Spinal Cord Stimulation in the 21st Century — Reviewing Innovation in Neuromodulation

INTRODUCTION Low back pain (LBP) is a pervasive problem impacting health systems across the world. In the United States, chronic LBP impacts up to 40% of Americans and results in excessive financial strain on the healthcare budget, estimated at up to $100 billion annually.1 Furthermore, treatment results are often disappointing, with the traditional pathway of conservative measures, narcotic pain medication, and surgical decompression and/or fusion leading to both patient and provider frustration, complications, and diminished patient productivity and quality of life. This has naturally led to questions from policymakers regarding the utility of healthcare dollars spent on back pain. In this milieu, a variety of neuromodulation techniques have found a niche in the management of this patient population, with indications commonly quoted including failed back surgery syndrome (FBSS), chronic neuropathic pain, and complex regional pain syndrome (CRPS), among others.1,2 From its inception on the basis of Melzak and Wall’s gate theory³, to its first human trial in the 1960s,⁴ and to the modern era, spinal cord stimulation has undergone a series of innovations that have expanded indications and improved patient outcomes. The goal of this study is to summarize the most important clinical trials involving both traditional SCS and newer stimulation paradigms to provide an overview of the current state of affairs of this rapidly-growing field

Delta oscillation coupled propagating fast ripples precede epileptiform discharges in patients with focal epilepsy.

Epileptiform spikes are used to localize epileptogenic brain tissue. The mechanisms that spontaneously trigger epileptiform discharges are not yet elucidated. Pathological fast ripple (FR, 200-600 Hz) are biomarkers of epileptogenic brain, and we postulated that FR network interactions are involved in generating epileptiform spikes. Using macroelectrode stereo intracranial EEG (iEEG) recordings from a cohort of 46 patients we found that, in the seizure onset zone (SOZ), propagating FR were more often followed by an epileptiform spike, as compared with non-propagating FR (p \u3c 0.05). Propagating FR had a distinct frequency and larger power (p \u3c 1e-10) and were more strongly phase coupled to the peak of iEEG delta oscillation, which likely correspond with the DOWN states during non-REM sleep (p \u3c 1e-8), than non-propagating FR. While FR propagation was rare, all FR occurred with the highest probability within +/- 400 msec of epileptiform spikes with superimposed high-frequency oscillations (p \u3c 0.05). Thus, a sub-population of epileptiform spikes in the SOZ, are preceded by propagating FR that are coordinated by the DOWN state during non-REM sleep

Capturing Initial Understanding and Impressions of Surgical Therapy for Parkinson\u27s Disease

Background: Deep Brain Stimulation (DBS) is an underutilized surgical therapy for Parkinson\u27s Disease (PD). Both physician and patient hesitancies have been described as potential barriers to DBS, but the specifics of patient perceptions of DBS have not been well-characterized in the general PD population. Objective: To characterize the understanding and impressions of surgical therapy in PD patients prior to formal surgical evaluation. Methods: A 30-question survey assessing impressions of surgical therapy for PD and understanding of DBS for PD was administered to PD patients seen at an urban movement disorders clinic. Results: One hundred and two patients completed the survey. When asked if they would undergo a hypothetical risk-free, curative brain surgery for PD, 98 patients responded “yes.” Patients were more agreeable to “reversible,” “minimally-invasive,” and “incisionless” surgery. 51.2% thought DBS is an “effective” treatment for PD, 76.6% thought it was “invasive,” and 18.3% thought it was “reversible.” 45.2% reported fear of being awake during DBS surgery. Regarding costs, 52.4% were concerned that DBS was “very expensive” or “not covered by insurance.” Initial source of information and perceived treatment effectiveness were not associated with concerns about DBS effectiveness or threats to normality. Negative perceptions of past surgery were associated with concerns about DBS altering mood and personality. Conclusion: Overall, patients expressed concerns regarding procedural efficacy, invasiveness, cost, and irreversibility—independent of the original source of information. Future studies are required to allow us to better understand the impact of these initial findings on DBS hesitancy and underutilization

Deep Brain Stimulation: Awake and Asleep Options

A BRIEF HISTORY OF DBS AND NEUROIMAGING Stereotactic neurosurgery is founded on the ability to accurately localize and safely access targets within the brain in a minimally-invasive manner. The stereotactic method was first described in 1908 by Sir Victor Horsley and Robert Clarke at University College London, where they developed an apparatus for animal experimentation that allowed them to establish a threedimensional Cartesian coordinate system for targeting. At that time, however, x-rays were the only available form of imaging the human body and as such, localizing intracranial targets relied on a combination of knowledge from anatomical atlases and the visualization of a few intracranial landmarks such as the pineal gland or the foramen of Monroe. These landmarks could be visualized by filling the ventricles with air (pneumoencephalogram) or a contrast medium (ventriculogram) [Figure 1]. In 1947, Ernst Spiegel and Henry Wycis created the first human stereotactic frame that allowed for lesioning of deep brain nuclei for the treatment of psychiatric disease.2 With imaging limited to x-rays alone, a need arose for another means of confirming the appropriate location where a lesion would be made or an electrode would be implanted. Nicholas Wetzel and Ray S. Snider have been accredited with performing the first microelectrode recording (MER) in humans in 1958 during a pallidotomy.3 Over time, particularly with the popularization of thalamotomy for the treatment of Parkinson’s disease and with a growing appreciation of characteristic recordings of specific nuclei, MER became commonplace in stereotactic neurosurgery. Pages: 2-8

