Spinal Nerve Root Stimulation for Chronic Pain: A Systematic Review.

OBJECTIVE: Spinal cord stimulation (SCS) has been used as a minimally invasive and effective treatment modality for various chronic pain disorders, with the main target being stimulation of the dorsal columns; however, certain neuropathic pain areas involve dermatomes that are suboptimally covered by SCS. Stimulation of the spinal nerve roots has the advantage of targeting one or several dermatomes at the same time. The aim of this systematic review is to investigate the efficacy of spinal nerve root stimulation (SNRS) for chronic pain disorders. MATERIALS AND METHODS: A detailed literature review was performed through the Ovid Embase and MEDLINE data bases in addition to reference searching. Gray literature was included by searching through common search engines using a simplified search strategy. Studies included were focused on adult patients (aged >18 years), diagnosis of chronic pain syndrome (including but not limited to complex regional pain syndrome, persistent spinal pain syndrome, neuropathic pain secondary to trauma or infection, postherpetic pain, and cancer pain). Patients must have undergone SNRS insertion, with ≥six months of documented pain intensity scores on follow-up. RESULTS: A total of 40 studies underwent full text review, and 13 articles were included in final analysis. Mean preoperative pain intensity was 8.14 ± 0.74 on the visual analog scale, whereas mean postoperative pain intensity at one year was 3.18 ± 1.44. Of 119 patients, 83 (70%) achieved ≥50% reduction in pain intensity after SNRS, whereas 36 (30%) achieved <50% reduction in pain intensity. Only three studies assessed changes in analgesia medication dose and reported morphine equivalent doses varied by case series. Overall, there was a trend toward a reduction in analgesia medications in the postoperative period. CONCLUSIONS: SNRS led to a mean 44% reduction in pain intensity, with a low level of certainty. In addition, there is some evidence to suggest that using SNRS is associated with reduced use of analgesics, including morphine and gabapentin.

Magnetic resonance imaging datasets with anatomical fiducials for quality control and registration.

Tools available for reproducible, quantitative assessment of brain correspondence have been limited. We previously validated the anatomical fiducial (AFID) placement protocol for point-based assessment of image registration with millimetric (mm) accuracy. In this data descriptor, we release curated AFID placements for some of the most commonly used structural magnetic resonance imaging datasets and templates. The release of our accurate placements allows for rapid quality control of image registration, teaching neuroanatomy, and clinical applications such as disease diagnosis and surgical targeting. We release placements on individual subjects from four datasets (N = 132 subjects for a total of 15,232 fiducials) and 14 brain templates (4,288 fiducials), totalling more than 300 human rater hours of annotation. We also validate human rater accuracy of released placements to be within 1 - 2 mm (using more than 45,000 Euclidean distances), consistent with prior studies. Our data is compliant with the Brain Imaging Data Structure allowing for facile incorporation into neuroimaging analysis pipelines.

View cells in the hippocampus and prefrontal cortex of macaques during virtual navigation.

Cells selectively activated by a particular view of an environment have been found in the primate hippocampus (HPC). Whether view cells are present in other brain areas, and how view selectivity interacts with other variables such as object features and place remain unclear. Here, we explore these issues by recording the responses of neurons in the HPC and the lateral prefrontal cortex (LPFC) of rhesus macaques performing a task in which they learn new context-object associations while navigating a virtual environment using a joystick. We measured neuronal responses at different locations in a virtual maze where animals freely directed gaze to different regions of the visual scenes. We show that specific views containing task relevant objects selectively activated a proportion of HPC units, and an even higher proportion of LPFC units. Place selectivity was scarce and generally dependent on view. Many view cells were not affected by changing the object color or the context cue, two task relevant features. However, a small proportion of view cells showed selectivity for these two features. Our results show that during navigation in a virtual environment with complex and dynamic visual stimuli, view cells are found in both the HPC and the LPFC. View cells may have developed as a multiarea specialization in diurnal primates to encode the complexities and layouts of the environment through gaze exploration which ultimately enables building cognitive maps of space that guide navigation.

Decoding spatial locations from primate lateral prefrontal cortex neural activity during virtual navigation.

