Abnormalities of respiratory control and the respiratory motor unit

Neonatal Chlamydia muridarum respiratory infection causes neuroinflammation within the brainstem during the early postnatal period

Respiratory infections are one of the most common causes of illness and morbidity in neonates worldwide. In the acute phase infections are known to cause wide-spread peripheral inflammation. However, the inflammatory consequences to the critical neural control centres for respiration have not been explored. Utilising a well characterised model of neonatal respiratory infection, we investigated acute responses within the medulla oblongata which contains key respiratory regions. Neonatal mice were intranasally inoculated within 24 h of birth, with either Chlamydia muridarum or sham-infected, and tissue collected on postnatal day 15, the peak of peripheral inflammation. A key finding of this study is that, while the periphery appeared to show no sex-specific effects of a neonatal respiratory infection, sex had a significant impact on the inflammatory response of the medulla oblongata. There was a distinct sex-specific response in the medulla coincident with peak of peripheral inflammation, with females demonstrating an upregulation of anti-inflammatory cytokines and males showing very few changes. Microglia also demonstrated sex-specificity with the morphology of females and males differing based upon the nuclei. Astrocytes showed limited changes during the acute response to neonatal infection. These data highlight the strong sex-specific impact of a respiratory infection can have on the medulla in the acute inflammatory phase.

The molecular fingerprint of neuroinflammation in COVID-19: A comprehensive discussion on molecular mechanisms of neuroinflammation due to SARS-COV2 antigens

BACKGROUND AND OBJECTIVE

Severe acute respiratory syndrome coronavirus 2 attacks the neural system directly and indirectly via various systems, such as the nasal cavity, olfactory system, and facial nerves. Considering the high energy requirement, lack of antioxidant defenses, and high amounts of metal ions in the brain, oxidative damage is very harmful to the brain. Various neuropathic pain conditions, neurological disorders, and neuropsychiatric complications were reported in Coronavirus disease 2019, prolonged Coronavirus disease 2019, and after Coronavirus disease 2019 immunization. This manuscript offers a distinctive outlook on the interconnectedness between neurology and neuropsychiatry through its meticulous analysis of complications.

DISCUSSION

After recovering from Coronavirus disease 2019, approximately half of the patients reported developing Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Long Coronavirus disease 2019 imaging reports illustrated the hypometabolism in various parts of the brain, such as olfactory bulbs, limbic/paralimbic domains, the brainstem, and the cerebellum. Ninety imaging and neuropathological studies of Coronavirus disease 2019 have shown evidence of white matter, brainstem, frontotemporal, and oculofrontal lesions. Emotional functions, such as pleasant, long/short-term memory, movement, cognition and cognition in decision-making are controlled by these regions. The neuroinflammation and the mechanisms of defense are well presented in the discussion. The role of microglia activation, Inducible NO synthase, Cyclooxygenases ½, Reactive oxygen species, neurotoxic toxins and pro-inflammatory cytokines, such as Interleukin-1 beta, Interleukin-6 and Tumor Necrosis Factor-alpha are highlighted in neuronal dysfunction and death. Nuclear factor kappa-light-chain-enhancer of activated B cells, Mitogen-activated protein kinase, Activator Protein 1, and Interferon regulatory factors are the main pathways involved in microglia activation in Coronavirus disease 2019 neuroinflammation.

CONCLUSION

The neurological aspect of Coronavirus disease 2019 should be highlighted. Neurological, psychological, and behavioral aspects of Coronavirus disease 2019, prolonged Coronavirus disease 2019, and Coronavirus disease 2019 vaccines can be the upcoming issues. We need a global awareness where this aspect of the disease should be more considered in health research.

fMRI studies evaluating central respiratory control in humans

A plethora of neural centers in the central nervous system control the fundamental respiratory pattern. This control is ensured by neurons that act as pacemakers, modulating activity through chemical control driven by changes in the O₂/CO₂ balance. Most of the respiratory neural centers are located in the brainstem, but difficult to localize on magnetic resonance imaging (MRI) due to their small size, lack of visually-detectable borders with neighboring areas, and significant physiological noise hampering detection of its activity with functional MRI (fMRI). Yet, several approaches make it possible to study the normal response to different abnormal stimuli or conditions such as CO₂ inhalation, induced hypercapnia, volitional apnea, induced hypoxia etc. This review provides a comprehensive overview of the majority of available studies on central respiratory control in humans.

