Spinal deformity surgery in patients for whom blood transfusion is not an option: a single-center experience.

OBJECTIVE: Spinal deformity surgery is associated with significant blood loss, often requiring the transfusion of blood and/or blood products. For patients declining blood or blood products, even in the face of life-threatening blood loss, spinal deformity surgery has been associated with high rates of morbidity and mortality. For these reasons, patients for whom blood transfusion is not an option have historically been denied spinal deformity surgery. METHODS: The authors retrospectively reviewed a prospectively collected data set. All patients declining blood transfusion who underwent spinal deformity surgery at a single institution between January 2002 and September 2021 were identified. Demographics collected included age, sex, diagnosis, details of any prior surgery, and medical comorbidities. Perioperative variables included levels decompressed and instrumented, estimated blood loss, blood conservation techniques used, length of surgery, length of hospital stay, and complications from surgery. Radiographic measurements included, where appropriate, sagittal vertical axis correction, Cobb angle correction, and regional angular correction. RESULTS: Spinal deformity surgery was performed in 31 patients (18 male, 13 female) over 37 admissions. The median age at surgery was 41.2 years (range 10.9-70.1 years), and 64.5% had significant medical comorbidities. A median of 9 levels (range 5-16 levels) were instrumented per surgery, and the median estimated blood loss was 800 mL (range 200-3000 mL). Posterior column osteotomies were performed in all surgeries, and pedicle subtraction osteotomies in 6 cases. Multiple blood conservation techniques were used in all patients. Preoperative erythropoietin was administered prior to 23 surgeries, intraoperative cell salvage was used in all, acute normovolemic hemodilution was performed in 20, and perioperative administration of antifibrinolytic agents was performed in 28 surgeries. No allogenic blood transfusions were administered. Surgery was staged intentionally in 5 cases, and there was 1 unintended staging due to intraoperative blood loss from a vascular injury. There was 1 readmission for a pulmonary embolus. There were 2 minor postoperative complications. The median length of stay was 6 days (range 3-28 days). Deformity correction and the goals of surgery were achieved in all patients. Two patients underwent revision surgery during the follow-up period: one for pseudarthrosis and the other for proximal junctional kyphosis. CONCLUSIONS: With proper preoperative planning and judicious use of blood conservation techniques, spinal deformity surgery may be performed safely in patients for whom blood transfusion is not an option. The same techniques can be applied widely to the general population in order to minimize blood loss and the need for allogeneic blood transfusion.

The Effect of Cervical Fusion on Functional Sagittal Spinal Alignment Based on the Inflection Point: Case Series Study.

STUDY DESIGN: A retrospective radiologic study. OBJECTIVE: The inflection point is the disc space between a lordotic and kyphotic segment of spine. To our knowledge, there has been no study evaluating changes in functional sagittal alignment determined by inflection points after cervical fusion surgery. The purpose is to identify changes in functional sagittal alignment after cervical fusion as determined by functional segments between cervicothoracic and thoracolumbar inflection points. METHODS: Standing radiographs of the sagittal whole spine were taken in 62 patients who underwent cervical fusion procedures. We identified cervicothoracic and thoracolumbar inflection points in the sagittal plane and measured Cobb angles of resulting "functional" cervical, thoracic, and lumbar segments. We also measured the C2 and T1 sagittal vertical axis (SVA) distance to S1 and the anatomic cervical lordosis, thoracic kyphosis, lumbar lordosis, spinopelvic parameters, and T1 sagittal slope. We compared the pre- and post-op values. RESULTS: The functional cervical segment and T1 sagittal slope increased postoperatively. C2 and T1 SVA distance to S1 decreased postoperatively. In patients with a single level fusion or lower instrumented vertebra (LIV) proximal or equal to C6, functional cervical segment, and anatomic cervical lordosis increased postoperatively. In those with multiple level fusion or LIV distal or equal to C7, the C2 SVA distance to S1 decreased postoperatively. CONCLUSIONS: After cervical fusion surgery, functional cervical sagittal parameters determined by the inflection point improve without changes in the anatomic sagittal parameters. Postoperative changes in functional sagittal parameters were affected by the number of fused levels and LIV.

