Intramuscular coherence enables robust assessment of modulated supra-spinal input in human gait: an inter-dependence study of visual task and walking speed

Intramuscular high-frequency coherence is increased during visually guided treadmill walking as a consequence of increased supra-spinal input. The influence of walking speed on intramuscular coherence and its inter-trial reproducibility need to be established before adoption as a functional gait assessment tool in clinical settings. Here, fifteen healthy controls performed a normal and a target walking task on a treadmill at various speeds (0.3 m/s, 0.5 m/s, 0.9 m/s, and preferred) during two sessions. Intramuscular coherence was calculated between two surface EMG recordings sites of the Tibialis anterior muscle during the swing phase of walking. The results were averaged across low-frequency (5-14 Hz) and high-frequency (15-55 Hz) bands. The effect of speed, task, and time on mean coherence was assessed using three-way repeated measures ANOVA. Reliability and agreement were calculated with the intra-class correlation coefficient and Bland-Altman method, respectively. Intramuscular coherence during target walking was significantly higher than during normal walking across all walking speeds in the high-frequency band as obtained by the three-way repeated measures ANOVA. Interaction effects between task and speed were found for the low- and high-frequency bands, suggesting that task-dependent differences increase at higher walking speeds. Reliability of intramuscular coherence was moderate to excellent for most normal and target walking tasks in all frequency bands. This study confirms previous reports of increased intramuscular coherence during target walking, while providing first evidence for reproducibility and robustness of this measure as a requirement to investigate supra-spinal input.Trial registration Registry number/ClinicalTrials.gov Identifier: NCT03343132, date of registration 2017/11/17

Intramuscular coherence during challenging walking in incomplete spinal cord injury: Reduced high-frequency coherence reflects impaired supra-spinal control

Individuals regaining reliable day-to-day walking function after incomplete spinal cord injury (iSCI) report persisting unsteadiness when confronted with walking challenges. However, quantifiable measures of walking capacity lack the sensitivity to reveal underlying impairments of supra-spinal locomotor control. This study investigates the relationship between intramuscular coherence and corticospinal dynamic balance control during a visually guided Target walking treadmill task. In thirteen individuals with iSCI and 24 controls, intramuscular coherence and cumulant densities were estimated from pairs of Tibialis anterior surface EMG recordings during normal treadmill walking and a Target walking task. The approximate center of mass was calculated from pelvis markers. Spearman rank correlations were performed to evaluate the relationship between intramuscular coherence, clinical parameters, and center of mass parameters. In controls, we found that the Target walking task results in increased high-frequency (21-44 Hz) intramuscular coherence, which negatively related to changes in the center of mass movement, whereas this modulation was largely reduced in individuals with iSCI. The impaired modulation of high-frequency intramuscular coherence during the Target walking task correlated with neurophysiological and functional readouts, such as motor-evoked potential amplitude and outdoor mobility score, as well as center of mass trajectory length. The Target walking effect, the difference between Target and Normal walking intramuscular coherence, was significantly higher in controls than in individuals with iSCI [F(1.0,35.0) = 13.042, p < 0.001]. Intramuscular coherence obtained during challenging walking in individuals with iSCI may provide information on corticospinal gait control. The relationships between biomechanics, clinical scores, and neurophysiology suggest that intramuscular coherence assessed during challenging tasks may be meaningful for understanding impaired supra-spinal control in individuals with iSCI

Cerebrospinal fluid pressure dynamics reveal signs of effective spinal canal narrowing in ambiguous spine conditions

