Respiratory motor control disrupted by spinal cord injury: mechanisms, evaluation, and restoration

Accessory respiratory muscles performance among people with spinal cord injury while singing songs with different musical parameters

People with spinal cord injury (SCI) experience respiratory dysfunctions which include hypersecretions, bronchospasm, and respiratory muscles weakness. Singing therapy has been implemented as part of respiratory muscle training (RMT) to improve their muscle strength. Singing different types and genres of songs may elicit specific recruitment of respiratory muscles, attributed to the variation of the songs' characteristics including tempo, pitch, and rhythmic complexity. This study aims to determine the effect of singing songs with different characteristics on the accessory respiratory muscle performance among people with SCI. Thirteen male SCI participants of ASIA A and B (C4 -T11) were recruited. Respiratory muscle signals were retrieved by placing two mechanomyography (MMG) sensors on the sternocleidomastoid (SCM) and rectus abdominis (RA) muscles. Eight music experts categorized several songs into four categories based on their pitch, tempo, and rhythmic complexity. Each participant sang one song from each category. Findings showed statistically significant difference in RA and SCM responses among all categories (P < 0.01). The SCM muscle is most active while singing high pitch songs. While the RA is most active during slow tempo and easy rhythmic complexity. This shows that different accessory respiratory muscle is activated by people with SCI while singing songs with different characteristics. Clinicians could benefit from this knowledge while prescribing singing therapy or exercise among people with SCI in the future.

Factors Associated With Tracheostomy in Ventilated Pediatric Trauma Patients. A National Trauma Database Study

PURPOSE

The purpose of the study was to find the factors that were associated with tracheostomy procedures in ventilated pediatric trauma patients.

METHODS

The Trauma Quality Improvement Program (TQIP) database of the calendar year 2017 through 2019 was accessed for the study. All patients <18 years old and who were on mechanical ventilation for more than 96 hours were included in the study. Multiple logistic regression analysis was performed to find the factors that were associated with a tracheostomy.

RESULTS

Out of 2653 patients, 1907 (71.88%) patients underwent tracheostomy. The patients who underwent tracheostomy had a lower median [IQR] of Glasgow Coma Scale (GCS) (3 [3-8] vs 5 [3-10], P < .001) and had a higher proportion of severe spine injury (On Abbreviated Injury Scale [AIS]≥3) (11.6% vs 8.8%, P = .044) when compared with patients who did not have tracheostomy. Lower GCS scores and severe spine injury were associated with higher odds of tracheostomy, with all P values <.05. Higher proportion of tracheostomy procedures were performed at level I pediatric trauma centers as compared to non-designated pediatric centers (odds ratio [95% CI]: 1.848 [1.524-2.242], P < .001).

CONCLUSION

A lower GCS score, severe spine injury and highest level trauma centers were associated with a tracheostomy.

Efficacy of Wheelchair Skills Training Program in Enhancing Sitting Balance and Pulmonary Function in Chronic Tetraplegic Patients: A Randomized Controlled Study

Background and Objectives: This study aimed to evaluate the effectiveness of a wheelchair skills training program (WSTP) in improving sitting balance and pulmonary function in patients with chronic tetraplegia resulting from cervical spinal cord injury (cSCI). Materials and Methods: Twenty-four patients were randomly divided into WSTP and control groups. The WSTP group participated in the WSTP for eight weeks, while the control group underwent conventional physical therapy for the same eight-week period. Sitting balance was evaluated using the activity-based balance level evaluation (ABLE) scale, and pulmonary function was evaluated using forced vital capacity (FVC), forced expiratory volume in one second (FEV1), and peak expiratory flow (PEF). Results: The WSTP group showed significant improvements in both sitting balance and pulmonary function during the intervention period (p < 0.05), whereas the control group did not show any significant changes. A strong positive correlation was found between ABLE scores and all three pulmonary function parameters across all time points. Conclusions: Our results suggest that the WSTP significantly improves sitting balance and specific aspects of lung function in patients with tetraplegia.

Correlation between Respiratory Dysfunction and Dysphagia in Individuals with Acute Traumatic Cervical Spinal Cord Injury

Introduction

Aspiration pneumonia is one of the most frequent and fatal life-threatening complications among individuals with acute traumatic cervical spinal cord injury (CSCI). However, the mechanism of dysphagia among individuals with CSCI is not well understood. Morbidity and mortality associated with CSCI may result from the interplay between respiratory dysfunction and dysphagia. This study aimed to elucidate the effect of respiratory dysfunction on the swallowing function of individuals with acute traumatic CSCI.

Methods

A prospective cohort study was conducted involving 54 individuals with acute traumatic CSCI who were admitted within 2 weeks following injury. Dysphagia was evaluated using the Dysphagia Severity Scale (DSS) and the Functional Oral Intake Scale (FOIS). Respiratory function was evaluated by measuring the cough peak flow (CPF), forced expiratory volume in 1 s (FEV1.0), FEV1.0/forced vital capacity (FEV1.0%), and percent vital capacity (%VC). We recorded these parameters at weeks 2, 4, 8, and 12 following injury and analyzed pertinent changes over time and significant correlations.

Results

Among 54 individuals (46 men and 8 women) recruited in this study, 48 (88.9%) had restrictive ventilatory impairment and 17 (31.5%) had severe dysphagia (DSS level 1-4) 2 weeks following injury. However, respiratory function and swallowing function significantly improved thereafter. CPF, FEV1.0, and %VC were significantly correlated with the severity of dysphagia during each period.

Conclusions

Restrictive ventilatory impairment, poor cough force, and dysphagia are closely related, and the evaluation of respiratory function plays an important role in evaluating dysphagia.