Visualization of Fluoroscopic Imaging in Orthopedic Surgery: Head-Mounted Display vs Conventional Monitor.

Purpose. See-through head-mounted displays (HMDs) can be used to view fluoroscopic imaging during orthopedic surgical procedures. The goals of this study were to determine whether HMDs reduce procedure time, number of fluoroscopic images required, or number of head turns by the surgeon compared with standard monitors. Methods. Sixteen orthopedic surgery residents each performed fluoroscopy-guided drilling of 8 holes for placement of tibial nail distal interlocking screws in an anatomical model, with 4 holes drilled while using HMD and 4 holes drilled while using a standard monitor. Procedure time, number of fluoroscopic images needed, and number of head turns by the resident during the procedure were compared between the 2 modalities. Statistical significance was set at P < .05. Results. Mean (SD) procedure time did not differ significantly between attempts using the standard monitor (55 [37] seconds) vs the HMD (56 [31] seconds) (P = .73). Neither did mean number of fluoroscopic images differ significantly between attempts using the standard monitor vs the HMD (9 [5] images for each) (P = .84). Residents turned their heads significantly more times when using the standard monitor (9 [5] times) vs the HMD (1 [2] times) (P < .001). Conclusions. Head-mounted displays lessened the need for residents to turn their heads away from the surgical field while drilling holes for tibial nail distal interlocking screws in an anatomical model; however, there was no difference in terms of procedure time or number of fluoroscopic images needed using the HMD compared with the standard monitor.

Bibliometric and Visualized Analysis of Scientific Publications on Ossification of the Posterior Longitudinal Ligament Based on Web of Science.

BACKGROUND: In recent years, there has been increasing study of ossification of the posterior longitudinal ligament (OPLL), leading to many articles on this topic. We aimed to identify trends in OPLL-related research and to analyze the most highly cited scientific articles on OPLL. METHODS: We searched the Web of Science Core Collection database for all articles on OPLL. The years of publication, countries, journals, institutions, and total citations were extracted and analyzed. Results related to countries, institutions, and keywords were subjected to co-occurrence analysis using VOSviewer software. The top 100 most-cited articles on OPLL were analyzed. RESULTS: A total of 876 articles related to OPLL were identified. The frequency of publication on OPLL has increased substantially over time. Among all countries, Japan has contributed the most articles on OPLL (n = 349). The most productive institution has been Hirosaki University (n = 57). Spine topped the list of journals and has published 120 OPLL-related articles, which received 4221 total citations. The surgical treatment of OPLL has been the most common research focus in the OPLL literature. CONCLUSIONS: The scientific literature on OPLL has rapidly expanded in recent years. This study represents the first bibliometric analysis of scientific articles on OPLL and can serve as a useful guide to clinicians and researchers in the field.

Changes in patients' depression and anxiety associated with changes in patient-reported outcomes after spine surgery.

