Post-pandemic paradigm shift toward telemedicine and tele-education; an updated survey of the impact of Covid-19 pandemic on neurosurgery residents in United States.

Background: Several strategies were implemented during the Covid-19 pandemic to enhance residency training and patient care. Objective: This study aims to assess the post-pandemic landscape of neurosurgical training and practice. Method: A survey consisting of 28 questions examining the challenges faced in neurosurgery and the adaptive measures was conducted among US neurosurgery residents from May 2022 to May 2023. Results: This study encompassed 59 neurosurgical residents, predominantly male (72.9%) and in later years of training (66.1%) and were distributed across 25 states. Telemedicine and tele-education were pivotal during the pandemic, with virtual lecture series, standalone lectures, and virtual discussions highly favored. Remote didactic learning increased for nearly half of the residents, while 54.2% resumed in-person instruction. Telemedicine was deemed effective by 86.4% for evaluating neurosurgical patients. Access to teaching environments was restricted for 61.0% of residents, impacting their training. The pandemic significantly influenced elective surgeries, with complete cancellations reported by 42.4%. Reduced faculty engagement was noted by 35.6% of residents, while 47.5% reported a negative impact on the overall resident experience. The majority (76.3%) considered changes to their training reasonable given the global health situation. Conclusions: Strategies implemented during the peak of the pandemic remain crucial in shaping neurosurgery training. Telemedicine has become indispensable, with widespread adoption. Tele-education has also expanded, providing additional learning opportunities. However, traditional didactic courses and hands-on experiences remain essential for comprehensive training. Balancing technology-driven methods with established approaches is crucial for optimizing neurosurgical education and maintaining high-quality patient care.

Distinct Time-resolved Brain-wide Coactivations in Oxygenated and Deoxygenated Hemoglobin.

OBJECTIVE: Human resting-state networks (RSNs) estimated from oxygenated (HbO) and deoxygenated hemoglobin (HbR) data exhibit strong similarities, while task-based studies show different dynamics in HbR and HbO responses. Such a discrepancy might be explained due to time-averaged estimations of RSNs. Our study investigated differences between HbO and HbR on time-resolved brain-wide coactivation patterns (CAPs). APPROACH: Diffuse optical tomography was reconstructed from resting-state whole-head functional near-infrared spectroscopy data of HbR and HbO in individual healthy participants. Timeaveraged RSNs were obtained using the group-level independent component analysis. Time-resolved CAPs were estimated using a clustering approach on the time courses of all obtained RSNs. Characteristics of the RSNs and CAPs from HbR and HbO were compared. MAIN RESULTS: Spatial patterns of HbR and HbO RSNs exhibited significant similarities. Meanwhile, HbR CAPs revealed much more organized spatial and dynamic characteristics than HbO CAPs. The entire set of HbR CAPs suggests a superstructure resulted from brain-wide neuronal dynamics, which is less evident in the set of HbO CAPs. These differences between HbO and HbR CAPs were consistently replicated in individual session data. CONCLUSION: Our results suggest that human resting brain-wide neuronal activations are preserved better in time-resolved brainwide patterns, i.e., CAPs, from HbR than those from HbO, while such a difference is lost between time-averaged HbR and HbO RSNs. SIGNIFICANCE: Our results reveal, for the first time, HbR concentration fluctuations are more directly coupled with resting dynamics of brain-wide neuronal activations in human brains.

Early neurological changes in aging cervical spine: insights from PROMIS mobility assessment.