Objective. Decoding the intended trajectories from brain signals using a brain-computer interface system could be used to improve the mobility of patients with disabilities.Approach. Neuronal activity associated with spatial locations was examined while macaques performed a navigation task within a virtual environment.Main results.Here, we provide proof of principle that multi-unit spiking activity recorded from the lateral prefrontal cortex (LPFC) of non-human primates can be used to predict the location of a subject in a virtual maze during a navigation task. The spatial positions within the maze that require a choice or are associated with relevant task events can be better predicted than the locations where no relevant events occur. Importantly, within a task epoch of a single trial, multiple locations along the maze can be independently identified using a support vector machine model.Significance. Considering that the LPFC of macaques and humans share similar properties, our results suggest that this area could be a valuable implant location for an intracortical brain-computer interface system used for spatial navigation in patients with disabilities.

Surgical Interventions Targeting the Nucleus Caudalis for Craniofacial Pain: A Systematic and Historical Review.

INTRODUCTION: Craniofacial pain is a prevalent group of conditions, and when refractory to conventional treatments, it poses a significant burden. The last decade has seen a renewed interest in the multimodal management of pain. Interventions targeting the nucleus caudalis (NC) of the trigeminocervical complex have been available as a treatment option since the 1930s, yet evidence for efficacy remains limited. MATERIALS AND METHODS: We present a systematic review of the literature providing a historical perspective on interventions targeting the NC leading up to the present. We examine the various intervention techniques, clinical indications, and procedural efficacy. A novel outcome-reporting scheme was devised to enable comparison among studies owing to historically variable reporting methods. RESULTS: A review of the literature revealed 33 retrospective studies published over the last 80 years, reporting on 827 patients. The most common technique was the open NC dorsal root entry zone nucleotomy/tractotomy; however, there has been an emergence of novel approaches such as endoscopic and spinal cord stimulation in the last ten years. Regardless of intervention technique or preoperative diagnosis, 87% of patients showed improvement with treatment. CONCLUSIONS: The literature surrounding NC intervention techniques is reviewed. Recent advancements and the wide range of craniofacial pain syndromes for which these interventions show potential efficacy are discussed. New and less invasive techniques continue to emerge as putative therapeutic options. However, prospective studies are lacking. Furthermore, the evidence supporting even well-established techniques remains of poor quality. Future work should be prospective, use standard outcome reporting, and address efficacy comparisons between intervention type and preoperative diagnosis.

High-fidelity, simulation-based microsurgical training for neurosurgical residents.

OBJECTIVE: Simulation is increasingly recognized as an important supplement to operative training. The live rat femoral artery model is a well-established model for microsurgical skills simulation. In this study, the authors present an 11-year experience incorporating a comprehensive, longitudinal microsurgical training curriculum into a Canadian neurosurgery program. The first goal was to evaluate training effectiveness, using a well-studied rating scale with strong validity. The second goal was to assess the impact of the curriculum on objective measures of subsequent operating room performance during postgraduate year (PGY)-5 and PGY-6 training. METHODS: PGY-2 neurosurgery residents completed a 1-year curriculum spanning 17 training sessions divided into 5 modules of increasing fidelity. Both perfused duck wing and live rat vessel training models were used. Three modules comprised live microvascular anastomosis. Trainee performance was video recorded and blindly graded using the Objective Structured Assessment of Technical Skills Global Rating Scale. Eleven participants who completed the training curriculum and 3 subjects who had not participated had their subsequent operative performances evaluated when they were at the PGY-5 and PGY-6 levels. RESULTS: Eighteen participants completed 106 microvascular anastomoses during the study. There was significant improvement in 6 measurable skills during the curriculum. The mean overall score was significantly higher on the fifth attempt compared with the first attempt for all 3 live anastomotic modules (p < 0.001). Each module had a different improvement profile across the skills assessed. Those who completed the microvascular skills curriculum demonstrated a greater number of independent evaluations during superficial surgical exposure, deep exposure, and primary maneuvers at the PGY-5 and PGY-6 levels. CONCLUSIONS: High-fidelity microsurgical simulation training leads to significant improvement in microneurosurgical skills. Transfer of acquired skills to the operative environment and durability for at least 3 to 4 years show encouraging preliminary results and are subject to ongoing investigation.