OBJECTIVE: The authors conducted a study to analyze associations between changes in depression/anxiety before and 12 months after spine surgery, as well as changes in scores using the Patient-Reported Outcomes Measurement Information System (PROMIS) at the same time points. METHODS: Preoperatively and 12 months postoperatively, the authors assessed PROMIS scores for depression, anxiety, pain, physical function, sleep disturbance, and satisfaction with participation in social roles among 206 patients undergoing spine surgery for deformity correction or degenerative disease. Patients were stratified according to preoperative/postoperative changes in depression and anxiety, which were categorized as persistent, improved, newly developed postoperatively, or absent. Multivariate regression was used to control for confounders and to compare changes in patient-reported outcomes (PROs). RESULTS: Fifty patients (24%) had preoperative depression, which improved in 26 (52%). Ninety-four patients (46%) had preoperative anxiety, which improved in 70 (74%). Household income was the only preoperative characteristic that differed significantly between patients whose depression persisted and those whose depression improved. Compared with the no-depression group, patients with persistent depression had less improvement in all 4 domains, and patients with postoperatively developed depression had less improvement in pain, physical function, and satisfaction with social roles. Compared with the group of patients with postoperatively improved depression, patients with persistent depression had less improvement in pain and physical function, and patients with postoperatively developed depression had less improvement in pain. Compared with patients with no anxiety, those with persistent anxiety had less improvement in physical function, sleep disturbance, and satisfaction with social roles, and patients with postoperatively developed anxiety had less improvement in pain, physical function, and satisfaction with social roles. Compared with patients with postoperatively improved anxiety, patients with persistent anxiety had less improvement in pain, physical function, and satisfaction with social roles, and those with postoperatively developed anxiety had less improvement in pain, physical function, and satisfaction with social roles. All reported differences were significant at p < 0.05. CONCLUSIONS: Many spine surgery patients experienced postoperative improvements in depression/anxiety. Improvements in 12-month PROs were smaller among patients with persistent or postoperatively developed depression/anxiety compared with patients who had no depression or anxiety before or after surgery and those whose depression/anxiety improved after surgery. Postoperative changes in depression/anxiety may have a greater effect than preoperative depression/anxiety on changes in PROs after spine surgery. Addressing the mental health of spine surgery patients may improve postoperative PROs.■ CLASSIFICATION OF EVIDENCE Type of question: causation; study design: prospective cohort study; evidence: class III.

SRS-22r legacy scores can be accurately translated to PROMIS scores in adult spinal deformity patients.

BACKGROUND CONTEXT: Patient-Reported Outcomes Measurement Information System (PROMIS) facilitates comparisons of treatment effectiveness across populations and diseases. In adult spinal deformity (ASD), the disease-specific Scoliosis Research Society-22r (SRS-22r) tool assesses outcomes. Existing data must be translated to PROMIS to make comparisons. PURPOSE: To develop and validate a method to translate SRS-22r scores to PROMIS scores in surgical ASD patients. STUDY DESIGN: Retrospective cohort study. PATIENT SAMPLE: A total of 158 ASD surgery patients from an ongoing registry of patients who underwent spine surgery at a tertiary care center from 2015 to 2017 were included. OUTCOME MEASURES: PROMIS and SRS-22r questionnaires were completed at 387 visits (150 preoperative [derivation sample]; 237 postoperative [validation sample]). METHODS: Using the derivation sample, we modeled PROMIS domains as functions of age and SRS-22r domains using linear regression. The most parsimonious model was selected. In the validation cohort, we used the derived regression equations to estimate PROMIS scores from SRS-22r scores. RESULTS: The following significant associations were found (p<.001): PROMIS Pain Interference is dependent on age and SRS-22r Pain, Physical Function, and Patient Satisfaction; PROMIS Physical Function is dependent on age and SRS-22r Pain and Physical Function; PROMIS Anxiety is dependent on SRS-22r Mental Health; PROMIS Depression is dependent on age and SRS-22r Mental Health; and PROMIS Satisfaction with Social Roles is dependent on age and SRS-22r Pain, Physical Function (p=.011), Mental Health, and Patient Satisfaction. Correlations were strong to very strong between estimated and actual PROMIS scores in the validation cohort (p<.001): Pain Interference, r=0.78; Physical Function, r=0.66; Anxiety, r=0.83; Depression, r=0.80; and Satisfaction with Social Roles, r=0.71. CONCLUSIONS: PROMIS scores estimated from SRS-22r scores using our model correlate strongly with actual PROMIS scores. SRS-22r scores may be translated to PROMIS scores in all evaluated domains for ASD patients. Orthopedic surgeons can use this method to compare legacy measures with PROMIS scores.

The Top 100 Most-Cited Articles on Kyphoplasty and Vertebroplasty.

