Spirometry in amyotrophic lateral sclerosis

Ongoing trials in motor neurone disease

Motor neurone disease (MND) is a group of progressive neurodegenerative disorders that cause disability from weakness and lead to death from respiratory failure. The pathophysiology of the several forms of MND is unknown, but recent advances have led to clinical trials of therapeutic agents based on an improved understanding of the pathologic processes. The design of clinical trials in MND is challenging, because an effective drug cannot restore strength, but rather slow the rate of progression. Measurement of progression poses difficulties, and an optimum end-point measure has not been determined. This article will include the clinical features of MND, present the leading hypotheses about causes as they relate to drug therapy, discuss factors to consider in selecting informative end-point measures, and will review past and current drug trials.

Bipap improves survival and rate of pulmonary function decline in patients with ALS

Amyotrophic Lateral Sclerosis (ALS) is a progressive motor neuron disease that frequently causes death within five years of diagnosis. The majority of deaths are due to pulmonary complications resulting from respiratory muscle weakness and bulbar involvement. A promising respiratory intervention is the recently introduced bi-level intermittent positive pressure (Bipap), which is a noninvasive ventilator modality shown to reduce the work of breathing and improve not only gas exchange, but also exercise tolerance and sleep quality. The aim of this study was to assess the utility of Bipap in prolonging survival in ALS. We retrospectively analyzed the results of Bipap use in 122 patients followed at Hahnemann University. All patients in this study were offered Bipap when their forced vital capacity (FVC) dropped below 50% of predicted value. Group 1 (n=38) accepted Bipap and used it more than 4 h/day. Group 2 (n=32) did not tolerate Bipap well and used it less than 4 h/day. Group 3 (n=52) refused to try Bipap. There was a statistically significant improvement in survival from initiation of Bipap in Group 1 (14.2 months) compared to Group 2 (7.0 months, P=0.002) or 3 (4.6 months, P<0.001) respectively. Furthermore, when the slope of vital capacity decline was examined, the group that used Bipap more than 4 h/day had slower decline in vital capacity (-3.5% change/month) compared to Group 2 (-5.9% change/month, P=0.02) and Group 3 (-8.3% change/month, P<0.001). We conclude that Bipap can significantly prolong survival and slow the decline of FVC in ALS. Our results suggest that all patients with ALS be offered Bipap when their FVC drops below 50%, at the onset of dyspnea, or when a rapid drop in %FVC is noted.

Polysomnographic studies in amyotrophic lateral sclerosis

We retrospectively reviewed 17 polysomnograms (PSG) in symptomatic amyotrophic lateral sclerosis (ALS) patients to assess the type and frequency of sleep disordered events and correlated these findings with pulmonary function tests (PFTs), presenting complaints, presence of bulbar dysfunction, and response to bi-level positive airway pressure (PAP) treatment. PSG revealed abnormalities in 16 patients. Complaints of orthopnea, daytime sleepiness (but not morning headaches) and a low negative inspiratory force (NIF) correlated with sleep disruption. However, neither the forced vital capacity (FVC) nor the NIF reliably predicted any specific PSG finding. Twelve of 13 patients treated with bi-level PAP responded favorably. Since the response to bi-level PAP is frequently gratifying, PSG should strongly be considered in ALS patients with suspected sleep disturbances.

Guidelines for the use and performance of quantitative outcome measures in ALS clinical trials

ALS is a motor neuron disease defined as a progressive, neurological disorder, resulting from variable and combined degeneration of upper and lower motor neurons. The heterogeneity of clinical involvement early in the course of the disease makes it difficult to diagnose, as well as to identify one unique outcome measure to quantify neurological changes in the course of the disease. Since clinical evidence of upper and lower motor neuron degeneration must exist in four anatomical regions (bulbar, cervical, thoracic, and lumbosacral), outcome measures should assess these regions. The WFN Airline House recommendations specify the purpose, properties, and the preferred parameters which serve as outcome measures in ALS clinical trials. The purpose of this document is to serve as a review of these outcome measures in terms of their advantages, disadvantages, sensitivity, reliability, and other characteristics, as well as their proper performance in ALS clinical trials. Generally these outcome measures are allocated to four areas: respiratory function, muscle strength, general function, and bulbar function. Our review leads us to believe that respiratory function and strength provide the most useful information, both for research and clinical purposes, and are essential as outcome measures. Inclusion of bulbar and general function parameters in trial design may increase the possibility of identifying a beneficial effect of therapeutic intervention. It is essential to note that the guidelines and recommendations put forth are intended to provide initial evaluation and critique of the proper employment and performance of these outcome measures in ALS clinical trials, based on the available literature and our experience.