Application of the anatomical fiducials framework to a clinical dataset of patients with Parkinson's disease.

Establishing spatial correspondence between subject and template images is necessary in neuroimaging research and clinical applications such as brain mapping and stereotactic neurosurgery. Our anatomical fiducial (AFID) framework has recently been validated to serve as a quantitative measure of image registration based on salient anatomical features. In this study, we sought to apply the AFIDs protocol to the clinic, focusing on structural magnetic resonance images obtained from patients with Parkinson's disease (PD). We confirmed AFIDs could be placed to millimetric accuracy in the PD dataset with results comparable to those in normal control subjects. We evaluated subject-to-template registration using this framework by aligning the clinical scans to standard template space using a robust open preprocessing workflow. We found that registration errors measured using AFIDs were higher than previously reported, suggesting the need for optimization of image processing pipelines for clinical grade datasets. Finally, we examined the utility of using point-to-point distances between AFIDs as a morphometric biomarker of PD, finding evidence of reduced distances between AFIDs that circumscribe regions known to be affected in PD including the substantia nigra. Overall, we provide evidence that AFIDs can be successfully applied in a clinical setting and utilized to provide localized and quantitative measures of registration error. AFIDs provide clinicians and researchers with a common, open framework for quality control and validation of spatial correspondence and the location of anatomical structures, facilitating aggregation of imaging datasets and comparisons between various neurological conditions.

Dorsal Root Entry Zone Lesioning for Brachial Plexus Avulsion Injuries: Case Series and Literature Review.

Introduction: Brachial plexus avulsion (BPA) injuries commonly occur secondary to motor vehicle collisions, usually in the young adult population. These injuries are associated with significant morbidity, and up to 90% of patients suffer from deafferentation pain. Neuromodulation procedures can be efficacious in the treatment of refractory neuropathic pain, although the treatment of pain due to BPA can be challenging. Dorsal root entry zone (DREZ) lesioning is a classical and effective neurosurgical technique which has become underutilized in treating refractory root avulsion pain. Methods: A systematic review of the different technical nuances, procedural efficacy, and complication profiles regarding DREZ lesioning for BPA injuries in the literature is included. We also present an institutional case series of 7 patients with BPA injuries who underwent DREZ lesioning. Results: In the literature, 692 patients were identified to have undergone DREZ lesioning for pain related to BPA. In 567 patients, the surgery was successful in reducing pain intensity by over 50% in comparison to baseline (81.9%). Complications included transient motor deficits (11%) and transient sensory deficits (11%). Other complications including permanent disability, cardiovascular complications, infections, or death were rare (<1.9%). In our case series, all but one patient achieved >50% reduction in pain intensity, with the mean pre-operative pain of 7.9 ± 0.63 (visual analog scale) reduced to 2.1 ± 0.99 at last follow-up (p < 0.01). Conclusion: Both the literature and the current case series demonstrate excellent pain severity reduction following DREZ ablation for deafferentation pain secondary to BPA.

Paresthesia-Free Spinal Nerve Root Stimulation for the Treatment of Chronic Neuropathic Pain.

OBJECTIVE: Stimulation of the dorsal spinal roots, or spinal nerve root stimulation (SNRS), is a neuromodulation modality that can target pain within specific dermatomal distributions. The use of paresthesia-free stimulation has been described with conventional dorsal column spinal cord stimulation, although has yet to be described for SNRS. This objective of this study was to investigate the efficacy of paresthesia-free high-frequency (1000-1200 Hz) SNRS in the treatment of intractable, dermatomal neuropathic pain. MATERIALS AND METHODS: A retrospective chart review was performed on 14 patients implanted with SNRS in varying distributions: Ten patients initially received tonic stimulation and crossed over to a paresthesia-free paradigm and four patients received only paresthesia-free stimulation. The primary outcome was reduction in pain severity (visual analog scale [VAS]), measured at baseline and follow-up to 24 months with paresthesia-free stimulation. RESULTS: All 14 patients who received paresthesia-free stimulation had significant improvement in pain severity at a mean follow-up of 1.39 ± 0.15 years (VAS 7.46 at baseline vs. 3.25 at most recent follow-up, p < 0.001). Ten patients were initially treated with tonic stimulation and crossed over to paresthesia-free stimulation after a mean of 61.7 months. Baseline pain in these crossover patients was significantly improved at last follow-up with tonic stimulation (VAS 7.65 at baseline vs. 2.83 at 48 months, p < 0.001), although all patients developed uncomfortable paresthesias. There was no significant difference in pain severity between patients receiving tonic and paresthesia-free stimulation. CONCLUSIONS: We present real-world outcomes of patients with intractable dermatomal neuropathic pain treated with paresthesia-free, high-frequency SNRS. We demonstrate its effectiveness in providing pain reduction at a level comparable to tonic SNRS up to 24 months follow-up, without producing uncomfortable paresthesias.