Transcutaneous Spinal Cord Stimulation Facilitates Respiratory Functional Performance in Patients with Post-Acute COVID-19

BACKGROUND

A growing number of studies have reported Coronavirus disease (COVID-19) related to both respiratory and central nervous system dysfunctions. This study evaluates the neuromodulatory effects of spinal cord transcutaneous stimulation (scTS) on the respiratory functional state in healthy controls and patients with post-COVID-19 respiratory deficits as a step toward the development of a rehabilitation strategy for these patients.

METHODS

In this before-after, interventional, case-controlled clinical study, ten individuals with post-acute COVID-19 respiratory deficits and eight healthy controls received a single twenty-minute-long session of modulated monophasic scTS delivered over the T5 and T10 spinal cord segments. Forced vital capacity (FVC), peak forced inspiratory flow (PIF), peak expiratory flow (PEF), time-to-peak of inspiratory flow (tPIF), and time-to-peak of expiratory flow (tPEF), as indirect measures of spinal motor network activity, were assessed before and after the intervention.

RESULTS

In the COVID-19 group, the scTS intervention led to significantly increased PIF (p = 0.040) and PEF (p = 0.049) in association with significantly decreased tPIF (p = 0.035) and tPEF (p = 0.013). In the control group, the exposure to scTS also resulted in significantly increased PIF (p = 0.010) and significantly decreased tPIF (p = 0.031). Unlike the results in the COVID-19 group, the control group had significantly decreased PEF (p = 0.028) associated with significantly increased tPEF (p = 0.036). There were no changes for FVC after scTS in both groups (p = 0.67 and p = 0.503).

CONCLUSIONS

In post-COVID-19 patients, scTS facilitates excitation of both inspiratory and expiratory spinal neural networks leading to an immediate improvement of respiratory functional performance. This neuromodulation approach could be utilized in rehabilitation programs for patients with COVID-19 respiratory deficits.

Association between neutrophil percentage-to-albumin ratio and pneumonia in patients with traumatic spinal cord injury

STUDY DESIGN

Retrospective cohort study.

OBJECTIVES

To investigate the association between neutrophil percentage-to-albumin ratio (NPAR) and pneumonia in patients with SCI.

SETTING

Department of Rehabilitation Medicine Center, West China Hospital, Sichuan University.

METHODS

SCI patients admitted to West China Hospital within 24 h of injury were consecutively enrolled. Blood samples were collected on admission. Pneumonia was diagnosed based on chest radiography and clinician records of patient symptoms and laboratory tests. Multivariable logistic regression analysis was performed to determine the relationship between NPAR and pneumonia. Receiver operating characteristic (ROC) curves were generated to assess the predictive value of NPAR.

RESULTS

A total of 264 SCI patients were included, of whom 65 (24.6%) developed pneumonia. NPAR was positively correlated with pneumonia (OR 2.66, 95% CI, 1.06-6.71, p = 0.038). Patients in the upper NPAR tertile (2.35-3.71) had a higher risk of pneumonia than patients in the lower tertile (1.66-2.12) after adjustment for potential confounders (OR 2.55, 95% CI, 1.05-6.19, p = 0.039). The risk of pneumonia increased stepwise across NPAR tertiles (p for trend = 0.031). The optimal cutoff value of NPAR for predicting pneumonia was 2.17 with a sensitivity of 0.82 and a specificity of 0.50. There was a significant interaction between NPAR and neurological level of injury (p for interaction = 0.034), with no significant association between NPAR and pneumonia in patients with cervical SCI.

CONCLUSIONS

A higher NPAR was independently associated with higher risk of pneumonia in a dose-dependent manner in patients with non-cervical SCI.

Inspiratory Muscle Performance Is Related to Seated Balance Function in People With Spinal Cord Injury: An Observational Study

OBJECTIVE

To examine the relationship between inspiratory muscle performance (IMP) and functional sitting balance (FSB) in persons with chronic spinal cord injury (SCI). We hypothesized that a moderate correlation would be found between IMP and FSB and that individuals with better balance would have better IMP.

DESIGN

The SCI-specific modification of the Function in Sitting Test (FIST-SCI) measured FSB. The IMP measures included (1) maximal inspiratory pressure (MIP), (2) sustained MIP (SMIP), and (3) inspiratory duration. Upper extremity motor score (UEMS) and level of injury (LOI) were taken from International Standards for Neurological Classification of Spinal Cord Injury examinations. Spearman correlational analyses assessed relationships among these factors in the sample (N=37). Mann-Whitney U tests explored differences between 2 comparison group pairs (tetraplegia group [TG] vs paraplegia group [PG]; independent transfer group [ITG] vs assisted transfer group [ATG]). Regression analysis examined variables predictive of FSB in the TG.

SETTING

Research facility.

PARTICIPANTS

Volunteers with tetraplegia (n=21, American Spinal Injury Association Impairment Scale (AIS) A=8, B=7, C=6) and paraplegia (n=16, AIS A=9, B=4, C=3) (N=37).

INTERVENTION

Not applicable.

MAIN OUTCOME MEASURES

IMP, LOI, UEMS, FIST-SCI.

RESULTS

UEMS, MIP, SMIP, and LOI had moderate to high correlations with FIST-SCI scores (ρ=0.720 (P<.001), 0.480 (P=.003), 0.467 (P=.004), 0.527 (P=.001), respectively). UEMS, MIP, and FIST-SCI scores were higher in the PG and ITG than the TG and ATG, respectively (PG vs. TG P values=<.001, .008, .002, respectively, and ITG vs. ATG P values=<.001, .032, <.001, respectively). Further, SMIP and UEMS predicted FIST-SCI balance scores in the TG, accounting for 55% of total variance (P<.001) (FIST-SCI=11.88+0.03 [SMIP]+0.425 [UEMS]).

