Increased Surgeon-specific Experience and Volume is Correlated With Improved Clinical Outcomes in Lumbar Fusion Patients.

STUDY DESIGN: The present study design was that of a single center, retrospective cohort study to evaluate the influence of surgeon-specific factors on patient functional outcomes at 6 months following lumbar fusion. Retrospective review of a prospectively maintained database of patients who underwent neurosurgical lumbar instrumented arthrodesis identified the present study population. OBJECTIVE: This study seeks to evaluate surgeon-specific variable effects on patient-reported outcomes such as Oswestry Disability Index (ODI) and the effect of North American Spine Society (NASS) concordance on outcomes in the setting of variable surgeon characteristics. SUMMARY OF BACKGROUND DATA: Lumbar fusion is one of the fastest growing procedures performed in the United States. Although the impact of surgeon-specific factors on patient-reported outcomes has been contested, studies examining these effects are limited. METHODS: This is a single center, retrospective cohort study analyzing a prospectively maintained database of patients who underwent neurosurgical lumbar instrumented arthrodesis by 1 of 5 neurosurgery fellowship trained spine surgeons. The primary outcome was improvement of ODI at 6 months postoperative follow-up compared with preoperative ODI. RESULTS: A total of 307 patients were identified for analysis. Overall, 62% of the study population achieved minimum clinically important difference (MCID) in ODI score at 6 months. Years in practice and volume of lumbar fusions were statistically significant independent predictors of MCID ODI on multivariable logistic regression ( P =0.0340 and P =0.0343, respectively). Concordance with evidence-based criteria conferred a 3.16 (95% CI: 1.03, 9.65) times greater odds of achieving MCID. CONCLUSION: This study demonstrates that traditional surgeon-specific variables predicting surgical morbidity such as experience and procedural volume are also predictors of achieving MCID 6 months postoperatively from lumbar fusion. Independent of surgeon factors, however, adhering to evidence-based guidelines can lead to improved outcomes.

Clinical Outcomes at One-year Follow-up for Patients With Surgical Site Infection After Spinal Fusion.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: To compare health-related quality of life outcomes at one-year follow-up between patients who did and did not develop surgical site infection (SSI) after thoracolumbar spinal fusion. SUMMARY OF BACKGROUND DATA: SSI is among the most common healthcare-associated complications. As healthcare systems increasingly emphasize the value of delivered care, there is an increased need to understand the clinical impact of SSIs. MATERIALS AND METHODS: A retrospective 3:1 (control:SSI) propensity-matched case-control study was conducted for adult patients who underwent thoracolumbar fusion from March 2014 to January 2020 at a single academic institution. Exclusion criteria included less than 18 years of age, incomplete preoperative and one-year postoperative patient-reported outcome measures, and revision surgery. Continuous and categorical data were compared via independent t tests and χ 2 tests, respectively. Intragroup analysis was performed using paired t tests. Regression analysis for ∆ patient-reported outcome measures (postoperative minus preoperative scores) controlled for demographics. The α was set at 0.05. RESULTS: A total of 140 patients (105 control, 35 SSI) were included in final analysis. The infections group had a higher rate of readmission (100% vs. 0.95%, P <0.001) and revision surgery (28.6% vs. 12.4%, P =0.048). Both groups improved significantly in Physical Component Score (control: P =0.013, SSI: P =0.039), Oswestry Disability Index (control: P <0.001, SSI: P =0.001), Visual Analog Scale (VAS) Back (both, P <0.001), and VAS Leg (control: P <0.001, SSI: P =0.030). Only the control group improved in Mental Component Score ( P <0.001 vs. SSI: P =0.228), but history of a SSI did not affect one-year improvement in ∆MCS-12 ( P =0.455) on regression analysis. VAS Leg improved significantly less in the infection group (-1.87 vs. -3.59, P =0.039), which was not significant after regression analysis (ß=1.75, P =0.050). CONCLUSION: Development of SSI after thoracolumbar fusion resulted in increased revision rates but did not influence patient improvement in one-year pain, functional disability, or physical and mental health status.

Low-voltage fast seizures in humans begin with increased interneuron firing.