Motor neuron disease presenting with respiratory failure

Respiratory failure accounts for the majority of deaths in amyotrophic lateral sclerosis (ALS) but only rarely is ALS diagnosed on the basis of respiratory insufficiency. We report four ALS patients presenting with acute respiratory failure. In three patients we have performed EMG needle examination of both hemidiaphragms which showed severe denervation. We reviewed 25 patients previously described presenting with respiratory failure. Almost all patients showed upper limbs weakness and diaphragm involvement; few patients had bulbar dysfunction. The prognosis of these patients is not always in permanent ventilator dependence. Rapidly progressive ventilatory failure may be a striking initial sign of ALS; the main reason is a weakened diaphragm. There are possibilities of significant improvement after a period of rest with ventilatory assistance. In the initial phase of the disease, bulbar dysfunction is not the more common reason of acute respiratory failure.

Respiratory function deterioration is not time-linked with upper-limb onset in amyotrophic lateral sclerosis

INTRODUCTION

In amyotrophic lateral sclerosis (ALS), symptoms apparently spread following regional rules, and depending on the site of onset. We examined if respiratory function deterioration appears earlier or is more severe in patients with upper-limb onset.

MATERIAL & METHODS

We compared the results of various pulmonary function tests (PFT) obtained at diagnosis depending on the site of onset in 49 ALS patients. In a longitudinal study, we compared the deterioration of forced vital capacity (FVC) in relation to the site of onset, and analyzed the time elapsed to reach values below 80% of predicted according to site of onset, and we compared the survival depending on the site of onset.

RESULTS

No significant differences in PFT were found in the upper-limb onset group in any of the analysis performed. No differences in survival were detected in any disease onset group.

CONCLUSION

Pulmonary function deterioration does not appear to be time-linked to arm onset in ALS.

Neuromuscular disease: rehabilitation and electrodiagnosis. 2. Nerve disease

The purpose of this section of the Self-Directed Physiatric Education Program Study Guide on rehabilitation in diseases affecting nerve and muscle is to assist practitioners and trainees in physical medicine and rehabilitation by providing an overview of the evaluation, treatment, and rehabilitative care of patients with inherited and acquired neuropathies. Both diffuse and focal processes are discussed. Current research is briefly reviewed, and the utility and limitations of electrodiagnostic studies are discussed.

Clinical significance of upper airway dysfunction in motor neurone disease

BACKGROUND

To assess the occurrence, functional characteristics and prognostic value of upper airway dysfunction in motor neurone disease, 27 patients unselected for respiratory symptoms were studied.

METHODS

Upper airway function was evaluated by analysis of the maximal flow-volume loop. Neurological diagnosis was established from the clinical history and physical examination. The degree of impairment was quantified by the Appel score.

RESULTS

Twelve patients (group A) showed abnormalities of the maximal flow-volume loop consistent with flow limitation (seven patients) or instability of upper airway function (gross oscillations of airflow, five patients). The remaining 15 patients (group B) exhibited a normal or generally reduced maximal flow-volume loop, suggestive of muscle weakness. No differences were observed between groups in general physical condition, rate of disease progression, or duration of disease.

CONCLUSIONS

Upper airway dysfunction in patients with motor neurone disease was a frequent finding. It was present more often, but not exclusively, in patients with bulbar features and was unrelated to prognosis.

Percutaneous endoscopic gastrostomy in patients with amyotrophic lateral sclerosis and impaired pulmonary function