Spinal canal narrowing with consecutive spinal cord compression is considered a key mechanism in degenerative cervical myelopathy (DCM). DCM is a common spine condition associated with progressive neurological disability, and timely decompressive surgery is recommended. However, the clinical and radiological diagnostic workup is often ambiguous, challenging confident proactive treatment recommendations. Cerebrospinal fluid pressure dynamics (CSFP) are altered by spinal canal narrowing. Therefore, we aim to explore the potential value of bedside CSFP assessments for qualitative and quantitative assessment of spinal canal narrowing in DCM. In this prospective case series, seven patients with DCM underwent bedside lumbar puncture with measurement of CSFP dynamics and routine CSF analysis (NCT02170155). The patients were enrolled when standard diagnostic algorithms did not permit a clear treatment decision. Measurements include baseline CSFP, cardiac-driven CSFP peak-to-trough amplitude (CSFPp), and the Queckenstedt's test (firm pressure on jugular veins) in neutral and reclined head position. From the Queckenstedt's test, proxies for craniospinal elastance (i.e., relative pulse pressure coefficient; RPPC-Q) were calculated analogously to infusion testing. CSFP metrics were deemed suspicious of canal narrowing when numbers were lower than the minimum value from a previously tested elderly spine-healthy cohort (N = 14). Mean age was 56 ± 13 years (range, 38-75; 2F); symptom severity was mostly mild to moderate (mean mJOA, 13.5 ± 2.6; range, 9-17). All the patients showed some extent of cervical stenosis in the MRI of unclear significance (5/7 following decompressive cervical spine surgery with an adjacent level or residual stenosis). Baseline CSFP was normal except for one patient (range, 4.7-17.4 mmHg). Normal values were found for CSFPp (0.4-1.3 mmHg) and the Queckenstedt's test in normal head positioning (9.-25.3 mmHg). During reclination, the Queckenstedt's test significantly decreased in one, and CSFPp in another case (>50% compared to normal position). RPPC-Q (0.07-0.19) aligned with lower values from spine-healthy (0.10-0.44). Routine CSF examinations showed mild total protein elevation (mean, 522 ± 108 mg/ml) without further evidence for the disturbed blood brain barrier. Intrathecal CSFP measurements allow discerning disturbed from normal CSFP dynamics in this population. Prospective longitudinal studies should further evaluate the diagnostic utility of CSFP assessments in DCM

Development of a core measurement set for research in degenerative cervical myelopathy: a study protocol (AO Spine RECODE-DCM CMS)

INTRODUCTION Progress in degenerative cervical myelopathy (DCM) is hindered by inconsistent measurement and reporting. This impedes data aggregation and outcome comparison across studies. This limitation can be reversed by developing a core measurement set (CMS) for DCM research. Previously, the AO Spine Research Objectives and Common Data Elements for DCM (AO Spine RECODE-DCM) defined 'what' should be measured in DCM: the next step of this initiative is to determine 'how' to measure these features. This protocol outlines the steps necessary for the development of a CMS for DCM research and audit. METHODS AND ANALYSIS The CMS will be developed in accordance with the guidance developed by the Core Outcome Measures in Effectiveness Trials and the Consensus-based Standards for the selection of health Measurement Instruments. The process involves five phases. In phase 1, the steering committee agreed on the constructs to be measured by sourcing consensus definitions from patients, professionals and the literature. In phases 2 and 3, systematic reviews were conducted to identify tools for each construct and aggregate their evidence. Constructs with and without tools were identified, and scoping reviews were conducted for constructs without tools. Evidence on measurement properties, as well as on timing of assessments, are currently being aggregated. These will be presented in phase 4: a consensus meeting where a multi-disciplinary panel of experts will select the instruments that will form the CMS. Following selection, guidance on the implementation of the CMS will be developed and disseminated (phase 5). A preliminary CMS review scheduled at 4 years from release. ETHICS AND DISSEMINATION Ethical approval was obtained from the University of Cambridge (HBREC2019.14). Dissemination strategies will include peer-reviewed scientific publications; conference presentations; podcasts; the identification of AO Spine RECODE-DCM ambassadors; and engagement with relevant journals, funders and the DCM community

Queckenstedt's test repurposed for the quantitative assessment of the cerebrospinal fluid pulsatility curve