Closing the Gap between Inpatient and Outpatient Settings: Integrating Pulmonary Rehabilitation and Technological Advances in the Comprehensive Management of Frail Patients

Pulmonary rehabilitation (PR) is a well-established intervention supported by strong evidence that is used to treat patients affected by chronic respiratory diseases. However, several barriers still affect its spreading in rehabilitation clinical practices. Although chronic respiratory diseases are common age-related disorders, there is still a gap of knowledge regarding the implementation of sustainable strategies integrating PR in the rehabilitation management of frail patients at high risk of respiratory complications. Therefore, in the present study, we characterized the effects of PR in frail patients, highlighting the evidence supporting its role in improving the complex rehabilitative management of these patients. Moreover, we propose a novel organizational model promoting PR programs for frail patients in both inpatient and outpatient settings. Our model emphasizes the role of interdisciplinary care, specifically tailored to patients and environmental characteristics. In this scenario, cutting-edge technology and telemedicine solutions might be implemented as safe and sustainable strategies filling the gap between inpatient and outpatient settings. Future research should focus on large-scale sustainable interventions to improve the quality of life and global health of frail patients. Moreover, evidence-based therapeutic paths should be promoted and taught in training courses promoting multiprofessional PR knowledge to increase awareness and better address its delivery in frail patients.

Medullary astrocytes mediate irregular breathing patterns generation in chronic heart failure through purinergic P2X7 receptor signalling

Background

Breathing disorders (BD) (apnoeas/hypopneas, periodic breathing) are highly prevalent in chronic heart failure (CHF) and are associated with altered central respiratory control. Ample evidence identifies the retrotrapezoid nucleus (RTN) as an important chemosensitivity region for ventilatory control and generation of BD in CHF, however little is known about the cellular mechanisms underlying the RTN/BD relationship. Within the RTN, astrocyte‐mediated purinergic signalling modulates respiration, but the potential contribution of RTN astrocytes to BD in CHF has not been explored.

Methods

Selective neuron and/or astrocyte-targeted interventions using either optogenetic and chemogenetic manipulations in the RTN of CHF rats were used to unveil the contribution of the RTN on the development/maintenance of BD, the role played by astrocytes in BD and the molecular mechanism underpinning these alterations.

Findings

We showed that episodic photo-stimulation of RTN neurons triggered BD in healthy rats, and that RTN neurons ablation in CHF animals eliminates BD. Also, we found a reduction in astrocytes activity and ATP bioavailability within the RTN of CHF rats, and that chemogenetic restoration of normal RTN astrocyte activity and ATP levels improved breathing regularity in CHF. Importantly, P"X/ P2X7 receptor (P2X7r) expression was reduced in RTN astrocytes from CHF rats and viral vector-mediated delivery of human P2X7 P2X7r into astrocytes increases ATP bioavailability and abolished BD.

Interpretation

Our results support that RTN astrocytes play a pivotal role on BD generation and maintenance in the setting CHF by a mechanism encompassing P2X7r signalling.

Funding

This study was funded by the National Research and Development Agency of Chile (ANID).

Neurologic complications of coronavirus and other respiratory viral infections

In humans, several respiratory viruses can have neurologic implications affecting both central and peripheral nervous system. Neurologic manifestations can be linked to viral neurotropism and/or indirect effects of the infection due to endothelitis with vascular damage and ischemia, hypercoagulation state with thrombosis and hemorrhages, systemic inflammatory response, autoimmune reactions, and other damages. Among these respiratory viruses, recent and huge attention has been given to the coronaviruses, especially the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic started in 2020. Besides the common respiratory symptoms and the lung tropism of SARS-CoV-2 (COVID-19), neurologic manifestations are not rare and often present in the severe forms of the infection. The most common acute and subacute symptoms and signs include headache, fatigue, myalgia, anosmia, ageusia, sleep disturbances, whereas clinical syndromes include mainly encephalopathy, ischemic stroke, seizures, and autoimmune peripheral neuropathies. Although the pathogenetic mechanisms of COVID-19 in the various acute neurologic manifestations are partially understood, little is known about long-term consequences of the infection. These consequences concern both the so-called long-COVID (characterized by the persistence of neurological manifestations after the resolution of the acute viral phase), and the onset of new neurological symptoms that may be linked to the previous infection.

Stroke and breathing

Stroke remains a leading cause of neurologic disability with wide ranging effects, including a variety of respiratory abnormalities. Stroke may influence the central control of the respiratory drive and breathing pattern, airway protection and maintenance, and the respiratory mechanics of inspiration and expiration. In the acute phase of stroke, the central control of breathing is affected by changes in consciousness, cerebral edema, and direct damage to brainstem respiratory centers, resulting in abnormalities in respiratory pattern and loss of airway protection. Common acute complications related to respiratory dysfunction include dysphagia, aspiration, and pneumonia. Respiratory control centers are located in the brainstem, and brainstem stroke causes specific patterns of respiratory dysfunction. Depending on the exact location and extent of stroke, respiratory failure may occur. While major respiratory abnormalities often improve over time, sleep-disordered breathing remains common in the subacute and chronic phases and worsens outcomes. Respiratory mechanics are impaired in hemiplegic or hemiparetic stroke, contributing to worse cardiopulmonary health in stroke survivors. Interventions to address the respiratory complications are under researched, and further investigation in this area is critical to improving outcomes among stroke survivors.