Amyotrophic lateral sclerosis is a rapidly progressive disease of unknown etiology resulting in tetraparalysis, dysarthria, dysphagia, and ultimately death from respiratory insufficiency. In the course of the disease, recurrent episodes of aspiration, pneumonia, dehydration, and malnutrition may necessitate nasoenteral tube placement, an inconvenient and unattractive arrangement in patients with dribbling and impaired swallowing. A percutaneous endoscopic gastrostomy seemed a better, though potentially hazardous, alternative in view of the often severely restricted pulmonary function of these patients. Therefore, we prospectively investigated the use of percutaneous endoscopic gastrostomy in 68 consecutive patients with amyotrophic lateral sclerosis. Minimum required pulmonary function was defined as forced vital capacity (FVC) of 1 L or more and CO2 gas exchange capability as pCO2 of 45 mm Hg or less. The methodology of insertion was adapted to facilitate the early removal of gastric air. Fifty-five patients (median FVC, 1.7 L; pCO2, 40 mm Hg) were eligible for the gastrostomy procedure, and 13 patients (median FVC, 0.8 L; pCO2, 47 mm Hg) were not. Despite the fact that modification of the method of insertion rendered the procedure more difficult, the success rate was 89% (49/55); it was 96% (49/51) when failures related to distorted anatomy were excluded. The procedure-related mortality rate was 1.8% and the 24-hour in-hospital mortality rate was 3.6%, mainly related to respiratory insufficiency. The 30-day out-of-hospital mortality rate was 11.5%. Major complications (3.6%) consisted of a spontaneously draining cutaneous abscess in 2 cases. Peristomal redness was present in 6 cases, and 5 patients required analgesics for wound pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Onset, natural history and outcome in idiopathic adult motor neuron disease

Cases of adult-onset idiopathic motor neuron disease (MND) identified from January 1970 through December 1986 were studied in a defined area of California. The patients were followed prospectively throughout the illness in 99% of cases. Among 708 cases aged 25-74 years at onset, the most common type (86%) was typical, sporadic amyotrophic lateral sclerosis (SporALS). The risk of bulbar onset and shorter survival times increased with age in both men and women. About 4%, mainly younger men, experienced unusually long courses with milder paralysis, but could not be identified early in the illness. They probably represent one extreme of the ALS spectrum rather than a distinct subtype. Familial ALS (FamALS) was diagnosed in 7%. It developed earlier in life but ran a slightly longer course, which suggests a different disease process. Overall there was a statistically significant predominance of males, especially in 17 cases (2%) of progressive muscular atrophy (PMA). There were 26 cases (4%) classified as primary lateral sclerosis (PLS). Progressive bulbar palsy was not found; that diagnosis usually denotes merely the bulbar onset of ALS.

Pulmonary function at diagnosis of amyotrophic lateral sclerosis. Rate of deterioration

The purpose of this study was to determine the degree of respiratory muscle impairment in patients with newly diagnosed amyotrophic lateral sclerosis (ALS) and the subsequent rate of decline of respiratory function. Thirty-one of 36 patients had respiratory muscle weakness at presentation, although only 7 complained of any respiratory symptoms. Vital capacity (percent predicted) was significantly lower in the symptomatic group (55.9 +/- 20.3) compared with the asymptomatic group (76.4 +/- 21.0). Respiratory muscle impairment as measured by vital capacity (percent predicted) was related to stage of disease at presentation. Rate of decline of respiratory muscle strength as measured by VC (-3.5 percent/month), negative inspiratory pressure (NIF) (+2.9 cm H2O/month), and positive expiratory pressure (PEP) (-3.4 cm H2O/month) tended to be linear with a great deal of interpatient variability. It is concluded that early measurement of respiratory muscle strength in ALS with subsequent follow-up studies may be useful in determining overall prognosis and in decision making.

Pulmonary Manifestations of Neurological Disease

Breathing is a complicated act that requires sophisticated control mechanisms. The nervous system coordinates 3 fundamentally important components of respiration. The central nervous system has a central pattern generator that, along with appropriate feedback mechanisms, establishes both the resiratory rate and the depth of respirations. The peripheral nervous system facilitates transmission of these respiratory commands to the ventilatory muscles. The nervous system also contributes to the control of airway size. Laryngeal function is coordinated with inspiration, and local nerves in the lung have a major role in determining bronchial patency. Finally, the nervous system acts in incompletely understood ways to regulate perfusion of the lungs and to match local pulmonary blood flow with ventilation. Failure of the nervous system to adequately control these 3 different aspects of respiration may result in lifethreatening illness. Understanding how the nervous system affects control of ventilation, airway patency, and pulmonary perfusion therefore will enable intensivists to recognize and manage the pulmonary complications of neurological disease.

Lung function testing in adults with preferential nasal breathing

Three adult patients with asthma with preferential nasal breathing were found to have a typical pattern of lung function test results with substantial between test variation. This condition can be identified as a cause of unsatisfactory performance in respiratory tests by observing the patient's reaction after the nostrils have been occluded.

