Gait and balance in adults with Friedreich's ataxia

Spatiotemporal Gait Analysis of Patients with Spinocerebellar Ataxia Types 3 and 10 Using Inertial Measurement Units: A Comparative Study

Given the high morbidity related to the progression of gait deficits in spinocerebellar ataxias (SCA), there is a growing interest in identifying biomarkers that can guide early diagnosis and rehabilitation. Spatiotemporal parameter (STP) gait analysis using inertial measurement units (IMUs) has been increasingly studied in this context. This study evaluated STP profiles in SCA types 3 and 10, compared them to controls, and correlated them with clinical scales. IMU portable sensors were used to measure STPs under four gait conditions: self-selected pace (SSP), fast pace (FP), fast pace checking-boxes (FPCB), and fast pace with serial seven subtractions (FPS7). Compared to healthy subjects, both SCA groups had higher values for step time, variability, and swing time, with lower values for gait speed, cadence, and step length. We also found a reduction in speed gain capacity in both SCA groups compared to controls and an increase in speed dual-task cost in the SCA10 group. However, there were no significant differences between the SCA groups. Swing time, mean speed, and step length were correlated with disease severity, risk of falling and functionality in both clinical groups. In the SCA3 group, fear of falling was correlated with cadence. In the SCA10 group, results of the Montreal cognitive assessment test were correlated with step time, mean speed, and step length. These results show that individuals with SCA3 and SCA10 present a highly variable, short-stepped, slow gait pattern compared to healthy subjects, and their gait quality worsened with a fast pace and dual-task involvement.

Quantitative Gait and Balance Outcomes for Ataxia Trials: Consensus Recommendations by the Ataxia Global Initiative Working Group on Digital-Motor Biomarkers

With disease-modifying drugs on the horizon for degenerative ataxias, ecologically valid, finely granulated, digital health measures are highly warranted to augment clinical and patient-reported outcome measures. Gait and balance disturbances most often present as the first signs of degenerative cerebellar ataxia and are the most reported disabling features in disease progression. Thus, digital gait and balance measures constitute promising and relevant performance outcomes for clinical trials.This narrative review with embedded consensus will describe evidence for the sensitivity of digital gait and balance measures for evaluating ataxia severity and progression, propose a consensus protocol for establishing gait and balance metrics in natural history studies and clinical trials, and discuss relevant issues for their use as performance outcomes.

Standing Balance Conditions and Digital Sway Measures for Clinical Trials of Friedreich's Ataxia

BACKGROUND

Progressive loss of standing balance is a feature of Friedreich's ataxia (FRDA).

OBJECTIVES

This study aimed to identify standing balance conditions and digital postural sway measures that best discriminate between FRDA and healthy controls (HC). We assessed test-retest reliability and correlations between sway measures and clinical scores.

METHODS

Twenty-eight subjects with FRDA and 20 HC completed six standing conditions: feet apart, feet together, and feet tandem, both with eyes opened (EO) and eyes closed. Sway was measured using a wearable sensor on the lumbar spine for 30 seconds. Test completion rate, test-retest reliability with intraclass correlation coefficients, and areas under the receiver operating characteristic curves (AUCs) for each measure were compared to identify distinguishable FRDA sway characteristics from HC. Pearson correlations were used to evaluate the relationships between discriminative measures and clinical scores.

RESULTS

Three of the six standing conditions had completion rates over 70%. Of these three conditions, natural stance and feet together with EO showed the greatest completion rates. All six of the sway measures' mean values were significantly different between FRDA and HC. Four of these six measures discriminated between groups with >0.9 AUC in all three conditions. The Friedreich Ataxia Rating Scale Upright Stability and Total scores correlated with sway measures with P-values <0.05 and r-values (0.63-0.86) and (0.65-0.81), respectively.

CONCLUSION

Digital postural sway measures using wearable sensors are discriminative and reliable for assessing standing balance in individuals with FRDA. Natural stance and feet together stance with EO conditions suggest use in clinical trials for FRDA. © 2024 International Parkinson and Movement Disorder Society.

