The influence of somatosensory and muscular deficits on postural stabilization: Insights from an instrumented analysis of subjects affected by different types of Charcot-Marie-Tooth disease

Upper and lower limb tremor in Charcot-Marie-Tooth neuropathy type 1A and the implications for standing balance

BACKGROUND

Neuropathic tremor occurs in Charcot-Marie-Tooth neuropathy type 1A (CMT1A; hereditary motor and sensory neuropathy, HMSN), although the pathophysiological mechanisms remain to be elucidated. Separately, lower limb tremor has not been explored in CMT1A and could be associated with imbalance as in other neuropathies. The present study aimed to determine tremor characteristics in the upper and lower limbs in CMT1A and relate these findings to clinical disability, particularly imbalance.

METHODS

Tremor and posturography studies were undertaken in phenotyped and genotyped CMT1A patients. Participants underwent detailed clinical assessment, tremor study recordings, and nerve conduction studies. Tremor stability index was calculated for upper limb tremor and compared to essential tremor.

RESULTS

Seventeen patients were enrolled. Postural and kinetic upper limb tremors were evident in 65%, while postural and orthostatic lower limb tremors were seen in 35% of CMT1A patients. Peak upper limb frequencies were lower distally (~ 6 Hz) and higher proximally (~ 9 Hz), were unchanged by weight-loading, and not impacted by fatigue. The tremor stability index was significantly higher in CMT1A than in essential tremor. A 5-6 Hz lower limb tremor was recorded which did not vary along the limb and was unaffected by fatigue. Balance was impaired in patients with postural lower limb tremor. A high frequency peak on posturography was associated with 'good' balance.

CONCLUSIONS

Tremor is a common clinical feature in CMT1A, distinct from essential tremor, mediated by a complex interaction between peripheral and central mechanisms. Postural lower limb tremor is associated with imbalance; strategies aimed at tremor modulation could be of therapeutic utility.

Home-based multi-sensory and proximal strengthening program to improve balance in Charcot-Marie-Tooth disease Type 1A: A proof of concept study

INTRODUCTION/AIMS

People with Charcot-Marie-Tooth Disease (CMT) frequently report problems with balance, which lead to an increased risk of falls. Evidence is emerging of training interventions to improve balance for people with CMT, but to date all have relied on clinic-based treatment and equipment. This proof-of-concept study explored whether a multi-modal program of proprioceptive rehabilitation and strength training can be delivered at home, to improve balance performance in people with CMT Type 1A.

METHODS

Fourteen participants with CMT Type 1A were recruited into this randomized, two-arm study. Baseline assessments included measures of disease severity, posturography, physical function, and patient-reported outcome measurements. All participants received one falls education session. Participants were randomized to either 12 weeks of balance training or 12 weeks of usual activities. The intervention comprised a home-based, multi-sensory balance training and proximal strengthening program, supported by three home visits from a physiotherapist.

RESULTS

Thirteen participants completed the study. The intervention was successfully implemented and well tolerated, with high participation levels. Functional measures of balance and walking showed strong effect sizes in favor of the training group. Posturography testing demonstrated moderate improvements in postural stability favoring the intervention group. Inconsistent changes were seen in lower limb strength measures.

DISCUSSION

The intervention was feasible to implement and safe, with some evidence of improvement in balance performance. This supports future studies to expand this intervention to larger trials of pragmatic, home-delivered programs through current community rehabilitation services and supported self-management pathways.

Vibration perception among children and adolescents with Charcot-Marie-tooth disease and implications for foot posture

BACKGROUND

Alterations in vibration perception among children and adolescents with Charcot-Marie-Tooth disease might explain observed changes in foot posture. Therefore, this cross-sectional study compared the vibration perception of the lower limbs in youths with and without Charcot-Marie-Tooth disease and verified the cut-off value of the distal vibration perception for the Charcot-Marie-Tooth group. In addition, associations between dynamic plantar pressure, vibration perception and isometric muscle strength were investigated.

METHODS

Participants aged 9-18 (Charcot-Marie-Tooth group n = 32; Typical group n = 32) had vibration perception measured by a 128-Hz graduated tuning fork. The static and dynamic foot posture were evaluated by the Foot Posture Index and pressure distribution measuring system, respectively. For the Charcot-Marie-Tooth group, a hand-held dynamometer evaluated the isometric muscle strength of the lower limbs.

