Electrophysiological assessment of corticorespiratory pathway function in amyotrophic lateral sclerosis

The Effect of Deep and Slow Breathing on Retention and Cognitive Function in the Elderly Population

The purpose of this study was to apply deep and slow breathing to the elderly, who can be classified as potential dementia patients, to confirm changes in the cognitive functions of learning and memory. Forty-five elderly subjects were randomly and evenly divided into a rest group (RG), a before group (BG), and an after group (AG). Measurements of their cognitive abilities were obtained before testing (PT), 30 min after learning (STT), and 24 h after learning (LTT). After PT measurements were obtained from all three groups, the RG and AG conducted new cognitive skills learning, while the BG performed deep and slow breathing (DSB) for 30 min before learning new cognitive skills. After all the three groups underwent 30 min of learning, the STT was performed. Subsequently, the AG performed DSB for 30 min. Finally, 24 h after learning, the LTT was conducted for all three groups. Changes were compared and analyzed by measuring the retention of new cognitive skills and attention, working memory, and spatial perception of cognitive functions. A two-way repeated measure analysis of variance measured the effect of the application of DSB in the three groups. These results demonstrated a significant interaction of time and time*group in all measurements of retention and attention, working memory, and spatial perception. This study confirms the benefit of DSB as part of a dementia prevention training protocol.

Utility of phrenic nerve conduction studies for identification of patients with neuromuscular diseases requiring invasive mechanical ventilation

INTRODUCTION/AIMS

Predicting when a patient will require invasive mechanical ventilation (IMV) is a major challenge in routine care for some neuromuscular diseases. In this study, we prospectively investigated whether phrenic nerve conduction studies (PNCS) can predict when IMV will be required in patients with amyotrophic lateral sclerosis (ALS), Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyneuropathy (CIDP), and myotonic dystrophy (DM).

METHODS

PNCS amplitude (avAMP) and latency (avLAT) were compared between patients who required IMV (IMV group) and those who did not (non-IMV group). PNCS were performed in 62 healthy controls and in patients with four different diseases that may require IMV: ALS (n = 56), GBS (n = 72), CIDP (n = 38), and DM (n = 24).

RESULTS

The IMV group consisted of 12 patients with ALS, 14 with GBS, 2 with CIDP, and 4 with DM. avAMP was significantly lower in the IMV group with ALS than in the non-IMV group (P < .05), but no significant difference was observed in avLAT. avAMP was significantly lower and avLAT was significantly longer in the IMV group with GBS than in the non-IMV group (both P < .05). Receiver operating characteristic analysis showed that the avAMP cutoff between the IMV and non-IMV groups was 184.3 μV (area under the curve = 0.921; sensitivity, 84.6%; specificity, 88.2%) for ALS and GBS.

DISCUSSION

PNCSs may aid in determining whether a patient with ALS or GBS requires IMV.

Electrophysiological assessment of respiratory function

While the traditional lung function tests are used to assess lung capacity and pulmonary function, they cannot evaluate respiratory driving function and the integrity of the conduction pathway from the central nervous system to the respiratory motor neuron in the spinal cord and to the diaphragm. The inspiratory trigger is sent from the central nervous system through the phrenic nerve and drives the diaphragm to generate inspiratory movement. Therefore, phrenic nerve stimulation and diaphragmatic electromyography are two fundamental methods to assess respiratory function. There are several useful tools to assess respiratory motor system including electrical or magnetic phrenic nerve stimulation, diaphragmatic needle electromyography, and diaphragmatic ultrasound. By these means, physicians can assess current respiratory status in different neurological diseases that affect respiratory muscles, follow-up of the severity of respiratory impairment, help to predict the chance of successfully weaning from ventilatory support, and confirm clinical diagnoses such as diaphragmatic myoclonus. Although some of these tests require special training, applying these neurophysiological assessments in clinical practice is highly recommended.

Unstable control of breathing can lead to ineffective noninvasive ventilation in amyotrophic lateral sclerosis

Upper airway obstruction with decreased central drive (ODCD) is one of the causes of ineffective noninvasive ventilation (NIV) in amyotrophic lateral sclerosis (ALS). The aim of this study is to determine the mechanism responsible for ODCD in ALS patients using NIV.

This is a prospective study that included ALS patients with home NIV. Severity of bulbar dysfunction was assessed with the Norris scale bulbar subscore; data on upper or lower bulbar motor neuron predominant dysfunction on physical examination were collected. Polysomnography was performed on every patient while using NIV and the ODCD index (ODCDI: number of ODCD events/total sleep time) was calculated. To determine the possible central origin of ODCD, controller gain was measured by inducing a hypocapnic hyperventilation apnoea. Sonography of the upper airway during NIV was performed to determine the location of the ODCD.

30 patients were enrolled; three (10%) had ODCDI >5 h⁻¹. The vast majority of ODCD events were produced during non-rapid eye movement sleep stages and were a consequence of an adduction of the vocal folds. Patients with ODCDI >5 h⁻¹ had upper motor neuron predominant dysfunction at the bulbar level, and had greater controller gain (1.97±0.33 versus 0.91±0.36 L·min⁻¹·mmHg⁻¹; p<0.001) and lower carbon dioxide (CO₂) reserve (4.00±0.00 versus 10.37±5.13 mmHg; p=0.043). ODCDI was correlated with the severity of bulbar dysfunction (r= −0.37; p=0.044), controller gain (r=0.59; p=0.001) and CO₂ reserve (r= −0.35; p=0.037).

ODCD events in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar level.