Scientometric Research and Critical Analysis of Gait and Balance in Older Adults

Gait and balance have emerged as a critical area of research in health technology. Gait and balance studies have been affected by the researchers' slow follow-up of research advances due to the absence of visual inspection of the study literature across decades. This study uses advanced search methods to analyse the literature on gait and balance in older adults from 1993 to 2022 in the Web of Science (WoS) database to gain a better understanding of the current status and trends in the field for the first time. The study analysed 4484 academic publications including journal articles and conference proceedings on gait and balance in older adults. Bibliometric analysis methods were applied to examine the publication year, number of publications, discipline distribution, journal distribution, research institutions, application fields, test methods, analysis theories, and influencing factors in the field of gait and balance. The results indicate that the publication of relevant research documents has been steadily increasing from 1993 to 2022. The United States (US) exhibits the highest number of publications with 1742 articles. The keyword "elderly person" exhibits a strong citation burst strength of 18.04, indicating a significant focus on research related to the health of older adults. With a burst factor of 20.46, Harvard University has made impressive strides in the subject. The University of Pittsburgh displayed high research skills in the area of gait and balance with a burst factor of 7.7 and a publication count of 103. The research on gait and balance mainly focuses on physical performance evaluation approaches, and the primary study methods include experimental investigations, computational modelling, and observational studies. The field of gait and balance research is increasingly intertwined with computer science and artificial intelligence (AI), paving the way for intelligent monitoring of gait and balance in the elderly. Moving forward, the future of gait and balance research is anticipated to highlight the importance of multidisciplinary collaboration, intelligence-driven approaches, and advanced visualization techniques.

Digital gait markers to potentially distinguish fragile X-associated tremor/ataxia syndrome, Parkinson's disease, and essential tremor

Background

Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disease that affects carriers of a 55-200 CGG repeat expansion in the fragile X messenger ribonucleoprotein 1 (FMR1) gene, may be given an incorrect initial diagnosis of Parkinson's disease (PD) or essential tremor (ET) due to overlapping motor symptoms. It is critical to characterize distinct phenotypes in FXTAS compared to PD and ET to improve diagnostic accuracy. Fast as possible (FP) speed and dual-task (DT) paradigms have the potential to distinguish differences in gait performance between the three movement disorders. Therefore, we sought to compare FXTAS, PD, and ET patients using quantitative measures of functional mobility and gait under self-selected (SS) speed, FP, and DT conditions.

Methods

Participants with FXTAS (n = 22), PD (n = 23), ET (n = 20), and controls (n = 20) underwent gait testing with an inertial sensor system (APDM™). An instrumented Timed Up and Go test (i-TUG) was used to measure movement transitions, and a 2-min walk test (2MWT) was used to measure gait and turn variables under SS, FP, and DT conditions, and dual-task costs (DTC) were calculated. ANOVA and multinomial logistic regression analyses were performed.

Results

PD participants had reduced stride lengths compared to FXTAS and ET participants under SS and DT conditions, longer turn duration than ET participants during the FP task, and less arm symmetry than ET participants in SS gait. They also had greater DTC for stride length and velocity compared to FXTAS participants. On the i-TUG, PD participants had reduced sit-to-stand peak velocity compared to FXTAS and ET participants. Stride length and arm symmetry index during the DT 2MWT was able to distinguish FXTAS and ET from PD, such that participants with shorter stride lengths were more likely to have a diagnosis of PD and those with greater arm asymmetry were more likely to be diagnosed with PD. No gait or i-TUG parameters distinguished FXTAS from ET participants in the regression model.

Conclusion

This is the first quantitative study demonstrating distinct gait and functional mobility profiles in FXTAS, PD, and ET which may assist in more accurate and timely diagnosis.

The Responsiveness of Gait and Balance Outcomes to Disease Progression in Friedreich Ataxia

To identify gait and balance measures that are responsive to change during the timeline of a clinical trial in Friedreich ataxia (FRDA), we administered a battery of potential measures three times over a 12-month period. Sixty-one ambulant individuals with FRDA underwent assessment of gait and balance at baseline, 6 months and 12 months. Outcomes included GAITRite® spatiotemporal gait parameters; Biodex Balance System Postural Stability Test (PST) and Limits of Stability; Berg Balance Scale (BBS); Timed 25-Foot Walk Test; Dynamic Gait Index (DGI); SenseWear MF Armband step and energy activity; and the Friedreich Ataxia Rating Scale Upright Stability Subscale (FARS USS). The standardised response mean (SRM) or correlation coefficients were reported as effect size indices for comparison of internal responsiveness. Internal responsiveness was also analysed in subgroups. SenseWear Armband daily step count had the largest effect size of all the variables over 6 months (SRM = -0.615), while the PST medial-lateral index had the largest effect size (SRM = 0.829) over 12 months. The FARS USS (SRM = 0.824) and BBS (SRM = -0.720) were the only outcomes able to detect change over 12 months in all subgroups. The DGI was the most responsive outcome in children, detecting a mean change of -2.59 (95% CI -3.52 to -1.66, p < 0.001, SRM = -1.429). In conclusion, the FARS USS and BBS are highly responsive and can detect change in a wide range of ambulant individuals with FRDA. However, therapeutic effects in children may be best measured by the DGI.

