Deep Brain Stimulation for Obesity: From a Theoretical Framework to Practical Application.

Obesity remains a pervasive global health problem. While there are a number of nonsurgical and surgical options for treatment, the incidence of obesity continues to increase at an alarming rate. The inability to curtail the growing rise of the obesity epidemic may be related to a combination of increased food availability and palatability. Research into feeding behavior has yielded a number of insights into the homeostatic and reward mechanisms that govern feeding. However, there remains a gap between laboratory investigations of feeding physiology in animals and translation into meaningful treatment options for humans. In addition, laboratory investigation may not be able to recapitulate all aspects of human food consumption. In a landmark pilot study of deep brain stimulation (DBS) of the lateral hypothalamic area for obesity, we found that there was an increase in resting metabolic rate as well as a decreased urge to eat. In this review, the authors will review some of the work relating to feeding physiology and research surrounding two nodes involved in feeding homeostasis, nucleus accumbens (NAc) and hypothalamus, and use this to provide a framework for future investigations of DBS as a viable therapeutic modality for obesity.

Deep brain stimulation for psychiatric diseases: a pooled analysis of published studies employing disease-specific standardized outcome scales.

BACKGROUND: Deep brain stimulation (DBS) has emerged in recent years as a novel therapy in the treatment of refractory psychiatric disease, including major depressive disorder (MDD), obsessive-compulsive disorder (OCD), and Tourette's syndrome (TS). Standardized outcome scales were crucial in establishing that DBS was an effective therapy for movement disorders. OBJECTIVE: In order to better characterize the evidence supporting DBS for various psychiatric diseases, we performed a pooled analysis of those studies which incorporated specific standardized rating scales. METHODS: A Medline search was conducted to identify all studies reporting DBS for MDD, OCD, and TS. The search yielded a total of 49 articles, of which 24 were included: 4 related to MDD (n = 48), 10 to OCD (n = 64), and 10 to TS (n = 46). RESULTS: A meta-analysis of DBS for MDD, OCD, and TS in studies employing disease-specific standardized outcome scales showed that the outcome scales all improved in a statistically significant fashion for these psychiatric diseases. Our pooled analysis suggests that DBS for TS has the highest efficacy amongst the psychiatric diseases currently being treated with DBS, followed by OCD and MDD. CONCLUSION: DBS for psychiatric diseases remains investigational; however, even when studies failing to incorporate standardized outcome scales are excluded, there is statistically significant evidence that DBS can improve symptoms in MDD, OCD, and TS. Standardized disease-specific outcome scales facilitate pooled analysis and should be a required metric in future studies of DBS for psychiatric disease.

A Multicenter Study Investigating the Surgeon Experience with a Robotic-Assisted Exoscope as Part of the Neurosurgical Armamentarium.

BACKGROUND: Improvement of visualization tools in neurosurgery such as the exoscope has raised the question of how this technology compares to the conventional microscope for surgeon ergonomics, discomfort, and patient outcomes. Exoscopes have the advantage of greater optical zoom, resolution, and illumination at a lower light intensity. Heads-up display for both the primary surgeon and other assistants permits neutral positioning of the surgeons while placing the camera in more angled positions. In a survey sample, this study assesses the surgeon experience utilizing 3D exoscope in general neurosurgery cases. METHODS: Data weere recorded by 8 surgeons at 5 separate hospitals utilizing a mobile phone application survey. Surgeons recorded information about case type, intraoperative clinical outcomes such as blood loss and extent of resection, whether fluorescence visualization was used, as well as surgeon pain when compared to matched cases using conventional tools. RESULTS: A total of 155 neurosurgical cases were recorded in this multisite study, including 72% cranial cases and 28% spinal cases. Of the cranial cases, 76% were brain tumor resections (31% of which were brain metastases). Surgeons reported significantly less neck (P < 0.0001) and back (P < 0.0001) pain in cases when using the robotic exoscope compared with the conventional microscope or surgical loupes. Surgeons did not convert to a microscope in any case. CONCLUSIONS: The exoscope provides excellent delineation of tissue with high resolution. Surgeon pain was markedly reduced with the robotic exoscope when compared with conventional technology, which may reduce work-related injury and fatigue, potentially leading to better patient outcomes.

Prevalence of Long-Term Low Back Pain After Symptomatic Lumbar Disc Herniation.