CONCLUSIONS

The relationship between IMP and balance appears preserved after SCI. FSB was predicted, in part, via UEMS and SMIP in the TG. Future research should focus on the effect of SCI-based breathing interventions on FSB.

Spinal Cord Injury Impairs Lung Immunity in Mice

Pulmonary infection is a leading cause of morbidity and mortality after spinal cord injury (SCI). Although SCI causes atrophy and dysfunction in primary and secondary lymphoid tissues with a corresponding decrease in the number and function of circulating leukocytes, it is unknown whether this SCI-dependent systemic immune suppression also affects the unique tissue-specific antimicrobial defense mechanisms that protect the lung. In this study, we tested the hypothesis that SCI directly impairs pulmonary immunity and subsequently increases the risk for developing pneumonia. Using mouse models of severe high-level SCI, we find that recruitment of circulating leukocytes and transcriptional control of immune signaling in the lung is impaired after SCI, creating an environment that is permissive for infection. Specifically, we saw a sustained loss of pulmonary leukocytes, a loss of alveolar macrophages at chronic time points postinjury, and a decrease in immune modulatory genes, especially cytokines, needed to eliminate pulmonary infections. Importantly, this injury-dependent impairment of pulmonary antimicrobial defense is only partially overcome by boosting the recruitment of immune cells to the lung with the drug AMD3100, a Food and Drug Administration-approved drug that mobilizes leukocytes and hematopoietic stem cells from bone marrow. Collectively, these data indicate that the immune-suppressive effects of SCI extend to the lung, a unique site of mucosal immunity. Furthermore, preventing lung infection after SCI will likely require novel strategies, beyond the use of orthodox antibiotics, to reverse or block tissue-specific cellular and molecular determinants of pulmonary immune surveillance.

Respiratory Training and Plasticity After Cervical Spinal Cord Injury

While spinal cord injuries (SCIs) result in a vast array of functional deficits, many of which are life threatening, the majority of SCIs are anatomically incomplete. Spared neural pathways contribute to functional and anatomical neuroplasticity that can occur spontaneously, or can be harnessed using rehabilitative, electrophysiological, or pharmacological strategies. With a focus on respiratory networks that are affected by cervical level SCI, the present review summarizes how non-invasive respiratory treatments can be used to harness this neuroplastic potential and enhance long-term recovery. Specific attention is given to "respiratory training" strategies currently used clinically (e.g., strength training) and those being developed through pre-clinical and early clinical testing [e.g., intermittent chemical stimulation via altering inhaled oxygen (hypoxia) or carbon dioxide stimulation]. Consideration is also given to the effect of training on non-respiratory (e.g., locomotor) networks. This review highlights advances in this area of pre-clinical and translational research, with insight into future directions for enhancing plasticity and improving functional outcomes after SCI.

Peripheral Immune Dysfunction: A Problem of Central Importance after Spinal Cord Injury

Simple Summary

Spinal cord injury can result in an increased vulnerability to infections, but until recently the biological mechanisms behind this observation were not well defined. Immunosuppression and concurrent sustained peripheral inflammation after spinal cord injury have been observed in preclinical and clinical studies, now termed spinal cord injury-induced immune depression syndrome. Recent research indicates a key instigator of this immune dysfunction is altered sympathetic input to lymphoid organs, such as the spleen, resulting in a wide array of secondary effects that can, in turn, exacerbate immune pathology. In this review, we discuss what we know about immune dysfunction after spinal cord injury, why it occurs, and how we might treat it.

Abstract

Individuals with spinal cord injuries (SCI) exhibit increased susceptibility to infection, with pneumonia consistently ranking as a leading cause of death. Despite this statistic, chronic inflammation and concurrent immune suppression have only recently begun to be explored mechanistically. Investigators have now identified numerous changes that occur in the peripheral immune system post-SCI, including splenic atrophy, reduced circulating lymphocytes, and impaired lymphocyte function. These effects stem from maladaptive changes in the spinal cord after injury, including plasticity within the spinal sympathetic reflex circuit that results in exaggerated sympathetic output in response to peripheral stimulation below injury level. Such pathological activity is particularly evident after a severe high-level injury above thoracic spinal cord segment 6, greatly increasing the risk of the development of sympathetic hyperreflexia and subsequent disrupted regulation of lymphoid organs. Encouragingly, studies have presented evidence for promising therapies, such as modulation of neuroimmune activity, to improve regulation of peripheral immune function. In this review, we summarize recent publications examining (1) how various immune functions and populations are affected, (2) mechanisms behind SCI-induced immune dysfunction, and (3) potential interventions to improve SCI individuals’ immunological function to strengthen resistance to potentially deadly infections.

Respiratory axon regeneration in the chronically injured spinal cord

Promoting the combination of robust regeneration of damaged axons and synaptic reconnection of these growing axon populations with appropriate neuronal targets represents a major therapeutic goal following spinal cord injury (SCI). A key impediment to achieving this important aim includes an intrinsic inability of neurons to extend axons in adult CNS, particularly in the context of the chronically-injured spinal cord. We tested whether an inhibitory peptide directed against phosphatase and tensin homolog (PTEN: a central inhibitor of neuron-intrinsic axon growth potential) could restore inspiratory diaphragm function by reconnecting critical respiratory neural circuitry in a rat model of chronic cervical level 2 (C2) hemisection SCI. We found that systemic delivery of PTEN antagonist peptide 4 (PAP4) starting at 8 weeks after C2 hemisection promoted substantial, long-distance regeneration of injured bulbospinal rostral Ventral Respiratory Group (rVRG) axons into and through the lesion and back toward phrenic motor neurons (PhMNs) located in intact caudal C3-C5 spinal cord. Despite this robust rVRG axon regeneration, PAP4 stimulated only minimal recovery of diaphragm function. Furthermore, re-lesion through the hemisection site completely removed PAP4-induced functional improvement, demonstrating that axon regeneration through the lesion was responsible for this partial functional recovery. Interestingly, there was minimal formation of putative excitatory monosynaptic connections between regrowing rVRG axons and PhMN targets, suggesting that (1) limited rVRG-PhMN synaptic reconnectivity was responsible at least in part for the lack of a significant functional effect, (2) chronically-injured spinal cord presents an obstacle to achieving synaptogenesis between regenerating axons and post-synaptic targets, and (3) addressing this challenge is a potentially-powerful strategy to enhance therapeutic efficacy in the chronic SCI setting. In conclusion, our study demonstrates a non-invasive and transient pharmacological approach in chronic SCI to repair the critically-important neural circuitry controlling diaphragmatic respiratory function, but also sheds light on obstacles to circuit plasticity presented by the chronically-injured spinal cord.