Anteroposterior Stability: A Determinant of Gait Dysfunction and Falls in Spinocerebellar Ataxia

Background:

Establishing an association between gait variability and direction specific balance indices may help in identifying the risk of falls in patients with spinocerebellar ataxia (SCA) which may help in developing an appropriate intervention. This study is intended to identify the association between balance and gait parameters especially gait variability in these patients.

Methods:

Patients with genetically confirmed SCA (n = 24) as well as controls (n = 24) who met the study criteria were recruited. Gait was assessed using the GAITRite system and balance was assessed using dynamic posturography (Biodex) to record direction-specific dynamic balance indices. Disease severity was assessed using international cooperative ataxia rating scale (ICARS).

Results:

The mean age of the SCA group (38.83 ± 13.03 years) and the control group (36.38 ± 9.09 years) were comparable. The age of onset of illness was 32 ± 10.62 years and duration of 5.67 ± 3.62 years. The mean ICARS was 45.10 ± 16.75. There was a significant difference in the overall balance index (OBI), anterior–posterior index (API), medial/lateral index (MLI) between SCA patients (4.56 ± 2.09, 3.49 ± 1.88, 2.94 ± 1.32) and the controls (2.72 ± 1.25, 2.08 ± 0.85, 1.85 ± 0.97). However, correlation was observed only between gait stability and balance parameters in API direction.

Conclusions:

There was an increased anteroposterior oriented balance deficit in patients with SCA, which was significantly correlating with the gait parameters. The balance training intervention may focus on improving anteroposterior direction to prevent falls and improving walking efficiency.

Gauging Gait Disorders with a Method Inspired by Motor Control Theories: A Pilot Study in Friedreich's Ataxia

To date, it has been challenging for clinicians and researchers alike to use the multiple outcome measures available to create a meaningful clinical picture and perform effective longitudinal follow-up. It has been found that instrumented gait analysis can provide information associated with a patient’s performance and help to remedy the shortcomings of the currently available outcome measures. The goal of this methodological article is to set the background and justify a new outcome measure inspired by the motor control theories to analyze gait using spatiotemporal parameters. The method is applied in a population of individuals living with Friedreich’s ataxia (FRDA), a neurodegenerative disease. The sample population consisted of 19 subjects, 11 to 65 years of age with FRDA, who either ambulated independently, with a cane, or with a rollator. Three scores based on the distance from healthy normative data were used: Organization Score, Variability Score, and an overall measurement, the Global Ambulation Score. The scores were then compared to the Scale for Assessment and Rating of Ataxia (SARA) Gait Score (SARA-GS), a clinical scale currently being used for gait analysis in FRDA. Organization Scores demonstrated a longitudinal deterioration in the gait characteristics from independent ambulators to those who ambulated with a rollator. Variability Scores mostly reflected dynamic instability, which became greater as the requirement of an ambulation aid or the switch from a cane to a rollator was imminent. The global value given by the Global Ambulation Score, which takes into consideration both the Organization Score, the Variability Score, and the level of assistive device, demonstrated a logarithmic relationship with the SARA-GS. Overall, these results highlight that both components introduced should be analyzed concurrently and suggest that the Global Ambulation Score may be a valuable outcome measure for longitudinal disease progression.

Vitamin D Supplementation Improves the Effects of the Rehabilitation Program on Balance and Pressure Distribution in Patients after Anterior Cervical Interbody Fusion-Randomized Control Trial

STUDY DESIGN

A double-blinded, randomized controlled trial.

BACKGROUND

Surgery is effective in reducing pain intensity in patients with cervical disc disease. However, functional measurements demonstrated that the results have been not satisfactory enough. Thus, rehabilitation programs combined with the supplementation of vitamin D could play an essential role.

METHODS

The study recruited 30 patients, aged 20 to 70 years, selected for anterior cervical interbody fusion (ACIF). The patients were randomly divided into the placebo (Pl) and vitamin D (3200 IU D3/day) supplemented groups. The functional tests limits of stability (LOS), risk of falls (RFT), postural stability (PST), Romberg test, and foot pressure distribution were performed before supplementation (BS-week 0), five weeks after supplementation (AS-week 5), four weeks after surgery (BSVR-week 9), and 10 weeks after supervising rehabilitation (ASVR-week 19).

RESULTS

The concentration of 25(OH)D3 in the serum, after five weeks of supplementation, was significantly increased, while the Pl group maintained the same. The RFT was significantly reduced after five weeks of vitamin D supplementation. Moreover, a further significant decrease was observed following rehabilitation. In the Pl group, no changes in the RFT were observed. The overall postural stability index (OSI), LOS, and the outcomes of the Romberg test significantly improved in both groups; however, the effects on the OSI were more pronounced in the D3 group at the end of the rehabilitation program.

