Long-term whole-body vibration training in two late-onset Pompe disease patients

Degeneration of muscle spindles in a murine model of Pompe disease

Pompe disease is a debilitating medical condition caused by a functional deficiency of lysosomal acid alpha-glucosidase (GAA). In addition to muscle weakness, people living with Pompe disease experience motor coordination deficits including an instable gait and posture. We reasoned that an impaired muscle spindle function might contribute to these deficiencies and therefore analyzed proprioception as well as muscle spindle structure and function in 4- and 8-month-old Gaa-/- mice. Gait analyses showed a reduced inter-limb and inter-paw coordination in Gaa-/- mice. Electrophysiological analyses of single-unit muscle spindle proprioceptive afferents revealed an impaired sensitivity of the dynamic and static component of the stretch response. Finally, a progressive degeneration of the sensory neuron and of the intrafusal fibers was detectable in Gaa-/- mice. We observed an increased abundance and size of lysosomes, a fragmentation of the inner and outer connective tissue capsule and a buildup of autophagic vacuoles in muscle spindles from 8-month-old Gaa-/- mice, indicating lysosomal defects and an impaired autophagocytosis. These results demonstrate a structural and functional degeneration of muscle spindles and an altered motor coordination in Gaa-/- mice. Similar changes could contribute to the impaired motor coordination in patients living with Pompe disease.

A Systematic Review investigating the Effectiveness of Exercise training in Glycogen Storage Diseases

Introduction

Glycogen storage diseases (GSDs) are rare inborn errors of carbohydrate metabolism typically with skeletal muscle and liver involvement. In those with skeletal muscle involvement, the majority display symptoms of exercise intolerance which can cause profound exercise limitation and impair everyday living and quality of life (QoL). There are no curative treatments for GSDs, thus therapeutic options, such as exercise training, are aimed at improving QoL by alleviating signs and symptoms. In order to investigate the effectiveness of exercise training in adults with GSDs, we systematically reviewed the literature.

Methods

In this review we conducted searches within SCOPUS and MEDLINE to identify potential papers for inclusion. These papers were independently assessed for inclusion and quality by two authors. We identified 23 studies which included aerobic training, strength training or respiratory muscle training in patients with McArdles (n = 41) and Pompe disease (n = 139).

Results

In McArdle disease, aerobic exercise training improved aerobic capacity (VO2 peak) by 14-111% with further benefits to functional capacity and well-being. Meanwhile, strength training increased muscle peak power by 100-151% and reduced disease severity. In Pompe disease, a combination of aerobic and strength training improved VO2 peak by 9-10%, muscle peak power by 64%, functional capacity and well-being. Furthermore, respiratory muscle training (RMT) improved respiratory muscular strength [maximum inspiratory pressure (MIP) increased by up to 65% and maximum expiratory pressure (MEP) by up to 70%], with additional benefits shown in aerobic capacity, functional capacity and well-being.

Conclusion

This adds to the growing body of evidence which suggests that supervised exercise training is safe and effective in improving aerobic capacity and muscle function in adults with McArdle or Pompe disease. However, the literature base is limited in quality and quantity with a dearth of literature regarding exercise training in other GSD subtypes.

Characterization of Gait and Postural Regulation in Late-Onset Pompe Disease

Pompe disease is a multisystemic disorder with the hallmark of progressive skeletal muscle weakness that often results in difficulties in walking and balance. However, detailed characterization of gait and postural regulation with this disease is lacking. The objective of this investigation was to determine if differences exist between the gait and postural regulation of LOPD patients and a matched control group. The gaits of 16 patients with LOPD were assessed using a gait analysis mobile system (RehaGait) and a dynamometric treadmill (FDM-T 1.8). The Interactive Balance System (IBS) was used to evaluate postural regulation and stability. All measures were compared to individual reference data. Demographic (age, gender), morphological (body height, body mass) and clinical data (muscle strength according to the Medical Research Council Scale (MRC Scale), as well as the 6-min walking test and a 10-m fast walk) were also recorded. Compared to individual reference data, LOPD patients presented with reduced gait velocity, cadence and time in single stand. A total of 87% of LOPD patients had abnormalities during posturographic analysis presenting with differences in postural subsystems. This study provides objective data demonstrating impaired gait and posture in LOPD patients. For follow-up analysis and as outcome measurements during medical or physiotherapeutic interventions, the findings of this investigation may be useful.

Adapted physical activity and therapeutic exercise in late-onset Pompe disease (LOPD): a two-step rehabilitative approach

Aerobic exercise, training to sustain motor ability, and respiratory rehabilitation may improve general functioning and quality of life (QoL) in neuromuscular disorders. Patients with late-onset Pompe disease (LOPD) typically show progressive muscle weakness, respiratory dysfunction and minor cardiac involvement. Characteristics and modalities of motor and respiratory rehabilitation in LOPD are not well defined and specific guidelines are lacking. Therefore, we evaluated the role of physical activity, therapeutic exercise, and pulmonary rehabilitation programs in order to promote an appropriate management of motor and respiratory dysfunctions and improve QoL in patients with LOPD. We propose two operational protocols: one for an adapted physical activity (APA) plan and the other for an individual rehabilitation plan, particularly focused on therapeutic exercise (TE) and respiratory rehabilitation.

An update on diagnosis and therapy of metabolic myopathies

INTRODUCTION

Metabolic myopathies are a heterogeneous group of disorders characterized by inherited defects of enzymatic pathways involved in muscle fiber energetics. Diagnosing metabolic myopathies requires a thoroughly taken individual and family history, a meticulous neurologic exam, exercise tests, blood and urine tests, needle-electromyography, nerve-conduction studies, muscle biopsy, targeted genetic tests, or next-generation sequencing. There is limited evidence from the literature to guide treatment of metabolic myopathies. Treatment is largely limited to non-invasive/invasive symptomatic measures. However, promising results have been achieved with enzyme replacement therapy in Pompe disease (GSD-II). Primary coenzyme-Q deficiency responds favorably to coenzyme-Q supplementation. MNGIE responds to allogeneic hematopoietic stem cell transplantation, orthotopic liver transplantation, and carrier erythrocyte entrapped thymidine phosphorylase enzyme therapy. MADD may respond to riboflavin. Areas covered: This review aims to summarize and discuss recent findings and new insights concerning diagnosis and treatment of metabolic myopathies. Expert commentary: Except for GSD-II, coenzyme-Q deficiency, and MNGIE, treatment of metabolic myopathies is usually palliative and supportive (non-invasive or invasive). Non-invasive symptomatic treatment includes physiotherapy, diet, administration of drugs, conservative orthopedic measures, and respiratory non-invasive support. Important is the avoidance of triggers for episodic forms of fatty acid oxidation disorders. Invasive measures include orthopedic surgery and invasive mechanical ventilation.