Early Versus Late Tracheostomy in Patients With Acute Traumatic Spinal Cord Injury: A Systematic Review and Meta-analysis

BACKGROUND

Acute traumatic spinal cord injuries (SCIs) often result in impairments in respiration that may lead to a sequelae of pulmonary dysfunction, increased risk of infection, and death. The optimal timing for tracheostomy in patients with acute SCI is currently unknown. This systematic review and meta-analysis aims to assess the optimal timing of tracheostomy in SCI patients and evaluate the potential benefits of early versus late tracheostomy.

METHODS

We searched Medline, PubMed, Embase, Cochrane Central, Cochrane Database of Systematic Reviews, and PsycINFO for published studies. We included studies on adults with SCI who underwent early or late tracheostomy and compared outcomes. In addition, studies that reported a concomitant traumatic brain injury were excluded. Data were extracted independently by 2 reviewers and copied into R software for analysis. A random-effects meta-analysis was performed to estimate the pooled odds ratio (OR) or mean difference (MD).

RESULTS

Eight studies with a total of 1220 patients met our inclusion criteria. The mean age and gender between early and late tracheostomy groups were similar. The majority of the studies performed an early tracheostomy within 7 days from either time of injury or tracheal intubation. Patients with a cervical SCI were twice as likely to undergo an early tracheostomy (OR = 2.13; 95% confidence interval [CI], 1.24-3.64; P = .006) compared to patients with a thoracic SCI. Early tracheostomy reduced the mean intensive care unit (ICU) length of stay by 13 days (95% CI, -19.18 to -7.00; P = .001) and the mean duration of mechanical ventilation by 18.30 days (95% CI, -24.33 to -12.28; P = .001). Although the pooled risk of in-hospital mortality was lower with early tracheostomy compared to late tracheostomy, the results were not significant (OR = 0.56; 95% CI, 0.32-1.01; P = .054). In the subgroup analysis, mortality was significantly lower in the early tracheostomy group (OR = 0.27; P = .006). Finally, no differences in pneumonia between early and late tracheostomy groups were noted.

CONCLUSIONS

Based on the available data, patients with early tracheostomy within the first 7 days of injury or tracheal intubation had higher cervical SCI, shorter ICU length of stay, and shorter duration of mechanical ventilation compared to late tracheostomy. The risk of in-hospital mortality may be lower following an early tracheostomy. However, due to the quality of studies and insufficient clinical data available, it is challenging to make conclusive interpretations. Future prospective trials with a larger patient population are needed to fully assess short- and long-term outcomes of tracheostomy timing following acute SCI.

Prognostic value of early leukocyte fluctuations for recovery from traumatic spinal cord injury

BACKGROUND

Acute traumatic spinal cord injury (SCI) induces a systemic immune response involving circulating white blood cells (WBCs). How this response is influenced by overall trauma severity, the neurological level of injury and/or correlates with patient outcomes is poorly understood. The objective of this study was to identify relationships between early changes in circulating WBCs, injury characteristics and long-term patient outcomes in individuals with traumatic SCI.

METHODS

We retrospectively analysed data from 161 SCI patients admitted to Brisbane's Princess Alexandra Hospital (exploration cohort). Logistic regression models in conjunction with receiver operating characteristic (ROC) analyses were used to assess the strength of specific links between the WBC response, respiratory infection incidence and neurological outcomes (American Spinal Injury Association Impairment Scale (AIS) grade conversion). An independent validation cohort from the Trauma Hospital Berlin, Germany (n = 49) was then probed to assess the robustness of effects and disentangle centre effects.

RESULTS

We find that the extent of acute neutrophilia in human SCI patients is positively correlated with New Injury Severity Scores but inversely with the neurological outcome (AIS grade). Multivariate analysis demonstrated that acute SCI-induced neutrophilia is an independent predictor of AIS grade conversion failure, with an odds ratio (OR) of 4.16 and ROC area under curve (AUC) of 0.82 (P < 0.0001). SCI-induced lymphopenia was separately identified as an independent predictor of better recovery (OR = 24.15; ROC AUC = 0.85, P < 0.0001). Acute neutrophilia and increased neutrophil-lymphocyte ratios were otherwise significantly associated with respiratory infection presentation in both patient cohorts.

CONCLUSIONS

Our findings demonstrate the prognostic value of modelling early circulating neutrophil and lymphocyte counts with patient characteristics for predicting the longer term recovery after SCI.

A Review of Different Stimulation Methods for Functional Reconstruction and Comparison of Respiratory Function after Cervical Spinal Cord Injury

Background

Spinal cord injury (SCI) is a common severe trauma in clinic, hundreds of thousands of people suffer from which every year in the world. In terms of injury location, cervical spinal cord injury (CSCI) has the greatest impact. After cervical spinal cord injury, the lack of innervated muscles is not enough to provide ventilation and other activities to complete the respiratory function. In addition to the decline of respiratory capacity, respiratory complications also have a serious impact on the life of patients. The most commonly used assisted breathing and cough equipment is the ventilator, but in recent years, the functional electrical stimulation method is being used gradually and widely.