OBJECTIVE: Lumbar disc herniation (LDH) is a global issue associated with potentially debilitating long-term consequences, including chronic low back pain (LBP). Short-term outcomes (<2 years) of patients with LDH have been extensively studied and demonstrate improvements in back and leg pain for both operative and conservative management. However, these improvements may not be sustained long-term (>2 years); patients with LDH may develop recurrent disc herniations, progressive degenerative disc disease, and LBP regardless of management strategy. Therefore, our objective is to determine the prevalence of chronic LBP after LDH, understand the relationship between LDH and chronic LBP, and investigate the relationship between radiological findings and postoperative pain outcomes. METHODS: We performed a literature review on the PubMed database via a combination medical subject heading and keyword-based approach for long-term LBP outcomes in patients with LDH. RESULTS: Fifteen studies (2019 patients) evaluated surgical and/or nonoperative outcomes of patients with LDH . Regardless of surgical or nonoperative management, 46.2% of patients with LDH experienced some degree of LBP long-term (range 2-27 years) as compared to a point prevalence of LBP in the general population of only 11.9%. CONCLUSIONS: Patients with LDH are more likely to experience long-term LBP compared to the general population (46.2% vs. 11.9%). Additionally, understanding the relationship between radiological findings and pain outcomes remains a major challenge as the presence of radiological changes and the degree of LBP do not always correlate. Therefore, higher quality studies are needed to better understand the relationship between radiological findings and pain outcomes.

Brain tissue oxygen-based therapy and outcome after severe traumatic brain injury: a systematic literature review.

Observational clinical studies demonstrate that brain hypoxia is associated with poor outcome after severe traumatic brain injury (TBI). In this study, available medical literature was reviewed to examine whether brain tissue oxygen (PbtO2)-based therapy is associated with improved patient outcome after severe TBI. Clinical studies published between 1993 and 2010 that compared PbtO2-based therapy combined with intracranial and cerebral perfusion pressure (ICP/CPP)-based therapy to ICP/CPP-based therapy alone were identified from electronic databases, Index Medicus, bibliographies of pertinent articles, and expert consultation. For analysis, each selected paper had to have adequate data to determine odds ratios (ORs) and confidence intervals (CIs) of outcome described by the Glasgow outcome score (GOS). Seven studies that compared ICP/CPP and PbtO2- to ICP/CPP-based therapy were identified. There were no randomized studies and no comparison studies in children. Four studies, published in 2003, 2009, and 2010 that included 491 evaluable patients were used in the final analysis. Among patients who received PbtO2-based therapy, 121(38.8%) had unfavorable and 191 (61.2%) had a favorable outcome. Among the patients who received ICP/CPP-based therapy 104 (58.1%) had unfavorable and 75 (41.9%) had a favorable outcome. Overall PbtO2-based therapy was associated with favorable outcome (OR 2.1; 95% CI 1.4-3.1). Summary results suggest that combined ICP/CPP- and PbtO2-based therapy is associated with better outcome after severe TBI than ICP/CPP-based therapy alone. Cross-organizational practice variances cannot be controlled for in this type of review and so we cannot answer whether PbtO2-based therapy improves outcome. However, the potentially large incremental value of PbtO2-based therapy provides justification for a randomized clinical trial.

Minimally Invasive Posterior Cervical Foraminotomy Using 3-Dimensional Total Navigation: 2-Dimensional Operative Video.

Minimally invasive posterior cervical foraminotomy (MPCF) has shown comparable outcomes to those of an open approach, with shorter operation times and length of hospital stays, as well as decreased blood loss and inpatient analgesic use. This surgical technique is mainly used to treat unilateral radiculopathy due to foraminal soft disc fragments or bone spurs. Three-dimensional (3D) navigation-guidance facilitates the surgical workflow, and it is utilized in planning the incision, determining the extent of the medial facetectomy, and confirming sufficient decompression, especially in the lower cervical spine and cervicothoracic junction, where the shoulders make localization with fluoroscopy difficult. In this video, we present the case of a 49-yr-old male patient with mechanical neck pain and C8 radiculopathy due to multilevel cervical spinal stenosis with disc herniations and C7-T1 right-sided foraminal stenosis. There was loss of cervical lordosis at the upper levels. The patient underwent anterior cervical discectomy and fusion (ACDF) at the C4-5, C5-6, and C6-7 levels to treat mechanical neck pain and restore lordosis. In order to avoid an extra-level fusion and preserve motion, we performed a right-sided C7-T1 MPCF using a portable intraoperative computed tomography (iCT) scanner (Airo®; Brainlab AG, Feldkirchen, Germany), combined with 3D computer navigation to address the patient's radicular symptoms. Patient consent was obtained prior to performing the procedure.

Intraoperative image guidance for cervical spine surgery.