Effects of Respiratory Muscle Training on Baroreflex Sensitivity, Respiratory Function, and Serum Oxidative Stress in Acute Cervical Spinal Cord Injury

Background: respiratory complications are a leading cause of morbidity and mortality in individuals with spinal cord injury (SCI). We examined the effects of respiratory muscle training (RMT) in patients with acute cervical SCI. Methods: this prospective trial enrolled 44 adults with acute cervical SCI, of which twenty received RMT and twenty-four did not receive RMT. Respiratory function, cardiovascular autonomic function, and reactive oxidative species (ROS) were compared. The experimental group received 40-min high-intensity home-based RMT 7 days per week for 10 weeks. The control group received a sham intervention for a similar period. The primary outcomes were the effects of RMT on pulmonary and cardiovascular autonomic function, and ROS production in individuals with acute cervical SCI. Results: significant differences between the two groups in cardiovascular autonomic function and the heart rate response to deep breathing (p = 0.017) were found at the 6-month follow-up. After RMT, the maximal inspiratory pressure (p = 0.042) and thiobarbituric acid-reactive substances (TBARS) (p = 0.006) improved significantly, while there was no significant difference in the maximal expiratory pressure. Significant differences between the two groups in tidal volume (p = 0.005) and the rapid shallow breathing index (p = 0.031) were found at 6 months. Notably, the SF-36 (both the physical (PCS) and mental (MCS) component summaries) in the RMT group had decreased significantly at the 6-month follow-up, whereas the clinical scores did not differ significantly (p = 0.333) after RMT therapy. Conclusions: High-intensity home-based RMT can improve pulmonary function and endurance and reduce breathing difficulties in patients with respiratory muscle weakness after injury. It is recommended for rehabilitation after spinal cord injury.

Neuroinvasion of SARS-CoV-2 may play a role in the breakdown of the respiratory center of the brain

The recent outbreak of the novel coronavirus, SARS-CoV-2, has emerged to be highly pathogenic in nature. Although lungs are considered as the primary infected organs by SARS-CoV-2, some of the other organs, including the brain, have also been found to be affected. Here, we have discussed how SARS-CoV-2 might infect the brain. The infection of the respiratory center in the brainstem could be hypothesized to be responsible for the respiratory failure in many COVID-19 patients. The virus might gain entry through the olfactory bulb and invade various parts of the brain, including the brainstem. Alternatively, the entry might also occur from peripheral circulation into the central nervous system by compromising the blood-brain barrier. Finally, yet another possible entry route could be its dispersal from the lungs into the vagus nerve via the pulmonary stretch receptors, eventually reaching the brainstem. Therefore, screening neurological symptoms in COVID-19 patients, especially toward the breakdown of the respiratory center in the brainstem, might help us better understand this disease.

Respiratory and sleep-related complications of multiple system atrophy

PURPOSE OF REVIEW

The purpose of this article is to provide a contemporary review of sleep issues affecting patients with multiple system atrophy (MSA).

RECENT FINDINGS

Prodromal symptoms of MSA may occur years prior to diagnosis, including autonomic dysfunction such as orthostatic hypotension, urogenital dysfunction, rapid eye movement (REM) sleep behavior disorder (RBD), and stridor. Patients may also develop sleep-related respiratory disorders such as obstructive sleep apnea (OSA), central sleep apnea (CSA), and stridor. The development of stridor is associated with a shortened lifespan and sudden death, which may be further accelerated by autonomic instability. MSA appears to follow a 'prion-like' disease progression.

SUMMARY

MSA is a rapidly progressive neurodegenerative disease characterized by a combination of autonomic failure and motor symptoms. MSA is often misdiagnosed as the initial presentation mimics other neurodegenerative disorders. There are diagnostic criteria to identify possible, probable, and definite MSA. Prodromal symptoms may occur years prior to diagnosis, including autonomic dysfunction such as orthostatic hypotension, urogenital dysfunction, REM RBD, and stridor. In previous years, treatment consisted of tracheostomy but did not address the component of CSA, which commonly coexisted or developed later because of destruction of medullary chemoreceptors. Positive airway pressure may be as effective as tracheostomy alone in ameliorating obstruction at the vocal cord level.