CONCLUSIONS

Our data suggest that vitamin D supplementation positively affected the rehabilitation program in patients implemented four weeks after ACIF by reducing the risk of falls and improving postural stability.

The sit to stand to sit postural transition variability in the five time sit to stand test in older people with different fall histories

BACKGROUND

It has been proved that increased motion variability can be indicative of lack of stability. Despite the extensive literature on single sit to stand/stand to sit postural transitions analysis in older people, no studies to this date have assessed the sit to stand to sit (STSTS) transition variability in older adults.

RESEARCH QUESTION

To investigate the variability in STSTS transition during the five times sit to stand (FTSS) test in older people with different fall histories.

METHODS

Seventy-five older (80.5 ± 7.5) and twenty-five younger (27.7 ± 6.5) subjects participated in the study. The older participants were categorized into three groups of non-fallers, once-fallers, and multiple-fallers based on their fall histories. Subjects were fitted with an IMU at their lower backs and asked to fully stand up and then sit down again five times in a row. The angular rotation of the trunk in the sagittal plane was recorded. Using the DTW method, the first STSTS transition of each subject was compared to the last transition and the variability was measured. The correlation between STSTS variability and older participants' Berg balance scale (BBS) was investigated.

RESULTS

The STSTS variability results were significantly different in older fallers (multiple-fallers and once-fallers) compared to both younger participants and older non-fallers. The results yielded a sensitivity of 85.4 % and a specificity of 83.3 % in recognizing older fallers from older non-fallers and a sensitivity and specificity of 86.7 % and 85.7 % respectively in recognizing older multiple-fallers from other older participants. The STSTS variability was found to be significantly correlated with BBS.

SIGNIFICANCE

The findings demonstrated a strong indication of variability in the STSTS transition in older fallers and a significant correlation between STSTS variability and BBS. The results suggest that variability analysis of the STSTS transition has the potential to be used for fall risk analysis in older adults.

Mitochondrial dysfunction in neurons in Friedreich's ataxia

Friedreich's ataxia is a multisystemic genetic disorder within the family of mitochondrial diseases that is characterized by reduced levels of the essential mitochondrial protein frataxin. Based on clinical evidence, the peripheral nervous system is affected early, neuronal dysfunction progresses towards the central nervous system, and other organs (such as heart and pancreas) are affected later. However, little attention has been given to the specific aspects of mitochondria function altered by frataxin depletion in the nervous system. For years, commonly accepted views on mitochondria dysfunction in Friedreich's ataxia stemmed from studies using non-neuronal systems and may not apply to neurons, which have their own bioenergetic needs and present a unique, extensive neurite network. Moreover, the basis of the selective neuronal vulnerability, which primarily affects large sensory neurons in the dorsal root ganglia, large principal neurons in the dentate nuclei of the cerebellum, and pyramidal neurons in the cerebral cortex, remains elusive. In order to identify potential misbeliefs in the field and highlight controversies, we reviewed current knowledge on frataxin expression in different tissues, discussed the molecular function of frataxin, and the consequences of its deficiency for mitochondria structural and functional properties, with a focus on the nervous system.

Quantitative Gait Analysis and Cerebrospinal Fluid Tap Test for Idiopathic Normal-pressure Hydrocephalus

We investigated gait performance utilizing a quantitative gait analysis for 2 groups: (1) idiopathic normal-pressure hydrocephalus (INPH) patients who had a positive response to the cerebrospinal fluid tap test (CSFTT) and (2) healthy controls. The aims of the study were (1) to analyze the characteristics of gait features, (2) to characterize changes in gait parameters before and after the CSFTT, and (3) to determine whether there was any relationship between stride time and stride length variability and Frontal Assessment Battery (FAB) scores in INPH patients. Twenty-three INPH patients and 17 healthy controls were included in this study. Compared with healthy controls, the gait of INPH patients was characterized by lower velocity, shorter stride length, and more broad-based gait. Patients with INPH had a longer stance phase with increased double-limb support. Variability in stride time and stride length was increased in INPH patients. Stride time and stride length variability were correlated with FAB score. After the CSFTT, gait velocity, stride length, and step width significantly improved. There were significant decreases in stride time and stride length variability. These results suggest that the CSFTT for INPH patients might improve the so-called balance-related gait parameter (ie, step width) as well. Stride time and stride length variability also responded to the CSFTT. Association between FAB scores and both stride time and stride length variability suggests involvement of similar circuits producing gait variability and frontal lobe functions in INPH patients.

