Quantitative analysis of upright standing in adults with late-onset Pompe disease

Abstract

Pompe disease is a rare disorder producing muscle weakness and progressive impairments in performing daily motor activities, such as walking and standing. Most studies have focused on dysfunctions at cellular level, restricting the examination of gross motor functions to qualitative or subjective rating scales evaluations. With the aim of providing an instrumented quantification of upright standing in Pompe disease, we used a force platform to measure the center of pressure over three foot positions and with eyes open and closed. Amplitude and variability of body sway were measured to determine the level of postural stability, while power spectrum analysis and nonlinear computations were performed to explore the structure of the postural control. In comparison with healthy participants, patients with Pompe disease showed a reduced level of postural stability, but irrelevant variations in frequency content and spatio-temporal structure of the sway motion were detected. Changes in foot position did not increase the postural instability associated with Pompe disease, but prominent worsening occurred in the patients when they stand with eyes closed, particularly along the anterior-posterior direction. These results provide objective elements to monitor deficiencies of upright standing in Pompe disease, emphasizing the specific contributions of sway direction and sensory deficits.

Selective improvements in balancing associated with offline periods of spaced training

“…Increasing of temporal and spatial complexity reflects the need to integrate many information for the coordination and optimization of the postural performance. This interpretation is shared with most of the relevant literature 28 , 29 , 44 – 49 .…”

“…For example, the loss of ability to produce adaptive and complex motor pattern in many postural disorders is associated with a decrease in ApEn 29 , 45 , 49 , while increases in ApEn are reported when postural training is adopted to improve sensory and/or motor coordination in several contexts 28 , 47 , 48 , 50 .…”

“…During the learning time course, the overall postural stability progressively improved across the sessions of practice, but changes in spatio-temporal dynamics and in the spectral contents of the postural oscillations occurred specifically along the anterior-posterior (AP) direction and only one week after the end of the training. Typically, the AP and medial-lateral (ML) directional components exhibit functional differences also during quiet stance, with more unstable movements along the AP than ML direction 27 – 29 .…”

Design and Validation of a Low-Cost Portable Device to Quantify Postural Stability

“…It is also clearly indicated that greater instability along the AP direction than the ML direction during quiet standing (1.62 > 1.05 and 0.52 > 0.42). This is consistent with literature and it is commonly understood that the passive mechanical constraints at ankle and knee joints largely minimizes the ML motion, while more degrees of freedom are available for the movements along the AP direction [27]. …”

Characterization of Gait and Postural Regulation in Late-Onset Pompe Disease

“…Additionally, analysis of these features might be a tool for following up on future therapeutic strategies (i.e., next level ERT order gene therapy) [9]. There is a paucity in this research, with one study reporting reduced spatio-temporal parameters during gait in 22 LOPD patients on ERT [10] and another showing deficits in standing postural stability among five LOPD patients [11].…”