FINDINGS

Children with Charcot-Marie-Tooth disease presented impaired vibration perception at the distal phalanx of the hallux and head of the first metatarsal compared to their typically developing peers, while adolescents with Charcot-Marie-Tooth disease showed impairment in all the tested regions compared to their typically developing peers. The cut-off value for vibration perception for participants with Charcot-Marie-Tooth disease was 5.7, considering the original grade of the tuning-fork 128 Hz. Among the associations established for the Charcot-Marie-Tooth group, a greater vibration perception at the distal phalanx of the hallux was associated with a longer rearfoot contact time (β = 31.02, p = 0.04).

INTERPRETATION

These new findings may guide the clinical evaluation and rehabilitation treatment for children and adolescents with Charcot-Marie-Tooth disease.

Understanding medication safety and Charcot-Marie-Tooth disease: a patient perspective

Background Charcot-Marie-Tooth disease is a common inherited neuropathy where patients may be sensitive to adverse effects of certain medicines; however, information about medication safety in this group of people is limited. Objective This study aimed to investigate the experience of Australian individuals with Charcot-Marie-Tooth disease in using medications, including perceived impact of drug-induced adverse effects. Secondarily, it aimed to determine whether individuals with Charcot-Marie-Tooth disease feel adequately supported to make decisions about medication safety. Setting Focus groups and interviews (face-to-face or telephone) of individuals with Charcot-Marie-Tooth disease in Australia. Method A mixed methods qualitative study was conducted between September 2015 and August 2016 using semi-structured interviews. Thematic analysis of interview transcripts was conducted independently by two researchers using inductive coding until concept saturation was achieved. Main outcome measure Perceptions of medicines safety in people with Charcot-Marie-Tooth disease, including barriers to making informed decisions about medication safety. Results Twenty-four adults with Charcot-Marie-Tooth disease participated. Anaesthetics (18%) and pregabalin (15%) were the medications most frequently reported as impacting on Charcot-Marie-Tooth symptoms. Participants sought medication information primarily from general practitioners or neurologists. The main barriers identified by participants were a perceived poor understanding in non-specialist health professionals about Charcot-Marie-Tooth disease and lack of attention to medication safety concerns in people with Charcot-Marie-Tooth disease; this resulted in dissatisfaction about the advice provided. Many individuals who faced uncertainty in obtaining and understanding medicines information turned to internet resources, peer groups, and use of complementary and alternative medicines to self-manage Charcot-Marie-Tooth exacerbations. Conclusion Participants reported drug-related adverse effects and a difficulty in obtaining safety information about medication. This study highlights the need for improved evidence about medication safety in people with Charcot-Marie-Tooth disease. Development of evidence-based resources, increased awareness amongst health professionals about Charcot-Marie-Tooth disease and a team-based care approach could facilitate shared decisions about medication use for people with Charcot-Marie-Tooth disease.

An adapted dance program for children with Charcot-Marie-Tooth disease: An exploratory study

BACKGROUND

Charcot-Marie-Tooth disease (CMT) is a rare hereditary peripheral neuropathy. Its sensorimotor clinical manifestations are heterogeneous, and it might also influence cognitive functions. Physical activity is recommended for adults with CMT, however there is a lack of studies focusing on the effects of physical activity in children with CMT. Dance practice is beneficial for motor and cognitive functions. Adapted dance is interesting for children with CMT because it could address the functional deficits.

OBJECTIVES

To evaluate the feasibility of an adapted dance program and to explore its effects on motor and cognitive functions in children with CMT.

METHODS

Five children with CMT followed a 10-week dance program added to regular care, while four others received only regular care. Feasibility of the program was assessed by participation and retention rates. Motor (CMT clinical characteristics, muscular force and power, postural control, pain) and cognitive (rhythm task, sustained attention, short term memory) abilities were evaluated before and after the program.

RESULTS

The high participation and retention rates (89% and 100%) suggest that a dance program is feasible in children with CMT. Significant benefits were noted for both motor (CMT clinical characteristics, strength of leg muscle groups, pain during physical activity) and cognitive (rhythm task, attention) functions for the dance group.

CONCLUSION

The results suggest that an adapted dance program is feasible and can have beneficial effects on motor and cognitive functions of children with CMT. Dance appears as a new approach adapted for these children. Further research is needed to confirm these results.

Outcome measures in the clinical evaluation of ambulatory Charcot-Marie-Tooth 1A subjects

BACKGROUND

The outcome measures (OMs) in clinical trials for Charcot-Marie-Tooth disease (CMT) still represent an issue. A recent study highlighted that three additional clinical OMs, the 10-Meter Walk Test (10MWT), the 9-Hole Peg Test, and foot dorsal flexion dynamometry, further improve discrimination between severely and mildly affected patients. Another study has recently assessed the validity and reliability of the 6-Minute Walk Test (6MWT).