Early Rehabilitation Program and Vitamin D Supplementation Improves Sensitivity of Balance and the Postural Control in Patients after Posterior Lumbar Interbody Fusion: A Randomized Trial

BACKGROUND

The introduction of early rehabilitation exercise is the foundation of treatment post-Posterior lumbar interbody fusion (PLIF) surgery, and the search for additional sources of reinforcement physiotherapy seems to be very important.

METHODS

The patients were randomly divided into the vitamin D3 (n = 15; D3) supplemented group and received 3200 IU per day for five weeks before surgery and the placebo group (n = 18; Pl) received vegetable oil during the same time. The patients began the supervisor rehabilitation program four weeks after surgery.

RESULTS

The limits of stability (LOS) were significantly improved in the D3 group after 5 and 14 weeks (p < 0.05), while in the Pl group, progress was only observed after 14 weeks (p < 0.05). The LOS were also higher in the D3 group than in the Pl group after five weeks of supervised rehabilitation (p < 0.05). In the postural stability (PST) test, significant progress was observed in the D3 group after 14 weeks (p < 0.02). In addition, neither rehabilitation nor supplementation had significant effects on the risk of falls (RFT).

CONCLUSIONS

Vitamin D supplementation seems to ameliorate the effects of an early postoperative rehabilitation program implemented four weeks after posterior lumbar interbody fusion. Early physiotherapy treatment after PLIF surgery combined with vitamin D supplementation appears to be a very important combination with regard to the patients' recovery process.

Test-retest reliability of an instrumented electronic walkway system (GAITRite) for the measurement of spatio-temporal gait parameters in young patients with Friedreich's ataxia

BACKGROUND

Friedreich ataxia (FRDA) affects the spatio-temporal parameters (STP) of gait. To our knowledge, proper tools to measure the variability of ataxic gait have not been validated yet. The aims of the present study were: (1) to measure the reproducibility of STP and gait scores in young patients with FRDA and (2) to describe the characteristics of gait parameters in this population.

METHODS

Thirty-six patients (18 males, 18 females) with diagnosis of FRDA (mean age 16.4 ± 4.5 years) were asked to walk barefoot at a self-selected pace along the pressure sensitive walkway (GAITRite^®). Three trials were recorded for each patient and repeated 48 h later. Collected data was put into statistical analysis tests to determine reliability and variability of STPs and two other gait scores: The Functional Ambulation Performance score (FAP) and the Gait Variability Index (GVI).

RESULTS

All STPs showed strong or very strong reliability (ICC > 0.7) and a low variability. The two parameters showing the lowest reliability (0.71 and 0.74) were the base of support and the foot progression angle. The FAP score and the GVI showed strong reliability (ICC > 0.8).

CONCLUSIONS

The GAITRite system allows feasible and reliable measurements of gait parameters in young patients with FRDA. Lower reliability found for the weakest parameters was attributed to the software automatic errors and the ankle laxity noted in every patient.

From motor performance to participation: a quantitative descriptive study in adults with autosomal recessive spastic ataxia of Charlevoix-Saguenay

BACKGROUND

Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS) is a recessive neurological disorder with cerebellar, pyramidal and neuropathic features. Natural history data are urgently needed to increase trial readiness. This study aimed to describe the clinical phenotype including dexterity, coordination, strength, mobility, balance, disease severity, participation, and quality of life observed in adults with ARSACS homozygous for the c.8844delT mutation.

METHODS

Cross-sectional study with comparisons between disease stages and with reference values. Outcome measures included Standardized Finger-to-Nose Test, Grip/pinch strength, LEMOCOT, Six-Minute Walk Test, 10-Meter Walk Test, Berg Balance Scale, Spastic Paraplegia Rating Scale, Scale for the Assessment and Rating of Ataxia, LIFE-H, and SF-12.

RESULTS

Twenty-eight participants were recruited with a mean age of 38.1 years. The majority presented with lower limb coordination and fine dexterity scores below three standard deviations compare to reference values, scored under predicted values for mobility measures and were at increased risk of fall. Participants at an earlier disease stage performed better than the others, but individual variability was observed.

CONCLUSIONS

Results showed overall impaired motor performances and, even in a genetically homogeneous ARSACS population, an individual variability within disease stages. This study lays the foundation for a longitudinal study using quantified measurements.