Coexisting central and obstructive sleep apnea and mild diurnal hypoventilation associated with unilateral diaphragmatic dysfunction and brainstem lesion

A 63-year old man was diagnosed with coexisting central (CSA) and obstructive (OSA) sleep apnea, crescendo-decrescendo (CD) periodic breathing (PB), frequent sustained desaturation hypoxemia events related to prolonged hypopnea and mild diurnal hypoventilation. Unilateral diaphragmatic dysfunction (DD) related to diabetic phrenic neuropathy was identified. Magnetic resonance imaging (MRI) scans of the head disclosed frontal-subcortical white matter (WM) lesions, while brainstem MRI found a small punctiform defect in the median area of the pons. Continuous positive airway pressure (CPAP) therapy was ineffective, while a one-month bi-level positive airway pressure (BIPAP) trial provided better outcomes.

Factors Associated With Prolonged Mechanical Ventilation and Reventilation in Acute Cervical Spinal Cord Injury Patients

MINI: In this study, respiratory function at the time of extubation can be useful optimal clinical guidelines for weaning and extubation attempts in patients with acute cervical spinal cord injury. Serum thiobarbituric acid-reactive substances level at admission can be a useful predictor for severity in acute cervical patients with spinal cord injury.

STUDY DESIGN

Patients who had suffered from acute blunt cervical spinal cord injury (SCI) and admitted our hospital within 24 hours after injury were included in the study.

OBJECTIVE

We compared the respiratory function and serum reactive oxidative stress (ROS) after acute cervical SCI, and tried to find out the valuable predictors of weaning in patients with acute cervical SCI.

SUMMARY OF BACKGROUND DATA

Ventilation impairment is a major complication of acute cervical SCI. Evidence of oxygen radical formation in secondary injury from animal SCI models demonstrates an immediate postinjury increase in ROS production after SCI. We hypothesize that the serum ROS is associated with the severity of patients with acute cervical SCI.

METHODS

Thirty-eight adult patients who had acute cervical SCI and 58 healthy volunteers were enrolled. Respiratory function at admission, at the time of extubation and at 48 hours after extubation, serum oxidative stress, Injury Severity Score and Japanese Orthopaedic Association score at admission were compared.

RESULTS

The most notable predictor of mechanical ventilation more than 48 hours was serum thiobarbituric acid-reactive substances (TBARS) level at admission (P = 0.027), and the cut-off value of serum TBARS level was 731.7 μmol/L (sensitivity 87.5% and specificity 78.9%). For the reventilation ≤5 days, the notable predictors were respiratory function at the time of extubation (maximal inspiratory pressure, P = 0.040; maximal expiratory pressure, P = 0.020; and tidal volume, P = 0.036) and serum TBARS level at admission (P = 0.013), the cut-off value of serum TBARS level at admission was 762.3 μmol/L (sensitivity 100% and specificity 90.0%).

CONCLUSION

In this study, respiratory function (maximal inspiratory pressure, maximal expiratory pressure, and tidal volume) at the time of extubation can be useful optimal clinical guidelines for weaning and extubation attempts in patients with acute cervical SCI. Serum TBARS level at admission can be a useful predictor for severity in acute cervical SCI patients.

LEVEL OF EVIDENCE

3.

The Pathophysiology of Dying

The pathophysiology of dying and death, related to veterinary patients, has warranted less attention than normal and abnormal physiologic processes related to life preservation. In addition, many veterinary patients are euthanized, which prevents observation of natural disease progression, while ameliorating suffering. Acute death in human medicine can serve as a model for understanding mechanisms of death in veterinary patients under certain conditions. The specific cause of cardiac arrest in several different models of disease elucidates end-stage disease processes. Understanding the path to death and dying in veterinary patients physiologically serves to guide best practices focused on alleviating suffering.

Respiratory repercussions of neurological diseases and how best to manage them

Introduction: The high incidence of respiratory impairments in patients with neurological diseases is recognized, but the design, dosage, and effectiveness of interventions to manage them are seen as an ongoing challenge.Areas covered: This article summarizes the evidence regarding the respiratory impairments in major neurological diseases, and how to best manage them.Expert opinion: On the balance of available evidence, respiratory impairments are part of the clinical profile of neurological diseases including Multiple Sclerosis, Stroke, and Parkinson's Disease, acquiring more importance as the pathologies progress. It is recognized that knowledge gaps remain in some areas of relevance related to respiratory function and further research is required. When considering the therapeutic options, the respiratory training emerges as the approach with most evidence. However, important questions remain unsolved: what kind, how much, and how to best include respiratory interventions is uncertain. At present, respiratory programs also fail to include clinically relevant factors such as ambulation and trunk stability.