Many studies have shown that the prevalence of degenerative spinal cord compression increases with age. However, most cases at early stages are asymptomatic, and their diagnosis remains challenging. Asymptomatic cervical spinal cord compression (ASCC) patients are more likely to experience annular tears, herniated disks, and later develop symptomatic compression. Asymptomatic individuals do not typically undergo spinal cord imaging; therefore, an assessment test that is both sensitive and specific in diagnosing ASCC may be helpful. It has been demonstrated that the Patient Reported Outcome Measure Information System (PROMIS) mobility test is sensitive in detecting degenerative cervical myelopathy (DCM) symptoms. We investigated the use of the PROMIS mobility test in assessing clinical dysfunction in ASCC. In this study, 51 DCM patients and 42 age-matched healthy control (HC) were enrolled. The degree of cervical spinal cord compression was assessed using the high-resolution cervical spinal cord T2 Weighted (T2w) MRIs, which were available for 14 DCM patients. Measurements of the spinal cords anterior-posterior (AP) diameter at the region(s) that were visibly compressed as well as at different cervical spine levels were used to determine the degree of compression. The age-matched HC cohort had a similar MRI to establish the normal range for AP diameter. Twelve (12) participants in the HC cohort had MRI evidence of cervical spinal cord compression; these individuals were designated as the ASCC cohort. All participants completed the PROMIS mobility, PROMIS pain interference (PI), PROMIS upper extremity (UE), modified Japanese orthopedic association (mJOA), and neck disability index (NDI) scoring scales. We examined the correlation between the AP diameter measurements and the clinical assessment scores to determine their usefulness in the diagnosis of ASCC. Furthermore, we examine the sensitivity and specificity of PROMIS mobility test and mJOA. Compared to the HC group, the participants in the ASCC and DCM cohorts were significantly older (p = 0.006 and p < 0.0001, respectively). Age differences were not observed between ASCC and DCM (p > 0.999). Clinical scores between the ASCC and the HC group were not significantly different using the mJOA (p > 0.99), NDI (p > 0.99), PROMIS UE (p = 0.23), and PROMIS PI (p = 0.82). However, there were significant differences between the ASCC and HC in the PROMIS mobility score (p = 0.01). The spinal cord AP diameter and the PROMIS mobility score showed a significant correlation (r = 0.44, p = 0.002). Decreasing PROMIS mobility was significantly associated with a decrease in cervical spinal cord AP diameter independent of other assessment measures. PROMIS mobility score had a sensitivity of 77.3% and specificity of 79.4% compared to 59.1% and 88.2%, respectively, for mJOA in detecting cervical spinal cord compression. Certain elements of ASCC are not adequately captured with the traditional mJOA and NDI scales used in DCM evaluation. In contrast to other evaluation scales utilized in this investigation, PROMIS mobility score shows a significant association with the AP diameter of the cervical spinal cord, suggesting that it is a sensitive tool for identifying early disability associated with degenerative change in the aging spine. In a comparative analysis of PROMIS mobility test against the standard mJOA, the PROMIS mobility demonstrated higher sensitivity for detecting cervical spinal cord compression. These findings underscore the potential use of PROMIS mobility score in clinical evaluation of the aging spine.

Degenerative cervical myelopathy: establishing severity thresholds for neuromotor dysfunction in the aging spine using the NIH Toolbox Assessment Scale.

Degenerative cervical myelopathy (DCM) is a leading cause of age-related non-traumatic spinal cord disorders resulting from chronic degeneration of the cervical spine. While traditional clinical assessments rely on patient-reported measures, this study used the NIH Toolbox Motor Battery (NIHTBm) as an objective, quantitative measure to determine DCM severity. The objective is to define NIHTBm cutoff values that can accurately classify the severity of DCM neuromotor dysfunction. A case-controlled pilot study of patients with DCM and age-matched controls. The focus was an in-depth quantitative motor assessment using the NIHTBm to understand the severity of neuromotor deficits due to degenerative spine disease. Motor assessments, dexterity, grip strength, balance, and gait speed were measured in 45 DCM patients and 37 age-matched healthy subjects (HC). Receiver operating curve (ROC) analysis determined cutoff values for mild and moderate-to-severe myelopathy which were validated by comparing motor assessment scores with disability scores. The ROC curves identified thresholds for mild dexterity impairment (T-score range 38.4 - 33.5, AUC 0.77), moderate-to-severe dexterity impairment (< 33.5, AUC 0.70), mild grip strength impairment (47.4 - 32.0, AUC 0.80), moderate-to-severe grip strength impairment (< 32.0, AUC 0.75), mild balance impairment (36.4 - 33.0, AUC 0.61), and moderate-to-severe balance impairment (< 33.0, AUC 0.78). Mild gait speed impairment was defined as 0.78-0.6 m/sec (AUC 0.65), while moderate-to-severe gait speed impairment was < 0.6 m/sec (AUC 0.65). The NIHTB motor score cutoff points correlated negatively with the DCM neck disability index (NDI) and showed balance and dexterity measures as independent indicators of DCM dysfunction. The use of NIHTB allows for precise delineation of DCM severity by establishing cutoff values corresponding to mild and moderate-to-severe myelopathy. The use of NIHTB in DCM allows enhanced clinical precision, enabling clinicians to better pinpoint specific motor deficits in DCM and other neurological disorders with motor deficits, including stroke and traumatic brain injury (TBI). Furthermore, the utility of objective assessment, NIHTB, allows us to gain a better understanding of the heterogeneity of DCM, which will enhance treatment strategies. This study serves as a foundation for future research to facilitate the discovery of innovative treatment strategies for DCM and other neurological conditions.

The current state of spinal cord functional magnetic resonance imaging and its application in clinical research.

