Elsevier

Neuromuscular Disorders

Volume 29, Issue 10, October 2019, Pages 786-793
Neuromuscular Disorders

Changes detected in swallowing function in Friedreich ataxia over 12 months

https://doi.org/10.1016/j.nmd.2019.08.013Get rights and content

Highlights

  • Measurable changes detected in swallowing function in 12 months.

  • Decline in function observed at three anatomical sites considered important for safe swallowing.

  • Individual anatomical sites may be precursors to widespread functional decline in swallowing.

Abstract

Friedreich ataxia (FRDA) is a multisystem neurodegenerative disorder and the most common hereditary ataxia. Dysphagia (swallowing impairment) is present in 98% of individuals with FRDA and is characterized by lingual and pharyngeal dysfunction (manifesting in impaired bolus preparation and transfer, and post-swallow residue in the mouth and pharynx), delayed swallow initiation, and entry of material into the airway (penetration/aspiration). Dysphagia severity correlates with disease severity and duration however no longitudinal studies describe changes in function in FRDA. The aim of this study was to investigate the progression of dysphagia in FRDA over one year. Fifty-nine individuals with FRDA and confirmed dysphagia were recruited and 23 of them underwent a second assessment 12 months later. Assessments of swallowing related quality of life, oral motor function (Frenchay Dysarthria Assessment 2nd Ed [FDA-2]) and functional swallowing via videofluoroscopy were conducted. Trials of thin liquid, puree and biscuit were interpreted using the Bethlehem Assessment Scale and the Penetration-Aspiration Scale by two blinded raters. Data from the videofluoroscopy revealed a decline in tongue function, pharyngeal clearance and cricopharyngeal function on solid food. However, severity of penetration/aspiration did not increase. Swallowing-related quality of life and oral-motor function remained stable. A decline in function was observed at three anatomical sites considered important for safe and effective swallowing (tongue, pharyngeal, and cricopharyngeal). However, these deficits did not translate into any meaningful functional decline in swallowing related health over 12 months for individuals with FRDA.

Introduction

Friedreich ataxia (FRDA) is an autosomal recessive neurodegenerative condition resulting from deficiency of frataxin. In 96% of affected individuals, it is caused by homozygosity for a GAA trinucleotide repeat expansion in intron 1 of FXN [1], with the size of the smaller allele (GAA1) inversely correlated with symptom onset and severity [2]. FRDA is the most common of the hereditary ataxias, affecting approximately 1 in 29,000 individuals in European populations [3]. Symptoms often present in the teenage years (but can appear earlier or later [4], [5]) and include progressive gait and limb ataxia, auditory [6] and optic neuropathy [7], cardiomyopathy, scoliosis, dysarthria [8] and dysphagia [9], [10]. These symptoms impose significant morbidity and negatively impact on quality of life (QOL) [9–11].

Dysphagia is present in almost all individuals with FRDA [9]. Delayed pharyngeal swallowing initiation is common, as are lingual dysfunction and reduced clearance of solid foods from the pharyngeal structures [9], [10], reflecting underlying motor and sensory impairment. Approximately one-third of individuals with FRDA aspirate barium on videofluoroscopy (VFSS) with fluids and/or solids, and many of those do so silently [9]. A relationship is known to exist between aspiration and penetration of the airway and oromotor function relating to coughing, swallowing, and saliva control (X2(1, N = 30) = 5.98, p = 0.01) [9]. Aspiration can occur at any stage of disease progression [9], necessitating the need for monitoring of swallowing function in affected individuals.

Dysphagia is known to present significant challenges for individuals with FRDA, including reduced ability to participate in social gatherings and overall QOL [9], [10]. Significant positive correlations have been reported between swallowing-related QOL and dysphagia (as determined via VFSS), disease severity and duration [9], suggesting swallowing function progressively declines in this population. The rate at which swallowing function changes is unknown. Longitudinal data on swallowing function in FRDA may provide valuable prognostic information on the clinical course of the disease and further inform our understanding of the underlying disease mechanisms in FRDA.

Here we describe the rate of dysphagia progression over one year using scales deemed best clinical practice. An understanding of the relationship between disease and dysphagia progression is important to guide management and intervention [12], [13], [14], given dysphagia treatment has been shown to be less effective in the later stages of other neurodegenerative diseases [12]. Longitudinal data on swallowing function in FRDA will also provide valuable information on the clinical course of the disease, enhancing our understanding of the progression of this area of morbidity.

Section snippets

Participants

Twenty-three of 59 individuals from a previous study [9] participated in swallowing assessment at two timepoints (timepoint 1; TP1, and timepoint 2; TP2). Participants were recruited through the Friedreich Ataxia Clinic in Melbourne, Australia, and all had a genetically confirmed diagnosis of FRDA (homozygous for FXN intron 1 GAA expansions) (Table 1). Participants were excluded if they presented with a neurological disorder other than FRDA, or a speech and/or swallowing impairment prior to the

Participant characteristics

Twenty-three of the original 59 (40%) participants completed the second assessment (Fig. 1). Seventeen participants repeated the Swal-QOL (mean age 37.48 years, standard deviation 13.71 years), 9 participated in repeat FDA-2 assessment, and 12 underwent VFSS (Table 1). Repeated assessments were completed as close to 12 months apart as possible which coincided with the participants’ yearly visit to the FRDA clinic. On average, Swal-QOL assessment was conducted 332.4 days apart (range 194–423

Discussion

Small but measurable changes in swallowing function were observed in individuals with FRDA over a one-year period. Changes in swallowing function were observed between timepoints on self-report measures of dysphagia symptoms, oromotor performance on respiration tasks and oral and pharyngeal clearance of solid textures of food as determined via VFSS. These changes were observed in the absence of significant change to disease severity. Whilst this study is small in scale, it is the largest study

Acknowledgments

The authors wish to thank the participants for their involvement in this study and the staff at the Friedreich Ataxia Clinic and Monash Health Diagnostic Imaging departments for assistance with subject recruitment and VFSS, respectively.

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