Upper airway obstructions in ALS patients using NIV have a central origin, and are associated with instability in the control of breathing and an upper motor neuron predominant dysfunction at the bulbar levelhttp://bit.ly/2WEMt28

Thoracoabdominal asynchrony and paradoxical motion in middle stage amyotrophic lateral sclerosis

AIM

To assess thoracoabdominal asynchrony (TAA) and the presence of paradoxical motion in middle stage amyotrophic lateral sclerosis (ALS) and its relationships with chest wall tidal volume (V_T,CW), breathing pattern and cough peak flow (CPF).

METHODS

Phase angle (θ) between upper (RCp) and lower ribcage (RCa) and abdomen (AB), as well as percentage of inspiratory time for the lower ribcage (IP_RCa) and abdomen (IP_AB) moving in opposite directions were quantified using optoelectronic plethysmography in 12 ALS patients during quiet breathing and coughing. Paradoxical motion of the compartments was based on threshold values of θ and IP, obtained in twelve age and sex matched healthy persons.

RESULTS

During quiet breathing, significantly higher RCa and AB θ (p < .05), IP_RCa (p = 0.001) and IP_AB (p < 0.05) were observed in ALS patients as compared to controls. In ALS patients, correlations between RCa and AB θ with forced vital capacity (FVC) (r=-0.773, p < 0.01), vital capacity (r=-0.663, p < 0.05) and inspiratory capacity (IC) (r=-0.754, p < 0.01), as well as between RCp and RCa θ with FVC (r=-0.608, p < 0.05) and CPF (r=-0.601, p < 0.05) were found. During coughing, correlations between RCp and AB θ with CPF (r=-0.590, p < 0.05), IC (r=-0.748, p < 0.01) and V_T,CW (r=-0.608, p < 0.05), as well as between RCa and AB θ with CPF (r=-0.670, p < 0.05), IC (r=-0.713, p < 0.05) and peak expiratory flow (r=-0.727, p < 0.05) were also observed in ALS patients. ALS patients with paradoxical motion presented lower vital capacity and FVC_%pred (p < 0.05) compared to those without paradoxical motion.

CONCLUSIONS

Middle stage ALS patients exhibit TAA and paradoxical motion during quiet spontaneous breathing and coughing. In addition, diaphragmatic weakness (i.e. decrease in excursion of the RCa and AB compartments) was observed earlier in the lower ribcage rather than the abdominal compartment in this population.

Breathing: Motor Control of Diaphragm Muscle

Breathing occurs without thought but is controlled by a complex neural network with a final output of phrenic motor neurons activating diaphragm muscle fibers (i.e., motor units). This review considers diaphragm motor unit organization and how they are controlled during breathing as well as during expulsive behaviors.

Sleep disorders and respiratory function in amyotrophic lateral sclerosis

Sleep disorders in amyotrophic lateral sclerosis (ALS) present a significant challenge to the management of patients. Issues include the maintenance of adequate ventilatory status through techniques such as non-invasive ventilation, which has the ability to modulate survival and improve patient quality of life. Here, a multidisciplinary approach to the management of these disorders is reviewed, from concepts about the underlying neurobiological basis, through to current management approaches and future directions for research.

Breathing new life into treatment advances for respiratory failure in amyotrophic lateral sclerosis patients

SUMMARY In the last three decades, improvements in respiratory management are responsible for increasing survival and improving quality of life for amyotrophic lateral sclerosis (ALS) patients. Nowadays, ALS patients with respiratory involvement are offered a support treatment other than the traditional respiratory palliative care. Knowledge about available respiratory support potentialities is essential for appropriate, customized and effective treatment of ALS, which should probably be started sooner than the conventional approach. There is evidence supporting that respiratory support has a larger impact than riluzole on survival. Noninvasive ventilation is essential in the treatment of ALS patients with respiratory involvement. In this article methods to determine respiratory failure in ALS, mechanical invasive and noninvasive ventilation, telemetry, diaphragm pacing, cough aids and respiratory exercise are reviewed, after a brief overlook of respiratory insufficiency in ALS.

Ventilatory control in ALS

Amyotrophic lateral sclerosis (ALS) is a fatal, progressive neurodegenerative disease. ALS selectively causes degeneration in upper and lower (spinal) motor neurons, leading to muscle weakness, paralysis and death by ventilatory failure. Although ventilatory failure is generally the cause of death in ALS, little is known concerning the impact of this disorder on respiratory motor neurons, the consequences of respiratory motor neuron cell death, or the ability of the respiratory control system to "fight back" via mechanisms of compensatory respiratory plasticity. Here we review known effects of ALS on breathing, including possible effects on rhythm generation, respiratory motor neurons, and their target organs: the respiratory muscles. We consider evidence for spontaneous compensatory plasticity, preserving breathing well into disease progression despite dramatic loss of spinal respiratory motor neurons. Finally, we review current and potential therapeutic approaches directed toward preserving the capacity to breathe in ALS patients.

Management of respiratory symptoms in ALS

Respiratory insufficiency is a frequent feature of ALS and is present in almost all cases at some stage of the illness. It is the commonest cause of death in ALS. FVC is used as important endpoint in many clinical trials, and in decision-making events for patients with ALS, although there are limitations to its predictive utility. There are multiple causes of respiratory muscle failure, all of which act to produce a progressive decline in pulmonary function. Diaphragmatic fatigue and weakness, coupled with respiratory muscle weakness, lead to reduced lung compliance and atelectasis. Increased secretions increase the risk of aspiration pneumonia, which further compromises respiratory function. Bulbar dysfunction can lead to nutritional deficiency, which in turn increases the fatigue of respiratory muscles. Early recognition of respiratory decline and symptomatic intervention, including non-invasive ventilation can significantly enhance both quality of life and life expectancy in ALS. Patients with respiratory failure should be advised to consider an advance directive to avoid emergency mechanical ventilation.