Evidence for Surgical Management of Facial Pain and Headache

Headache and facial pain are a commonly encountered wide spectrum of complex medical conditions. Unfortunately, aside from treating trigeminal neuralgias, interest in surgical management of facial pain and headache from the neurosurgical community has been historically low. The reasons for this are multifactorial and include waning reimbursement, lack of evidence to support a number of pain procedures, and the absence of pain education in neurosurgical residency programs. In this article, we present surgical therapies currently available for headache and facial pain and review the published evidence for commonly performed neurosurgical treatments for craniofacial pains. TRIGEMINAL NEURALGIA Trigeminal neuralgia (TN) is one of the many types of facial pain syndromes, which has a good evidence-based data for the benefit of surgical management. It is also one of the common conditions treated with microvascular decompression (MVD), internal neurolysis (IN), radiofrequency (RF) rhizotomy, glycerol rhizotomy, and gamma knife radiosurgery (GKRS). TN is thought to occur as a result of compression of the root entry zone of the nerve by the neighboring offending artery igniting the hyper-excitable axons at the trigeminal root.1,2 In contemporary neurosurgery, the first line of management for patients suffering from this debilitating disease is medical treatment with carbamazepine or gabapentin. In cases of failed medical therapy or drug intolerance, or simply when patients do not prefer to take these medications for a long period of time, surgical options should be considered. Neurosurgical management of TN include three modalities: craniotomy for MVD or IN, percutaneous techniques, and GKRS. Percutaneous techniques can be further divided into glycerol rhizotomy, balloon compression, and radiofrequency rhizotomy. Pages: 50-5

Advancements in Stereotactic Epilepsy Surgery: Stereo-EEG, Laser Interstitial Thermotherapy, and Responsive Neurostimulation

Stereotactic interventions form an increasingly significant portion of the minimally invasive approaches for surgical management of epilepsy.1,2 This manuscript will review the application of three recent stereotactic techniques in the modern epilepsy surgery armamentarium, namely stereotactic electroencephalography (SEEG), responsive neural stimulation (RNS) and laser interstitial thermal therapy (LITT). While these interventions are a contemporary advancement, they are intellectually indebted to some of the most major developments and pioneers in the history of neurosurgery. Sir Victor Horsley, the father of modern neurosurgery, and Robert Clarke developed the first stereotactic frame in 1908, but use of the stereotactic coordinate space did not find wide use until it could be paired with intracranial imaging. Acquisition of pneumoencephalograms and/ or arterial angiography (developed by Dandy and Moniz, respectively) with a stereotactic reference frame enabled Spiegel and Wycis to precisely localize brain structures.3 The ability to attain sub-millimeter accuracy followed the advent of computed tomography (CT) and magnetic resonance imaging (MRI). These advancements were applied to epilepsy first by Bancaud and Talairach with their development of SEEG.4 While LITT and RNS represent more recent advancements, they are indebted to the work of Lars Leksell and Alim Benabid for their pioneering work in stereotactic ablative therapy and deep brain stimulation (DBS), respectively. Pages: 32-3

A Methodology for Systematic Volumetric Analysis of Perioperative Cranial Imaging in Neurosurgical Patients

Background Although objective assessment of perioperative imaging provides a rigorous evaluation method of neurosurgical techniques in epilepsy, its use remains far from mainstream. Open surgery remains the gold standard for treatment of mesial temporal lobe epilepsy (MTLE); however, stereotactic laser ablation is a promising minimally invasive alternative. Nevertheless, the variables that may affect seizure outcome in stereotactic laser amygdalohippocampectomy (SLAH) remain unclear. While an objective endpoint such as ablated mesial temporal volumes may be significant, a standard methodology for calculating such volumes has yet to be proposed. Objectives To formulate and test a methodology, which can aid in critical evaluation of laser trajectories, and ablation cavities in seizure patients. Methods We performed a retrospective study involving 16 patients undergoing SLAH our institution’s approved IRB protocol. Preoperative MRIs were processed and segmented. Postoperative MRIs were co-registered to preoperative MRIs. Laser trajectories and ablation cavities were segmented from this co-registered image. Segmented trajectories, and cavities were superimposed upon the initial MRI. The percentage of each structure affected was calculated, using a voxel by voxel comparison. Results We were successfully able to determine ablation volumes and critically evaluate laser placement. Conclusion This semi-automated methodology showcases a systematic workflow that objectively evaluates perioperative imaging in neurosurgical patients. Pages: 16-2