Adenosine 2A receptor inhibition protects phrenic motor neurons from cell death induced by protein synthesis inhibition

Respiratory motor neuron survival is critical for maintenance of adequate ventilation and airway clearance, preventing dependence to mechanical ventilation and respiratory tract infections. Phrenic motor neurons are highly vulnerable in rodent models of motor neuron disease versus accessory inspiratory motor pools (e.g. intercostals, scalenus). Thus, strategies that promote phrenic motor neuron survival when faced with disease and/or toxic insults are needed to help preserve breathing ability, airway defense and ventilator independence. Adenosine 2A receptors (A2A) are emerging as a potential target to promote neuroprotection, although their activation can have both beneficial and pathogenic effects. Since the role of A2A receptors in the phrenic motor neuron survival/death is not known, we tested the hypothesis that A2A receptor antagonism promotes phrenic motor neuron survival and preserves diaphragm function when faced with toxic, neurodegenerative insults that lead to phrenic motor neuron death. We utilized a novel neurotoxic model of respiratory motor neuron death recently developed in our laboratory: intrapleural injections of cholera toxin B subunit (CtB) conjugated to the ribosomal toxin, saporin (CtB-Saporin). We demonstrate that intrapleural CtB-Saporin causes: 1) profound phrenic motor neuron death (~5% survival); 2) ~7-fold increase in phrenic motor neuron A2A receptor expression prior to cell death; and 3) diaphragm muscle paralysis (inactive in most rats; ~7% residual diaphragm EMG amplitude during room air breathing). The A2A receptor antagonist istradefylline given after CtB-Saporin: 1) reduced phrenic motor neuron death (~20% survival) and 2) preserved diaphragm EMG activity (~46%). Thus, A2A receptors contribute to neurotoxic phrenic motor neuron death, an effect mitigated by A2A receptor antagonism.

Syringobulbia in Patients with Chiari Malformation Type I: A Systematic Review

This study aimed to summarize the clinical features, diagnosis, and treatment of Chiari malformation type I- (CM-1-) associated syringobulbia. We performed a literature review of CM-1-associated syringobulbia in PubMed, Ovid MEDLINE, and Web of Science databases. Our concerns were the clinical features, radiologic presentations, treatment therapies, and prognoses of CM-1-associated syringobulbia. This review identified 23 articles with 53 cases. Symptoms included headache, neck pain, cranial nerve palsy, limb weakness/dysesthesia, Horner syndrome, ataxia, and respiratory disorders. The most frequently involved area was the medulla. Most of the patients also had syringomyelia. Surgical procedures performed included posterior fossa decompression, foramen magnum decompression, cervical laminectomy, duraplasty, and syringobulbic cavity shunt. Most patients experienced symptom alleviation or resolution postoperatively. A syringobulbic cavity shunt provided good results in refractory cases. Physicians should be aware of the possibility of syringobulbia in CM-1 patients, especially those with symptoms of sudden-onset brain-stem involvement. The diagnosis relies on the disorder's specific symptomatology and magnetic resonance imaging. Our review suggests that the initial therapy should be posterior fossa decomposition with or without duraplasty. In refractory cases, additional syringobulbic cavity shunt is the preferred option.

Surgical Management and Risk Factors of Postoperative Respiratory Dysfunction of Cavernous Malformations Involving the Medulla Oblongata

OBJECTIVE

To evaluate surgical management of cavernous malformations (CMs) involving the medulla oblongata and to predict risk factors of postoperative respiratory dysfunction (RDF).

METHODS

Patient data from individuals who underwent surgical treatment for CMs involving the medulla oblongata were retrospectively reviewed. Patients with postoperative RDF and/or deficits of the cough reflex (CR, ≥7 days) were deemed as having bad respiratory statuses. A binary logistic regression analysis tested the association of preoperative predictors with bad postoperative respiratory status.

RESULTS

The study consisted of 69 patients. Preoperatively, 9 patients (13.0%) had dyspnea, and 4 (5.8%) had hypoxemia. Postoperatively, 11 patients (15.9%) had bad respiratory statuses, including RDF as a respiratory rhythm disorder and/or dyspnea in 6 patients, and ≥7 days of CR deficits in 5 patients. With a mean follow-up duration of 35.3 months, the neurologic status improved in 45 patients (68.2%), remained unchanged in 11 (16.7%), and worsened in 10 (15.1%) relative to the preoperative baseline. A multivariate logistic regression analysis identified that the independent adverse factors of bad postoperative respiratory status were multiple preoperative hemorrhages, large lesion size, and surgical intervention during the chronic period (>8 weeks).