INTRODUCTION: Over the last several decades, both percutaneous kyphoplasty (PKP) and percutaneous vertebroplasty (PVP) have been used for pain relief in patients with osteoporotic vertebral compression fractures. The purpose of our study was to use citation analysis to identify and review the top 100 most-cited publications regarding PKP and PVP. METHODS: All databases of the Web of Science were searched using the keywords "kyphoplasty" and "vertebroplasty." All publications with >100 citations were identified and the results were ranked in descending order of citations. The 100 most-cited publications were included for analysis. RESULTS: A total of 6271 publications on PKP and PVP were identified. The number of citations of the 100 most-cited studies ranged from 735 to 109, with a mean of 225.3 citations per study. The most productive period was 2001-2010, which produced 79 of the top 100 publications. Thirteen journals published these 100 studies, with Spine publishing the largest number (23) of studies. Most of the identified articles originated in the United States, with France and Switzerland found to be the next most heavily represented countries of origin of the 11 countries that produced them. Most of the studies focused on treatment of osteoporotic vertebral compression fractures, followed by pathologic fractures caused by tumors. CONCLUSIONS: We identified the 100 most-cited publications on PKP and PVP and performed a bibliometric analysis characterizing distinguishing features of these studies. This list can help guide clinical decision making and future research directions as clinicians and researchers continue to explore these controversial therapeutic techniques.

Crossing the Cervicothoracic Junction in Cervical Arthrodesis Results in Lower Rates of Adjacent Segment Disease Without Affecting Operative Risks or Patient-Reported Outcomes.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the risks and benefits of crossing the cervicothoracic junction (CTJ) in cervical arthrodesis. SUMMARY OF BACKGROUND DATA: Whether the CTJ should be crossed in cervical arthrodesis remains up for debate. Keeping C7 as the distal end of the fusion risks adjacent segment disease (ASD) and can result in myelopathy or radiculopathy. Longer fusions are thought to increase operative risk and complexity but result in lower rates of ASD. MATERIALS AND METHODS: Patients undergoing cervical spine fusion surgery ending at C7 or T1 with ≥1-year follow-up were included. To evaluate operative risk, estimated blood loss (EBL), operative time, and length of hospital stay were collected. To evaluate patient-reported outcomes (PROs), Neck Disability Index (NDI) and SF-12 questionnaires (PCS12 and MCS12) were obtained at follow-up. Revision surgery data were also obtained. RESULTS: A total of 168 patients were included and divided into a C7 end-of-fusion cohort (NC7=59) and a T1 end-of-fusion cohort (NT1=109). Multivariate regression analysis adjusting for age, sex, race, surgical approach, and number of levels fused showed that EBL (P=0.12), operative time (P=0.07), and length of hospital stay (P=0.06) are not significantly different in the C7 and T1 end-of-fusion cohorts. Multivariate regression of PROs showed no significant difference in NDI (P=0.70), PCS12 (P=0.23), or MCS12 (P=0.15) between cohorts. Fisher analysis showed significantly higher revision rates in the C7 end-of-fusion cohort (7/59 for C7 vs. 2/109 for T1; odds ratio, 6.4; 95% confidence interval, 1.2-65.1; P=0.01). CONCLUSIONS: Crossing the CTJ in cervical arthrodesis does not increase operative risk as measured by blood loss, operative time, and length of hospital stay. However, it leads to lower revision rates, likely because of the avoidance of ASD, and comparable PROs. Thus, crossing the CTJ may help prevent ASD without negatively affecting operative risk or long-term PROs.

US regional variations in rates, outcomes, and costs of spinal arthrodesis for lumbar spinal stenosis in working adults aged 40-65 years.

