Chronic Neuromuscular Disease Research Articles

Quantitative measures of neurological function in chronic neuromuscular diseases and ataxia

Interexaminer and intraexaminer reliability were determined for 30 quantitative measures of neurological function, including sensory threshold, tendon reflexes, maximum isometric strength, and timed tests and coded ratings of functional ability, in patients with Charcot-Marie-Tooth disease (n = 30), idiopathic polyneuropathy (n = 16) and spinocerebellar degeneration (n = 30). Five of 6 sensory and reflex measures had interexaminer reliability greater than 0.80 when the neurologists' examinations were 1 h apart; 2 of 7 achieved this level when the examinations were separated by 1 month. Interexaminer reliability between physical therapists was greater than 0.80 for 19 of 20 measures of strength and functional ability. Intraexaminer reliability coefficients greater than 0.80 were found for 13 of 24 sensory and reflex measures, 28 of 30 isometric strength measures, 24 of 30 timed tests and 5 of 6 coded ratings of functional ability. Electro-oculography, oral diadochokinetic syllable rates, hand and foot accelerometry, and tracings of sine and square waves were examined as quantitative indices of ataxia for patients with spinocerebellar degeneration. Of 11 measures of ataxia, only the oral diadochokinetic syllable rate test had acceptable reliability.

Vascularized muscle fibers: etiopathogenesis and clinical significance

Contrary to common assumption, internal vascularization of muscle fiber occurs independent of muscle fiber splitting. Review of 1091 cases who underwent muscle biopsies demonstrated muscle fibers with internal blood vessels in a wide variety of chronic neuromuscular disease states, predominantly in patients with chronic neurogenic diseases. Many of these cases show evidence of internal disorganization or focal degeneration of muscle fibers, in particular, formation of targets, targetoids or similar structural alterations. Internal vascularization of muscle fiber probably occurs as a “healing” or “reparative process” in such fibers. Myopathic features, especially secondary myopathic changes (as seen in chronic denervation-reinnervation) are common and appear to be a necessary accompaniment of this phenomena. The vascularized muscle fiber is more likely to be seen in a distal lower extremity muscle than in a proximal limb muscle biopsy.

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 <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.

Determinants of respiratory muscle weakness in stable chronic neuromuscular disorders

In neuromuscular disease, the precise relationship between general and respiratory muscle weakness is at present unclear. That relationship and the influence on respiratory muscle strength of such factors as type and duration of neuromuscular disease, distribution of general muscle weakness, and nutritional status were studied in 30 patients with stable chronic neuromuscular disease not presenting with respiratory symptoms. The degree of general muscle weakness was assessed by clinical examination of the strength of 17 muscle groups, yielding a general muscle strength index. The degree of respiratory muscle weakness was assessed by measuring maximal static inspiratory and expiratory mouth pressures. Maximal inspiratory (mean ± SD: 68 ± 28 percent predicted) and expiratory (66 ± 29 percent predicted) mouth pressures were frequently reduced, but did not correlate with general muscle strength. The ability to estimate the degree of respiratory muscle weakness improved to some extent when the type of neuromuscular disease and the distribution of general muscle weakness were taken into account: thus, maximal expiratory mouth pressure was significantly lower (p < 0.05) in myopathy than in polyneuropathy, and in proximal than in distal muscle weakness. Duration of neuromuscular disease and nutritional status did not influence respiratory muscle strength. It is concluded that in stable chronic neuromuscular disease, respiratory muscle involvement depends on a complexity of factors, in particular the type of neuromuscular disease and the distribution, rather than the degree, of general muscle weakness. In the individual patient, however, only direct measurement of maximal inspiratory and expiratory mouth pressures allows accurate assessment of respiratory muscle strength. These tests ought to complement neurologic examination.

Electromyography in infants and children.

Electromyography (EMG) is of proven value in the diagnosis of acute and chronic neuromuscular diseases in infants and children. When this technique is combined with nerve conduction studies, including repetitive nerve stimulation studies, it is often possible upon completion of the studies to identify the disorder as one of nerve, neuromuscular junction, or muscle. The purpose of this article is to review the principles and techniques of EMG in infants and children and to describe the EMG findings in several neuromuscular disorders.

