Spinal Cord Stimulators: an Introduction

Pain can be divided into two broad categories, nociceptive pain and neuropathic pain. Nociceptive pain is a dull, throbbing pain which results from irritated nerves after physical tissue injury. This is seen commonly in cancer or after a fracture. Nociceptive pain is amenable to treatment with pain medications such as opioids and/or anti-inflammatories. Neuropathic pain is described as burning, shooting, or shocking pain. This type of pain results from nerve damage or abnormal nerve conduction such as pain exhibited with failed back syndrome, post surgical pain, neuromas, shingles, and complex regional pain syndrome (previously called RSD or causalgia). Neuropathic pain tends to be resistant to treatment with pain medications. Neurostimulation has been an effective treatment option for the management of chronic neuropathic pain. It is a reversible therapy which can even be tested before permanent implantation. Spinal cord stimulation (SCS) is an adjustable, non-destructive, neuromodulatory procedure which delivers therapeutic doses of electrical current to the spinal cord or to a targeted nerve. This low-voltage stimulation can block the transmission of pain. The enthusiasm for SCS began with the introduction of the gate control theory for pain control by Melzack and Wall in 1965 1.They noted that stimulation of large myelinated fibers of peripheral nerves resulted in paresthesias and blocked the activity in small nociceptive projections. In other words, pain receptors compete with each other and with other sensory afferents. Appropriate stimulation of a “rival” afferent can effectively block a pain signal. This is why rubbing your chin after its been hit relieves the pain – the bump is still present, but the rubbing blocks it. The SCS system is implanted in a space surrounding the spinal cord, called the epidural space, where it stimulates the dorsal columns which can mask the sensation of pain by producing a tingling sensation

Occipital nerve stimulator systems: Review of complications and surgical techniques

Introduction: Stimulation of the occipital nerves is becoming more widely accepted in the treatment of occipital neuritis and migraine disorders. Objective: Presently, equipment available for spinal cord stimulation is adapted for insertion into the subcutaneous space over the occipital nerves. Many technical factors need to be reassessed to optimize the therapy. Methods: We performed a retrospective review of patients implanted from 2003 to 2007 at a single center. We aimed to analyze the rate of surgical complications related to implantation technique. A total of 28 patients were present for analysis. Patients were followed up to 60 months with a mean follow-up of 21 months. Results: There is a 32% revision rate for electrode migration or displacement, 3.6% removal rate for infection, and a 21% removal rate for lack of efficacy. Although not well studied secondary to small patient populations, this was consistent with a review of the literature which demonstrated a 10-60% revision rate. Other factors such as anchoring strategy, strain relief, and battery location were all considered in the analysis and will be presented. A major determination was that use of a second incision with an additional strain relief loop had only a 10% revision rate of the lead while those without this additional strain relief loop had a 62.5% revision rate. Conclusion: Many technical factors need to be addressed for optimization of occipital nerve stimulation

Case Report: Intramedullary Cervical Spinal Cord Hemangioblastoma with an Evaluation of von Hippel-Lindau Disease

History of Present Illness MO is a 49 year old male with a history of multiple sclerosis who presents with a one year history of progressive numbness in his shoulders bilateral and upper back. The patient describes occasional sharp pains that radiate to his first three fingers on his right hand. He denies weakness, clumsiness, difficulty walking, or bladder/bowel dysfunction. He describes no problems with handwriting, or fine motor skills

An evaluation of neuroplasticity and behavior after deep brain stimulation of the nucleus accumbens in an animal model of depression.