CONCLUSIONS

Postoperative RDF and CR deficits could commonly occur in patients with CMs involving the medulla oblongata. However, patients with fewer preoperative hemorrhages, small lesion size, and operation within 8 weeks of the last bleeding are prone to be associated with a reduced possibility of bad postoperative respiratory status.

Syringobulbia in pediatric patients with Chiari malformation type I

OBJECTIVE Syringobulbia (SB) is a rare entity, with few cases associated with Chiari malformation type I (CM-I) in the pediatric population. The authors reviewed all pediatric cases of CM-I-associated SB managed at their institution in order to better understand the presentation, treatment, and surgical outcomes of this condition. METHODS A prospectively maintained institutional database of craniovertebral junction abnormalities was analyzed to identify all cases of CM-I and SB from the MRI era (i.e., after 1984). The authors recorded presenting symptoms, physical examination findings, radiological findings, surgical treatment strategy, intraoperative findings, and outcomes. SB cases associated with tumors, infections, or type II Chiari malformations were excluded. RESULTS The authors identified 326 pediatric patients with CM-I who were surgically treated. SB was identified in 13 (4%) of these 326 patients. Headache and neck pain were noted in all 13 cases. Cranial nerve abnormalities were common: vagus and glossopharyngeal nerve dysfunction was the most frequent observation. Other cranial nerves affected included the trigeminal, abducens, and hypoglossal nerves. Several patients exhibited multiple cranial nerve palsies at presentation. Central sleep apnea was present in 6 patients. Syringomyelia (SM) was present in all 13 patients. SB involved the medulla in all cases, and extended rostrally into the pons and midbrain in 2 patients; in 1 of these 2 cases the cavity extended further rostrally to the cerebrum (syringocephaly). SB communicated with the fourth ventricle in 7 of the 13 cases. All 13 patients were treated with posterior fossa decompression with intradural exploration to ensure CSF egress out of the fourth ventricle and through the foramen magnum. The foramen of Magendie was found to be occluded by an arachnoid veil in 9 cases. Follow-up evaluation revealed that SB improved before SM. Cranial nerve palsies regressed in 11 of the 13 patients, and SB improved in all 13. CONCLUSIONS The incidence of SB in our surgical series of pediatric patients with CM-I was 4%, and all of these patients had accompanying SM. The SB cavity involved the medulla in all cases and was found to communicate with the fourth ventricle in 54% of cases. Posterior fossa decompression with intradural exploration and duraplasty is an effective treatment for these patients.

Microstructural cerebral lesions are associated with the severity of central sleep apnea with Cheyne-Stokes-respiration in heart failure and are modified by PAP-therapy

This study investigated the association of microstructural cerebral lesions with central sleep apnea with Cheyne-Stokes-respiration (CSA-CSR) in heart failure (HF) patients and the effect of positive airway pressure therapy (PAP) of CSA-CSR on these lesions. PAP-therapy was initiated in patients with HF with midrange and with reduced ejection fraction (NYHA≥II; left ventricular ejection fraction <50%) and proven CSA-CSR. Cerebral magnetic resonance imaging (MRI) scans at 3T including diffusion tensor imaging were obtained before and after 4 months of PAP-therapy. Cerebral MRI scans revealed microstructural lesions in all 11 patients with HF with midrange or reduced ejection fraction and CSA-CSR (64±8years, 82% male, left ventricular ejection fraction 37±11%) that were focussed on the brainstem and frontal cerebral regions. This microstructural damage correlated with the severity of CSA-CSR and 4 months of PAP-therapy lead to voxel clusters of altered fiber integrity in these lesions. Microstructural cerebral lesions might contribute to the pathophysiology of CSA-CSR in HF. In these patients PAP-therapy induces neuronal plasticity.

