Prog Neurol Surg [journal]
- Preface. [Introductory Journal Article]
- Prog Neurol Surg 2015.:IX-XI.
- Technology for Peripheral Nerve Stimulation. [Journal Article, Review]
- Prog Neurol Surg 2015.:1-19.
Peripheral nerve stimulation (PNS) has been in use for over 50 years to treat patients suffering from chronic pain who have failed conservative treatments. Despite this long history, the devices being used have changed very little. In fact, current PNS technology was developed specifically for spinal cord stimulation. The use of technology developed for other applications in PNS has led to an unnecessary number of device complications and the limited adoption of this promising therapy. The following chapter provides an overview of PNS technology throughout the years, outlining both the benefits and limitations. We will briefly explore the electrophysiology of PNS stimulation, with an emphasis on technology and indication-specific devices. Finally, design and technical requirements of an ideal PNS device will be discussed.
- Regulation of Peripheral Nerve Stimulation Technology. [Journal Article, Review]
- Prog Neurol Surg 2015.:225-37.
The number of peripheral nerve stimulation (PNS) indications, targets, and devices is expanding, yet the development of the technology has been slow because many devices used for PNS do not have formal regulatory approval. Manufacturers have not sought Food and Drug Administration (FDA) approval for PNS devices because of a perceived lack of interest amongst practitioners and patients. Without FDA approval, companies cannot invest in marketing to educate the implanters and the patients about the benefits of PNS in the treatment of chronic pain. Violation of this has resulted in governmental investigation and prosecution. Most of the PNS devices currently used to treat chronic pain are FDA approved for epidural spinal cord stimulation. Many of the complications seen in PNS surgery can be attributed to the lack of purpose-built hardware with FDA approval. Despite the lack of regulatory approval, there are insurance companies that approve PNS procedures when deemed medically necessary. As the targets and indications for PNS continue to expand, there will be an even greater need for customized technological solutions. It is up to the medical device industry to invest in the design and marketing of PNS technology and seek out FDA approval. Market forces will continue to push PNS into the mainstream and physicians will increasingly have the choice to implant devices specifically designed and approved to treat chronic peripheral nerve pain.
- Sphenopalatine Ganglion Stimulation in Neurovascular Headaches. [Journal Article, Review]
- Prog Neurol Surg 2015.:106-16.
The interest for the sphenopalatine ganglion (SPG) in neurovascular headaches dates back to 1908 when Sluder presented his work on the role of the SPG in 'nasal headaches', which are now part of the trigeminal autonomic cephalalgias and cluster headache (ICHD-III-beta). Since then various interventions with blocking or lesional properties have targeted the SPG (transnasal injection of lidocaine and other agents, alcohol or steroid injections, radiofrequency lesions, or even ganglionectomy); success rates vary, but benefit is usually transient. Here we briefly review some anatomophysiological characteristics of the SPG and hypotheses about its pathophysiological role in neurovascular headaches before describing recent therapeutic results obtained with electrical stimulation of the SPG. Based on results of a prospective randomized controlled study, SPG stimulation appears to be an effective treatment option for patients with chronic cluster headaches; efficacy data indicate that acute electrical stimulation of the SPG provides significant attack pain relief and in many cases pain freedom compared to sham stimulation. Moreover, in some patients SPG stimulation has been associated with a significant and clinically meaningful reduction in cluster headache attack frequency; this preventive effect of SPG stimulation warrants further investigation. For migraine attacks, the outcome of a proof-of-concept study using a temporary electrode implanted in the pterygopalatine fossa was less encouraging; however, an ongoing multicenter trial is evaluating the efficacy of long-term SPG stimulation against sham stimulation for acute and preventive treatment in patients with frequent migraine.
- Stimulation of the Dorsal Root Ganglion. [Journal Article, Research Support, Non-U.S. Gov't, Review]
- Prog Neurol Surg 2015.:213-24.
Dorsal root ganglion (DRG) stimulation has recently emerged as a new neuromodulation modality that stays on the intersection of the peripheral and central nervous system. With DRG location within the spinal column and with electrodes for DRG stimulation placed through the intraspinal epidural space, it may make more sense to group DRG stimulation together with more commonly used spinal cord stimulation (SCS) rather than peripheral nerve stimulation (PNS), particularly if one agrees that the stimulation delivered to DRG partly works downstream at the spinal cord level. Based on current experience, it appears that DRG stimulation of the spinal cord is as effective as SCS in relieving various neuropathic pain syndromes including pain due to failed back surgery syndrome, complex regional pain syndromes, and chronic postsurgical pain. In addition to its efficacy, DRG stimulation of the spinal cord is associated with a lower rate of migrations and lack of positional side effects that may be seen with SCS and PNS. Here we summarize the knowledge base and clinical evidence for DRG stimulation of the spinal cord, and present hypotheses of its mechanism of action.