Quantification of gait in children with mitochondrial disease

Mitochondrial disorders are multisystem conditions that can potentially affect gait in many ways. The aim of this study was to select the optimal protocol to quantify the spatiotemporal parameters of gait in ambulatory children with mitochondrial disorders based on feasibility, test-retest reliability, and the difference between patients and controls. Gait at self-selected pace was quantified in ambulatory children with a genetically confirmed primary mitochondrial disease using the GAITRite electronic walkway. Three protocols were tested: pre-exercise, post-exercise (after a 3-min walking test), and recovery. In 14 ambulatory patients, we showed good to perfect reliability for velocity, cadence, step length, step time, step time variability, and step width in the recovery condition. The difference between patients and 70 individually age- and gender matched healthy controls only became apparent in the post-exercise protocol. In conclusion, measuring spatiotemporal parameters of gait using the GAITRite in ambulatory children with mitochondrial disease is feasible and reliable for most of the parameters measured. When using gait analysis in future studies in children with mitochondrial disease, we advise i) to use an exercise test prior to the gait analysis, ii) to let children practice the test before the actual data collection, and iii) not to use symmetry parameters.

Identification of spatiotemporal gait parameters and pressure-related characteristics in children with Angelman syndrome: A pilot study

BACKGROUND

Angelman syndrome (AS) leads to clinical manifestations that include intellectual impairments, developmental delay and poor motor function. Initiatives to develop therapeutics implie an urgent need to identify methods that accurately measure the motor abilities.

METHODS

Six children with AS (6 to 9 years old) walked on an instrumented walkway to get spatiotemporal parameters (STPs) and center of pressure (CoP). These outcomes were compared to typically developing children (TD): 44 TD 6 to 9 years old and 20 TD 4 to 5 years old.

RESULTS

Analysis revealed differences in all STPs and gait variability index when compared to TD individuals. When AS participants were compared to younger TD individuals, except step length, STPs were different. Analysis of the CoP pathway revealed a less consistent and efficient pathway in AS.

CONCLUSIONS

We could delineate the functional difference between children with AS and TD children. The variability of STP and the CoP were the most valuable components in gait to be considered in AS.

Clinical management of Friedreich's Ataxia: a report of two cases

Introduction

Friedreich's ataxia (FDRA) is the most common autosomal recessive, early-onset ataxia. FDRA is a progressive neurodegenerative disease that mainly affects the posterior (dorsal) columns of the spinal cord resulting in sensory ataxia. It manifests in initial symptoms of poor coordination and gait disturbance.

Case presentation

We present two cases, a brother (54 years old) and sister (56 years old), with FDRA that are chronically institutionalized for incomplete quadriplegia without spasticity. Gait and postural ataxia, cerebellar dysarthria, oculomotor dysfunction, musculoskeletal deformities, hearing impairment, hypertrophic cardiomyopathy, and diabetes mellitus are also present. Neurological examination reveals extensor plantar responses and diminished to absent tendon reflexes. Both are wheelchair bound, cannot perform daily tasks and need assistance.

Discussion

Although there is no cure that can alter the natural course of the disease physiotherapy, management of spasticity and neuropathic pain, symptomatic treatment of heart failure and diabetes and nursing care can grant the patients quality of life.

Feeding difficulties, a key feature of the Drosophila NDUFS4 mitochondrial disease model

Mitochondrial diseases are associated with a wide variety of clinical symptoms and variable degrees of severity. Patients with such diseases generally have a poor prognosis and often an early fatal disease outcome. With an incidence of 1 in 5000 live births and no curative treatments available, relevant animal models to evaluate new therapeutic regimes for mitochondrial diseases are urgently needed. By knocking down ND-18, the unique Drosophila ortholog of NDUFS4, an accessory subunit of the NADH:ubiquinone oxidoreductase (Complex I), we developed and characterized several dNDUFS4 models that recapitulate key features of mitochondrial disease. Like in humans, the dNDUFS4 KD flies display severe feeding difficulties, an aspect of mitochondrial disorders that has so far been largely ignored in animal models. The impact of this finding, and an approach to overcome it, will be discussed in the context of interpreting disease model characterization and intervention studies.This article has an associated First Person interview with the first author of the paper.

Psychometric properties of outcome measures evaluating decline in gait in cerebellar ataxia: A systematic review

Cerebellar ataxia often results in impairment in ambulation secondary to gait pattern dysfunction and compensatory gait adjustments. Pharmaceutical and therapy-based interventions with potential benefit for gait in ataxia are starting to emerge, however evaluation of such interventions is hampered by the lack of outcome measures that are responsive, valid and reliable for measurement of gait decline in cerebellar ataxia. This systematic review aimed for the first time to evaluate the psychometric properties of gait and walking outcomes applicable to individuals with cerebellar ataxia. Only studies evaluating straight walking were included. A comprehensive search of three databases (MEDLINE, CINAHL and EMBASE) identified 53 studies meeting inclusion criteria. Forty-nine were rated as 'poor' as assessed by the COnsensus-based Standards for the selection of health Measurement INstruments checklist. The primary objective of most studies was to explore changes in gait related to ataxia, rather than to examine psychometric properties of outcomes. This resulted in methodologies not specific for psychometric assessment. Thirty-nine studies examined validity, 11 examined responsiveness and 12 measured reliability. Review of the data identified double and single support and swing percentage of the gait cycle, velocity, step length and the Scale for Assessment and Rating of Ataxia (SARA) gait item as the most valid and responsive measures of gait in cerebellar ataxia. However, further evaluation to establish their reliability and applicability for use in clinical trials is clearly warranted. We recommend that inter-session reliability of gait outcomes should be evaluated to ensure changes are reflective of intervention effectiveness in cerebellar ataxia.