Methods

About hundred related academic papers are cited for data analysis. They all have the following characteristics: (1) basic conditions of patients were reported, (2) patients had received nerve or muscle stimulation and the basic parameters, and (3) the results were evaluated based on some indicators.

Results

The papers mentioned above are classified as four kinds of stimulation methods: muscle electric/magnetic stimulation, spinal dural electric stimulation, intraspinal microstimulation, and infrared light stimulation. This paper describes the stimulation principle and application experiment. Finally, this paper will compare the indexes and effects of typical stimulation methods, as well as the two auxiliary methods: training and operation.

Conclusions

Although there is limited evidence for the treatment of respiratory failure by nerve or muscle stimulation after cervical spinal cord injury, the two techniques seem to be safe and effective. At the same time, light stimulation is gradually applied to clinical medicine with its strong advantages and becomes the development trend of nerve stimulation in the future.

A Primary Care Provider's Guide to Managing Respiratory Health in Subacute and Chronic Spinal Cord Injury

Respiratory complications following spinal cord injury (SCI) have remained the leading cause of death across the lifespan and are one of the most common reasons for hospitalization. Complications from altered respiratory physiology after SCI include atelectasis, pneumonia, venous thromboembolic disease, and sleep-disordered breathing. The risk for complications is greater with higher SCI levels and severity, and mortality from pneumonia is heightened compared to the general population. Optimal primary care for individuals with SCI includes appropriate surveillance for SCI-specific respiratory disease, key preventive care including promotion of influenza immunization and respiratory muscle training, and early identification and treatment of pneumonia with institution of aggressive secretion management strategies. The respiratory physiology and specific management of respiratory complications after SCI is reviewed.

Design, Development, and Characterization of BreathForce: A Respiratory Training System for Patients with Spinal Cord Injuries

In this effort, we report the development of a portable inspiratory-expiratory training device for use in rehabilitation of participants with cardiovascular and respiratory motor deficits. The device uses existing airway restriction components to establish a manually adjustable respiratory training apparatus and includes an integrated pressure sensor with custom software to direct and track therapy sessions. The battery-powered system promotes proven rehabilitation methodologies performed at the clinic in a platform to be translated to the home for participants with spinal cord injuries.

Impact Of Spinal Cord Injury On Sleep: Current Perspectives

Sleep disorders are commonly encountered in people living with spinal cord injury (SCI). Primary sleep disorders such as sleep-disordered breathing (SDB), sleep-related movement disorders, circadian rhythm sleep-wake disorders, and insomnia disorder are common conditions after SCI but remain under-recognized, underdiagnosed and therefore remain untreated for a majority of patients. Sleep disturbances in people living with SCI are associated with significant impairments of daytime function and quality of life. Previous reviews have described findings related mainly to SDB but have not examined the relationship between other sleep disorders and SCI. This narrative review examines various sleep abnormalities and related functional and physical impairments in people living with SCI. It discusses new evidence pertaining to management, highlights existing limitations in the literature and recommends future directions for research.

Somatotopy of corticospinal tract fibres of the intercostal muscles: report of a case and review of literature

This study aimed at describing the first case of subcortical stimulation of the corticospinal tract leading to selective contraction of the intercostal muscles during surgery for removal of a tumour centred in the right central lobule/supplementary motor area. A 53-year-old male presented with partial motor seizures. Imaging demonstrated a low-grade glioma affecting the posterior aspect of the superior and middle frontal gyri and invading the precentral gyrus. Preoperative motor Transcranial Magnetic Stimulation and advanced diffusion tractography were performed to establish the relationship of the tumour with the motor cortex and corticospinal tract. Intraoperative motor mapping and monitoring were performed with monopolar stimulation ("train of 5" technique). At the posterior margin of resection, subcortical stimulation demonstrated a selective response from intercostal muscles, medial to responses from the lower limb and lateral to responses from the upper limb. PubMed literature search was performed to identify any case reporting similar findings. There were no cases previously reported in the literature. The location of the subcortical response for intercostal muscles confirms the somatotopy of the corticospinal tract. Intercostal muscles are controlled by selective fibres within the corticospinal tract. Damage to these fibres can lead to paralysis of voluntary respiratory muscles. Further studies are needed to define the cortico-subcortical network controlling voluntary respiratory muscles.

Respiratory muscle activation patterns during maximum airway pressure efforts are different in women and men