Since its development, spinal cord functional magnetic resonance imaging (fMRI) has utilized various methodologies and stimulation protocols to develop a deeper understanding of a healthy human spinal cord that lays a foundation for its use in clinical research and practice. In this review, we conducted a comprehensive literature search on spinal cord fMRI studies and summarized the recent advancements and resulting scientific achievements of spinal cord fMRI in the following three aspects: the current state of spinal cord fMRI methodologies and stimulation protocols, knowledge about the healthy spinal cord's functions obtained via spinal cord fMRI, and fMRI's exemplary usage in spinal cord diseases and injuries. We conclude with a discussion that, while technical challenges exist, novel fMRI technologies for and new knowledge about the healthy human spinal cord have been established. Empowered by these developments, investigations of pathological and injury states within the spinal cord have become the next important direction of spinal cord fMRI. Recent clinical investigations into spinal cord pathologies, for example, fibromyalgia, multiple sclerosis, spinal cord injury, and cervical spondylotic myelopathy, have already provided deep insights into spinal cord impairments and the time course of impairment-caused changes. We expect that future spinal cord fMRI advancement and research development will further enhance our understanding of various spinal cord diseases and provide the foundation for evaluating existing and developing new treatment plans.

Network organization of resting-state cerebral hemodynamics and their aliasing contributions measured by functional near-infrared spectroscopy.

Objective. Spontaneous fluctuations of cerebral hemodynamics measured by functional magnetic resonance imaging (fMRI) are widely used to study the network organization of the brain. The temporal correlations among the ultra-slow, <0.1 Hz fluctuations across the brain regions are interpreted as functional connectivity maps and used for diagnostics of neurological disorders. However, despite the interest narrowed in the ultra-slow fluctuations, hemodynamic activity that exists beyond the ultra-slow frequency range could contribute to the functional connectivity, which remains unclear.Approach. In the present study, we have measured the brain-wide hemodynamics in the human participants with functional near-infrared spectroscopy (fNIRS) in a whole-head, cap-based and high-density montage at a sampling rate of 6.25 Hz. In addition, we have acquired resting state fMRI scans in the same group of participants for cross-modal evaluation of the connectivity maps. Then fNIRS data were deliberately down-sampled to a typical fMRI sampling rate of ∼0.5 Hz and the resulted differential connectivity maps were subject to a k-means clustering.Main results. Our diffuse optical topographical analysis of fNIRS data have revealed a default mode network (DMN) in the spontaneous deoxygenated and oxygenated hemoglobin changes, which remarkably resemble the same fMRI network derived from participants. Moreover, we have shown that the aliased activities in the down-sampled optical signals have altered the connectivity patterns, resulting in a network organization of aliased functional connectivity in the cerebral hemodynamics.Significance.The results have for the first time demonstrated that fNIRS as a broadly accessible modality can image the resting-state functional connectivity in the posterior midline, prefrontal and parietal structures of the DMN in the human brain, in a consistent pattern with fMRI. Further empowered by the fast sampling rate of fNIRS, our findings suggest the presence of aliased connectivity in the current understanding of the human brain organization.

Brain-Wide Diffuse Optical Tomography Based on Cap-Based, Whole-Head fNIRS Recording.

Diffuse optical tomography (DOT), based on functional near-infrared spectroscopy, is a portable, low-cost, noninvasive functional neuroimaging technology for studying the human brain in normal and diseased conditions. The goal of the present study was to evaluate the performance of a cap-based brain-wide DOT (BW-DOT) framework in mapping brain-wide networked activities. We first analyzed point-spread-function (PSF)-based metrics on a realistic head geometry. Our simulation results indicated that these metrics of the optode cap varied across the brain and were of lower quality in brain areas deep or away from the optodes. We further reconstructed brain-wide resting-state networks using experimental data from healthy participants, which resembled the template networks established in the fMRI literature. The preliminary results of the present study highlight the importance of evaluating PSF-based metrics on realistic head geometries for DOT and suggest that BW-DOT technology is a promising functional neuroimaging tool for studying brain-wide neural activities and large-scale neural networks, which was not available by patch-based DOT. A full-scope evaluation and validation in more realistic head models and more participants are needed in the future to establish the findings of the present study further.Clinical relevance- Via simulations and experimental evaluation, this work establishes a novel framework to image large-scale brain networks, which benefits the patient population, such as bedridden patients, infants, etc., who otherwise cannot undergo conventional brain monitoring modalities like fMRI and PET.

Correcting physiological noise in whole-head functional near-infrared spectroscopy.

