseline, after trial, and during each follow-up visit to score their pain on a visual analog scale (VAS) for pain now, worst pain last week, least pain last week, and mean pain last week. Pain location, electrophysiologic parameters, and number of reprogrammings were collected as well. Furthermore, each patient was asked if he/she would redo the procedure post trial and at each of the follow-up visits. RESULTS: A total of 21 patients were prospectively followed up long term. With a mean follow-up of 40.8 months, a significant mean reduction in patient self-reported pain from baseline to postoperative of 75.79% pain reduction was seen at follow-up 1 and 62.52% at follow-up 2. A significant decrease was obtained for, respectively, pain at the present moment, VAS pain worst last week, VAS pain least last week, and VAS pain mean last week in comparison with baseline VAS scores. All patients indicated that they would redo the procedure. CONCLUSION: Percutaneous implantation of small profile paddle leads in patients with FBSS and lumboischialgia produces favorable results over the long term that are at least comparable with surgical implanted paddle leads. The percutaneous approach also allows nonsurgically trained pain physicians to introduce paddle leads. Indices like if patients would redo the procedure may be more appropriate for analyzing long-term outcomes than the arbitrarily taking 50% reduction in VAS scores.

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.

Percutaneously implanted plates in failed back surgery syndrome (FBSS).

OBJECTIVE: To evaluate the clinical efficacy of pain suppression in back area and lower extremities by recently developed plate electrodes for spinal cord stimulation through percutaneous access. METHODS: A retrospective analysis is performed: 20 consecutive patients with both lower extremity pain and low back pain, with low back counting for at least 30% of the overall pain were implanted with a small profile plate type lead, S-Series (SJM), via percutaneous approach. Patients were asked to rate their back and leg pain as well as their overall satisfaction and data on quality of life (QOL) on a (0-10 point) visual analog scale (VAS) before and after implantation. Medication use, functional pain (pain when bending forward, moving), and patient satisfaction scores also were collected. RESULTS: A significant reduction of 55% and 45.7% in, respectively, VAS legs and VAS back pain was found. One year postoperatively the reduction was still present, respectively, 43% and 27% for the legs and the back. In 17 patients (85%) a clinically relevant reduction (defined as reduction of 2 points or 30% in VAS) in back pain was seen, with a mean decrease of 4.3 points (2.0-10.0) or 52% (22-100). Only three patients had no reduction in back pain, although they had reduction of their pain in the lower extremities. A significant and clinically relevant improvement of 66% and 70% was seen, respectively, for general satisfaction and QOL, respectively. One year postoperatively this improvement was still present, respectively, 69% and 75% for the satisfaction and QOL. Importantly functional pain also decreased by 51%. No infections occurred. Mean duration of post-op wound pain was 13.5 hours. CONCLUSION: Percutaneous implantation of the S-Series plate electrodes using a 10 gauge epidural needle combines the advantages of a minimal invasive technique with the possibility to cover the back area supplementing leg coverage in 85% of the failed back surgery syndrome patients.

Vagus nerve stimulation as a potential modulator of periictal psychotic episodes: A report of four cases.

Drug resistant epilepsy (DRE) has been associated with a high incidence of psychotic disorders. Patients can develop psychosis after starting a new antiseizure medication, after undergoing resective surgery, or after implantation of a vagus nerve stimulation (VNS) system. The aim of this study was to investigate the modulation effect of VNS on psychotic episodes in DRE patients with a pre-existing history of periictal psychotic episodes (PPE). We retrospectively report the outcome of four patients from a single tertiary center with PPE prior to implantation. None of the implanted patients developed de novo PPE after VNS therapy. Regarding seizure outcome, all patients demonstrated a response to VNS with two who experienced who status epilepticus and three patients wtih a change in semiology with after VNS implantation. PPE disappeared in all the study patients, two of them at 6 months post-implantation and in the others after 2 and 3 years, respectively. 18F-FDG-PET results showed hypermetabolism in both anterior insular and medial frontal lobes which disappeared in the 18F -FDG-PET 4 years post-implantation. Based on the results of this series of cases we suggest that VNS therapy may be useful to modulatet PPE in patients with DRE, though effectiveness may be time-dependent.

A Cost-Consequence Analysis Examining the Differences Between Non-Rechargeable and Rechargeable Systems.