BACKGROUND: Recent interest has demonstrated the nucleus accumbens (NAcc) as a potential target for the treatment of depression with deep brain stimulation (DBS). OBJECTIVE: To demonstrate that DBS of the NAcc is an effective treatment modality for depression and that chemical and structural changes associated with these behavioral changes are markers of neuroplasticity. METHODS: A deep brain stimulator was placed in the NAcc of male Wistar-Kyoto rats. Groups were divided into sham (no stimulation), intermittent (3 h/d for 2 weeks), or continuous (constant stimulation for 2 weeks). Exploratory and anxietylike behaviors were evaluated with the open-field test before and after stimulation. Tissue samples of the prefrontal cortex (PFC) were processed with Western blot analysis of markers of noradrenergic activity that included the noradrenergic synthesizing enzyme tyrosine hydroxylase. Analysis of tissue levels for catecholamines was achieved with high-performance liquid chromatography. Morphological properties of cortical pyramidal neurons were assessed with Golgi-Cox staining. RESULTS: Subjects undergoing intermittent and continuous stimulation of the NAcc exhibited an increase in exploratory behavior and reduced anxietylike behaviors. Tyrosine hydroxylase expression levels were decreased in the PFC after intermittent and continuous DBS, and dopamine and norepinephrine levels were decreased after continuous stimulation. Golgi-Cox staining indicated that DBS increased the length of apical and basilar dendrites in pyramidal neurons of the PFC. CONCLUSION: Deep brain stimulation induces behavioral improvement in and neurochemical and morphological alterations of the PFC that demonstrate changes within the circuitry of the brain different from the target area of stimulation. This observed dendritic plasticity may underlie the therapeutic efficacy of this treatment

Spinal Shock: Differentiation from Neurogenic Shock and Key Management Approaches

The conceptual differentiation of spinal and neurogenic shock tends to be misunderstood among clinicians. In order to better illustrate the differences in definition, presentation, and development of spinal shock (SS) from neurogenic and other forms of shock, we present herein a clinically relevant summary of typical characteristics of SS. First described in the eighteenth century, the continued investigation into the disease process and the response of neural structures to spinal cord trauma have led to a more complete description and understanding. We will begin in the first part of the chapter describing the etiology of SS, including a working definition, as it pertains to complete spinal cord injuries (SCIs). This is followed by the summary of pathophysiology and clinical presentations associated with each clinical phase of SS. Finally, we explore treatment options and considerations as they relate to incomplete SCI. We hope that by presenting a clear and well-delineated overview of SS, we will allow the clinician to better understand and more accurately predict the evolution of this process. This, in turn, should facilitate the ability to deliver better care for the patient

Routine replacement of a vagal nerve stimulator generator leading to asystole

A 52-year-old female with a longstanding history of drug-resistant epilepsy that included focal impaired awareness seizure presented at end of service of her vagus nerve stimulator (VNS) generator. She had undergone a generator replacement in 2010 without complication. However, her latest replacement was accompanied by multiple bouts of asystole. We discuss the case, possible causes of the asystole, and its relevance to the future of VNS generator replacement and epilepsy treatment. Keywords: VNS, Asystole, Generator, Replacemen

Spinal cord stimulation: an update.

Spinal cord stimulation has been used in the treatment of many chronic pain disorders since 1967. In this update, the indications for spinal cord stimulation are reviewed with attention to recent publications. A focused review of the literature on abdominal and visceral pain syndromes is also provided. Furthermore, the technology has evolved from the use of monopolar electrodes to complex electrode arrays. Similarly, the power source has changed from a radio frequency-driven system to a rechargeable impulse generator. These topics are covered, along with a short discussion of implant technique. Finally, we include a review of complications of such therapy. SCS as a technology and therapy continues to evolve

Development of an Educational Curriculum for Spinal Cord Stimulation.

BACKGROUND: Spinal cord stimulators (SCSs) are used for treating chronic pain. The number of SCSs implanted each year is on the increase. The North American Neuromodulation Society (NANS) education committee aimed to develop a SCS curriculum as a tool to guide physicians at different training levels, based on the most recent evidence. MATERIAL AND METHODS: A multidisciplinary (anesthesiology, physical medicine, neurosurgery, and neurology), taskforce representing the education committee of the NANS met to develop a SCS curriculum following the Accreditation Council for Graduate Medical Education (ACGME) milestones. The task force used the best available evidence and knowledge to develop the curriculum. Once developed, the SCS curriculum was then approved by the NANS board. RESULTS: The task force developed a SCS training curriculum. Milestones included patient care and procedural skills, system-based practice, medical knowledge, interpersonal communication, practice based learning and professionalism. Each milestone was defined for three categories, early learner, advanced learner, and practitioner. CONCLUSION: A multidisciplinary task force of the NANS education committee developed a SCS training curriculum that defines ACGME milestones for basic learners, advanced learners, and practitioners