PURPOSE Before the era of spinal imaging, presence of a spinal canal block was tested through gross changes in cerebrospinal fluid pressure (CSFP) provoked by manual compression of the jugular veins (referred to as Queckenstedt's test; QT). Beyond these provoked gross changes, cardiac-driven CSFP peak-to-valley amplitudes (CSFPp) can be recorded during CSFP registration. This is the first study to assess whether the QT can be repurposed to derive descriptors of the CSF pulsatility curve, focusing on feasibility and repeatability. METHOD Lumbar puncture was performed in lateral recumbent position in fourteen elderly patients (59.7±9.3 years, 6F) (NCT02170155) without stenosis of the spinal canal. CSFP was recorded during resting state and QT. A surrogate for the relative pulse pressure coefficient was computed from repeated QTs (i.e., RPPC-Q). RESULTS Resting state mean CSFP was 12.3 mmHg (IQR 3.2) and CSFPp was 1.0 mmHg (0.5). Mean CSFP rise during QT was 12.5 mmHg (7.3). CSFPp showed an average 3-fold increase at peak QT compared to the resting state. Median RPPC-Q was 0.18 (0.04). There was no systematic error in the computed metrics between the first and second QT. CONCLUSION This technical note describes a method to reliably derive, beyond gross CSFP increments, metrics related to cardiac-driven amplitudes during QT (i.e., RPPC-Q). A study comparing these metrics as obtained by established procedures (i.e., infusion testing) and by QT is warranted

We Choose to Call it 'Degenerative Cervical Myelopathy': Findings of AO Spine RECODE-DCM, an International and Multi-Stakeholder Partnership to Agree a Standard Unifying Term and Definition for a Disease

STUDY DESIGN Modified DELPHI Consensus Process. OBJECTIVE To agree a single unifying term and definition. Globally, cervical myelopathy caused by degenerative changes to the spine is known by over 11 different names. This inconsistency contributes to many clinical and research challenges, including a lack of awareness. METHOD AO Spine RECODE-DCM (Research objectives and Common Data Elements Degenerative Cervical Myelopathy). To determine the index term, a longlist of candidate terms and their rationale, was created using a literature review and interviews. This was shared with the community, to select their preferred terms (248 members (58%) including 149 (60%) surgeons, 45 (18%) other healthcare professionals and 54 (22%) People with DCM or their supporters) and finalized using a consensus meeting. To determine a definition, a medical definition framework was created using inductive thematic analysis of selected International Classification of Disease definitions. Separately, stakeholders submitted their suggested definition which also underwent inductive thematic analysis (317 members (76%), 190 (59%) surgeons, 62 (20%) other healthcare professionals and 72 (23%) persons living with DCM or their supporters). Using this definition framework, a working definition was created based on submitted content, and finalized using consensus meetings. RESULTS Degenerative Cervical Myelopathy was selected as the unifying term, defined in short, as a progressive spinal cord injury caused by narrowing of the cervical spinal canal. CONCLUSION A consistent term and definition can support education and research initiatives. This was selected using a structured and iterative methodology, which may serve as an exemplar for others in the future

Intramuscular coherence enables robust assessment of modulated supra-spinal input in human gait : an inter-dependence study of visual task and walking speed

Intramuscular high-frequency coherence is increased during visually guided treadmill walking as a consequence of increased supra-spinal input. The influence of walking speed on intramuscular coherence and its inter-trial reproducibility need to be established before adoption as a functional gait assessment tool in clinical settings. Here, fifteen healthy controls performed a normal and a target walking task on a treadmill at various speeds (0.3 m/s, 0.5 m/s, 0.9 m/s, and preferred) during two sessions. Intramuscular coherence was calculated between two surface EMG recordings sites of the Tibialis anterior muscle during the swing phase of walking. The results were averaged across low-frequency (5-14 Hz) and high-frequency (15-55 Hz) bands. The effect of speed, task, and time on mean coherence was assessed using three-way repeated measures ANOVA. Reliability and agreement were calculated with the intra-class correlation coefficient and Bland-Altman method, respectively. Intramuscular coherence during target walking was significantly higher than during normal walking across all walking speeds in the high-frequency band as obtained by the three-way repeated measures ANOVA. Interaction effects between task and speed were found for the low- and high-frequency bands, suggesting that task-dependent differences increase at higher walking speeds. Reliability of intramuscular coherence was moderate to excellent for most normal and target walking tasks in all frequency bands. This study confirms previous reports of increased intramuscular coherence during target walking, while providing first evidence for reproducibility and robustness of this measure as a requirement to investigate supra-spinal input.Trial registration Registry number/ClinicalTrials.gov Identifier: NCT03343132, date of registration 2017/11/17