Intraoperative image-guidance in spinal surgery has been influenced by various technological developments in imaging science since the early 1990s. The technology has evolved from simple fluoroscopic-based guidance to state-of-art intraoperative computed tomography (iCT)-based navigation systems. Although the intraoperative navigation is more commonly used in thoracolumbar spine surgery, this newer imaging platform has rapidly gained popularity in cervical approaches. The purpose of this manuscript is to address the applications of advanced image-guidance in cervical spine surgery and to describe the use of intraoperative neuro-navigation in surgical planning and execution. In this review, we aim to cover the following surgical techniques: anterior cervical approaches, atlanto-axial fixation, subaxial instrumentation, percutaneous interfacet cage implantation as well as minimally invasive posterior cervical foraminotomy (PCF) and unilateral laminotomy for bilateral decompression. The currently available data suggested that the use of 3D navigation significantly reduces the screw malposition, operative time, mean blood loss, radiation exposure, and complication rates in comparison to the conventional fluoroscopic-guidance. With the advancements in technology and surgical techniques, 3D navigation has potential to replace conventional fluoroscopy completely.

Less Invasive Cervical Decompression via Unilateral Tubular Laminotomy Using 3-Dimensional Total Navigation: 2-Dimensional Operative Video.

This video demonstrates the step-by-step surgical technique for a less invasive cervical unilateral laminotomy for bilateral decompression (cervical ULBD). This technique allows surgeons to address bilateral cervical pathology while minimizing approach-related complications.1 In the video, we present the case of a 72-yr-old female patient with a past medical history of C3-C4 anterior cervical discectomy and fusion who presented in clinic with persistent posterior spinal cord compression and signal change. The patient had bilateral hand numbness, weakness, poor dexterity, and a positive Hoffman's sign. The patient was treated via a C3-C4 less invasive cervical ULBD using a mobile 3-dimensional (3D) C-arm (Ziehm Vision RFD 3D®, Nürnberg, Germany) combined with 3D computer navigation. Patient consent was obtained prior to performing the procedure. Contrary to anterior techniques, posterior cervical approaches avoid potential dysphasia, recurrent laryngeal nerve injury, and adjacent segment degeneration. Furthermore, the less invasive cervical ULBD results in decreased pain and postoperative narcotic usage, shorter hospital stays and fewer infections compared to open approaches, as well as a lower risk for postlaminectomy kyphosis and deformity, since it requires less muscle disruption and bony removal. Additionally, the use of total 3D navigation facilitates the workflow and minimizes radiation exposure.

Disease Stabilization of DYT1-Positive Primary Generalized Dystonia With Deep Brain Stimulation of the Globus Pallidus Interna: A 15-Year Follow-up.

BACKGROUND AND IMPORTANCE: Primary generalized dystonia (PGD) is a genetic form of dystonia that frequently displays pharmacological resistance and progresses quickly after onset. Deep brain stimulation (DBS) has been used successfully to treat refractory dystonia, specifically globus pallidus interna (GPi) DBS for DYT1-positive PGD patients. Long-term follow-up of the safety and efficacy falls short of the longevity seen in other diseases treated with DBS. CASE PRESENTATION: A male patient presented for neurosurgical evaluation with scapular winging, hand contractures, and violent truncal spasms, which forced him to be bedridden. After failing conservative therapy, the 18-yr-old patient was implanted with bilateral GPi-DBS. DBS parameter adjustments were made primarily within the first 3 yr after implantation, with nominal changes thereafter. Initial settings were contact of 3 + 0-, amplitude of 4.9 V, frequency of 185 Hz, and pulse width of 270 µsec on the left and 3 + 0-, 2.8 V, 185 Hz, and 120 µsec on the right. Current settings are 3 + 2 + 1-, 5.2 V, 130 Hz, 330 µsec on the left and 3 + 0-, 3.5 V, 185 Hz, and 180 µsec on the right and have been relatively unchanged in the past 4 yr. Unified dystonia rating scale scores reveal a significant decrease in dystonic symptoms. CONCLUSION: While prior reports have shown that GPi-DBS is effective for dystonia, this is the first with 15 yr of long-term follow-up showing disease stabilization, suggesting that stimulation is efficacious and can potentially prevent disease progression. This report reaffirms previous reports that recommend early surgical intervention before the onset of permanent musculoskeletal deficits.

Material characterization and selection for 3D-printed spine models.

