Voluntary and magnetically evoked muscle contraction protocol in males with Duchenne muscular dystrophy: Safety, feasibility, reliability, and validity

The unconditioned fear response in vertebrates deficient in dystrophin

Dystrophin loss due to mutations in the Duchenne muscular dystrophy (DMD) gene is associated with a wide spectrum of neurocognitive comorbidities, including an aberrant unconditioned fear response to stressful/threat stimuli. Dystrophin-deficient animal models of DMD demonstrate enhanced stress reactivity that manifests as sustained periods of immobility. When the threat is repetitive or severe in nature, dystrophinopathy phenotypes can be exacerbated and even cause sudden death. Thus, it is apparent that enhanced sensitivity to stressful/threat stimuli in dystrophin-deficient vertebrates is a legitimate cause of concern for patients with DMD that could impact neurocognition and pathophysiology. This review discusses our current understanding of the mechanisms and consequences of the hypersensitive fear response in preclinical models of DMD and the potential challenges facing clinical translatability.

Assessment of Motor Unit Potentials Duration as the Biomarker of DT-DEC01 Cell Therapy Efficacy in Duchenne Muscular Dystrophy Patients up to 12 Months After Systemic-Intraosseous Administration

Duchenne muscular dystrophy (DMD) is a lethal X-linked disease caused by mutations in the dystrophin gene, leading to muscle degeneration and wasting. Electromyography (EMG) is an objective electrophysiological biomarker of muscle fiber function in muscular dystrophies. A novel, DT-DEC01 therapy, consisting of Dystrophin Expressing Chimeric (DEC) cells created by fusing allogeneic myoblasts from normal donors with autologous myoblasts from DMD-affected patients, was assessed for safety and preliminary efficacy in boys of age 6-15 years old (n = 3). Assessments included EMG testing of selected muscles of upper (deltoideus, biceps brachii) and lower (rectus femoris and gastrocnemius) extremities at the screening visit and at 3, 6, and 12 months following systemic-intraosseous administration of a single low dose of DT-DEC01 therapy (Bioethics Committee approval no. 46/2019). No immunosuppression was administered. Safety of DT-DEC01 was confirmed by the lack of therapy-related Adverse Events or Serious Adverse Events up to 22 months following DT-DEC01 administration. EMG of selected muscles of both, ambulatory and non-ambulatory patients confirmed preliminary efficacy of DT-DEC01 therapy by an increase in motor unit potentials (MUP) duration, amplitudes, and polyphasic MUPs at 12 months. This study confirmed EMG as a reliable and objective biomarker of functional assessment in DMD patients after intraosseous administration of the novel DT-DEC01 therapy.

A New Instrument to Assess Dynamic Balance in Children with Duchenne Muscular Dystrophy: Four Square Step Test and Its Validity, Reliability and Feasibility

AIM

The aim of this study was to investigate validity, reliability and feasibility of the Four Square Step Test (FSST) in children with Duchenne Muscular Dystrophy (DMD).

METHODS

The study included 44 children with DMD aged 5-12 years. The functional level of the children was determined by using the Brooke Lower Extremity Functional Classification (BLEFC). The concurrent validity of the FSST, a dynamic balance assessment, was investigated by analyzing the association between FSST and Timed Up and Go Test (TUG), North Star Ambulatory Assessment (NSAA) and Six-Minute Walk Test (6MWT) distance. The intra- and inter-rater reliability of the FSST was determined by using the Intra Class Correlation Coefficient (ICC) while the feasibility of the test was determined by calculating the percentage of children who successfully completed the test in accordance with the test instructions.

RESULTS

The FSST score of the children (mean age 9.25 ± 2.14 years) was 11.91 ± 3.43 and the BLEFC level ranged from Level 1 (65.9%) to Level 3 (9.1%). FSST had positive, moderate relation with BLEFC (r = 0.447; p = .002); positive, strong relation with TUG (r_s = 0.623), and negative, moderate correlations with NSAA (r_s = -0.529) and 6MWT distance (r_s = -0.592) (p < .001). Intra-rater (ICC: 0.965) and inter-rater (ICC: 0.991) reliability was "excellent," and the test was feasible with successful performance of 88% children.

DISCUSSION

The FSST is a valid, reliable and feasible instrument to assess dynamic balance as well as having the ability to reflect falling risk and different functional levels of children with DMD.

Feasibility and Safety of Applying the Functional Electrical Stimulation to Child with Facioscapulohumeral Dystrophy: A Case Report

AIMS

This study aims to investigate the feasibility and safety of short-term functional electrical stimulation (FES) training of the quadriceps femoris muscles in a child with facioscapulohumeral muscular dystrophy (FSHD).

METHODS

A 7-year-old child with FSHD received treatment due to a decrease in functional performance and difficulty climbing stairs. The child was followed up with a home-based exercise program. FES was applied twice a week during stair climbing for six weeks. Muscle activation of the quadriceps femoris was measured using superficial electromyography, muscle strength was measured with a hand-held dynamometer, and functional performance was assessed with the 6-Minute Walk and the Stair Climb Tests before and after the treatment period.

RESULTS

At the end of the treatment, there was an improvement in muscle activation. While muscle strength increased in the quadriceps femoris muscle of the non-dominant side, it remained constant on the dominant side. Functional performance test results also improved.

CONCLUSIONS

FES was a feasible and safe tool to use in our case, a child with FSHD.