Proximal myopathy: diagnostic approach and initial management

Abstract

Proximal myopathy presents as symmetrical weakness of proximal upper and/or lower limbs. There is a broad range of underlying causes including drugs, alcohol, thyroid disease, osteomalacia, idiopathic inflammatory myopathies (IIM), hereditary myopathies, malignancy, infections and sarcoidosis. Clinical assessment should aim to distinguish proximal myopathy from other conditions that can present similarly, identify patients who need prompt attention, like those with cardiac, respiratory or pharyngeal muscle involvement, and determine underlying cause of myopathy. Initial evaluation should include simple tests, like creatine kinase, thyroid function and (25)OH vitamin D levels, but further evaluation including neurophysiological studies, muscle imaging and muscle biopsy should be considered for patients in whom no toxic, metabolic or endocrine cause is found, and in those with clinical features suggestive of inflammatory or hereditary myopathy. Additionally, screening for malignancy and testing for anti-Jo1 antibody is indicated for selected patients with IIM. Management depends on underlying cause, and includes measures, such as removal of offending agent, correction of endocrine or metabolic problem, corticosteroids and immunosuppressive therapy for IIM, and physical therapy, rehabilitation and genetic counselling for muscular dystrophies.

Idiopathic inflammatory myopathies and the lung

“…The involvements of the respiratory muscles and the limb muscles are sometimes dissociated [165]. Patients suspected of having respiratory muscle involvement should be identified promptly because it is potentially life threatening [166].…”

“…Patients with symptoms suggestive of respiratory muscle involvement should be closely monitored in hospital with a daily assessment of FVC using a bedside spirometer rather than peak flow [166]. Patients with FVC <15 mL·kg −1 should be referred to an intensive care unit for monitoring and possible noninvasive mechanical ventilation [166].…”

“…Patients with FVC <15 mL·kg −1 should be referred to an intensive care unit for monitoring and possible noninvasive mechanical ventilation [166]. The other critical predictive parameters include maximal inspiratory and expiratory pressures <30% predicted, and VC <55% predicted [167].…”

Russian Association of Endocrinologists recommendations for diagnosis, treatment and prevention of vitamin D deficiency in adults

“…Дефицит витамина D приводит к миопатии, что может проявляться мышечной слабостью, особенно в проксимальных группах мышц, трудностями при ходьбе, поддержании равновесия и склонностью к падениям, что закономерно увеличивает риск пере-ломов [52,53].…”

More than healthy bones: a review of vitamin D in muscle health

“…Low 25(OH)D levels may also be a cofounder in alcoholic skeletal muscle myopathy [Wijnia et al 2013]. Osteomalacia is documented to cause proximal muscle myopathy [Russell, 1994;Suresh and Wimalaratna, 2013]. In Saudi Arabia, women who are veiled and heavily covered while outdoors have been shown to develop a proximal muscle weakness that is reversible with vitamin D supplementation [Al-Said et al 2009].…”