Vagus nerve stimulation for epilepsy: A review of central mechanisms

Scott E. Krahl, Kevin B. Clark

Date of publication: 31-Oct-2012

Abstract

In a previous paper, the anatomy and physiology of the vagus nerve was discussed in an attempt to explain which vagus nerve fibers and branches are affected by clinically relevant electrical stimulation. This companion paper presents some of vagus nerve stimulation's putative central nervous system mechanisms of action by summarizing known anatomical projections of vagal afferents and their effects on brain biogenic amine pathways and seizure expression.

Motor cortex stimulation for facial chronic neuropathic pain: A review of the literature

Guillermo A. Monsalve

Date of publication: 31-Oct-2012

Background:Facial chronic neuropathic pain (FCNP) is a disabling clinical entity, its incidence is increasing within the chronic pain population. There is indication for neuromodulation when conservative treatment fails. Motor cortex stimulation (MCS) has emerged as an alternative in the advanced management of these patients. The aim of this work is to review the worldwide literature on MCS for FCNP.

Deep brain stimulation of the subthalamic nucleus in Parkinson's disease: Why so successful?

Ersoy Kocabicak, Sonny K. H. Tan, Yasin Temel

Date of publication: 31-Oct-2012

Abstract

The subthalamic nucleus (STN), historically referred to as the corpus Luysii, is a relatively small nucleus located in the junction between the diencephalon and midbrain. An important discovery was made in the late 1980s by Miller and DeLong putting the focus on the STN demonstrating abnormal hyperactivity in this area in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) treated non-human primates. Shortly after, Benazzouz and colleagues showed STN deep brain stimulation (DBS) to significantly improve MPTP induced parkinsonian symptoms, including rigidity and bradykinesia in monkeys. In the same year, Pollak et al. were the first to publish a French case report describing the potential of STN DBS in a patient with advanced Parkinson's disease (PD) in whom they observed improvement of akinesia. Many other prospective studies showed similar improvements of motor symptoms and the lowering of required levodopa dosage. The great success of STN DBS for the treatment of advanced PD is underlined by the growing number of patients treated. STN DBS also provided additional insight into the role of the STN, which is important not only in motor control but also in cognitive and emotional functions.

The role of intraoperative magnetic resonance imaging in glioma surgery

Danny Liang, Michael Schulder

Date of publication: 31-Oct-2012

Abstract

For patients with gliomas, the goal of surgery is to maximize the extent of tumor resection while avoiding injury to functional tissue. The hope is to improve patients’ survival and maintain the highest quality of life as possible. However, because of the infiltrative nature of gliomas these two goals often oppose each other so a compromise must be met. Many tools have been developed to help with this challenge of glioma surgery. Over the past two decades, intraoperative-magnetic resonance imaging (iMRI) has emerged as an increasingly important modality to enhance surgical safety while providing the surgeon with updated information to guide their resection. Here the authors review the studies that demonstrate a positive correlation between extent of resection (EOR) and overall survival (OS), although the data is clearer in patients with low-grade gliomas (LGG) and still somewhat controversial in those with higher-grade tumors. We will then review some of the studies that support the role of iMRI and how it has impacted glioma surgery by increasing the EOR. The value of iMRI usage in regards to overall patient outcome can be extrapolated through its effect on EOR. Overall, available data support the safe use of iMRI and as an effective adjunct in glioma surgery.

Management strategies after nondiagnostic results with frameless stereotactic needle biopsy: Retrospective review of 28 patients

Ellen L. Air, Ronald E. Warnick, Christopher M. McPherson

Date of publication: 31-Oct-2012

Background:Although frameless stereotactic needle biopsy is an accepted procedure for the diagnosis of intracranial lesions, findings are nondiagnostic in 2–15% of patients and no recommendations yet exist to guide subsequent care. After reviewing the postoperative course after nondiagnostic biopsy of 28 patients, we developed a paradigm to guide management in the future.

Dorsal column stimulator applications

Claudio Yampolsky, Santiago Hem, Damián Bendersky

Date of publication: 31-Oct-2012

Background:Spinal cord stimulation (SCS) has been used to treat neuropathic pain since 1967. Following that, technological progress, among other advances, helped SCS become an effective tool to reduce pain.

Vagal nerve stimulation for pharmacoresistant epilepsy in children

Jason S. Hauptman, Gary W. Mathern

Date of publication: 31-Oct-2012

Abstract

Vagus nerve stimulation (VNS) is an adjunctive treatment for adult patients with pharmacoresistant epilepsy. Little is known about VNS therapy for children with epilepsy. This article will: (1) Review the contemporary medical literature related to VNS therapy in children with epilepsy, (2) describe the experience of VNS treatment in 153 children less than 18 years of age, in the University of California, Los Angeles (UCLA) Pediatric Epilepsy Surgery Program, from 1998 to 2012, and (3) describe the surgical technique used for VNS implantation at UCLA. Review of the literature finds that despite different etiologies and epilepsy syndromes in children, VNS appears to show a similar profile of efficacy for seizure control compared to adults, and low morbidity and mortality. The UCLA experience is similar to that reported in the literature for children. VNS constitutes about 21% of our pediatric epilepsy surgery volume. We have implanted VNS in infants as young as six months of age and the most common etiology is the Lennox-Gastaut Syndrome. About 5% of the patients are seizure-free with VNS therapy and there is a low rate of surgically related complications. The UCLA surgical approach emphasizes minimal direct manipulation of the vagus nerve and adequate wire loops, to prevent a lead fracture. In summary, VNS is a viable palliative treatment for medically refractory epilepsy in children, with outcomes and complications equal to adult patients. Being a small child is not a contraindication for VNS therapy, if needed for refractory epilepsy.

Brain imaging correlates of peripheral nerve stimulation

Ausaf A. Bari, Nader Pouratian

Date of publication: 31-Oct-2012

Abstract

Direct peripheral nerve stimulation is an effective treatment for a number of disorders including epilepsy, depression, neuropathic pain, cluster headache, and urological dysfunction. The efficacy of this stimulation is ultimately due to modulation of activity in the central nervous system. However, the exact brain regions involved in each disorder and how they are modulated by peripheral nerve stimulation is not fully understood. The use of functional neuroimaging such as SPECT, PET and fMRI in patients undergoing peripheral nerve stimulation can help us to understand these mechanisms. We review the literature for functional neuroimaging performed in patients implanted with peripheral nerve stimulators for the above-mentioned disorders. These studies suggest that brain activity in response to peripheral nerve stimulation is a complex interaction between the stimulation parameters, disease type and severity, chronicity of stimulation, as well as nonspecific effects. From this information we may be able to understand which brain structures are involved in the mechanism of peripheral nerve stimulation as well as define the neural substrates underlying these disorders.

Iliac crest autograft versus alternative constructs for anterior cervical spine surgery: Pros, cons, and costs

Nancy E. Epstein

Date of publication: 17-Jul-2012

Background:Grafting choices available for performing anterior cervical diskectomy/fusion (ACDF) procedures have become a major concern for spinal surgeons, and their institutions. The “gold standard”, iliac crest autograft, may still be the best and least expensive grafting option; it deserves to be reassessed along with the pros, cons, and costs for alternative grafts/spacers.

The diagnosis and management of synovial cysts: Efficacy of surgery versus cyst aspiration

Nancy E. Epstein, Jamie Baisden

Date of publication: 17-Jul-2012

Background:The surgical management of lumbar synovial cysts that have extruded into the spinal canal remains controversial (e.g. decompression with/without fusion).