Impact of exercise-induced fatigue on the strength, postural control, and gait of children with a neuromuscular disease

Static Postural Control Deficits in Adults with Myotonic Dystrophy Type 1, Steinert Disease

BACKGROUND

Myotonic dystrophy type 1 (DM1) is characterized by progressive and predominantly distal muscle atrophy and myotonia. Gait and balance impairments, resulting in falls, are frequently reported in this population. However, the extent to which individuals with DM1 rely more on a specific sensory system for balance than asymptomatic individuals (AI) is unknown.

OBJECTIVE

Evaluate postural control performance in individuals with DM1 and its dependence on vision compared to AI.

METHODS

20 participants with DM1, divided into two groups based on their diagnosis, i.e. adult and congenital phenotype, and 12 AI participants were recruited. Quiet standing postural control was assessed in two visual conditions: eyes-open and eyes-closed. The outcomes measures were center of pressure (CoP) mean velocity, CoP range of displacement in anteroposterior and mediolateral axis, and the 95% confidence ellipse's surface. Friedman and Kruskal-Wallis analysis of variance were used to compare outcomes between conditions and groups, respectively.

RESULTS

Significant group effect and condition effect were observed on postural control performance. No significant difference was observed between the two DM1 groups. The significant differences observed between the AI group and the two DM1 groups in the eyes-open condition were also observed in the eyes-closed condition.

CONCLUSIONS

The result revealed poorer postural control performance in people with DM1 compared to AI. The DM1 group also showed similar decrease in performance than AI in eyes-closed condition, suggesting no excessive visual dependency.

Immediate effect of induced fatigue of the unaffected limb on standing balance, proprioception and vestibular symptoms in children with hemiplegia

OBJECTIVES

To study the effect of induced fatigue of the unaffected limb on the sensory components of standing balance; proprioception and vestibular symptoms in children with hemiplegic cerebral palsy.

METHODS

Setting: Outpatient Clinic of Faculty of Physical Therapy, Cairo University.

PATIENTS

Twenty-nine children with hemiplegic cerebral palsy [(ages 8.9 ± 2.3 years), motor ability I/II according to the GMFCS and spasticity of I/I+ according to the Modified Ashworth Scale].

OUTCOME MEASURES

Before and after the induced fatigue of the unaffected limb, the following measures were recorded: postural balance, using the Biodex Balance System and the Timed Up and Go test; vestibular sense, using the Paediatric Vestibular Symptom Questionnaire; and proprioception measures of both knees, using the Biodex isokinetic dynamometer.

RESULTS

There was a significant increase in the post-fatigue values for the overall stability index (p< 0.05), the Timed Up and Go test (p< 0.05), reposition errors of proprioception of the unaffected limb (p< 0.05) and the vestibular questionnaire (p< 0.05); there was a non-significant decrease in the post-fatigue values for reposition errors of proprioception of the affected limb (p= 0.859).

CONCLUSION

Fatigue of the unaffected limb negatively affects postural balance and related sensory systems (proprioception of the fatigued limb and vestibular function) but does not have an impact on proprioception of the unfatigued limb.

Assessment of fatigability in patients with spinal muscular atrophy: development and content validity of a set of endurance tests

BACKGROUND

Fatigability has emerged as an important dimension of physical impairment in patients with Spinal Muscular Atrophy (SMA). At present reliable and valid outcome measures for both mildly and severely affected patients are lacking. Therefore the primary aim of this study is the development of clinical outcome measures for fatigability in patients with SMA across the range of severity.

METHODS

We developed a set of endurance tests using five methodological steps as recommended by the 'COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN). In this iterative process, data from multiple sources were triangulated including a scoping review of scientific literature, input from a scientific and clinical multidisciplinary expert panel and three pilot studies including healthy persons (N = 9), paediatric patients with chronic disorders (N = 10) and patients with SMA (N = 15).

RESULTS

Fatigability in SMA was operationalised as the decline in physical performance. The following test criteria were established; one method of testing for patients with SMA type 2-4, a set of outcome measures that mimic daily life activities, a submaximal test protocol of repetitive activities over a longer period; external regulation of pace. The scoping review did not generate suitable outcome measures. We therefore adapted the Endurance Shuttle Walk Test for ambulatory patients and developed the Endurance Shuttle Box and Block Test and the - Nine Hole Peg Test for fatigability testing of proximal and distal arm function. Content validity was established through input from experts and patients. Pilot testing showed that the set of endurance tests are comprehensible, feasible and meet all predefined test criteria.

CONCLUSIONS

The development of this comprehensive set of endurance tests is a pivotal step to address fatigability in patients with SMA.

Co-administration of deflazacort and doxycycline: a potential pharmacotherapy for Duchenne muscular dystrophy

The standard therapy used in the treatment of Duchenne muscle dystrophy (DMD) is corticoids, such as deflazacort and prednisone. However, they have limited therapeutic value, and their combination with drugs already in use to treat other human diseases could potentially increase corticoid outcomes in DMD. In the present study, we evaluated whether a combined therapy of the corticoid deflazacort with doxycycline could result in greater improvement in mdx dystrophy than deflazacort alone. Deflazacort alone or deflazacort/doxycycline were administered for 36 days (starting on postnatal day 0) in drinking water. Histopathological, biochemical (creatine kinase), functional (forelimb muscle grip strength and fatigue) parameters and inflammatory markers (MMP-9, TNF-α, NF-kB) were evaluated in biceps brachii and diaphragm muscles of the mdx mice. The combined therapy was superior in improving the dystrophic phenotype compared to monotherapy. The primary results were observed in attenuating muscle fatigue, decreasing muscle total calcium and inflammatory markers and increasing β-dystroglycan, a main component of the dystrophin-protein complex. Furthermore, the combined therapy was effective in preventing the loss of body mass observed with deflazacort alone at this very early stage of therapy. The present study offers preclinical data to support further studies with deflazacort/doxycycline combined therapy in DMD clinical trials.