AIM

The aim of this study was to identify the most useful scales in the clinical evaluation of CMT1A patients.

DESIGN

Observational study of the baseline data collected in a multicenter, prospective, randomized, single blind, controlled study to evaluate the efficacy and safety of an innovative rehabilitation protocol based on treadmill training, stretching, respiratory, and proprioceptive exercises (TreSPE study) in CMT1A patients.

SETTING

The outpatient service of the four Italian centers involved, which are specialized in hereditary neuropathies.

POPULATION

Fifty-three subjects with a clinical and genetically confirmed diagnosis of CMT1A.

METHODS

At baseline, in addition to the CMT Neuropathy Score, all subjects underwent walking evaluation (6MWT, 10MWT), balance assessment (Berg Balance Scale [BBS], Short Physical Performance Battery [SPPB]) and a subjective evaluation of quality of life (SF36) and walking ability (Walk12).

RESULTS

Analyzing the baseline data, as expected, we found a strong correlation between walk and balance evaluation, proving the validity of these tests in investigating the functional impairment of CMT1A subjects. Particularly, we found that subjects with better balance control walk at higher speed and perceive less limitations in their physical activities or motor skills. This can be reconducted to the fact that ankle stability depends upon different factors such as anatomy integrity, muscle strength and proprioception.

CONCLUSIONS

We identify the 6MWT, 10MWT, and SPPB as the most useful scales, in addition to the CMTNS, to evaluate the functional impairment of CMT1A patients who retain their walking capability and we suggest the use of SPPB because of its rapidity to assess balance and gait disorders in clinical settings.

CLINICAL REHABILITATION IMPACT

In the clinical practice it is important to evaluate patients comprehensively but rapidly. These outcome measures can help us to correctly assess balance and walking ability in CMT1A patients.

Evaluation of muscle strength, balance and functionality of individuals with type 2 Charcot-Marie-Tooth Disease

BACKGROUND

Charcot-Marie-Tooth (CMT) disease is part of a group of genetically determined neuropathies. The intrinsic muscles of the feet and legs are affected early in the disease, impacting balance and mobility.

RESEARCH QUESTION

The purpose of this study was to evaluate individuals with type 2 Charcot-Marie-Tooth disease to understand how motor changes interfere in balance and function.

METHODS

The sample comprised 15 individuals with CMT2 from the same family (CMT2G) and a control group (CG) of healthy individuals matched for age and gender. The CMT individuals were classified using the Charcot-Marie-Tooth Neuropathy Score (CMTNS). Muscle strength of the ankle was assessed using a manual dynamometer. Balance was measured using a stabilometer and Berg's Balance Scale (BBS). Functional performance was measured by the Timed Up and Go Test (TUG).

RESULTS

There was a statistically significant difference between the CMT2G and the CG for right side (RS) and left side (LS) muscle strength (dorsiflexors-RS and LS: p < 0,0001; invertors-RS and LS: p < 0.0001; plantarflexors-RS: p < 0.0001; plantarflexors-LS: p = 0.0019; evertors-RS: p = 0.0016; evertors-LS: p<0.0001) in the parameters for the velocity and displacement of center of pressure (CoP) anterior-posterior (AP) in the stabilometry tests with eyes open (EO) and closed (EC) (VCoPAP-EO and VCoPAP-EC: p = 0.0123; DCoPAP-OE: p = 0.0183 and DCoPAP-EC: p = 0.0129), the Berg Balance Scale (p = 0.0066) and the TUG test (p = 0.0003).

SIGNIFICANCE

Thus when the severity of the disease is mild the instability is caused by the weakness of the dorsiflexors and plantarflexors. In patients considered moderate/severe, in addition to weakness of the leg muscles, loss of proprioception will contribute to impaired balance.

Electromyographic and biomechanical analysis of step negotiation in Charcot Marie Tooth subjects whose level walk is not impaired

BACKGROUND

Charcot-Marie-Tooth (CMT) is a slowly progressive disease characterized by muscular weakness and wasting with a length-dependent pattern. Mildly affected CMT subjects showed slight alteration of walking compared to healthy subjects (HS).

RESEARCH QUESTION

To investigate the biomechanics of step negotiation, a task that requires greater muscle strength and balance control compared to level walking, in CMT subjects without primary locomotor deficits (foot drop and push off deficit) during walking.