OBJECTIVEIt is important to identify differences in the treatment of common diseases over time and across geographic regions. Several studies have reported increased use of arthrodesis to treat lumbar spinal stenosis (LSS). The purpose of this study was to investigate geographic variations in the treatment of LSS by US region.METHODSThe authors reviewed inpatient and outpatient medical claims from 2010 to 2014 using the MarketScan Commercial Claims and Encounters database (Truven Health Analytics), which includes data on commercially insured members younger than 65 years. ICD-9 code 724.02 was used to identify patients aged ≥ 40 and < 65 years who underwent surgery for "spinal stenosis of the lumbar region" and for whom LSS was the only principal diagnosis. The primary outcome was the performance of spinal arthrodesis as part of the procedure. Geographic regions were based on patient residence and defined according to the US Census Bureau as the Northeast, Midwest, South, and West.RESULTSRates of arthrodesis, as opposed to decompression alone, varied significantly by region, from 48% in the South, to 42% in the Midwest, 36% in the Northeast, and 31% in the West. After controlling for patient age, sex, and Charlson Comorbidity Index values, the differences remained significant. Compared with patients in the Northeast, those in the South (OR 1.6, 95% CI 1.50-1.75) and Midwest (OR 1.3, 95% CI 1.18-1.41) were significantly more likely to undergo spinal arthrodesis. On multivariate analysis, patients in the West were significantly less likely to have a prolonged hospital stay (> 3 days) than those in the Northeast (OR 0.84, 95% CI 0.75-0.94). Compared with the rate in the Northeast, the rates of discharge to a skilled nursing facility were lower in the South (OR 0.41, 95% CI 0.31-0.55) and West (OR 0.72, 95% CI 0.53-0.98). The 30-day readmission rate was significantly lower in the West (OR 0.81, 95% CI 0.65-0.98) than in the Northeast and similar between the other regions. Mean payments were significantly higher in the Midwest (mean difference $5503, 95% CI $4279-$6762), South (mean difference $6187, 95% CI $5041-$7332), and West (mean difference $7732, 95% CI $6384-$9080) than in the Northeast.CONCLUSIONSThe use of spinal arthrodesis, as well as surgical outcomes and payments for the treatment of LSS, varies significantly by US region. This highlights the importance of developing national recommendations for the treatment of LSS.

Post-Interview Communication During Application to Orthopaedic Surgery Residency Programs.

BACKGROUND: Post-interview communication from residency programs to applicants is common during the U.S. residency match process. The goals of this study were to understand the frequency and type of post-interview communication, how this communication influences applicants' ranking of programs, whether programs use "second-look" visits to gauge or to encourage applicant interest, and the financial costs to applicants of second-look visits. METHODS: A post-match survey was sent to 1,198 applicants to one academic orthopaedic residency program over 2 years. The response rates were 15% in 2014 and 31% in 2015, totaling 293 responses used for analysis. RESULTS: Sixty-four percent of applicants reported having post-interview communication with one or more programs. Seventeen percent said that communication caused them to rank the contacting program higher or to keep the program ranked as number 1. Twenty percent felt pressured to reveal their rank position, and 8% were asked to rank a program first in exchange for the program's promise to rank the applicant first. Applicants who received post-interview communication had odds that were 13.5 times higher (95% confidence interval, 6.2 to 30 times higher) of matching to the programs that contacted them. Ninety percent of applicants said that communication from a program did not change how they ranked the program with which they eventually matched. Seventeen percent were encouraged to attend second-look visits, incurring a mean cost of $600 (range, $20 to $8,000). CONCLUSIONS: Orthopaedic residency programs continue to communicate with applicants in ways that violate the National Resident Matching Program's Match Communication Code of Conduct, and they continue to encourage second-look visits. To improve the integrity of the match, we suggest that programs use no-reply e-mails to minimize influence and pressure on applicants, interviewers and applicants review the Code of Conduct on interview day and provide instructions on reporting violations to the National Resident Matching Program, all post-interview communication be directed to a standardized or neutral third party, and programs actively discourage second-look visits and stop requiring second-look visits.

Investigation of central nervous system dysfunction in chronic pelvic pain using magnetic resonance spectroscopy and noninvasive brain stimulation.

BACKGROUND: Recent studies demonstrate that chronic pelvic pain is associated with altered afferent sensory input resulting in maladaptive changes in the neural circuitry of pain. To better understand the central changes associated with chronic pelvic pain, we investigated the contributions of critical pain-related neural circuits using single-voxel proton magnetic resonance spectroscopy (MRS) and transcranial direct current stimulation (tDCS). METHODS: We measured concentrations of neural metabolites in 4 regions of interest (thalamus, anterior cingulate cortex, primary motor, and occipital cortex [control]) at baseline and after 10 days of active or sham tDCS in patients with chronic pelvic pain. We then compared our results to those observed in healthy controls, matched by age and gender. RESULTS: We observed a significant increase in pain thresholds after active tDCS compared with sham conditions. There was a correlation between metabolite concentrations at baseline and quantitative sensory assessments. Chronic pelvic pain patients had significantly lower levels of NAA/Cr in the primary motor cortex compared with healthy patients. CONCLUSIONS: tDCS increases pain thresholds in patients with chronic pelvic pain. Biochemical changes in pain-related neural circuits are associated with pain levels as measured by objective pain testing. These findings support the further investigation of targeted cortical neuromodulatory interventions for chronic pelvic pain.

