Effects of Tonic Spinal Cord Stimulation on External Mechanical and Thermal Stimuli Perception Using Quantitative Sensory Testing: A Multicenter Stimulation ON-OFF Study on Chronic Pain Patients.

OBJECTIVES: Tonic spinal cord stimulation (SCS) is currently used to treat neuropathic pain. With this type of stimulation, an implantable pulse generator generates electrical paresthesias in the affected area through 1 or more epidural leads. The goal of this study was to evaluate the impact of tonic SCS on the sensory perception of chronic pain patients using quantitative sensory testing (QST). MATERIALS AND METHODS: Forty-eight patients (mean age: 57 y) with chronic leg pain due to failed back surgery syndrome or complex regional pain syndrome treated with SCS were recruited from 3 research centers. Test procedures included 2 sessions (stimulation On or Off), with measures of detection thresholds for heat, touch, vibration, and of pain thresholds for cold, heat, pressure, the assessment of dynamic mechanical allodynia, and temporal pain summation. Three different areas were examined: the most painful area of the most painful limb covered with SCS-induced paresthesias (target area), the contralateral limb, and the ipsilateral upper limb. Wilcoxon signed-rank tests were used to compare the mean difference between On and Off for each QST parameter at each area tested. P-values <0.05 were considered significant. RESULTS: Regarding the mean difference between On and Off, patients felt less touch sensation at the ipsilateral area (-0.4±0.9 g, P=0.0125) and were less sensitive at the contralateral area for temporal pain summation (-4.9±18.1 on Visual Analog Scale 0 to 100, P=0.0056) with SCS. DISCUSSION: It is not clear that the slight changes observed were clinically significant and induced any changes in patients' daily life. Globally, our results suggest that SCS does not have a significant effect on sensory perception.

A Review of Biomarkers Use in Parkinson with Deep Brain Stimulation: A Successful Past Promising a Bright Future.

BACKGROUND: Parkinson disease (PD) remains a common neurodegenerative disorder. Functional neurosurgery largely arose with the introduction of deep brain stimulation (DBS) as a potential option for PD unresponsive to medical management. Biomarkers are clinical and laboratory indicators of therapeutic success or failure. OBJECTIVE: To examine the current and published literature relating to the development and use of biomarkers in monitoring and determining the efficacy of DBS in PD. METHODS: The PubMed database was systematically searched using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines for systemic reviews. Studies that examined current or potential biomarkers measurable after DBS were included. Articles from 1952 to date were examined. RESULTS: The initial search identified 49 articles. Thirty articles met the inclusion criteria. Articles were subdivided into those addressing biomarkers with proven clinical usefulness and potential biomarkers that have future application. CONCLUSIONS: Biomarkers have been identified that can help to determine the effect of DBS on patients with PD. Current studies show that there are measured differences in electrophysiologic oscillations, gene expression, neuropeptide levels, metabolic function, inflammatory activity, and others in the central nervous system after DBS in PD. Local field potential and ß-band analysis stand as the clinically proven biomarkers of choice for DBS in PD. Many of the identified changes noted could be implemented as clinically useful biomarkers through which DBS may be monitored. Future studies are needed to determine which noted physiologic changes are most appropriately used as biomarkers and in which contexts they are most helpful.

Diagnostic Work-Up of a Giant Calcified Intracranial Aneurysm: Comparing 4D-CTA and Cerebral Angiogram Findings.

The risks associated with unruptured intracranial aneurysms can be neurologically debilitating and even fatal. Evaluation of these aneurysms is critical for determining what type of intervention is warranted, if at all. Cerebral angiography has long been the gold standard in the evaluation of intracranial aneurysms. However, this diagnostic modality is accompanied by several risks that are made clear to the patient before they consent to the procedure. These risks include the possibility of stroke, groin hematomas, contrast-induced anaphylaxis, contrast nephropathy, and catheter-associated infections. Dynamic CT angiography (4D-CTA) has been studied as an assessment tool for cerebral vasculopathies such as stroke, arteriovenous malformations, and aneurysms. It has been shown that 4D-CTA has the advantage of being less invasive and has a shorter examination time than cerebral angiography. In this article, we present a rare case of a giant calcified aneurysm and compare the findings of a cerebral angiogram and a 4D-CTA study.