Effects of alterations in pulmonary function and sleep variables on survival in patients with amyotrophic lateral sclerosis

Breathing abnormalities and nocturnal hypoventilation occur in patients with amyotrophic lateral sclerosis (ALS). A prospective study was undertaken to determine the relationship of pulmonary function test abnormalities with quality of sleep and survival in 21 patients with ALS. Results of spirometry including determination of maximal respiratory pressures and arterial blood gases were compared with several formal polysomnographic variables and then also with 18-month survival. The patients had mild to moderate pulmonary function deficits, but the quality of sleep was best related to age (mean age, 58.5 years). The results of pulmonary function tests and arterial blood gas measurements did not correlate well with the presence of nocturnal breathing events or survival time, but the maximal inspiratory pressure was 86% sensitive for predicting the presence of a nocturnal oxygen saturation nadir of 80% or less and 100% sensitive for predicting 18-month survival. Although obstructive breathing events occurred, the primary explanation for the decline in nocturnal oxygen saturation was hypoventilation. We conclude that routine pulmonary function tests may be useful for screening for reductions in nocturnal oxygen saturation and also may have prognostic value. Further studies may determine whether treatment of nocturnal hypoventilation will have an effect on survival in patients with ALS who have breathing impairment.

Acoustic analysis of voice in amyotrophic lateral sclerosis: a longitudinal case study

Acoustic measures of phonatory instability (coefficient of variation for amplitude, coefficient of variation for frequency, shimmer, jitter, and harmonics-to-noise ratio), phonatory limits (maximum fundamental frequency range and maximum duration of vowel phonation), and the nasal-oral amplitude ratio were measured five times throughout a 6-month period from the phonation of a 69-year-old male patient with amyotrophic lateral sclerosis (ALS), an age- and sex-matched control subject, and on one occasion from a 16-subject control group matched to the patient in age and sex. The patient was free of vocal symptoms at the initiation of the study. When compared to the other recording sessions, the final recording of the ALS patient was characterized by increased coefficient of variation for amplitude, increased coefficient of variation for frequency, increased shimmer, increased jitter, reduced harmonics-to-noise ratio, and reduced maximum vowel duration. These acoustic manifestations of increased phonatory instability and reduced phonatory limits over time were in contrast to the consistency observed in the phonation of the longitudinal control subject and were outside the range of plus or minus one standard deviation on most acoustic variables when compared to the control group. These findings support the potential use of acoustic analysis in reflecting progression of ALS and suggest the need for further studies to investigate the relationship between acoustic analysis of voice and manifestations of neurological disease.

Survival prediction in amyotrophic lateral sclerosis

This longitudinal study of 194 patients with sporadic ALS demonstrated that it is possible for physicians to predict the approximate survival time for an individual ALS patient given: (1) the age of the patient, (2) the duration of his weakness and (3) an estimate of his clinical disability (ALS Score). This information is of value in the clinical management of ALS patients, and it should facilitate construction of experimental therapeutic trials in ALS.

Bulbar amyotrophic lateral sclerosis: patterns of progression and clinical management

Patients with bulbar amyotrophic lateral sclerosis (ALS) are often referred to the otolaryngologist/head and neck surgeon and speech pathologist for evaluation and management of dysphagia and dysarthria. These patients comprise an unusual group because of the progressive and multi-system nature of their illness. The neuromuscular disabilities associated with bulbar ALS cause a myriad of related symptoms associated with swallowing, speech, and respiration. Although the rate of progression cannot be predicted, a general pattern of progression is noted. Bulbar disease accounts for the majority of the worst symptoms of ALS. The loss of the ability to swallow changes eating from a pleasurable task to a burden of survival. Loss of communication effectively imprisons the patient in a state of isolation. The progressive weakness of respiration, predominantly a spinal rather than bulbar manifestation, is the cause of death for nearly all ALS patients and is also discussed. The general patterns of progression of bulbar ALS are outlined in this paper. The development of symptoms are correlated with specific treatment recommendations to aid the clinician in devising an orderly plan of management for this progressive disease.

