A case of respiratory muscle weakness due to cytochrome c oxidase enzyme deficiency

O'Brien, Andrés; Blaivas, Mila; Albers, John J.; Wald, John J.; Watts, C. A. H.

doi:10.1183/09031936.98.12030742

Cited by 5 publications

(5 citation statements)

References 11 publications

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“…Additionally, nine patients demonstrated diaphragmatic strength two standard deviations below the limit of normal for our laboratory. The finding of muscle weakness in a significant percentage of our patients was unexpected as previous reports of respiratory muscle weakness associated with this disorder have been limited to case reports of respiratory failure (34,35). Our data suggest that milder degrees of respiratory muscle weakness are common in patients with mitochondrial myopathies and may contribute, at least in part, to their symptoms.…”

Section: Discussionsupporting

confidence: 39%

Unexplained Exertional Limitation

Flaherty

Wald

Weisman

et al. 2001

Am J Respir Crit Care Med

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Exercise intolerance is a common complaint, the cause of which often remains elusive after a comprehensive evaluation. In this report, we describe 28 patients with unexplained dyspnea or exertional limitation secondary to biopsy-proven mitochondrial myopathies. Patients were prospectively identified from a multidisciplinary dyspnea clinic at a tertiary referral center. All patients were without underlying pulmonary, cardiac, or other neuromuscular disorders. Patients underwent history, physical examination, complete pulmonary function testing, respiratory muscle testing, cardiopulmonary exercise testing, and muscle biopsy. Results were compared with a group of normal control subjects. The estimated period prevalence was 8.5% (28 of 331). Spirometry, lung volumes, and gas exchange were normal in patients and control subjects. Compared with control subjects, the patient group demonstrated decreased exercise capacity (maximum achieved V O(2) 67 versus 104% predicted; p < 0.0001) and respiratory muscle weakness (PI(max) 77 versus 115% predicted; p = 0.001). These patients have a characteristic exercise response that was hyperventilatory (peak VE/V CO(2); 55 versus 42) and hypercirculatory (maximum heart rate - baseline heart rate/V O(2)max - baseline V O(2)max; 91 versus 41) compared to control subjects. Patients stopping exercise due to dyspnea (n = 16) (as compared with muscle fatigue, n = 11) displayed weaker respiratory muscles (Pdi(max) 61 versus 115 cm H(2)O; p = 0.01) and were more likely to reach mechanical ventilatory limitation (V Emax/ MVV 0.81 versus 0.58; p = 0.02). The sensation of dyspnea was related to indices of respiratory muscle function including respiratory rate and inspiratory flow. We conclude that mitochondrial myopathies are more prevalent than previously reported. The characteristic physiological profile may be useful in the diagnostic evaluation of mitochondrial myopathy.

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Section: Discussionsupporting

confidence: 39%

Unexplained Exertional Limitation

Flaherty

Wald

Weisman

et al. 2001

Am J Respir Crit Care Med

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“…Several case reports have suggested that patients with mitochondrial myopathy may manifest respiratory muscle weakness [47,48]. These reports describe 3 patients (ages 27-70) that presented with acute respiratory failure requiring prolonged weaning from ventilatory support.…”

Section: Respiratory Muscle Functionmentioning

confidence: 95%

The Role of Cardiopulmonary Exercise Testing for Patients with Suspected Metabolic Myopathies and Other Neuromuscular Disorders

Flaherty¹,

Weisman²,

Zeballos³

et al. 2002

Clinical Exercise Testing

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Neuromuscular diseases (NMDs) can be associated with significant exercise limitation. As cardiopulmonary exercise testing (CPET) examines the integrated response to exercise, it has been investigated in multiple NMDs, proving itself particularly valuable in the evaluation of metabolic disorders, which exhibit typical patterns of exercise response. Disorders of carbohydrate metabolism usually demonstrate limitations of aerobic capacity and abnormalities of glycogen utilization. Lipid disorders seem to be associated with lesser aerobic limitation, while disorders of mitochondrial function seem to be associated with the greatest limitation in aerobic capacity. Furthermore, a hyperventilatory and hypercirculatory pattern seems to typify exercise response in these latter patients. As such, CPET can be used in the initial evaluation of patients with suspected carbohydrate or lipid metabolism as well as those with defects of mitochondrial function.Neuromuscular diseases can be associated with an abnormal muscle response to exercise. As such, these disorders may present with weakness, myalgia, abnormal fatigue, or exertional breathlessness [1, 2]. These disorders can be classified as those that are associated with impaired muscle energy metabolism, those associated with impaired muscle bulk, and those associated with impaired control of muscle contraction [2]. A general enumeration of these disorders is presented in table 1. As reviewed elsewhere in this book, exercise requires a close integration between skeletal muscle function, cardiovascular function with associated oxygen delivery, and ventilatory function with oxygenation of blood. As such, it is not surprising that myopathic disorders can significantly impact exercise capacity. This chapter reviews the pathophysiologic implications of myopathic disorders on exercise capacity and reviews clinical indications of exercise testing in the diagnosis and management of these disorders. Disorders of Muscle Energy MetabolismMetabolic myopathies are disorders of muscle energy metabolism. These disorders have been grouped into three broad categories: (1) defective carbohydrate utilization, (2) abnormal lipid utilization, and (3) mitochondrial

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“…In retrospect, they had experienced chronic respiratory symptoms which had been unrecognised, or had not come to medical attention [35][36][37][38]. In some instances, background respiratory dysfunction was worsened in the context of an acute illness or other metabolic stressors.…”

Section: Metabolic Myopathiesmentioning

confidence: 99%

Diagnosis of muscle diseases presenting with early respiratory failure

et al. 2014

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Here we describe a clinical approach and differential diagnosis for chronic muscle diseases which include early respiratory failure as a prominent feature in their presentation (i.e. respiratory failure whilst still ambulant). These patients typically present to neurology or respiratory medicine out-patient clinics and a distinct differential diagnosis of neuromuscular aetiologies should be considered. Amyotrophic lateral sclerosis and myasthenia gravis are the important non-muscle diseases to consider, but once these have been excluded there remains a challenging differential diagnosis of muscle conditions, which will be the focus of this review. The key points in the diagnosis of these disorders are being aware of relevant symptoms, which are initially caused by nocturnal hypoventilation or diaphragmatic weakness; and identifying other features which direct further investigation. Important muscle diseases to identify, because their diagnosis has disease-specific management implications, include adult-onset Pompe disease, inflammatory myopathy, and sporadic adult-onset nemaline myopathy. Cases which are due to metabolic myopathy or muscular dystrophy are important to diagnose because of their implications for genetic counselling. Myopathy from sarcoidosis and colchicine each has a single reported case with this presentation, but should be considered because they are treatable. Disorders which have recently had their genetic aetiologies identified include hereditary myopathy with early respiratory failure (due to TTN mutations), the FHL1-related syndromes, and myofibrillar myopathy due to BAG3 mutation. Recently described syndromes include oculopharyngodistal muscular dystrophy that awaits genetic characterisation.

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A case of respiratory muscle weakness due to cytochrome c oxidase enzyme deficiency

Cited by 5 publications

References 11 publications

Unexplained Exertional Limitation

Unexplained Exertional Limitation

The Role of Cardiopulmonary Exercise Testing for Patients with Suspected Metabolic Myopathies and Other Neuromuscular Disorders

Diagnosis of muscle diseases presenting with early respiratory failure

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