METHODS

We collected data (kinematic, kinetic, and surface electromyographic) during walking on level ground and step negotiation, from 98 CMT subjects with mild-to-moderate impairment. Twenty-one CMT subjects (CMT-NLW, normal-like-walkers) were selected for analysis, as they showed values of normalized ROM during swing and produced work at push-off at ankle joint comparable to those of 31 HS. Step negotiation tasks consisted in climbing and descending a two-step stair. Only the first step provided the ground reaction force data. To assess muscle activity, each EMG profile was integrated over 100% of task duration and the activation percentage was computed in four phases that constitute the step negotiation tasks.

RESULTS

In both tasks, CMT-NLW showed distal muscle hypoactivation. In addition, during step-ascending CMT-NLW subjects had relevant lower activities of vastus medialis and rectus femoris than HS in weight-acceptance, and, on the opposite, a greater activation as compared to HS in forward-continuance. During step-descending, CMT-NLW showed a reduced activity of tibialis anterior during controlled-lowering phase.

SIGNIFICANCE

Step negotiation revealed adaptive motor strategies related to muscle weakness due to disease in CMT subjects without any clinically apparent locomotor deficit during level walking. In addition, this study provided results useful for tailored rehabilitation of CMT patients.

Balance and falls in people with Charcot-Marie-Tooth disease: A cohort survey

Aim:

To explore the relationship between balance deficit, falls, and activities of daily living in a cohort with Charcot-Marie-Tooth disease.

Method:

A cohort survey of individuals with Charcot-Marie-Tooth disease attending a neurogenetic clinic was carried out. Surveys were sent to individuals on a database of a state-wide neurogenetic service located in Perth, Australia.

Results:

Out of 71 surveys, 40 were returned (56%). The cohort were predominantly male (68%), the average age was 55.5 years (range 18–84) and average age at symptom onset was 23 years (range 5–65). Excluding skeletal foot changes, balance deficits (87.5%) and loss of balance confidence (90%) were the most frequently rated symptoms and those most severely affecting physical functioning (71% and 64% respectively). Ankle splinting was frequently reported in this population (65%). The majority of participants (69%) had fallen at least once in the past year and 40% of fallers reported having never seen a physiotherapist.

Conclusions:

Despite balance deficits and loss of balance confidence being frequently reported to impact daily activities, and falls and near-falls being common in this cohort with Charcot-Marie-Tooth disease, more than a third had not seen a physiotherapist. Future management to reduce the disease burden should investigate the effects of a timely multidisciplinary approach to manage balance dysfunction, and strategies to reduce falls in this population.

Responsiveness of gait analysis parameters in a cohort of 71 CMT subjects

Detection of worsening in the slowly progressive Charcot-Marie-Tooth disease (CMT) is difficult. As previous clinical scales showed low responsiveness, novel outcome measures are under study, including innovative approaches such as quantitative muscle MRI and instrumented movement analysis. Since gait analysis proved able to reliably quantify CMT locomotor deficits, we aimed to explore whether it can be a sensitive-to-change outcome measure in CMT studies. Clinical and biomechanical evaluations were performed in 71 CMT subjects at baseline and after a mean (±sd) of 28.9 ± 9.5 months. Locomotor tasks included natural walking, ascending and descending steps. Instrumented analysis of such tasks provided indexes related to muscle strength (kinetic parameters) and joint movement (kinematic parameters). Parameter responsiveness was expressed as Standardized Response Mean (SRM). Considering the whole CMT group, several parameters showed moderate responsiveness; subgrouping subjects according to disease severity allowed reaching high responsiveness (SRM >0.80). CMT Examination Score showed moderate responsiveness (SRM 0.53) in the minimally affected group; kinematic parameters were more responsive in this group, whereas kinetic parameters in the most severely affected one. Biomechanical parameters can represent suitable outcome measures for CMT by showing moderate-to-high responsiveness. These data suggest that appropriate selection of patient population and outcome measures is crucial for clinical trials' design.