Maximum inspiratory and expiratory pressure values (PI_max and PE_max) are indirect measures of respiratory muscle strength that, in healthy adults, are known to be significantly lower in women compared to men. In part, sex differences in breathing kinematics, lung size, body composition, muscle mass, and muscle fiber composition are thought to be responsible for these effects. However, it is not known whether respiratory muscle activation during maximum respiratory efforts is also sex-specific. In this study, we addressed whether respiratory multi-muscle activation patterns during PI_max and PE_max efforts are different between healthy women and men. Forced vital capacity (FVC), forced expiratory volume in one second (FEV₁), PI_max, PE_max, and surface electromyographic (sEMG) activity recorded from respiratory muscles during these maximum airway pressure efforts were obtained in 13 women and 11 men. Percent predicted values of FVC and FEV₁ were not significantly different in these two groups (women vs. men: 112 ± 14 vs. 105 ± 15%, p = 0.29; and 92 ± 12 vs. 93 ± 13, p = 0.82, Mean ± SD, respectively), while PI_max and PE_max measures were significantly lower in women compared to men (68 ± 16 vs. 88 ± 19 cmH₂O, p = 0.011; and 69 ± 13 vs. 94 ± 17, p = 0.0004, respectively). Using vector-based methodology, by calculating the Similarity Index (SI) as measure of the resemblance between two sEMG patterns and the Magnitude (Mag) representing the overall amount sEMG during motor task, we have found that although the Mag values for both PI_max and PE_max tasks were not significantly different in two groups, the SIs revealed significant sex-dependent differences in muscle activation patterns (0.89 ± 0.08 vs. 0.97 ± 0.02, p = 0.016; and 0.77 ± 0.11 vs. 0.92 ± 0.04, p = 0.0006, respectively). During the PI_max effort, presented as the percentage of total sEMG amplitude, activity of upper trapezius muscle was significantly larger (p = 0.001) while activation of rectus abdominus, oblique, and lower paraspinal muscles were significantly smaller (p = 0.002, p = 0.040, p = 0.005, respectively) in women when compared to the men (50 ± 21 vs. 22 ± 11%; 2 ± 2 vs. 8 ± 7; 4 ± 3 vs. 9 ± 7, 2 ± 3 vs. 7 ± 6, respectively). During PE_max effort, the percentage of sEMG activity were significantly larger in upper and lower trapezius, and intercostal muscles (p = 0.038, p = 0.049, p = 0.037, respectively) and were significantly smaller in pectoralis, rectus abdominus, and oblique muscles (p = 0.021, p < 0.0001, p = 0.048, respectively) in women compared to men (16 ± 10 vs. 9 ± 4%; 16 ± 9 vs. 8 ± 5; 36 ± 12 vs. 25 ± 9; 6 ± 3 vs. 15 ± 5; 14 ± 5 vs. 20 ± 7, respectively). These findings indicate that respiratory muscle activation patterns during maximum airway pressure efforts in healthy individuals are sex-specific. This information should be considered during respiratory motor control evaluation and treatment planning for people with compromised respiratory motor function.

Mammalian Sterile20-like Kinases: Signalings and Roles in Central Nervous System

Mammalian Sterile20-like (MST) kinases are located upstream in the mitogen-activated protein kinase pathway, and play an important role in cell proliferation, differentiation, renewal, polarization and migration. Generally, five MST kinases exist in mammalian signal transduction pathways, including MST1, MST2, MST3, MST4 and YSK1. The central nervous system (CNS) is a sophisticated entity that takes charge of information reception, integration and response. Recently, accumulating evidence proposes that MST kinases are critical in the development of disease in different systems involving the CNS. In this review, we summarized the signal transduction pathways and interacting proteins of MST kinases. The potential biological function of each MST kinase and the commonly reported MST-related diseases in the neural system are also reviewed. Further investigation of MST kinases and their interaction with CNS diseases would provide the medical community with new therapeutic targets for human diseases.

Voluntary cough intensity and its influencing factors differ by sex in community-dwelling adults

Background:

Cough peak flow (CPF) is widely used for measuring voluntary cough intensity. However, the respective factors that affect CPF are not known. The aim of this study was to determine the factors affecting CPF by sex in community-dwelling adults.

Method:

We recruited participants using posters exhibited at a public gymnasium. Participation was voluntary, and all participants provided informed consent. Nonsmoking community residents (102 males, 49.6 ± 20.2 years of age; 101 females, 51.4 ± 18.4 years of age) participated in this study. The main outcome measures were sex differences in CPF, respiratory function, respiratory muscle strength, thorax extension, and grip strength. Factors affecting CPF by sex were analyzed using multiple regression analysis.

Results:

All parameters were higher in men than in women. CPF was affected by thorax expansion at the tenth rib, inspiratory muscle strength and forced expiration in 1 s in men, and thorax expansion at the tenth rib, inspiratory reserve volume, and expiratory muscle power in women. A weak negative correlation was observed between CPF and age (p = −0.24, p < 0.05) in women.

Conclusions:

The factors affecting CPF differed by sex in community-dwelling adults.

Clinical Trial Number: UMIN000023912

Electrical Neuromodulation of the Respiratory System After Spinal Cord Injury

Spinal cord injury (SCI) is a complex and devastating condition characterized by disruption of descending, ascending, and intrinsic spinal circuitry resulting in chronic neurologic deficits. In addition to limb and trunk sensorimotor deficits, SCI can impair autonomic neurocircuitry such as the motor networks that support respiration and cough. High cervical SCI can cause complete respiratory paralysis, and even lower cervical or thoracic lesions commonly result in partial respiratory impairment. Although electrophrenic respiration can restore ventilator-independent breathing in select candidates, only a small subset of affected individuals can benefit from this technology at this moment. Over the past decades, spinal cord stimulation has shown promise for augmentation and recovery of neurologic function including motor control, cough, and breathing. The present review discusses the challenges and potentials of spinal cord stimulation for restoring respiratory function by overcoming some of the limitations of conventional respiratory functional electrical stimulation systems.

