Elsevier

Gait & Posture

Volume 49, September 2016, Pages 353-357
Gait & Posture

Full length article
Postural instability in Charcot-Marie-Tooth 1A disease

https://doi.org/10.1016/j.gaitpost.2016.07.183Get rights and content

Highlights

  • CMT1A patients were less stable than controls.

  • The imbalance in CMT patients is related to dorsi-flexor muscle weakness.

  • Foot deformities and sensory impairments do not seem to play a role in CMT imbalance.

Abstract

The aim of this study was to evaluate the influence of somatosensory impairment, distal muscle weakness and foot deformities on the balance in 21 CMT1A patients using a baropodometric platform.

Stabilometric analysis by measuring sway area and velocity of a centre of pressure (CoP) both at open and closed eyes were used to assess postural imbalance. Static analysis, by measuring the load and the plantar surface of forefoot, midfoot and hindfoot was used to define the footprint shape and to assess as a whole foot deformities. Stabilometric and static results were compared with those of a control group. In CMT1A patients, stabilometric findings were correlated with static parameters, Achilles’ tendon retraction, distal muscle strength and CMT examination score (CMTES). CMT1A patients compared to controls had lower plantar surface and load on midfoot, and higher load on a forefoot. CMT1A patients had a greater postural instability, since they had a higher CoP velocity, both at open and closed eyes. Moreover, the CoP velocity correlated inversely with the strength of ankle dorsi-flexion muscles and directly with CMTES as whole and with the item “motor symptoms legs”. Postural imbalance was not correlated with sensory impairment and foot deformities as expressed by static analysis and Achilles’ tendon retraction.

In this study we demonstrated an altered balance in CMT1A patients during upright standing. The imbalance in our CMT patients seems to be related to the weakness of ankle dorsi-flexor muscles rather than sensory impairment or foot deformities. These results could be due to a mildly affected CMT1A population, evaluated in an early stage of the 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.

Section snippets

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.

References (21)

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