Myasthenia gravis: a nursing perspective.

Myasthenia gravis, a chronic neuromuscular disease, results in weakness of striated voluntary muscles. The muscles involved and the degree of weakness vary from patient to patient. Nursing care of the patient with muscle weakness from myasthenia gravis presents a challenge for the neuroscience nurse. Drug therapy and thymectomy treatments are discussed, along with their complications. Nursing interventions for other problems for the myasthenic patient, including impaired breathing patterns, inability to clear the airway, impaired communication, altered nutrition, self-care deficits, and impaired vision are described.

Changes in human skeletal muscles due to ageing. Histological and histochemical observations on autopsy material.

Morphological changes in human skeletal muscle with ageing are reported. Samples from the deltoid and the vastus lateralis muscles from 126 subjects, aged 20-80 years, were studied by light microscopy. The patients died suddenly due to accidents or from fatal diseases. Until their death, they had preserved normal physical activity corresponding to their age. Chronic diseases, inactivity or neuromuscular diseases which are known to lead to changes in the muscles were excluded. The frequency of neurogenic changes of muscles increased with increasing age. These results correlated with electrophysiological and morphological changes in the peripheral nerves due to ageing reported by other investigators. The neurogenic changes in persons over 70 years were overlapped by a type-2 fibre atrophy.

Clinical trials in chronic neuromuscular diseases: Proceedings of a colloquium at Totts Gap Institute, Bangor, PA, sponsored by The Muscular Dystrophy Association

Clinical trials in chronic neuromuscular diseases: Proceedings of a colloquium at Totts Gap Institute, Bangor, PA, sponsored by The Muscular Dystrophy Association

Physical Therapy for Children with Chronic Lung Disease

Chronic lung disease is a major health problem among children. Estimates suggest that one child in six has a chronic respiratory condition. This article reviews three common chronic respiratory conditions occurring in childhood for which physical therapy is usually recommended. The cause, pathophysiology, and medical treatment are explained for asthma, respiratory complications of chronic neuromuscular disease, and cystic fibrosis. The rationale for physical therapy and the concepts of treatment for the three disorders are presented. Major clinical studies that have attempted to document the efficacy of physical therapy are discussed. Questions for future research are proposed.

A unique outbreak of Pasteurella multocida in a chronic disease hospital.

An outbreak of Pasteurella multocida infection, involving seven patients on two adjacent wards, has been observed. All seven patients were debilitated and had underlying chronic neuromuscular and/or pulmonary disease and had a tracheostomy tube in situ. The isolates of P. multocida were of the same biotype and serotype, and had an identical antibiogram. Epidemiological studies failed to determine the source of these infections.

Becker-type muscular dystrophy.

This is a review of clinical, cardiologic, electrophysiologic, pathologic, and serum creatine kinase changes in eight families with slowly progressive X-linked Becker-type muscular dystrophy. All but one of the patients were able to walk until the age of 16 years, and most lived beyond 20. In every family, electromyography and muscle biopsy showed features which, on the basis of classical criteria, were interpreted as those of both myopathy and denervation, although among patients and among families, one or the other of these processes predominated. The most frequent biopsy picture was of fiber atrophy and hypertrophy, with many split and angulated fibers, and clumps of pyknotic nuclei. Necrosis, phagocytosis, regeneration, endomysial fibrosis, and some fatty infiltration were commonly seen. Review of a family originally described by Becker showed a similar biopsy picture; These pathologic changes are separable from those of Duchenne muscular dystrophy, but they often overlap with those seen in other chronic neuromuscular diseases.

Chronic Peripheral Neuromuscular Disorders in Childhood: Principles of Diagnosis and Management

The accurate diagnosis of chronic neuromuscular diseases is essential for prognostic and genetic purposes. In spite of the increasing use of new methods of investigation, such as quantitative electromyography, serum enzyme studies, histochemistry and electron microscopy, careful history taking and meticulous clinical examination, described here, are still of great value.