BACKGROUND: Functional near-infrared spectroscopy (fNIRS) has been increasingly employed to monitor cerebral hemodynamics in normal and diseased conditions. However, fNIRS suffers from its susceptibility to superficial activity and systemic physiological noise. The objective of the study was to establish a noise reduction method for fNIRS in a whole-head montage. NEW METHOD: We have developed an automated denoising method for whole-head fNIRS. A high-density montage consisting of 109 long-separation channels and 8 short-separation channels was used for recording. Auxiliary sensors were also used to measure motion, respiration and pulse simultaneously. The method incorporates principal component analysis and general linear model to identify and remove a globally uniform superficial component. Our denoising method was evaluated in experimental data acquired from a group of healthy human subjects during a visually cued motor task and further compared with a minimal preprocessing method and three established denoising methods in the literature. Quantitative metrics including contrast-to-noise ratio, within-subject standard deviation and adjusted coefficient of determination were evaluated. RESULTS: After denoising, whole-head topography of fNIRS revealed focal activations concurrently in the primary motor and visual areas. COMPARISON WITH EXISTING METHODS: Analysis showed that our method improves upon the four established preprocessing methods in the literature. CONCLUSIONS: An automatic, effective and robust preprocessing pipeline was established for removing physiological noise in whole-head fNIRS recordings. Our method can enable fNIRS as a reliable tool in monitoring large-scale, network-level brain activities for clinical uses.

Brain-wide functional diffuse optical tomography of resting state networks.

Objective.Diffuse optical tomography (DOT) has the potential in reconstructing resting state networks (RSNs) in human brains with high spatio-temporal resolutions and multiple contrasts. While several RSNs have been reported and successfully reconstructed using DOT, its full potential in recovering a collective set of distributed brain-wide networks with the number of RSNs close to those reported using functional magnetic resonance imaging (fMRI) has not been demonstrated.Approach.The present study developed a novel brain-wide DOT (BW-DOT) framework that integrates a cap-based whole-head optode placement system with multiple computational approaches, i.e. finite-element modeling, inverse source reconstruction, data-driven pattern recognition, and statistical correlation tomography, to reconstruct RSNs in dual contrasts of oxygenated (HbO) and deoxygenated hemoglobins (HbR).Main results.Our results from the proposed framework revealed a comprehensive set of RSNs and their subnetworks, which collectively cover almost the entire neocortical surface of the human brain, both at the group level and individual participants. The spatial patterns of these DOT RSNs suggest statistically significant similarities to fMRI RSN templates. Our results also reported the networks involving the medial prefrontal cortex and precuneus that had been missed in previous DOT studies. Furthermore, RSNs obtained from HbO and HbR suggest similarity in terms of both the number of RSN types reconstructed and their corresponding spatial patterns, while HbR RSNs show statistically more similarity to fMRI RSN templates and HbO RSNs indicate more bilateral patterns over two hemispheres. In addition, the BW-DOT framework allowed consistent reconstructions of RSNs across individuals and across recording sessions, indicating its high robustness and reproducibility, respectively.Significance.Our present results suggest the feasibility of using the BW-DOT, as a neuroimaging tool, in simultaneously mapping multiple RSNs and its potential values in studying RSNs, particularly in patient populations under diverse conditions and needs, due to its advantages in accessibility over fMRI.

Dynamic Activation Patterns of the Motor Brain Revealed by Diffuse Optical Tomography.

Diffuse optical tomography (DOT), a subset of functional near-infrared spectroscopy (fNIRS), is a noninvasive functional imaging modality for studying the human brain in normal and diseased conditions. It measures changes in concentrations of oxygenated hemoglobin (HbO) and deoxygenated hemoglobin (Hb) in the blood vasculature of the brain. In contrast to functional magnetic resonance imaging (fMRI), the gold standard in human brain imaging, DOT offers the advantage of higher temporal resolution, portability, lower cost, multiple contrasts and usability for persons who cannot otherwise utilize MRI-based imaging modalities, including bedridden patients and infants, etc. The goal of the present study was to evaluate performance of a DOT method in studying dynamic patterns of brain activations involving motor control. CW-fNIRS data were acquired in four sessions from a healthy male participant when he performed a motor task in a block-design experiment. Results from experimental data showed pronounced activity in the primary motor cortex (M1), contralateral to the clenching hand. It was further observed that the M1 activity was consistent over four sessions. Furthermore, temporal dynamics of motor activity at each session further revealed well-sequenced activation patterns among M1, premotor cortex (PMC), and supplementary motor area (SMA). Timed ipsilateral motor activity suppression was also observed several seconds after the onset of contralateral M1 activity. More importantly, these temporal dynamics were similarly observed in all four sessions. These preliminary results suggest that the DOT method has the sensitivity, reliability, and spatio-temporal resolutions to study activities originated from the motor cortices. A full-scope evaluation and validation in more participants on the motor system can establish it as a promising neuroimaging tool to study, such as, infants at the risk of cerebral palsy or elders with Parkinson's due to its portability and usability in clinical environments.