OBJECTIVE: Intracellular recordings from cells in entorhinal cortex tissue slices show that low-voltage fast (LVF) onset seizures are generated by inhibitory events. Here, we determined whether increased firing of interneurons occurs at the onset of spontaneous mesial-temporal LVF seizures recorded in patients. METHODS: The seizure onset zone (SOZ) was identified using visual inspection of the intracranial electroencephalogram. We used wavelet clustering and temporal autocorrelations to characterize changes in single-unit activity during the onset of LVF seizures recorded from microelectrodes in mesial-temporal structures. Action potentials generated by principal neurons and interneurons (ie, putative excitatory and inhibitory neurons) were distinguished using waveform morphology and K-means clustering. RESULTS: From a total of 200 implanted microelectrodes in 9 patients during 13 seizures, we isolated 202 single units; 140 (69.3%) of these units were located in the SOZ, and 40 (28.57%) of them were classified as inhibitory. The waveforms of both excitatory and inhibitory units remained stable during the LVF epoch (p > > 0.05). In the mesial-temporal SOZ, inhibitory interneurons increased their firing rate during LVF seizure onset (p < 0.01). Excitatory neuron firing rates peaked 10 seconds after the inhibitory neurons (p < 0.01). During LVF spread to the contralateral mesial temporal lobe, an increase in inhibitory neuron firing rate was also observed (p < 0.01). INTERPRETATION: Our results suggest that seizure generation and spread during spontaneous mesial-temporal LVF onset events in humans may result from increased inhibitory neuron firing that spawns a subsequent increase in excitatory neuron firing and seizure evolution. Ann Neurol 2018;84:588-600.

Suture Choice in Lumbar Dural Closure Contributes to Variation in Leak Pressures: Experimental Model.

STUDY DESIGN: Open-label laboratory investigational study; non-animal surgical simulation. OBJECTIVE: The authors perform a comparison of dural closure strength in a durotomy simulator across 2 different suture materials. SUMMARY OF BACKGROUND DATA: Incidental durotomy leading to persistent cerebrospinal fluid leak adds considerable morbidity to spinal procedures, often complicating routine elective lumbar spinal procedures. Using an experimental durotomy simulation, the authors compare the strength of closure using Gore-Tex with other suture types and sizes, using various closure techniques. METHODS: A comparison of dural closures was performed through an analysis of the peak pressure at which leakage occurred from a standardized durotomy closure in an established cerebrospinal fluid repair model with a premade L3 laminectomy. Nurolon was compared with Gore-Tex sutures sizes (for Gore-Tex, CV-6/5-0 and CV-5/4-0 was compared with Nurolon 4-0, 5-0, and 6-0). RESULTS: Thirty-six trials were performed with Nurolon 4-0, 5-0, and 6-0, whereas 21 trials were performed for 4-0 and 5-0 Gore-Tex. The mean peak pressure at which fluid leakage was observed was 21 cm H2O for Nurolon and 34 cm H2O for Gore-Tex. Irrespective of suture choice, all trials were grouped by closure technique: running suture, locked continuous, and interrupted suture. No significant difference was noted between the groups. For each of the 3 trials groups by closure technique, running, locked continuous, and interrupted, Gore-Tex closures had a significantly higher peak pressure to failure. Interrupted Gore-Tex was significantly higher than Interrupted Nurolon (P=0.007), running Gore-Tex was significantly higher than running Nurolon (P=0.034), and locked Gore-Tex was significantly higher than locked Nurolon (P=0.014). CONCLUSIONS: Durotomy closure in the lumbar spine with Gore-Tex suture may be a reasonable option for providing a watertight closure. In this laboratory study, Gore-Tex suture provided watertight dural closures that withstood higher peak pressures.

Cost-Effectiveness Data Regarding Spinal Cord Stimulation for Low Back Pain.

STUDY DESIGN: Review of published literature pertaining to spinal cord stimulation (SCS) cost data analysis. OBJECTIVE: To acquire, organize, and succinctly summarize the available literature regarding the costs associated with, and the cost-effectiveness of, SCS. SUMMARY OF BACKGROUND DATA: Chronic back and limb pain is a pervasive complaint in modern society, with estimated annual costs of medical care greater than $100 billion. The traditional standard medical management with or without intermittent surgical decompression/fusion has been plagued by high costs and inconsistent results, leading to poor patient satisfaction and functional outcome, and questions from policy makers regarding use of limited healthcare resources. Neuromodulation techniques, including SCS have recently become more common in the treatment of chronic back/leg pain, with clinical studies showing a high degree of efficacy in alleviating otherwise intractable pain. Given the relatively high upfront costs associated with the hardware and implantation, policy makers have, however, questioned their use in the framework of cost-containment and resource utilization. We reviewed the available literature summarizing cost data of SCS in chronic back and limb pain, as an understanding of these data will be vital to justify continued payment for this expensive, but often very effective, treatment modality. METHODS: We performed a PubMed literature search utilizing the following terms: "spinal cord stimulation," "SCS," "financial," "cost," "cost-effectiveness," and "cost-utility." All studies published in English and containing complete or partial cost evaluations of SCS for chronic back and limb pain were included. RESULTS: The search revealed 21 studies that evaluated cost data, with or without outcomes analysis and cost-utility analysis, for patients with chronic back and limb pain. The overwhelming majority of data presented shows that SCS is not only an effective treatment option for these patients, but also represents cost savings and efficient use of healthcare resources relative to current standards of care. Although not all studies performed cost-utility analyses, those that did tended to show SCS falling well within accepted thresholds of "willingness-to-pay" on the part of third-party payers. That being said, the articles included in this review were almost all small, retrospective, single-institution studies. In addition, many of them relied on modeling for their analyses, and published literature values for cost and/or outcomes data rather than prospectively collected patient data. Although the data presented in this review are encouraging, it should serve as a foundation for a thorough, prospective, cost-utility analysis of SCS in chronic back and limb pain so that the role of this important treatment modality may be cemented in the treatment paradigm for these patients without questions from third-party payers. CONCLUSION: The large majority of data covering costs of SCS argue in favor of the cost-effectiveness of this treatment modality for chronic neuropathic pain, especially in comparison to reoperation and medical management. Although most of the higher-quality evidence is relatively short-term, clinical experience with the durability of treatment benefit of SCS in these patients is promising. Given the pushback regarding high upfront costs of implantation, longer-term, prospective, randomized studies evaluating this topic will be important to help maintain third-party payer reimbursements for SCS. LEVEL OF EVIDENCE: 5.