Demographic and clinical features and rehabilitation outcomes of patients with Friedreich ataxia: A retrospective study

Objectives

This study aims to investigate the demographic and clinical features, and rehabilitation outcomes of Friedreich Ataxia patients in the inpatient setting.

Patients and methods

Between January 2000 and December 2012, a total of 37 Friedreich Ataxia patients (26 males, 11 females; mean age 29.2±9.6 years; range, 16 to 53 years) were included in the study. Demographic and clinical features of the patients and rehabilitation outcomes were reviewed retrospectively. Duration of rehabilitation, age at onset of disease, first onset of extremity, were determined. The Functional Ambulation Category (FAC) and Hoffer Ambulation Scale levels were used to assess the ambulation levels of patients. The Barthel Index scores were used to assess daily living activities of the patients before and after the treatment.

Results

The mean rehabilitation duration was 4.7±1.4 weeks. There was cardiac involvement in nine (24.3%) patients and obstructive/ restrictive pulmonary disease in five patients (13.5%). A total of 33 patients (89.2%) had severe ataxia, four (10.8%) had mild ataxia, 33 (89%) had dysarthria, 18 (48.6%) had scoliosis, 16 (43.2%) had kyphose, 15 (40.5%) had pes cavus, five (13%) had optic atrophy, and two (6%) had nystagmus of all patients. At the end of the rehabilitation program, all patients were discharged with functionally improved levels based on the FAC, Hoffer Ambulation Scale (p<0.05), and Barthel Index (p<0.001), indicating a statistically significant difference.

Conclusion

An appropriate and comprehensive rehabilitation program improves the ambulation level and independence level of daily activities in patients with Friedreich ataxia, which highlights the importance of rehabilitation in these patients.

A systematic review of the gait characteristics associated with Cerebellar Ataxia

BACKGROUND

Cerebellar Ataxias are a group of gait disorders resulting from dysfunction of the cerebellum, commonly characterised by slowly progressing incoordination that manifests as problems with balance and walking leading to considerable disability. There is increasing acceptance of gait analysis techniques to quantify subtle gait characteristics that are unmeasurable by current clinical methods This systematic review aims to identify the gait characteristics able to differentiate between Cerebellar Ataxia and healthy controls.

METHODS

Following systematic search and critical appraisal of the literature, gait data relating to preferred paced walking in Cerebellar Ataxia was extracted from 21 studies. A random-effect model meta-analysis was performed for 14 spatiotemporal parameters. Quality assessment was completed to detect risk of bias.

RESULTS

There is strong evidence that compared with healthy controls, Cerebellar Ataxia patients walk with a reduced walking speed and cadence, reduced step length, stride length, and swing phase, increased walking base width, stride time, step time, stance phase and double limb support phase with increased variability of step length, stride length, and stride time.

CONCLUSION

The consensus description provided here, clarifies the gait pattern associated with ataxic gait disturbance in a large cohort of participants. High quality research and reporting is needed to explore specific genetic diagnoses and identify biomarkers for disease progression in order to develop well-evidenced clinical guidelines and interventions for Cerebellar Ataxia.

Cerebellar ataxia

The cerebellum plays an integral role in the control of limb and ocular movements, balance, and walking. Cerebellar disorders may be classified as sporadic or hereditary with clinical presentation varying with the extent and site of cerebellar damage and extracerebellar signs. Deficits in balance and walking reflect the cerebellum's proposed role in coordination, sensory integration, coordinate transformation, motor learning, and adaptation. Cerebellar dysfunction results in increased postural sway, hypermetric postural responses to perturbations and optokinetic stimuli, and postural responses that are poorly coordinated with volitional movement. Gait variability is characteristic and may arise from a combination of balance impairments, interlimb incoordination, and incoordination between postural activity and leg movement. Intrinsic problems with balance lead to a high prevalence of injurious falls. Evidence for pharmacologic management is limited, although aminopyridines reduce attacks in episodic ataxias and may have a role in improving gait ataxia in other conditions. Intensive exercises targeting balance and coordination lead to improvements in balance and walking but require ongoing training to maintain/maximize any effects. Noninvasive brain stimulation of the cerebellum may become a useful adjunct to therapy in the future. Walking aids, orthoses, specialized footwear and seating may be required for more severe cases of cerebellar ataxia.