BACKGROUND: Spinal cord stimulation (SCS) is an effective treatment option to relieve chronic intractable pain, and failed back surgery syndrome (FBSS) is a key indication. OBJECTIVES: The objective of the current study was to analyze the cost consequences of using non-rechargeable (NR)-SCS and rechargeable (R)-SCS. METHODS: Real data taken from a review of 86 patients were used to simulate costs and review which patients might have benefitted more from R-SCS. Calculations were made to see what is the impact from a monetary point of view. RESULTS: On average, NR-SCS devices lasted for 58 months (M). Only 14 patients were not eligible to receive an R-SCS implant. We found that using R-SCS batteries would save up to €56.322 on average over a patient's life expectancy, which means a saving of 43% compared to using NR-SCS systems. In our analysis, we found that if R-SCS implants were used instead of NR-SCS batteries, a saving of €5,735,334.23 over patients' life expectancy would be made, which represented a 63% saving to the public health system. We found that R-SCS was cost-beneficial from second year compared to NR-SCS, saving up to 70% when patients are implanted for 9 years. CONCLUSIONS: This cost-consequences analysis suggests that R-SCS implants are more cost-beneficial than NR-SCS systems in well-selected patient candidates for this type of treatment.

All bursts are equal, but some are more equal (to burst firing): burstDR stimulation versus Boston burst stimulation.

Introduction: Since the introduction of burst spinal cord stimulation for neuropathic pain, several companies have developed their own version of burst stimulation, which is confusing the marketplace and clinicians of what burst stimulation truly is, the value and utilization of the therapy.Areas covered: We review those two burst stimulation designs and notice important differences. The original burstDRTM stimulation tries to mimic physiologic burst firing, which involves closely spaced high frequency sodium spikes nested on a calcium mediated plateau. This is realized by generating a train of 5 monophasic spikes of increasing amplitude with passive charge balance after the last spike, in contrast to the other burst designs which involve a version of cycling 4-5 spikes each being individually actively charge balanced spikes.Expert opinion: Based on the neurobiology of burst firing as well as abductive reasoning we like to clarify that burstDRTM is a true physiologic burst stimulation, and that other versions being called burst stimulation are essentially clustered tonic stimulation. This differentiating terminology will prevent confusion for healthcare providers, regulators, and the marketplace of what burst stimulation is.

Mimicking the brain: evaluation of St Jude Medical's Prodigy Chronic Pain System with Burst Technology.

The Prodigy is a new type of internal pulse generator that controls the delivery of electrical stimuli to nervous tissue. It is capable of delivering burst stimulation, which is a novel waveform that consists of closely spaced high-frequency electrical impulses delivered in packets riding on a plateau, and followed by a quiescent period. Its inception was based on mimicking burst firing in the nervous system and usually delivered by unmyelinated fibers that uniformly have a motivational affective homeostatic function. It thereby targets a multimodal salience network, even though the stimuli are delivered at the level of the spinal cord. As such, it is specifically capable of influencing the affective/attentional components of pain. Burst stimulation was initially safely applied off-label to the auditory cortex for tinnitus, and later also to the spinal cord, the somatosensory cortex for neuropathic pain, subcutaneously for failed back surgery syndrome, and cingulate cortex for addiction and tinnitus.

A 2-center comparative study on tonic versus burst spinal cord stimulation: amount of responders and amount of pain suppression.

INTRODUCTION: Spinal cord stimulation is a safe and effective procedure applied for medically intractable neuropathic pain and failed back surgery syndrome. Recently, a novel stimulation paradigm was developed, called burst stimulation consisting of intermittent packets of closely spaced high-frequency stimuli. The design consists of 40 Hz burst mode with 5 spikes at 500 Hz per burst, with a pulse width of 1 ms and 1 ms interspike interval delivered in constant current mode. METHODS AND MATERIALS: A retrospective analysis is performed looking at 102 patients from 2 neuromodulation centers, 1 in Belgium and 1 in the Netherlands. This consisted of 2 groups, 1 group who had become failures to tonic (conventional) stimulation and 1 group who still responded to tonic stimulation. All patients were switched from tonic to burst stimulation and the amount of responders as well as the amount of pain suppression was assessed. RESULTS: Overall burst stimulation was significantly better than tonic stimulation and baseline. On average the pain on numeric rating scale (NRS) improved from 7.8 at baseline to 4.9 with tonic to 3.2 with burst stimulation. For the Belgian and Dutch centers combined, 62.5% of nonresponders to tonic stimulation did respond to burst stimulation, on average, with 43% pain suppression. Most responders to tonic further improved with burst stimulation; on average, pain suppression improved from 50.6% to 73.6.3%. The results (from both centers) did not differ for the amount of obtained pain suppression, only for the amount of responders, which could be related to the different profile of the 2 participating centers. CONCLUSIONS: Burst seems to be significantly better than tonic stimulation. It can rescue an important amount of nonresponders to tonic stimulation and can further improve pain suppression in responders to tonic stimulation.