- Hypoglossal Nerve Stimulation for Obstructive Sleep Apnea. [Journal Article, Review]
- Prog Neurol Surg 2015.:94-105.
Obstructive sleep apnea (OSA) is a very frequent affliction that affects about 1-5% of the adult population in its severe form. Continuous positive airway pressure (CPAP) is the most commonly used treatment and is highly effective, but its use is limited by low long-term adherence rates and overall poor acceptance among the patients. Therefore, there is a need for developing alternative approaches to OSA treatment, including a more 'natural' concept of maintaining an open airway through neuromodulation. Here we review the concept, scientific rationale, and technical details of hypoglossal nerve stimulation. We also review results of published clinical studies with several hypoglossal stimulation devices that are being investigated today. Hypoglossal nerve stimulation appears to be a very promising treatment for patients with moderate-to-severe OSA. If its efficacy is confirmed, it will probably be complementary with CPAP therapy and initially aimed at patients unable or unwilling to use CPAP. Once it becomes a standard therapy, its advantages might prove sufficient to challenge CPAP as the first-line therapy.
- Sacral Nerve Stimulation in the Treatment of Bowel Disorders. [Journal Article, Review]
- Prog Neurol Surg 2015.:200-12.
Defecation problems occur in patients of all ages, but are more prevalent in the elderly, postpartum women, and patients with chronic and debilitating medical conditions. Most of the time, these problems respond to medical therapy and nonsurgical options, but it is not uncommon for patients to require surgical intervention. Sacral nerve stimulation (SNS) presents an alternative for patients with bowel dysfunction combining proven therapeutic benefits and limited surgical risks. Here we describe the common indications for SNS, patient selection, technical details of the procedure, published outcomes, and complications that can arise. Based on our review, SNS is an effective treatment option for fecal incontinence and may reduce the patients' clinical symptoms and help restore their quality of life. Future research studies may expand the role of this modality for other bowel disorders.
- Carotid Sinus/Nerve Stimulation for Treatment of Resistant Hypertension and Heart Failure. [Journal Article, Review]
- Prog Neurol Surg 2015.:83-93.
Hypertension and cardiovascular disease are leading causes of morbidity and mortality worldwide. The prevalence of resistant hypertension remains high and is expected to increase. Moreover, there are limitations to therapeutic interventions aimed at treating resistant hypertension and heart failure despite the wide availability of therapeutic agents and dietary and lifestyle modification. Device-based therapy by baroreflex activation via carotid sinus/nerve stimulation is currently undergoing investigation, and promising findings from clinical trials have been published. Baroreflex activation therapy may represent a new approach for treatment of these conditions by reducing sympathetic drive and increasing parasympathetic activity. Here we describe a new technology which is designed to deliver carotid sinus stimulation to electrically activate the carotid baroreceptors and baroreflex, thereby reducing blood pressure and improving cardiac function. The theory, surgical techniques, and clinical trials of carotid sinus stimulation are highlighted.
- Sacral Neuromodulation for Genitourinary Problems. [Journal Article, Review]
- Prog Neurol Surg 2015.:192-9.
Sacral neuromodulation (SNM) is a minimally invasive therapeutic option for many voiding dysfunction conditions. It is approved by the US FDA for refractory overactive bladder with and without incontinence and nonobstructive retention. Since SNM has shown a favorable response for these approved indications, other therapeutic applications have been proposed for various conditions such as painful bladder syndrome, chronic pelvic pain and neurological voiding dysfunction in both adult and pediatric age groups. SNM therapy with the most commonly used dedicated SNM device (InterStim) involves insertion of electrode(s) in the third and/or fourth sacral foramen next to the nerve root. The electrode is then connected to a battery-operated pulse generator. All patients need to have a test trial period before definitive device insertion. Here we discuss SNM therapy in functional urinary disorders and the technique of device insertion with the potential pitfalls.
- Trigeminal Ganglion Stimulation. [Journal Article, Review]
- Prog Neurol Surg 2015.:76-82.
Facial pain in the distribution of the trigeminal nerve, commonly identified as trigeminal neuralgia, should not be confused with trigeminal neuropathic pain. The latter is caused by an accidental and nonintentional nerve lesion. When the first-line pharmacological treatment fails to provide satisfactory pain relief, surgical treatment, such as microvascular decompression and neurodestructive interventions (radiofrequency or cryotherapy), is not indicated. The logical choice of technique becomes neuromodulation, but it may be challenging to perform in the facial area. Although the initial results of trigeminal ganglion stimulation were promising, they often were of short duration because of lead migration and inadequate stimulation coverage in the trigeminal nerve distribution. To ensure accurate placement and proper anchoring, a custom-made electrode was developed and produced, and its stereotactic implantation is guided by electromagnetic navigation. This technique has been used at our center for several years; the published results show at least 30% of pain relief in 75% of the patients and considerable reduction in medication use.