EFEITOS DA CANOAGEM ADAPTADA SOBRE O SISTEMA CARDIOPULMONAR DE PARAPLÉGICOS

RESUMO Introdução: As doenças cardiovasculares e pulmonares estão entre as principais causas de morbidade e mortalidade de indivíduos com lesão medular (LM). O treinamento físico pode ser uma alternativa terapêutica para prevenir ou amenizar complicações cardiopulmonares nessa população. Objetivo: Avaliar os efeitos do treinamento com canoagem adaptada, constituído por exercícios combinados (aeróbicos e de força), sobre variabilidade da frequência cardíaca (VFC), função pulmonar e força muscular respiratória de pessoas paraplégicas em decorrência da LM. Métodos: Participaram do estudo seis paraplégicos, cinco homens e uma mulher, média de idade de 31,50 ± 7,68 anos e índice de massa corporal médio de 24,00 ± 1,13 kg/m², nível de lesão de T4 a T9, que realizaram treinamento com canoagem adaptada por três meses. Os indivíduos foram avaliados por VFC, espirometria e manovacuometria antes e depois do treinamento. Resultados: Após o treinamento houve aumento não significativo de RR (12,7%), SDNN (24,3%), rMSSD (50,0%), pNN50 (478,6%), LF (ms²) (53,3%), HF (ms²) (158,8%), SD1 (50,6%), SD2 (23,2%) e SampEn (20,2%). Os índices HF (u.n) e LF/HF tiveram redução não significativa de 5,7 e 7,0%, respectivamente. Os maiores ganhos respiratórios foram para VVM (9,7%), Pimáx (8,5%) e Pemáx (11,0%), porém, não foram significativos. Conclusão: O protocolo proposto de três meses de canoagem adaptada não foi capaz de promover efeitos significativos sobre os parâmetros cardiopulmonares avaliados em indivíduos paraplégicos pós-LM, porém se observa uma tendência de melhora da maioria desses parâmetros. Nesse sentido, provavelmente, o estímulo de treinamento foi insuficiente.

Functional Magnetic Stimulation of Inspiratory and Expiratory Muscles in Subjects With Tetraplegia

BACKGROUND

Respiratory complications are major causes of morbidity and mortality in persons with a spinal cord injury, partly because of respiratory muscle paralysis. Earlier investigation has demonstrated that functional magnetic stimulation (FMS) can be used as a noninvasive technology for activating expiratory muscles, thus producing useful expiratory functions (simulated cough) in subjects with spinal cord injury.

OBJECTIVE

To evaluate the effectiveness of FMS for conditioning inspiratory and expiratory muscles in persons with tetraplegia.

DESIGN

A prospective before and after trial.

SETTING

FMS Laboratory, Louis Stokes Cleveland VA Medical Center, Cleveland, OH.

PARTICIPANTS

Six persons with tetraplegia.

METHOD

Each subject participated in a 6-week FMS protocol for conditioning the inspiratory and expiratory muscles. A magnetic stimulator was used with the center of a magnetic coil placed at the C7-T1 and T9-T10 spinous processes, respectively. Pulmonary function tests were performed before, during, and after the protocol.

MAIN OUTCOME MEASUREMENTS

Respiratory variables included maximal inspiratory pressure (MIP), inspiratory reserve volume (IRV), peak inspiratory flow (PIF), maximal expiratory pressure (MEP), expiratory reserve volume (ERV), and peak expiratory flow (PEF).

RESULTS

After 6 weeks of conditioning, the main outcome measurements (mean ± standard error) were as follows: MIP, 89.6 ± 7.3 cm H2O; IRV, 1.90 ± 0.34 L; PIF, 302.4 ± 36.3 L/min; MEP, 67.4 ± 11.1 cm H2O; ERV, 0.40 ± 0.06 L; and PEF, 372.4 ± 31.9 L/min. These values corresponded to 117%, 107%, 136%, 109%, 130%, and 124% of pre-FMS conditioning values, respectively. Significant improvements were observed in MIP (P = .022), PIF (P = .0001), and PEF (P = .0006), respectively. When FMS was discontinued for 4 weeks, these values showed decreases from their values at the end of the conditioning protocol, which suggests that continual FMS may be necessary to maintain improved respiratory functions.

CONCLUSION

FMS conditioning of the inspiratory and expiratory muscles improved voluntary inspiratory and expiratory functions. FMS may be a noninvasive technology for respiratory muscle training in persons with tetraplegia.

Development of a Novel Alarm System to Improve Adaptation to Non-invasive Ventilation in Patients With High Cervical Spinal Cord Injury

In this case report, we want to introduce a successful way of applying non-invasive ventilation (NIV) with a full face mask in patients with high cervical spinal cord injury through a novel alarm system for communication. A 57-year-old man was diagnosed with C3 American Spinal Injury Association impairment scale (AIS) B. We applied NIV for treatment of hypercapnia. Because of mouth opening during sleep, a full face mask was the only way to use NIV. However, he could not take off the mask by himself, and this situation caused great fear. To solve this problem, we designed a novel alarm system. The best intended motion of the patient was neck rotation. Sensing was performed by a balloon sensor placed under the head of the patient. A beep sound was generated whenever the pressure was above the threshold, and more than three consecutive beeps within 3,000 ms created a loud alarm for caregivers.

Pattern of Respiratory Deterioration in Sporadic Amyotrophic Lateral Sclerosis According to Onset Lesion by Using Respiratory Function Tests

Most amyotrophic lateral sclerosis (ALS) patients show focal onset of upper and lower motor neuron signs and spread of symptoms to other regions or the other side clinically. Progression patterns of sporadic ALS are unclear. The aim of this study was to evaluate the pattern of respiratory deterioration in sporadic ALS according to the onset site by using respiratory function tests. Study participants included 63 (42 cervical-onset [C-ALS] and 21 lumbosacral-onset [L-ALS]) ALS patients and 31 healthy controls. We compared respiratory function test parameters among the 3 groups. Age was 57.4±9.6 (mean±SD), 60.8±9, and 60.5±7 years, and there were 28, 15, and 20 male participants, in the C-ALS, L-ALS, and control groups, respectively. Disease duration did not differ between C-ALS and L-ALS patients. Sniff nasal inspiratory pressure (SNIP) was significantly low in C-ALS patients compared with controls. Maximal expiratory pressure (MEP) and forced vital capacity percent predicted (FVC% predicted) were significantly low in C-ALS and L-ALS patients compared with controls. Maximal inspiratory pressure to maximal expiratory pressure (MIP:MEP) ratio did not differ among the 3 groups. Eighteen C-ALS and 5 L-ALS patients were followed up. ΔMIP, ΔMEP, ΔSNIP, ΔPEF, and ΔFVC% predicted were higher in C-ALS than L-ALS patients without statistical significance. Fourteen C-ALS (77.8%) and 3 L-ALS (60%) patients showed a constant MIP:MEP ratio above or below 1 from the first to the last evaluation. Our results suggest that vulnerability of motor neurons in sporadic ALS might follow a topographic gradient.