Predisposing and precipitating risk factors for delirium in gastroenterology and hepatology: Subgroup analysis of 718 patients from a hospital-wide prospective cohort study

BACKGROUND AND AIMS Delirium is the most common acute neuropsychiatric syndrome in hospitalized patients. Higher age and cognitive impairment are known predisposing risk factors in general hospital populations. However, the interrelation with precipitating gastrointestinal (GI) and hepato-pancreato-biliary (HPB) diseases remains to be determined. PATIENTS AND METHODS Prospective 1-year hospital-wide cohort study in 29'278 adults, subgroup analysis in 718 patients hospitalized with GI/HPB disease. Delirium based on routine admission screening and a DSM-5 based construct. Regression analyses used to evaluate clinical characteristics of delirious patients. RESULTS Delirium was detected in 24.8% (178/718). Age in delirious patients (median 62 years [IQR 21]) was not different to non-delirious (median 60 years [IQR 22]), p = 0.45). Dementia was the strongest predisposing factor for delirium (OR 66.16 [6.31-693.83], p < 0.001). Functional impairment, and at most, immobility increased odds for delirium (OR 7.78 [3.84-15.77], p < 0.001). Patients with delirium had higher in-hospital mortality rates (18%; OR 39.23 [11.85-129.93], p < 0.001). From GI and HPB conditions, cirrhosis predisposed to delirium (OR 2.11 [1.11-4.03], p = 0.023), while acute renal failure (OR 4.45 [1.61-12.26], p = 0.004) and liver disease (OR 2.22 [1.12-4.42], p = 0.023) were precipitators. Total costs were higher in patients with delirium (USD 30003 vs. 10977; p < 0.001). CONCLUSION Delirium in GI- and HPB-disease was not associated with higher age per se, but with cognitive and functional impairment. Delirium needs to be considered in younger adults with acute renal failure and/or liver disease. Clinicians should be aware about individual risk profiles, apply preventive and supportive strategies early, which may improve outcomes and lower costs

Predisposing and Precipitating Risk Factors for Delirium in Elderly Patients Admitted to a Cardiology Ward: An Observational Cohort Study in 1,042 Patients.

Aim: Although the risk factors for delirium in general medicine are well-established, their significance in cardiac diseases remains to be determined. Therefore, we evaluated the predisposing and precipitating risk factors in patients hospitalized with acute and chronic heart disease. Methods and Results: In this observational cohort study, 1,042 elderly patients (≥65 years) admitted to cardiology wards, 167 with and 875 without delirium, were included. The relevant sociodemographic and cardiac- and medical-related clusters were assessed by simple and multiple regression analyses and prediction models evaluating their association with delirium. The prevalence of delirium was 16.0%. The delirious patients were older (mean 80 vs. 76 years; p < 0.001) and more often institutionalized prior to admission (3.6 vs. 1.4%, p = 0.05), hospitalized twice as long (12 ± 10 days vs. 7 ± 7 days; p < 0.001), and discharged more often to nursing homes (4.8 vs. 0.6%, p < 0.001) or deceased (OR, 2.99; 95% CI, 1.53-5.85; p = 0.003). The most relevant risk factor was dementia (OR, 18.11; 95% CI, 5.77-56.83; p < 0.001), followed by history of stroke (OR, 6.61; 95% CI 1.35-32.44; p = 0.020), and pressure ulcers (OR, 3.62; 95% CI, 1.06-12.35; p = 0.040). The predicted probability for developing delirium was highest in patients with reduced mobility and institutionalization prior to admission (PP = 31.2%, p = 0.001). Of the cardiac diseases, only valvular heart disease (OR, 1.57; 95% CI, 1.01-2.44; p = 0.044) significantly predicted delirium. The patients undergoing cardiac interventions did not have higher rates of delirium (OR, 1.39; 95% CI 0.91-2.12; p = 0.124). Conclusion: In patients admitted to a cardiology ward, age-related functional and cognitive impairment, history of stroke, and pressure ulcers were the most relevant risk factors for delirium. With regards to specific cardiological factors, only valvular heart disease was associated with risk for delirium. Knowing these factors can help cardiologists to facilitate the early detection and management of delirium