Full length articlePostural instability in Charcot-Marie-Tooth 1A disease
Introduction
Charcot-Marie-Tooth disease (CMT) is a hereditary motor sensory neuropathy. The most common subtype is CMT1A, a demyelinating form due to duplication in chromosome 17p11.2 [1]. The clinical features are progressive distal muscular atrophy and weakness, sensory loss, decrease or absence of deep tendon reflexes, and skeletal deformities (i.e. pes cavus, scoliosis etc.) [2]. Balance disturbances represent limiting factors for physical daily activity in CMT disease [3]. However, postural instability is still a critical aspect of CMT, since it has been scarcely investigated so far, and the basis of postural imbalance in CMT remains controversial.
In CMT1A patients, sensory deficit and distal muscle weakness have been invoked in pathogenesis of postural imbalance [4], [5], [6], [7], [8]. Nardone et al. [4] have not found a correlation between postural instability and sensory deficit whereas other authors have demonstrated the influence of proprioception [5] and pinprick [8] impairment on postural control in CMT1A patients. Moreover, some studies have focused their attention on ankle plantar-flexor muscle weakness as the main factor for postural instability [6], [8].
Other factors that could influence postural stability in CMT disease are structural foot deformities [9], [10] including foot bone deformities (e.g. pes cavus) as well as Achilles’ tendon shortening. The influence of foot deformity on balance, to our knowledge, has never been systematically investigated in CMT disease. However, it is likely that foot bone deformities may influence postural balance, since the foot, during upright standing, must be able to adapt to the ground surface in order to optimize stability as needed [11], [12]. Likewise, Achilles’ tendon shortening, may alter the foot mobility and reduce the ability to function optimally during quiet standing.
The aim of the present study was to investigate, by using a baropodometric platform, the influence of somatosensory impairment, distal muscle weakness and foot deformities on postural stability in a group of CMT1A patients.
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Subject and clinical evaluation
Twenty-one CMT1A patients (11 females; mean age 38.8 + 16.9 years) and 24 mean age-matched controls (13 females; mean age 43.0 + 20.8 years) were recruited for the study. Clinical data of patients are summarized in Table 1. Extended clinical data are reported in Supplementary Table 1. All subjects signed a written informed consent before enrolling into the study.
All CMT1A patients underwent standard neurological evaluation. Overall, clinical disability was assessed by applying CMT Examination Score
Results
Static and stabilometric results from patients and controls are summarized in Table 2.
Briefly, static analysis showed that CMT1A patients had a different footprint shape respect to control group. Notably, CMT1A patients showed smaller plantar surface and load on midfoot, and higher load on a forefoot. These findings were consistent with typical profile of pes cavus [15].
The stabilometric analysis demonstrated that CMT1A patients had a greater postural instability than controls since they had a
Discussion
In this study, we demonstrated that CMT1A patients with mild disability were less stable than controls during upright standing. Technically, the velocity of CoP rather than the sway area was the stabilometric parameters that reflected postural imbalance in our population. Our findings, regarding stabilometric analysis, are in line with previous reports that demonstrated that the velocity of CoP is more sensitive than sway area in depict quiet stance impairment [4], [5]. Moreover, we found that
Conflict of interest
None of the authors had any financial or personal relationships with other people or organizations that could inappropriately influence their work.
Acknowledgement
No acknowledgement.
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