Impact of automated ICA-based denoising of fMRI data in acute stroke patients

Different strategies have been developed using Independent Component Analysis (ICA) to automatically de-noise fMRI data, either focusing on removing only certain components (e.g. motion-ICA-AROMA, Pruim et al., 2015a) or using more complex classifiers to remove multiple types of noise components (e.g. FIX, Salimi-Khorshidi et al., 2014 Griffanti et al., 2014). However, denoising data obtained in an acute setting might prove challenging: the presence of multiple noise sources may not allow focused strategies to clean the data enough and the heterogeneity in the data may be so great to critically undermine complex approaches. The purpose of this study was to explore what automated ICA based approach would better cope with these limitations when cleaning fMRI data obtained from acute stroke patients. The performance of a focused classifier (ICA-AROMA) and a complex classifier (FIX) approaches were compared using data obtained from twenty consecutive acute lacunar stroke patients using metrics determining RSN identification, RSN reproducibility, changes in the BOLD variance, differences in the estimation of functional connectivity and loss of temporal degrees of freedom. The use of generic-trained FIX resulted in misclassification of components and significant loss of signal (< 80%), and was not explored further. Both ICA-AROMA and patient-trained FIX based denoising approaches resulted in significantly improved RSN reproducibility (p < 0.001), localized reduction in BOLD variance consistent with noise removal, and significant changes in functional connectivity (p < 0.001). Patient-trained FIX resulted in higher RSN identifiability (p < 0.001) and wider changes both in the BOLD variance and in functional connectivity compared to ICA-AROMA. The success of ICA-AROMA suggests that by focusing on selected components the full automation can deliver meaningful data for analysis even in population with multiple sources of noise. However, the time invested to train FIX with appropriate patient data proved valuable, particularly in improving the signal-to-noise ratio.

Airway management and mechanical ventilation in acute brain injury

Patients with acute neurologic disease often develop respiratory failure, the management of which profoundly affects brain physiology and long-term functional outcomes. This chapter reviews airway management and mechanical ventilation of patients with acute brain injury, offering practical strategies to optimize treatment of respiratory failure and minimize secondary brain injury. Specific concerns that are addressed include physiologic changes during intubation and ventilation such as the effects on intracranial pressure and brain perfusion; cervical spine management during endotracheal intubation; the role of tracheostomy; and how ventilation and oxygenation are utilized to minimize ischemia-reperfusion injury and cerebral metabolic distress.

Central hyperventilation syndrome due to massive pneumocephalus after endoscopic third ventriculostomy: a case report

Pneumocephalus is common after brain surgeries, but usually is not substantial enough to cause serious complications. We recently encountered a case of post-operative tachypnea after an endoscopic 3rd ventriculostomy. At first, we thought that the hyperventilation was the result of residual paralysis after emergence from anesthesia, but during further evaluation we found a massive pneumocephalus. In such unusual post-operative situations, physicians should consider surgery-related complications as the possible cause as well, along with the anesthetic factors.

Neurotoxicity of prenatal alcohol exposure on medullary pre-Bötzinger complex neurons in neonatal rats

Prenatal alcohol exposure disrupts the development of normal fetal respiratory function, but whether it perturbs respiratory rhythmical discharge activity is unclear. Furthermore, it is unknown whether the 5-hydroxytryptamine 2A receptor (5-HT_2AR) is involved in the effects of prenatal alcohol exposure. In the present study, pregnant female rats received drinking water containing alcohol at concentrations of 0%, 1%, 2%, 4%, 8% or 10% (v/v) throughout the gestation period. Slices of the medulla from 2-day-old neonatal rats were obtained to record respiratory rhythmical discharge activity. 5-HT_2AR protein and mRNA levels in the pre-Bötzinger complex of the respiratory center were measured by western blot analysis and quantitative RT-PCR, respectively. Compared with the 0% alcohol group, respiratory rhythmical discharge activity in medullary slices in the 4%, 8% and 10% alcohol groups was decreased, and the reduction was greatest in the 8% alcohol group. Respiratory rhythmical discharge activity in the 10% alcohol group was irregular. Thus, 8% was the most effective alcohol concentration at attenuating respiratory rhythmical discharge activity. These findings suggest that prenatal alcohol exposure attenuates respiratory rhythmical discharge activity in neonatal rats by downregulating 5-HT_2AR protein and mRNA levels.

Brainstem involvement as a cause of central sleep apnea: pattern of microstructural cerebral damage in patients with cerebral microangiopathy

Background

The exact underlying pathomechanism of central sleep apnea with Cheyne-Stokes respiration (CSA-CSR) is still unclear. Recent studies have demonstrated an association between cerebral white matter changes and CSA. A dysfunction of central respiratory control centers in the brainstem was suggested by some authors. Novel MR-imaging analysis tools now allow far more subtle assessment of microstructural cerebral changes. The aim of this study was to investigate whether and what severity of subtle structural cerebral changes could lead to CSA-CSR, and whether there is a specific pattern of neurodegenerative changes that cause CSR. Therefore, we examined patients with Fabry disease (FD), an inherited, lysosomal storage disease. White matter lesions are early and frequent findings in FD. Thus, FD can serve as a "model disease" of cerebral microangiopathy to study in more detail the impact of cerebral lesions on central sleep apnea.

Patients and Methods

Genetically proven FD patients (n = 23) and age-matched healthy controls (n = 44) underwent a cardio-respiratory polysomnography and brain MRI at 3.0 Tesla. We applied different MR-imaging techniques, ranging from semiquantitative measurement of white matter lesion (WML) volumes and automated calculation of brain tissue volumes to VBM of gray matter and voxel-based diffusion tensor imaging (DTI) analysis.