[Charcot-Marie-Tooth disease associated with hip dysplasia in an adolescent]

Charcot-Marie-Tooth disease (CMT) is classified into hereditary motor and sensory neuropathy and can induce severe neuro-orthopaedics deformities, disabling at an early age. Hip dysplasia is present in 6% of CMT patients affecting preferentially CMT1 patients and can appear from the age of 8 years. The pathophysiological is paradoxical because we are confronted with proximal osteoarthritis deformations but genetics research brings use new trail. The main functional complaint is a hip joint pain during walking. Four orthopaedics abnormalities can be revealed by physical and radiological exam: acetabular dysplasia, femoral dysplasia, high femoral antetorsion and excentric head of femur. The natural evolution, in the absence of treatment, is an early secondary osteoarthritis. The therapeutic management should be as early as possible with preventive measures and joint health. During the symptomatic phase, the only treatment is a surgical correction. A systematic clinical examination of the hip all CMT children and a radiograph of the pelvis at the slightest clinical suspicion is recommended.

Phenotypic Variability of Childhood Charcot-Marie-Tooth Disease

IMPORTANCE

Disease severity of childhood Charcot-Marie-Tooth disease (CMT) has not been extensively characterized, either within or between types of CMT to date.

OBJECTIVE

To assess the variability of disease severity in a large cohort of children and adolescents with CMT.

DESIGN, SETTING, AND PARTICIPANTS

A cross-sectional study was conducted among 520 children and adolescents aged 3 to 20 years at 8 universities and hospitals involved in the Inherited Neuropathies Consortium between August 6, 2009, and July 31, 2014, in Australia, Italy, the United Kingdom, and the United States. Data analysis was conducted from August 1, 2014, to December 1, 2015.

MAIN OUTCOMES AND MEASURES

Scores on the Charcot-Marie-Tooth Disease Pediatric Scale (CMTPedS), a well-validated unidimensional clinical outcome measure to assess disease severity. This instrument includes 11 items assessing fine and gross motor function, sensation, and balance to produce a total score ranging from 0 (unaffected) to 44 (severely affected).

RESULTS

Among the 520 participants (274 males) aged 3 to 20 years, CMT type 1A (CMT1A) was the most prevalent type (252 [48.5%]), followed by CMT2A (31 [6.0%]), CMT1B (15 [2.9%]), CMT4C (13 [2.5%]), and CMTX1 (10 [1.9%]). Disease severity ranged from 1 to 44 points on the CMTPedS (mean [SD], 21.5 [8.9]), with ankle dorsiflexion strength and functional hand dexterity test being most affected. Participants with CMT1B (mean [SD] CMTPedS score, 24.0 [7.4]), CMT2A (29.7 [7.1]), and CMT4C (29.8 [8.6]) were more severely affected than those with CMT1A (18.9 [7.7]) and CMTX1 (males: 15.3 [7.7]; females: 13.0 [3.6]) (P < .05). Scores on the CMTPedS tended to worsen principally during childhood (ages, 3-10 years) for participants with CMT4C and CMTX1 and predominantly during adolescence for those with CMT1B and CMT2A (ages, 11-20 years), while CMT1A worsened consistently throughout childhood and adolescence. For individual items, participants with CMT4C recorded more affected functional dexterity test scores than did those with all other types of CMT (P < .05). Participants with CMT1A and CMTX1 performed significantly better on the 9-hole peg test and balance test than did those with all other types of CMT (P < .05). Participants with CMT2A had the weakest grip strength (P < .05), while those with CMT2A and CMT4C exhibited the weakest ankle plantarflexion and dorsiflexion strength, as well as the lowest long jump and 6-minute walk test distances (P < .05). Multiple regression modeling identified increasing age (r = 0.356, β = 0.617, P < .001) height (r = 0.251, β = 0.309, P = .002), self-reported foot pain (r = 0.162, β = .114, P = .009), and self-reported hand weakness (r = 0.243, β = 0.203, P < .001) as independent predictors of disease severity.

CONCLUSIONS AND RELEVANCE

These results highlight the phenotypic variability within CMT genotypes and mutation-specific manifestations between types. This study has identified distinct functional limitations and self-reported impairments to target in future therapeutic trials.

XEN Gel Stent Early Failure-dye-enhanced Ab-externo Revision

The XEN gel stent is an ab-interno minimally invasive glaucoma surgery device that reduces intraocular pressure by creating a subconjunctival drainage pathway. XEN intents to provide a safer and less invasive mean of lowering intraocular pressure. As with any new device, there is still some lack of experience and knowledge concerning efficacy, technique, and complications. We report a novel surgical approach for early bleb failure after XEN implantation.

How to cite this article

Ferreira NP, Pinto JM, Teixeira F, Pinto LA. XEN Gel Stent Early Failure-dye-enhanced Ab-externo Revision. J Curr Glaucoma Pract 2018;12(3):139-141.

Postural instability in Charcot-Marie-Tooth 1A disease

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.