Thoracic outlet syndrome caused by synostosis of the first and second thoracic ribs: 2 case reports and review of the literature.

We present 2 cases of combined arterial and neurogenic thoracic outlet syndrome triggered by trauma in patients with congenital synostoses of the first and second ribs. These patients were successfully treated with supraclavicular resection of the first and second ribs and scalenectomy. We review these cases and the associated literature on thoracic outlet syndrome and rib synostosis.

Surgical treatment of osteochondroma of the proximal humerus: radiographic and early clinical results.

BACKGROUND: Symptomatic osteochondromas (OCEs) of the proximal humerus present a number of challenges, based upon their location and proximity to neurovascular structures. The purpose of this investigation was to evaluate the characteristics of these lesions and report the early results of surgical excision in children. METHODS: This is a retrospective case series of 31 pediatric patients with proximal humeral OCE treated with surgical excision. Radiographs and medical records were reviewed to evaluate tumor characteristics, treatment, and clinical results. The mean patient age was 13 (SD, 4) years, and the median follow-up was 11 months (range, 1 to 78 mo). RESULTS: From 1995 to 2009, 31 patients with proximal humeral OCE underwent surgical excision. Indications for surgery included pain in 25 (81%) and limited range of motion in 8 (26%). The OCE were most commonly posterolateral (23%) and posteromedial (16%). The site of OCE significantly influenced the extent of mass excision. OCEs located anteriorly, laterally, and posterolaterally had an average of 92% of mass excised (range, 69% to 100%), whereas those located posteromedially had an average of 68% of mass removed (range, 30% to 82%; P=0.02). Two patients (6%) had persistent postoperative pain, and 2 had recurrence. The deltopectoral approach was most commonly utilized (61%). For the posteromedial lesions, the direct medial approach led to more complete excision (79% vs. 51%). There were no neurovascular complications. CONCLUSIONS: Surgical excision of proximal humerus OCE led to favorable results, though persistent postoperative pain was seen with inadequate excision. Despite risks of neurovascular injury, a direct medial approach should be considered for posteromedial lesions. LEVEL OF EVIDENCE: Level IV-retrospective study.

Effects of motor cortex modulation and descending inhibitory systems on pain thresholds in healthy subjects.

UNLABELLED: Pain modulation can be achieved using neuromodulatory tools that influence various levels of the nervous system. Transcranial direct current stimulation (tDCS), for instance, has been shown to reduce chronic pain when applied to the primary motor cortex. In contrast to this central neuromodulatory technique, diffuse noxious inhibitory controls (DNIC) refers to endogenous analgesic mechanisms that decrease pain following the introduction of heterotopic noxious stimuli. We examined whether combining top-down motor cortex modulation using anodal tDCS with a bottom-up DNIC induction paradigm synergistically increases the threshold at which pain is perceived. The pain thresholds of 15 healthy subjects were assessed before and after administration of active tDCS, sham tDCS, cold-water-induced DNIC, and combined tDCS and DNIC. We found that both tDCS and the DNIC paradigm significantly increased pain thresholds and that these approaches appeared to have additive effects. Increase in pain threshold following active tDCS was positively correlated with baseline N-acetylaspartate in the cingulate cortex and negatively correlated with baseline glutamine levels in the thalamus as measured by magnetic resonance spectroscopy. These results suggest that motor cortex modulation may have a greater analgesic effect when combined with bottom-up neuromodulatory mechanisms, presenting new avenues for modulation of pain using noninvasive neuromodulatory approaches. PERSPECTIVE: This article demonstrates that both noninvasive motor cortex modulation and a descending noxious inhibitory controls paradigm significantly increase pain thresholds in healthy subjects and appear to have an additive effect when combined. These results suggest that existing pain therapies involving DNIC may be enhanced through combination with noninvasive brain stimulation.