The two most popular models used in anatomical training for residents, clinicians, or surgeons are cadavers and sawbones. The former is extremely costly and difficult to attain due to cost, ethical implications, and availability, while the latter is said to not have the same tactile fidelity or mechanical properties as human bone. This study examined the potential use of 3D-printed phantoms to emulate cadaveric, human vertebrae, in hopes of acting as a future use over cadavers. In so doing, we developed 3D-printed MedPhantom®, with the intended use to offer similar tactile feel, mechanical characteristics, and visual appearance as human bone. In order to quantify tactility, a mechanical test was developed where a 5-mm diameter diamond-coated bur spinning at 75,000 RPM swept across the specimens while continuously recording the resultant forces (N) and moments (N-cm), The bur sweep motion is common in orthopedic surgery and neurosurgery. Since most 3D-prints do not offer internal, trabecular structure similar to bone, an algorithm was written to create a stochastic framework of internal mesh to mimic cancellous bone within an STL (stereolithography) file. The ranges of mesh parameters were chosen after several visits with the neurosurgeons participating in the project. In order to quantify structural combinations of wall thickness, gap sizes, and varying cylindrical radii within a print, 1000 RPM compression test with a 5-mm diamond-coated bur was performed with resultant forces (N). Two sample t-test shows statistical significance that samples are not equal to the vertebrae (p < 0.05). Results from the bur sweep test showed 15% Gypsum® powder mixed with 100% Clear® Formlabs resin and 10% Castable® resin mixed with 90% Clear® resin were nearest to human, cadaveric vertebrae, with the difference of force and moment in the x-direction at only 5 N and 7-9 N-cm, respectively. Structural compression results showed that a 2 mm cortical wall, 4 mm or 5 mm gap size between cylinders inside the structure, and 0.25 mm radius of internal cylinders were the best fit parameters to match human vertebrae.

Scoliosis Secondary to Dystonia: A Case Report and Review of the Literature.

CASE: An adolescent girl presented with an atypical scoliotic curve, pelvic obliquity, back pain, and lower-extremity paresthesias. A workup revealed generalized primary torsion dystonia. The condition was refractory to medical treatment and necessitated implantation of a deep brain stimulator. The scoliosis required operative correction, and the patient underwent posterior spinal arthrodesis with hook-rod instrumentation, which resulted in successful correction through 7 years of follow-up. CONCLUSION: The differential diagnosis for adolescent scoliosis should include dystonia as a potential cause, especially when a patient presents with muscular contractures, an atypical scoliotic curve, pelvic obliquity, or changing curve characteristics.

Refractory Orthostatic Hypotension Caused by a Recurrent Hemangioblastoma: Case Report and Review of the Literature.

Refractory orthostatic hypotension (OH) has been described following surgery for posterior fossa tumors. We present the case of a patient with refractory OH following attempted surgical resection. We also reviewed the available literature to describe pathophysiologic mechanisms for this rare entity. A 58-year-old female was found to have a hemangioblastoma at the cervicomedullary junction following workup for dysphagia and coordination difficulties. She underwent successful suboccipital craniotomy and gross total resection. However, the patient's symptoms returned several years later and a magnetic resonance imaging (MRI) showed tumor recurrence. A surgical resection was attempted but could not be performed due to significant scarring. Following discharge, she returned to our care with severe syncopal episodes, refractory OH, and an inability to ambulate. Aggressive medical therapy resulted in a gradual improvement in her ability to ambulate and a reduction in her orthostatic episodes. Unfortunately she died due to sepsis from aspiration pneumonia several months later. A survey of the literature yielded a total of 10 reports (14 patients) with refractory OH as a result of tumors in the cervicomedullary region. Five of fourteen patients died from complications related to OH and brainstem compression while the remainder had some improvement and were discharged. Refractory OH can rarely be a presenting sign of a tumor in the cervicomedullary junction or can manifest following surgical resection of tumors in this region. Recognition of OH and the institution of medical therapy (sodium and fluid replacement) and pharmacotherapy may curb the significant morbidity associated with this condition.

Hybrid peripheral nerve sheath tumor.

In recent literature, there have been case reports of an extremely rare entity characterized by hybrid peripheral nerve tumors consisting of elements of neurofibroma, schwannoma, and/or perineurioma. The authors present a unique case of a patient with multiple painful hybrid tumors with negative genetic testing for neurofibromatosis Type 1 and no clinical evidence of neurofibromatosis Type 2 or schwannomatosis. A 28-year-old woman presented with tentatively diagnosed schwannomatosis. She had painful bilateral retromastoid scalp tumors as well as multiple other painful tumors in the distribution of the saphenous, femoral, and sciatic nerves. Her family history was significant for a paternal grandfather with a solitary schwannoma. The patient underwent multiple surgical procedures for tumor resection, including tumors in the regions of the retromastoid scalp, bilateral sciatic nerves, left femoral nerve, and left axilla. These tumors were examined and evaluated histologically. Within the tumors, components of both neurofibromas and schwannomas were found, even though these 2 peripheral nerve sheath tumors have been long considered to be distinct entities. This case report suggests a distinct syndrome that has not previously been appreciated.