Results

In 5 of 23 Fabry patients (22%) CSA-CSR was detected. Voxel-based DTI analysis revealed widespread structural changes in FD patients when compared to the healthy controls. When calculated as a separate group, DTI changes of CSA-CSR patients were most prominent in the brainstem. Voxel-based regression analysis revealed a significant association between CSR severity and microstructural DTI changes within the brainstem.

Conclusion

Subtle microstructural changes in the brainstem might be a neuroanatomical correlate of CSA-CSR in patients at risk of WML. DTI is more sensitive and specific than conventional structural MRI and other advanced MR analyses tools in demonstrating these abnormalities.

Neuroanatomical characteristics of the human pre-Bötzinger complex and its involvement in neurodegenerative brainstem diseases

The pre-Bötzinger complex has been identified as an essential part of the medullary respiratory network in mammals. Although well described in experimental animals, its localization in the human brain has remained elusive. Using serially sectioned brainstems from 19 normal individuals and patients suffering from neurodegenerative diseases (multiple system atrophy, n = 10; spinocerebellar ataxia type 3, n = 8), we have identified a circumscribed area of the ventrolateral medulla that represents the human homologue of the pre-Bötzinger complex and have mapped its longitudinal and horizontal extents. The presumed human pre-Bötzinger complex is characterized by an aggregation of loosely scattered, small and lipofuscin-rich neurons, which contain neurokinin 1 receptor as well as somatostatin, but are negative for markers of monoaminergic neurons and of motoneurons. In brains of patients suffering from multiple systems atrophy (with central respiratory deficits but without swallowing problems), pre-Bötzinger complex neurons were reduced, whereas pharyngeal motoneurons of the ambigual nucleus were not affected. In contrast, in brains of patients with spinocerebellar ataxia 3 (no reported central respiratory deficits but with dysphagia), pre-Bötzinger complex neurons were preserved, whereas ambigual motoneurons, which control swallowing, were diminished. These pathoanatomical findings support the view, that affection of the central respiratory network, including the pre-Bötzinger complex, contributes to breathing disorders in multiple system atrophy, whereas damage to ambigual motoneurons is important for pathogenesis of breathing disturbances and dysphagia in patients with spinocerebellar ataxia type 3. On the basis of these findings, the putative human homologue of the pre-Bötzinger complex can now be reliably delineated on pigment-Nissl-stained sections, making neuropathological investigations of central respiratory disturbances feasible.

Hypoventilation syndromes

A wide variety of mechanisms can lead to the hypoventilation associated with various medical disorders, including derangements in central ventilatory control, mechanical impediments to breathing, and abnormalities in gas exchange leading to increased dead space ventilation. The pathogenesis of hypercapnia in obesity hypoventilation syndrome remains somewhat obscure, although in many patients comorbid obstructive sleep apnea appears to play an important role. Hypoventilation in neurologic or neuromuscular disorders is primarily explained by weakness of respiratory muscles, although some central nervous system diseases may affect control of breathing. In other chest wall disorders, obstructive airways disease, and cystic fibrosis, much of the pathogenesis is explained by mechanical impediments to breathing, but an element of increased dead space ventilation also often occurs. Central alveolar hypoventilation syndrome involves a genetically determined defect in central respiratory control. Treatment in all of these disorders involves coordinated management of the primary disorder (when possible) and, increasingly, the use of noninvasive positive pressure ventilation.

Current tissue engineering and novel therapeutic approaches to axonal regeneration following spinal cord injury using polymer scaffolds

This review highlights current tissue engineering and novel therapeutic approaches to axonal regeneration following spinal cord injury. The concept of developing 3-dimensional polymer scaffolds for placement into a spinal cord transection model has recently been more extensively explored as a solution for restoring neurologic function after injury. Given the patient morbidity associated with respiratory compromise, the discrete tracts in the spinal cord conveying innervation for breathing represent an important and achievable therapeutic target. The aim is to derive new neuronal tissue from the surrounding, healthy cord that will be guided by the polymer implant through the injured area to make functional reconnections. A variety of naturally derived and synthetic biomaterial polymers have been developed for placement in the injured spinal cord. Axonal growth is supported by inherent properties of the selected polymer, the architecture of the scaffold, permissive microstructures such as pores, grooves or polymer fibres, and surface modifications to provide improved adherence and growth directionality. Structural support of axonal regeneration is combined with integrated polymeric and cellular delivery systems for therapeutic drugs and for neurotrophic molecules to regionalize growth of specific nerve populations.