Modulation of inhibitory systems to enhance motor rehabilitation: insights for the use of noninvasive brain stimulation

Motor impairment following stroke is a leading cause of disability in adults. Despite advances in motor rehabilitation techniques, many adult stroke survivors never approach full functional recovery. Intriguingly, children exhibit better rehabilitation outcomes when compared to adults suffering from comparable brain injuries, yet the reasons for this remain unclear. A common explanation is that neuroplasticity in adults is substantially limited following stroke, thus constraining the brain's ability to reorganize in response to neurological insult. This explanation, however, does not suffice for there is much evidence suggesting that neuroplasticity in adults is not limited following stroke. We hypothesize that diminished functional recovery in adults is in part due to inhibitory neuronal interactions, such as transcallosal inhibition, that serve to optimize motor performance as the brain matures. Following stroke, these inhibitory interactions pose rigid barriers to recovery by inhibiting activity in the affected regions and hindering recruitment of compensatory pathways. In contrast, children exhibit better rehabilitation outcomes in part because they have not fully developed the inhibitory interactions that impede functional recovery in adults. We suggest that noninvasive brain stimulation can be used in the context of motor rehabilitation following stroke to reduce the effects of existing inhibitory connections, effectively returning the brain to a state that is more amenable to rehabilitation. We conclude by discussing further research to explore this hypothesis and its implications

Modulation of inhibitory systems to enhance motor rehabilitation: insights for the use of noninvasive brain stimulation

Motor impairment following stroke is a leading cause of disability in adults. Despite advances in motor rehabilitation techniques, many adult stroke survivors never approach full functional recovery. Intriguingly, children exhibit better rehabilitation outcomes when compared to adults suffering from comparable brain injuries, yet the reasons for this remain unclear. A common explanation is that neuroplasticity in adults is substantially limited following stroke, thus constraining the brain's ability to reorganize in response to neurological insult. This explanation, however, does not suffice for there is much evidence suggesting that neuroplasticity in adults is not limited following stroke. We hypothesize that diminished functional recovery in adults is in part due to inhibitory neuronal interactions, such as transcallosal inhibition, that serve to optimize motor performance as the brain matures. Following stroke, these inhibitory interactions pose rigid barriers to recovery by inhibiting activity in the affected regions and hindering recruitment of compensatory pathways. In contrast, children exhibit better rehabilitation outcomes in part because they have not fully developed the inhibitory interactions that impede functional recovery in adults. We suggest that noninvasive brain stimulation can be used in the context of motor rehabilitation following stroke to reduce the effects of existing inhibitory connections, effectively returning the brain to a state that is more amenable to rehabilitation. We conclude by discussing further research to explore this hypothesis and its implications.(AU)

Evidence for the default network's role in spontaneous cognition.

A set of brain regions known as the default network increases its activity when focus on the external world is relaxed. During such moments, participants change their focus of external attention and engage in spontaneous cognitive processes including remembering the past and imagining the future. However, the functional contributions of the default network to shifts in external attention versus internal mentation have been difficult to disentangle because the two processes are correlated under typical circumstances. To address this issue, the present study manipulated factors that promote spontaneous cognition separately from those that change the scope of external attention. Results revealed that the default network increased its activity when spontaneous cognition was maximized but not when participants increased their attention to unpredictable foveal or peripheral stimuli. To examine the nature of participants' spontaneous thoughts, a second experiment used self-report questionnaires to quantify spontaneous thoughts during extended fixation epochs. Thoughts about one's personal past and future comprised a major focus of spontaneous cognition with considerable variability. Activity correlations between the medial temporal lobe and distributed cortical regions within the default network predicted a small, but significant, portion of the observed variability. Collectively, these results suggest that during passive states, activity within the default network reflects spontaneous, internally directed cognitive processes.