Adalimumab for maintenance of remission in Crohn's disease.

BACKGROUND: Conventional medications for Crohn's disease (CD) include anti-inflammatory drugs, immunosuppressants and corticosteroids. If an individual does not respond, or loses response to first-line treatments, then biologic therapies such as tumour necrosis factor-alpha (TNF-α) antagonists such as adalimumab are considered for treating CD. Maintenance of remission of CD is a clinically important goal, as disease relapse can negatively affect quality of life. OBJECTIVES: To assess the efficacy and safety of adalimumab for maintenance of remission in people with quiescent CD. SEARCH METHODS: We searched the Cochrane IBD Group Specialized Register, CENTRAL, MEDLINE, Embase, and clinicaltrials.gov from inception to April 2019. SELECTION CRITERIA: We considered for inclusion randomized controlled trials (RCTs) comparing adalimumab to placebo or to an active comparator. DATA COLLECTION AND ANALYSIS: We analyzed data on an intention-to-treat basis. We calculated risk ratios (RRs) and corresponding 95% confidence intervals (95% CI) for dichotomous outcomes. The primary outcome was failure to maintain clinical remission. We define clinical remission as a Crohn's Disease Activity Index (CDAI) score of < 150. Secondary outcomes were failure to maintain clinical response, endoscopic remission, endoscopic response, histological remission and adverse events (AEs). We assessed biases using the Cochrane 'Risk of bias' tool. We used GRADE to assess the overall certainty of evidence supporting the primary outcome. MAIN RESULTS: We included six RCTs (1158 participants). We rated four trials at low risk of bias and two trials at unclear risk of bias. All participants had moderate-to-severe CD that was in clinical remission. Four studies were placebo-controlled (1012 participants). Two studies (70 participants) compared adalimumab to active medication (azathioprine, mesalamine or 6-mercaptopurine) in participants who had an ileocolic resection prior to study enrolment. Adalimumab versus placebo Fifty-nine per cent (252/430) of participants treated with adalimumab failed to maintain clinical remission at 52 to 56 weeks, compared with 86% (217/253) of participants receiving placebo (RR 0.70, 95% CI 0.64 to 0.77; 3 studies, 683 participants; high-certainty evidence). Among those who received prior TNF-α antagonist therapy, 69% (129/186) of adalimumab participants failed to maintain clinical or endoscopic response at 52 to 56 weeks, compared with 93% (108/116) of participants who received placebo (RR 0.76, 95% CI 0.68 to 0.85; 2 studies, 302 participants; moderate-certainty evidence). Fifty-one per cent (192/374) of participants who received adalimumab failed to maintain clinical remission at 24 to 26 weeks, compared with 79% (149/188) of those who received placebo (RR 0.66, 95% CI 0.52 to 0.83; 2 studies, 554 participants; moderate-certainty evidence). Eighty-seven per cent (561/643) of participants who received adalimumab reported an AE compared with 85% (315/369) of participants who received placebo (RR 1.01, 95% CI 0.94 to 1.09; 4 studies, 1012 participants; high-certainty evidence). Serious adverse events were seen in 8% (52/643) of participants who received adalimumab and 14% (53/369) of participants who received placebo (RR 0.56, 95% CI 0.39 to 0.80; 4 studies, 1012 participants; moderate-certainty evidence) and withdrawal due to AEs was reported in 7% (45/643) of adalimumab participants compared to 13% (48/369) of placebo participants (RR 0.59, 95% CI 0.38 to 0.91; 4 studies, 1012 participants; moderate-certainty evidence). Commonly-reported AEs included CD aggravation, arthralgia, nasopharyngitis, urinary tract infections, headache, nausea, fatigue and abdominal pain. Adalimumab versus active comparators No studies reported failure to maintain clinical remission. One study reported on failure to maintain clinical response and endoscopic remission at 104 weeks in ileocolic resection participants who received either adalimumab, azathioprine or mesalamine as post-surgical maintenance therapy. Thirteen per cent (2/16) of adalimumab participants failed to maintain clinical response compared with 54% (19/35) of azathioprine or mesalamine participants (RR 0.23, 95% CI 0.06 to 0.87; 51 participants). Six per cent (1/16) of participants who received adalimumab failed to maintain endoscopic remission, compared with 57% (20/35) of participants who received azathioprine or mesalamine (RR 0.11, 95% CI 0.02 to 0.75; 51 participants; very low-certainty evidence). One study reported on failure to maintain endoscopic response at 24 weeks in ileocolic resection participants who received either adalimumab or 6-mercaptopurine (6-MP) as post-surgical maintenance therapy. Nine per cent (1/11) of adalimumab participants failed to maintain endoscopic remission compared with 50% (4/8) of 6-MP participants (RR 0.18, 95% CI 0.02 to 1.33; 19 participants). AUTHORS' CONCLUSIONS: Adalimumab is an effective therapy for maintenance of clinical remission in people with quiescent CD. Adalimumab is also effective in those who have previously been treated with TNF-α antagonists. The effect of adalimumab in the post-surgical setting is uncertain. More research is needed in people with recent bowel surgery for CD to better determine treatment plans following surgery. Future research should continue to explore factors that influence initial and subsequent biologic selection for people with moderate-to-severe CD. Studies comparing adalimumab to other active medications are needed, to help determine the optimal maintenance therapy for CD.