Chiari I malformation with underlying pseudotumor cerebri: Poor symptom relief following posterior decompression surgery.

INTRODUCTION: Pseudotumor cerebri (PTC) patients exhibit clear clinical signs and symptoms of higher intracranial pressure (ICP) without ventricular enlargement or mass lesions. The clinical picture of patients with PTC can sometimes be similar to that of Chiari Malformation type I (CMI). There is some evidence that Chiari I malformation and PTC may coexist, which raises the question of whether PTC is an idiopathic disease or a complication of posterior decompression surgery-treatment of choice for Chiari I malformation. PRESENTATION OF CASES: A retrospective review of electronic medical records of patients diagnosed with PTC at the University of Toledo Medical Center (UTMC) was performed. The objective was to determine whether PTC patients had a concurrent diagnosis of Chiari I malformation and whether the diagnosis of PTC occurred before or after posterior decompression surgery. Out of the 8 eligible patient medical records reviewed, 5 patients diagnosed with PTC had undergone posterior decompression surgery for Chiari I malformation at anywhere from several days to three years prior to being diagnosed with PTC. The diagnosis of PTC was based on temporary symptomatic relief following lumbar puncture which also showed elevated CSF opening pressures. Finally, a VP shunt was placed in each of the 5 patients to relieve the elevated intracranial pressure which resulted in the complete resolution of the patients' symptoms. DISCUSSION: Our study focuses on patients who were diagnosed with and treated for CMI then reported back to the clinic within several days to three years complaining of symptoms of headache. Upon re-presenting to the clinic, a CSF flow study was performed which showed normal flow of CSF. Then, these patients underwent a lumbar puncture which demonstrated an elevated opening pressure (and ICP) and a temporary relief of the headache with lumbar drainage. A VP shunt was placed for each patient to treat for PTC, and the patients' headaches were relieved. CONCLUSION: This study suggests that the presence of Chiari I malformation in a patient conceals the symptoms of PTC which may become apparent following posterior decompression surgery. Other possibilities could be that the patients are misdiagnosed for Chiari I malformation when they are in fact suffering from PTC, or that PTC is a complication of surgery.

A Comparison of Pharmacologic Therapeutic Agents Used for the Reduction of Intracranial Pressure After Traumatic Brain Injury.

OBJECTIVE: In neurotrauma care, a better understanding of treatments after traumatic brain injury (TBI) has led to a significant decrease in morbidity and mortality in this population. TBI represents a significant medical problem, and complications after TBI are associated with the initial injury and postevent intracranial processes such as increased intracranial pressure and brain edema. Consequently, appropriate therapeutic interventions are required to reduce brain tissue damage and improve cerebral perfusion. We present a contemporary review of literature on the use of pharmacologic therapies to reduce intracranial pressure after TBI and a comparison of their efficacy. METHODS: This review was conducted by PubMed query. Only studies discussing pharmacologic management of patients after TBI were included. This review includes prospective and retrospective studies and includes randomized controlled trials as well as cohort, case-control, observational, and database studies. Systematic literature reviews, meta-analyses, and studies that considered conditions other than TBI or pediatric populations were not included. RESULTS: Review of the literature describing the current pharmacologic treatment for intracranial hypertension after TBI most often discussed the use of hyperosmolar agents such as hypertonic saline and mannitol, sedatives such as fentanyl and propofol, benzodiazepines, and barbiturates. Hypertonic saline is associated with faster resolution of intracranial hypertension and restoration of optimal cerebral hemodynamics, although these advantages did not translate into long-term benefits in morbidity or mortality. In patients refractory to treatment with hyperosmolar therapy, induction of a barbiturate coma can reduce intracranial pressure, although requires close monitoring to prevent adverse events. CONCLUSIONS: Current research suggests that the use of hypertonic saline after TBI is the best option for immediate decrease in intracranial pressure. A better understanding of the efficacy of each treatment option can help to direct treatment algorithms during the critical early hours of trauma care and continue to improve morbidity and mortality after TBI.

Dynamic Four-Dimensional Computed Tomography Angiography for Neurovascular Pathologies.