Longitudinal gait and balance decline in Friedreich's Ataxia: A pilot study

INTRODUCTION

Friedreich's Ataxia (FA) is a devastating, progressive, neurodegenerative disease. Objective measures that detect changes in neurological function in FA patients are needed to facilitate therapeutic clinical trials. The purpose of this pilot study was to analyze longitudinal changes in gait and balance in subjects with FA using the GAITRite Walkway System^® and Biodex Balance System™, respectively, and to test the ability of these measures to detect change over time compared to the Friedreich's Ataxia Rating Scale (FARS).

METHODS

This was a 24-month longitudinal study comparing ambulatory FA subjects with age- and gender-matched, healthy controls. Eight FA subjects and 8 controls were tested at regular intervals using the GAITRite and Biodex Balance systems and the FARS.

RESULTS

In the FA group, comfortable and fast gait velocity declined 8.0% and 13.9% after 12 months and 24.1% and 30.3% after 24 months, respectively. Postural stability indices increased in FA subjects an average of 41% from baseline to 24 months, representing a decline in balance. Subjects with FA also demonstrated a 17.7% increase in FARS neurological exam scores over 24 months. There were no changes in gait or balance variables in controls. In the FA group, multiple gait and balance measures correlated significantly with FARS neurological exam scores.

CONCLUSIONS

The GAITRite and Biodex Balance systems provided objective and clinically relevant measures of functional decline in subjects with FA that correlated significantly with performance measures in the FARS. Gait velocity may be an important objective measure to identify disease progression in adults with FA.

Gait and Functional Mobility Deficits in Fragile X-Associated Tremor/Ataxia Syndrome

Fragile X-associated tremor/ataxia syndrome (FXTAS) results from a "premutation" (PM) size CGG repeat expansion in the fragile X mental retardation 1 (FMR1) gene. Cerebellar gait ataxia is the primary feature in some FXTAS patients causing progressive disability. However, no studies have quantitatively characterized gait and mobility deficits in FXTAS. We performed quantitative gait and mobility analysis in seven FMR1 PM carriers with FXTAS and ataxia, six PM carriers without FXTAS, and 18 age-matched controls. We studied four independent gait domains, trunk range of motion (ROM), and movement transitions using an instrumented Timed Up and Go (i-TUG). We correlated these outcome measures with FMR1 molecular variables and clinical severity scales. PM carriers with FXTAS were globally impaired in every gait performance domain except trunk ROM compared to controls. These included total i-TUG duration, stride velocity, gait cycle time, cadence, double-limb support and swing phase times, turn duration, step time before turn, and turn-to-sit duration, and increased gait variability on several measures. Carriers without FXTAS did not differ from controls on any parameters, but double-limb support time was close to significance. Balance and disability scales correlated with multiple gait and movement transition parameters, while the FXTAS Rating Scale did not. This is the first study to quantitatively examine gait and movement transitions in FXTAS patients. Gait characteristics were consistent with those from previous cohorts with cerebellar ataxia. Sensitive measures like the i-TUG may help determine efficacy of interventions, characterize disease progression, and provide early markers of disease in FXTAS.

A novel porcine model of ataxia telangiectasia reproduces neurological features and motor deficits of human disease

Ataxia telangiectasia (AT) is a progressive multisystem disorder caused by mutations in the AT-mutated (ATM) gene. AT is a neurodegenerative disease primarily characterized by cerebellar degeneration in children leading to motor impairment. The disease progresses with other clinical manifestations including oculocutaneous telangiectasia, immune disorders, increased susceptibly to cancer and respiratory infections. Although genetic investigations and physiological models have established the linkage of ATM with AT onset, the mechanisms linking ATM to neurodegeneration remain undetermined, hindering therapeutic development. Several murine models of AT have been successfully generated showing some of the clinical manifestations of the disease, however they do not fully recapitulate the hallmark neurological phenotype, thus highlighting the need for a more suitable animal model. We engineered a novel porcine model of AT to better phenocopy the disease and bridge the gap between human and current animal models. The initial characterization of AT pigs revealed early cerebellar lesions including loss of Purkinje cells (PCs) and altered cytoarchitecture suggesting a developmental etiology for AT and could advocate for early therapies for AT patients. In addition, similar to patients, AT pigs show growth retardation and develop motor deficit phenotypes. By using the porcine system to model human AT, we established the first animal model showing PC loss and motor features of the human disease. The novel AT pig provides new opportunities to unmask functions and roles of ATM in AT disease and in physiological conditions.