Flow-volume loop changes reflecting respiratory muscle weakness in chronic neuromuscular disorders

In order to identify the changes in pulmonary function and in the flow-volume loop due to respiratory muscle weakness, two groups of 10 nonsmokers with stable, chronic neuromuscular disease but without respiratory symptoms were studied: one without (Group 1) and one with (Group 2) respiratory muscle weakness as assessed by measurement of maximal static inspiratory and expiratory pressures. In Group 1, pulmonary function was normal except for increased ratio of one-second forced expiratory volume to forced vital capacity and forced expiratory flow at 25 to 75 percent forced vital capacity, which may reflect increased elastic lung recoil. Group 2 had mild volume restriction, appropriate for the degree of respiratory muscle weakness, and reduced inspiratory and expiratory flow rates. Pulmonary function was significantly more disturbed in Group 2 than in Group 1, and correlated well with maximal static inspiratory and expiratory pressures. Analysis of the flow-volume loop configuration revealed that four parameters describing effort-dependent portions were significantly related to maximal static inspiratory pressure and maximal static expiratory pressure. These parameters were peak expiratory flow, the slope of the ascending limb of the maximal expiratory curve, a drop of forced expiratory flow near residual volume, and forced inspiratory flow at 50 percent of vital capacity. A flow-volume loop score obtained from these four parameters was significantly higher in Group 2 than in Group 1 (2.8 +/- 1.03 versus 1.1 +/- 1.37; p less than 0.01). A flow-volume loop score of 2 or more had 80 percent specificity and 90 percent sensitivity in predicting respiratory muscle weakness in these patients with chronic neuromuscular disease. These data suggest that sensitive assessment of the flow-volume loop configuration as part of routine pulmonary function testing may help to suspect and identify respiratory muscle weakness.

Amyotrophic lateral sclerosis: Part 1. Clinical features, pathology, and ethical issues in management

Amyotrophic lateral sclerosis (ALS) is a progressive degenerative disease of the motor system in adults that occurs in sporadic, familial, and Western Pacific forms. Involvement of non-motor pathways has been increasingly recognized, both clinically and pathologically. Although the usual course is relentlessly progressive with death in half the cases within three years from onset, it can sometimes be protracted. Degeneration and loss of large motor neurons in the cerebral cortex, brainstem, and cervical and lumbar spinal cord are characteristic. Marked reduction in the number of large myelinated fibers is notable in the cervical and lumbar ventral roots. Peripheral nerves show reduced numbers of large myelinated fibers, acute axonal degeneration at all levels, and distal axonal atrophy. Motor end-plates reveal small or absent nerve terminals. Subclinical non-motor system involvement includes neuronal loss in Clarke's nucleus and dorsal root ganglia, degeneration of non-motor tracts in the spinal cord, loss of receptors in the dorsal horns of the spinal cord, and myelinated fiber loss with segmental demyelination in sensory and mixed nerves. The serious implications of the diagnosis of ALS make it mandatory to exclude similar potentially treatable disorders. Management should be multidisciplinary, and discussions with the patient and family members should be frank and frequent. Discussions about ventilatory support should take place early in the disease so that death from respiratory failure can be prevented, when that is desired, and conversely to obviate the discontent and anger that accompany involuntary life on a ventilator.

Motor neurone disease: towards better care

Even in the most severe forms of motor neurone disease--progressive bulbar palsy and amyotrophic lateral sclerosis--the symptoms and disabilities from progressive paralysis may be relieved in many patients by various symptomatic treatments. Quality of life may be improved even in the terminal stage, when narcotic administration should be considered. The physician's proper role is to offer and carefully supervise these treatments, not withhold them. Home care is recommended even for the most severely paralysed, though hospice care may be a good alternative. The underlying principle--to alleviate symptoms--applies to the management of all progressive incurable diseases.

Value of spirometric investigations in amyotrophic lateral sclerosis

The respiratory function has been studied in 37 patients with ALS. 15 of them (5 till death) were followed with serial spirometric tests. The data, as a whole, show a diminution of vital capacity, a diminution of forced expiratory volume per second, an increase of the residual volume and of the Motley index; blood gas analysis showed no significant alterations apart from slight hypoxemia. Patients with bulbar ALS presented marked abnormalities of the spirometric and blood gas analysis parameters. In the cases followed with serial spirometric tests VC, Motley index and FEV1 gradually deteriorated as the disease advanced. In the deceased patients a sudden and serious aggravation of these values occurred. This was especially true for FEV1 and Motley index during the 3 months preceding death. The variations in residual volume were less indicative. Finally, the influence of smoking and of pulmonary and bronchial pathology, present or past, was not significant.

Management of hypoventilation in motor neuron disease presenting with respiratory insufficiency

A 57-year-old man presented with a three-month history of somnolence, hypoventilation, cor pulmonale, and episodes of apnea during sleep. Neurological studies revealed motor neuron disease, mainly confined to the muscles of respiration, that was causing respiratory insufficiency in the supine position. Nighttime treatment of respiratory insufficiency has permitted independent activity during wakefulness.