Full length articleEvaluation of muscle strength, balance and functionality of individuals with type 2 Charcot-Marie-Tooth Disease
Introduction
Charcot-Marie-Tooth (CMT) disease is part of a group of genetically determined neuropathies with an estimated prevalence of 1:2500 and is the most prevalent hereditary neuropathy [1]. Most CMT cases can be classified into two main categories depending on the nature of the primary injury to the nerve fiber: CMT type 1 (CMT1), demyelinating pattern, presents motor conduction velocities in the upper limbs of less than 38 m/s, or CMT type 2 (CMT2), axonal pattern, which presents motor conduction velocities of more than 38 m/s. Barreto et al. [2] in a systematic review of epidemiological studies on CMT found the frequency of the main subtypes varied between 37.6 to 84% for CMT1, and 12 to 35.9% for CMT2.
Despite the great genetic heterogeneity of the disease, the phenotypes of the different CMT subtypes are similar [3]. In all forms, degeneration of the sensory and motor nerve fibers cause atrophy and muscle weakness, associated with loss of sensation, especially in the distal segments of the lower limbs [4]. The intrinsic muscles of the feet and legs are affected early in the disease, impacting balance and mobility [[5], [6]].
One sequela found in CMT disease is gait change, which is typically influenced by muscle weakness and sensory impairments [7]. In the most severe form of CMT disease respiratory disorders, such as the compromised maximum expiratory pressure (PEMax) observed in individuals with CMT2 by Garcez et al. (2015), may be present [8].
In the literature many authors note disorders of balance and functionality of patients with CMT [[4], [9], [10]]. They highlight muscle weakness and loss of proprioception as the main causes [4]. However, there is no consensus among the authors about how these variables affect balance and functionality. The focus of this study was to evaluate individuals with CMT2 in an attempt to understand how loss of strength interferes in balance and function.
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Sample and ethical consideration
An observational cross-sectional study was conducted through anamnesis (personal data, main complaint, history of current and past illness and family history) and kinesiological-functional evaluation (assessment of tendon reflexes, muscle tone, muscular strength, static and dynamic balance and functionality) of individuals with CMT2 belonging to the same multigenerational family, in the city of Tobias Barreto, Sergipe, Brazil. All measurements were performed with the patient barefoot without
Results
The sample comprised a group of 15 adult subjects with CMT2 disease (CMT2G), 8 females, and 7 males (age: 31.33 ± 13.41, height: 158.33 ± 7 cm, weight: 56.14 ± 8.16), who underwent a neurophysiological investigation as described by Neves and Kok [9], and a control group (CG) of 15 healthy subjects matched by age and gender with the CMT2 group (age: 29.53 ± 12.88, height: 172.07 ± 10, weight: 70.10 ± 12.73). There was no significant difference between the CMT2G and CG in terms of body mass index
Discussion
The evaluation of lower limb muscle strength, balance and functionality demonstrated changes in individuals with CMT type 2 when compared to individuals without CMT. These findings have already been described in the literature. The purpose of this study was to clarify how motor changes compromise balance and functionality in individuals with CMT disease.
This study demonstrated that muscle weakness of the plantarflexor, dorsiflexor, invertor and evertor muscles was related to greater
Conclusion
In the present study, individuals with CMT2 presented less strength, poorer balance and less functional performance when compared to healthy individuals. The findings of this study allow us to conclude that, initially, when CMT is mild, balance instability occurs mainly due to weakness of the dorsiflexor and plantar flexor muscles of the foot: It is no coincidence that the initial signs and symptoms of the disease also stem from the weakness of these muscles. It is suggested that with the
Limitations of the study
The main limitation of the study was to find patients available to make the evaluations, because it is a rarer type of CMT. In addition, the variability of the clinical aspects presented by individuals with CMT hinders the understanding and more solid conclusions about the disease.
Acknowledgments
The authors wish to acknowledge the support of the Charcot–Marie–Tooth Association of Tobias Barreto in the undertaking of this research.
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