Adalimumab for induction of remission in Crohn's disease.

BACKGROUND: Adalimumab is an IgG1 monoclonal antibody that targets and blocks tumor necrosis factor-alpha, a pro-inflammatory cytokine involved in the pathogenesis of Crohn's disease (CD). A significant proportion of people with CD fail conventional therapy or therapy with biologics or develop significant adverse events. Adalimumab may be an effective alternative for these individuals. OBJECTIVES: The objectives of this review were to assess the efficacy and safety of adalimumab for the induction of remission in CD. SEARCH METHODS: We searched MEDLINE, Embase, CENTRAL, the Cochrane IBD Group Specialized Register, ClinicalTrials.Gov and the World Health Organization trial registry (ICTRP) from inception to 16 April 2019. References and conference abstracts were searched to identify additional studies. SELECTION CRITERIA: Randomized controlled trials (RCTs) comparing any dose of adalimumab to placebo or an active comparator in participants with active CD were included. DATA COLLECTION AND ANALYSIS: Two authors independently screened studies, extracted data and assessed bias using the Cochrane 'Risk of bias' tool. The primary outcome was the failure to achieve clinical remission, as defined by the original studies. Clinical remission was defined as a Crohn's Disease Activity Index (CDAI) score of less than 150 points. Secondary outcomes included failure to achieve clinical response (defined as a decrease in CDAI of > 100 points or > 70 points from baseline), failure to achieve endoscopic remission and response, failure to achieve histological remission and response, failure to achieve steroid withdrawal, adverse events (AEs) and serious adverse events (SAEs), withdrawal from study due to AEs and quality of life measured by a validated instrument. We calculated the risk ratio (RR) and 95% confidence intervals (95% CI) for dichotomous outcomes. Data were pooled for analysis if the participants, interventions, outcomes and time frame were similar. Data were analyzed on an intention-to-treat basis. The overall certainty of the evidence was assessed using GRADE. MAIN RESULTS: Three placebo-controlled RCTs (714 adult participants) were included. The participants had moderate to severely active CD (CDAI 220 to 450). Two studies were rated as at low risk of bias and one study was rated as at unclear risk of bias. Seventy-six per cent (342/451) of adalimumab participants failed to achieve clinical remission at four weeks compared to 91% (240/263) of placebo participants (RR 0.85, 95% CI 0.79 to 0.90; high-certainty evidence). Forty-four per cent (197/451) of adalimumab participants compared to 66% (173/263) of placebo participants failed to achieve a 70-point clinical response at four weeks (RR 0.68, 95% CI 0.59 to 0.79; high-certainty evidence). At four weeks, 57% (257/451) of adalimumab participants failed to achieve a 100-point clinical response compared to 76% (199/263) of placebo participants (RR 0.77, 95% CI 0.69 to 0.86; high-certainty evidence). Sixty-two per cent (165/268) of adalimumab participants experienced an AE compared to 72% (188/263) of participants in the placebo group (RR 0.90, 95% CI 0.74 to 1.09; moderate-certainty evidence). Two percent (6/268) of adalimumab participants experienced a SAE compared to 5% (13/263) of participants in the placebo group (RR 0.44, 95% CI 0.17 to 1.15; low-certainty evidence). Lastly, 1% (3/268) of adalimumab participants withdrew due to AEs compared to 3% (8/268) of participants in the placebo group (RR 0.38, 95% CI 0.11 to 1.30; low-certainty evidence). Commonly reported adverse events included injection site reactions, abdominal pain, fatigue, worsening CD and nausea. Quality of life data did not allow for meta-analysis. Three studies reported better quality of life at four weeks with adalimumab (measured with either Inflammatory Bowel Disease Questionnaire or Short-Form 36; moderate-certainty evidence). Endoscopic remission and response, histologic remission and response, and steroid withdrawal were not reported in the included studies. AUTHORS' CONCLUSIONS: High-certainty evidence suggests that adalimumab is superior to placebo for induction of clinical remission and clinical response in people with moderate to severely active CD. Although the rates of AEs, SAEs and withdrawals due to AEs were lower in adalimumab participants compared to placebo, we are uncertain about the effect of adalimumab on AEs due to the low number of events. Therefore, no firm conclusions can be drawn regarding the safety of adalimumab in CD. Futher studies are required to look at the long-term effectiveness and safety of using adalimumab in participants with CD.