BACKGROUND: This article illustrates, summarizes, and reviews the multifaceted application of four-dimensional (4D) computed tomography angiography (CTA) in the characterization and diagnosis of various cerebrovascular and tumor-associated vascular pathologies through the presentation of clinical cases, including acute and chronic stroke, arteriovenous malformations, aneurysm, moyamoya disease, and hypervascularity associated with a tumor and its relationship to preoperative embolization. The technical nuances and limitations of the 4D-CTA technique are also discussed. CASE DESCRIPTION: We present 6 cases that best elucidate the application and technical nuances of 4D-CTA and its advantages over traditional digital subtraction angiography. Along with discussion of the utility of 4D-CTA, we also examine the limitations of this technique. CONCLUSIONS: Intracranial vascular lesions can be detected with 4D-CTA and clinically evaluated using information related to vascular flow dynamics. The use of 4D-CTA provides data related to ongoing vascular changes as well as accurate spatial delineation of cerebrovascular pathologies. Overall, 4D-CTA is increasing its role in neuroimaging by providing superior information regarding structural three-dimensional imaging quality and real-time flow.

Streptococcus Mutans: A Potential Risk Factor in Recurrent Hemorrhagic Stroke.

Stroke is the fifth leading cause of death and is responsible for approximately nine percent of all deaths worldwide. Cases of Streptococcus mutans (S. mutans)-induced intracerebral hemorrhage as a result of bloodstream infections have seldom been reported. New reports show that bacteria with specific collagen binding proteins (CBPs), such as the Cnm type produced by S. mutans, may inhibit platelet aggregation and cause bleeding. In this article, we report on a 62-year-old man with a recent history of left frontal intracerebral hemorrhage (ICH) who presented to the emergency department after a fall due to suspected seizure while in rehabilitation. Computed tomography (CT) scan of the brain showed a right cerebellar hemorrhage with surrounding edema and mass effect on the fourth ventricle. A suboccipital craniotomy to evacuate the cerebellar ICH was completed without complication. Radiologic and angiographic assessments regarding the etiology of this patient's stroke did not reveal any evidence of vascular pathology or mycotic aneurysms to explain his recurrent intracranial hemorrhages. Through persistent patient and family interviews, it came to light that a few weeks prior to the patient's first ICH, he was diagnosed with a bloodstream infection by S. mutans. Bacteremia is known to be associated with embolic stroke, but only recently has it been shown that bacteremia can also be implicated in hemorrhagic stroke. S. mutans of the k serotype have specific CBPs that are attracted to exposed collagen in previously damaged small vessel walls. These bacterial proteins can interrupt the blood clotting cascade through the prevention of platelet aggregation, increasing the risk of intracerebral hemorrhage.

Considerations in Spinal Fusion Surgery for Chronic Lumbar Pain: Psychosocial Factors, Rating Scales, and Perioperative Patient Education-A Review of the Literature.

OBJECTIVE: Despite widespread use of lumbar spinal fusion as a treatment for back pain, outcomes remain variable. Optimizing patient selection can help to reduce adverse outcomes. This literature review was conducted to better understand factors associated with optimal postoperative results after lumbar spinal fusion for chronic back pain and current tools used for evaluation. METHODS: The PubMed database was searched for clinical trials related to psychosocial determinants of outcome after lumbar spinal fusion surgery; evaluation of commonly used patient subjective outcome measures; and perioperative cognitive, behavioral, and educational therapies. Reference lists of included studies were also searched by hand for additional studies meeting inclusion and exclusion criteria. RESULTS: Patients' perception of good health before surgery and low cardiovascular comorbidity predict improved postoperative physical functional capacity and greater patient satisfaction. Depression, tobacco use, and litigation predict poorer outcomes after lumbar fusion. Incorporation of cognitive-behavioral therapy perioperatively can address these psychosocial risk factors and improve outcomes. The 36-Item Short Form Health Survey, European Quality of Life five dimensions questionnaire, visual analog pain scale, brief pain inventory, and Oswestry Disability Index can provide specific feedback to track patient progress and are important to understand when evaluating the current literature. CONCLUSIONS: This review summarizes current information and explains commonly used assessment tools to guide clinicians in decision making when caring for patients with lower back pain. When determining a treatment algorithm, physicians must consider predictive psychosocial factors. Use of perioperative cognitive-behavioral therapy and patient education can improve outcomes after lumbar spinal fusion.