An Overview of Chronic Spinal Pain: Revisiting Diagnostic Categories and Exploring an Evolving Role for Neurostimulation.

STUDY DESIGN: Topic overview. OBJECTIVE: To describe the varied etiologies resulting in chronic spinal pain and review the current available evidence for treatments. SUMMARY OF BACKGROUND DATA: Chronic pain conditions, especially those that affect the axial back and radiate to the extremities, affect a large population. This results in pronounced disability and a high socioeconomic burden. Our understanding of the underlying mechanisms for chronic pain is limited. This prevents a comprehensive diagnostic approach. Evidence from high-level clinical trials supporting treatments for chronic spinal pain is also limited. METHODS: Articles were identified through PubMed searches or already known to the author. The literature was reviewed and summarized, indicating the strength of evidence available for many treatment modalities. RESULTS: There are very few studies published that evaluate behavioral modifications for chronic spinal pain and only one long-term study investigating chronic pharmacological treatments. The data on the success of spinal surgeries to relieve chronic spinal pain suggest an unacceptably high failure rate. The best evidence (Level I) currently available suggests that spinal cord stimulation is a safe, effective, and durable treatment for chronic spinal pain. Recent clinical data support further investigation of new innovations and earlier therapeutic consideration of currently employed approaches. CONCLUSION: Currently, physicians are limited in the practice of evidence-based medicine regarding chronic spinal pain treatments due to both the paucity of data available and an inconsistent diagnostic nomenclature. The introduction of new neurostimulation modalities is promising but requires better characterization through ongoing prospective clinical investigation. LEVEL OF EVIDENCE: 5.

Cervical myelopathy: a clinical and radiographic evaluation and correlation to cervical spondylotic myelopathy.

STUDY DESIGN: Retrospective analysis of a cohort of patients treated between April 2006 and January 2008, and diagnosed with cervical degenerative disease. OBJECTIVE: To determine the correlation of the clinical findings associated with cervical myelopathy to the presence of spinal cord compression or cord signal abnormalities on magnetic resonance imaging (MRI). SUMMARY OF BACKGROUND DATA: There are numerous reports describing the radiographic features of cervical spondylosis, however, no publication specifically describes the association between the physical signs of cervical myelopathy and the presenting imaging findings. METHODS: Myelopathy was defined as the presence of greater than one long-tract sign localized to the cervical spinal cord (Hoffman or Babinski signs, clonus, hyper-reflexia, crossed abductor sign, and/or gait dysfunction) on physical examination in the absence of other neurologic condition(s). The presence of these signs, MRI imaging features of spinal cord compression and hyperintense T2 intraparenchymal cord signal abnormality, and patient demographics were recorded. RESULTS: One hundred three patients met inclusion criteria (age >18, symptomatic cervical degenerative disease and complete neurologic assessment). Of these, 54 had clinical findings of cervical myelopathy. Radiographic features of cord compression were present in 62% of patients, and 84% had myelopathy on examination. No patients without cord compression presented with myelopathy (P < 0.0001). Thirty-five percent of the patients presented with hyperintense signal on T2 MRI within the spinal cord parenchyma. This finding correlated with the presence of myelopathy (P < 0.0001). Multivariate analysis on the subset with cord compression indicates that the likelihood of myelopathy increased with the presence of cord signal hyperintensity (odds ratio [OR], 11.4), sensory loss (OR, 16.9), and age (OR, 1.10 per year). CONCLUSION: The diagnosis of cervical myelopathy is based on presenting symptoms and physical examination. This analysis illustrates that radiographic cervical spinal cord compression and hyperintense T2 intraparen chymal signal abnormalities correlate with the presence of myelopathic findings on physical examination.