Orbital Lymphaticovenous Malformation with Intradural Extension: Rare Case.

BACKGROUND: Orbital lymphaticovenous malformations (LVMs) are congenital vascular lesions that are typically infiltrative in nature. There have been reports of orbital LVMs extending intracranially through orbital fissures, but there have been no reports of intradural extension. CASE DESCRIPTION: We report the first case of orbital LVM extending intradurally through a bony defect in the medial orbital roof. A modified orbitozygomatic approach was used to successfully obliterate this lesion. Neurosurgical and ophthalmologic collaboration was used in the surgical management of this case. CONCLUSIONS: This case highlights the importance of an interdisciplinary approach when managing infiltrative orbital LVMs, as both ophthalmologic and neurosurgical expertise were critical in the success of the surgery.

Automated immunohistochemical method to analyze large areas of the human cortex.

BACKGROUND: There have been inconsistencies in the histological abnormalities found in the cerebral cortex from patients with schizophrenia, bipolar disorder and major depression. Discrepancies in previously published reports may arise from small sample sizes, inconsistent methodology and biased cell counting. METHODS: We applied automated quantification of neuron density, neuron size and cortical layer thickness in large regions of the cerebral cortex in psychiatric patients. This method accurately segments DAPI positive cells that are also stained with CUX2 and FEZF2. Cortical layer thickness, neuron density and neuron size were automatically computed for each cortical layer in numerous Brodmann areas. RESULTS: We did not find pronounced cytoarchitectural abnormalities in the anterior cingulate cortex or orbitofrontal cortex in patients with schizophrenia, bipolar disorder or major depressive disorder. There were no significant differences in layer thickness measured in immunohistochemically stained slides compared with traditional Nissl stained slides. Automated cell counts were correlated, reliable and consistent with manual counts, while being much less time-consuming. CONCLUSION: We demonstrate the validity of using a novel automated analysis approach to post-mortem brain tissue. We were able to analyze large cortical areas and quantify specific cell populations using immunohistochemical markers. Future analyses could benefit from efficient automated analysis.