A new study on Friedreich’s Ataxia entitled “Sensitivity of Spatiotemporal Gait Parameters in Measuring Disease Severity in Friedreich Ataxia,” was recently published in the journal Cerebellum.
Friedreich’s ataxia (FRDA) is an autosomal recessive disease, with gait ataxia being the main source of morbidity. Mobility progressively declines, from initial symptom onset at approximately 10–15 years of age to being unable to ambulate 10–15 years later.
FRDA affects nearly 1 in 30,000 caucasian individuals. Homozygous GAA trinucleotide expansions in intron 1 of FXN are found in 93% of the patients, while the remaining 7% of affected patients have an expanded GAA repeat on one allele and a point mutation or deletion on the other. The initial symptoms of FRDA are usually ‘clumsiness’ and gait ataxia with average symptom onset between 10 and 15 years. The progressive decline in gait is thought to be largely related to spinocerebellar degeneration, peripheral sensory neuropathy and cerebellar and vestibular pathology. However, the contribution of these functional neurological systems to gait deterioration remains unclear. Gait analysis measures gait quality, providing information on spatiotemporal characteristics of gait, compensatory mechanisms for deconditioning and impaired balance, an may be sensitive to early identification of specific pathologies.
In this regard, Sarah C. Milne from the Physiotherapy Department, Kingston Centre, Monash Health, Cheltenham in Australia and colleagues, examined the relationship between spatiotemporal gait parameters and clinical markers of disease severity in 13 patients with FRDA.
The patients were asked to walk along an 8.3-m GAITRite® mat six times each, at three different self-selected speeds: preferred, fast and slow. These speeds were selected as they reflect most aspects of daily walking. GAITRite® is a walkway used to measured both averaged and individual step parameters of gait. Its software calculates spatial and temporal parameters in response to sensory activation as a person walks across the walkway.
The results revealed a relationship between spatiotemporal gait characteristics at each of the walking speeds and Friedreich Ataxia Rating Scale (FARS) score and disease duration. When patients were walking fast, gait speed and cadence decreased with an increase in disease duration and the FARS score.
GAA1 repeat expansion was found to be negatively correlated with double-support percentage of the gait cycle in all speed conditions demonstrating a relationship between the genetic mutation and compensatory strategies for impaired dynamic balance. In all speed levels, there were correlations between spatiotemporal gait characteristics and the timed 25-ft walk test.
Results from this study strongly indicate that measuring gait decline through spatiotemporal gait parameters is an affective tool to be used in patients with FRDA. The researchers suggest that further studies should examine longitudinal changes with larger sample sizes to investigate the subtle gait changes over time that may sensitively track early response to therapeutic interventions.
Moreover, studies involving the peripheral and central nervous systems in gait dysfunction in FRDA are necessary.