Respiratory motor function in seated and supine positions in individuals with chronic spinal cord injury

This case-controlled clinical study was undertaken to investigate to what extent pulmonary function in individuals with chronic spinal cord injury (SCI) is affected by posture. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximal inspiratory pressure (PImax) and maximal expiratory pressure (PEmax) were obtained from 27 individuals with chronic motor-complete (n=13, complete group) and motor-incomplete (n=14, incomplete group) C2-T12 SCI in both seated and supine positions. Seated-to-supine changes in spirometrical (FVC and FEV1) and airway pressure (PImax and PEmax) outcome measures had different dynamics when compared in complete and incomplete groups. Patients with motor-complete SCI had tendency to increase spirometrical outcomes in supine position showing significant increase in FVC (p=.007), whereas patients in incomplete group exhibited decrease in these values with significant decreases in FEV1 (p=.002). At the same time, the airway pressure values were decreased in supine position in both groups with significant decrease in PEmax (p=.031) in complete group and significant decrease in PImax (p=.042) in incomplete group. In addition, seated-to-supine percent change of PImax was strongly correlated with neurological level of motor-complete SCI (ρ=-.77, p=.002). These results indicate that postural effects on respiratory performance in patients with SCI can depend on severity and neurological level of SCI, and that these effects differ depending on respiratory tasks. Further studies with adequate sample size are needed to investigate these effects in clinically specific groups and to study the mechanisms of such effects on specific respiratory outcome measures.

Respiratory management in the patient with spinal cord injury

Spinal cord injuries (SCIs) often lead to impairment of the respiratory system and, consequently, restrictive respiratory changes. Paresis or paralysis of the respiratory muscles can lead to respiratory insufficiency, which is dependent on the level and completeness of the injury. Respiratory complications include hypoventilation, a reduction in surfactant production, mucus plugging, atelectasis, and pneumonia. Vital capacity (VC) is an indicator of overall pulmonary function; patients with severely impaired VC may require assisted ventilation. It is best to proceed with intubation under controlled circumstances rather than waiting until the condition becomes an emergency. Mechanical ventilation can adversely affect the structure and function of the diaphragm. Early tracheostomy following short orotracheal intubation is probably beneficial in selected patients. Weaning should start as soon as possible, and the best modality is progressive ventilator-free breathing (PVFB). Appropriate candidates can sometimes be freed from mechanical ventilation by electrical stimulation. Respiratory muscle training regimens may improve patients' inspiratory function following a SCI.

Respiratory muscle training for respiratory deficits in neurodegenerative disorders: a systematic review

BACKGROUND

Studies of the impact of respiratory muscle training (RMT) on central neurodegenerative pathologies have been aimed at improving pulmonary function. However, there is no certainty about the effectiveness of RMT in patients affected by these groups of disorders. The purpose of this review was to assess the evidence regarding the efficacy of inspiratory muscle training (IMT) and expiratory muscle training (EMT) on respiratory function in patients with neurodegenerative disorders of the CNS.

METHODS

A comprehensive search from 1990 to September 2012 on MEDLINE, Physiotherapy Evidence Database (PEDro), PubMed, Cochrane Library, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases was made. Studies reporting on IMT and EMT in patients with neurodegenerative diseases were included. The selected studies were abstracted using a standardized data collection instrument and were assessed by a quality checklist created and adapted from CONSORT (Consolidated Standards for Reporting Trials) and TREND (Transparent Reporting of Evaluation with Nonrandomized Designs).

RESULTS

Twenty-four studies were identified by the search strategy. Only 19 studies met the criteria for full review. Ten studies met all the inclusion criteria and were included in the final analysis. Of the 16 parameters present in the quality assessment checklist, only six were achieved for the studies analyzed.

CONCLUSIONS

There is some evidence that RMT improves a number of respiratory function parameters in patients with Parkinson disease and multiple sclerosis; however, the number of studies and their quality are not sufficient to conclude whether IMT or EMT is effective in improving respiratory function in patients with neurodegenerative disorders of the CNS.

Cervical spinal demyelination with ethidium bromide impairs respiratory (phrenic) activity and forelimb motor behavior in rats

Although respiratory complications are a major cause of morbidity/mortality in many neural injuries or diseases, little is known concerning mechanisms whereby deficient myelin impairs breathing, or how patients compensate for such changes. Here, we tested the hypothesis that respiratory and forelimb motor functions are impaired in a rat model of focal dorsolateral spinal demyelination (ethidium bromide, EB). Ventilation, phrenic nerve activity and horizontal ladder walking were performed 7-14 days post-C2 injection of EB or vehicle (SHAM). EB caused dorsolateral demyelination at C2-C3 followed by significant spontaneous remyelination at 14 days post-EB. Although ventilation did not differ between groups, ipsilateral integrated phrenic nerve burst amplitude was significantly reduced versus SHAM during chemoreceptor activation at 7 days post-EB but recovered by 14 days. The ratio of ipsi- to contralateral phrenic nerve amplitude correlated with cross-sectional lesion area. This ratio was significantly reduced 7 days post-EB versus SHAM during baseline conditions, and versus SHAM and 14-day groups during chemoreceptor activation. Limb function ipsilateral to EB was impaired 7 days post-EB and partially recovered by 14 days post-EB. EB provides a reversible model of focal, spinal demyelination, and may be a useful model to study mechanisms of functional impairment and recovery via motor plasticity, or the efficacy of new therapeutic interventions to reduce severity or duration of disease.