Gait initiation and termination strategies in patients with Prader-Willi syndrome

Veronica Cimolin,Cristina Santovito,Nicola Cau,Graziano Grugni,Manuela Galli,Paolo Capodaglio

doi:10.1186/s12984-017-0257-7

Abstract

BackgroundGait Initiation (GI) is a functional task representing one of the first voluntary destabilizing behaviours observed in the development of a locomotor pattern as the whole body centre of mass transitions from a large to a small base of support. Conversely, Gait Termination (GT) consists in the transition from walking to standing which, in everyday life, is a very common movement. Compared to normal walking, it requires higher control of postural stability. For a safe GT, the forward movement of the body has to be slowed down to achieve a stable upright position. Stability requirements have to be fulfilled for safe GT. In individuals with Prader-Willi syndrome (PWS), excessive body weight negatively affects the movement, such as walking and posture, but there are no experimental studies about GI and GT in these individuals. The aim of this study was to quantitatively characterise the strategy of patients with PWS during GI and GT using parameters obtained by the Center of Pressure (CoP) track.MethodsTwelve patients with PWS, 20 obese (OG) and 19 healthy individuals (HG) were tested using a force platform during the GI and GT tasks. CoP plots were divided into different phases, and duration, length and velocity of the CoP trace in these phases were calculated and compared for each task.ResultsAs for GI, the results showed a significant reduction of the task duration and lower velocity and CoP length parameters in PWS, compared to OG and HG. In PWS, those parameters were reduced to a higher degree with respect to the OG. During GT, longer durations, similar to OG, were observed in PWS than HG. Velocity is reduced when compared to OG and HG, especially in medio-lateral direction and in the terminal part of GT.ConclusionsFrom these data, GI appears to be a demanding task in most of its sub-phases for PWS individuals, while GT seems to require caution only towards the end of the task. Breaking the cycle of gait into the phases of GI and GT and implementing specific exercises focusing on weight transfer and foot clearance during the transition phase from the steady condition to gait will possibly improve the effectiveness of rehabilitation and fall and injury prevention

Highlights

Gait Initiation (GI) is a functional task representing one of the first voluntary destabilizing behaviours observed in the development of a locomotor pattern as the whole body centre of mass (COM) transitions from a large to small base of support
The LAPA2A length was lower in Prader-Willi syndrome (PWS) than OG, but not with respect to HG: PWS showed similar values compared to HG
As for GI, the results showed a significant reduction of velocity and Center of Pressure (CoP) length parameters in PWS, with respect to the non-genetically obese subjects

Summary

Introduction

Gait Initiation (GI) is a functional task representing one of the first voluntary destabilizing behaviours observed in the development of a locomotor pattern as the whole body centre of mass transitions from a large to a small base of support. There is a body of literature on various “sub-tasks” of walking that may compromise stability, such as initiation, termination, turning, obstacle crossing, negotiating a raised surface and stair climbing In all these tasks balance is challenged during the transition from one, either statically stable or dynamically stable movement pattern, to another [1]. GI is a functional task representing one of the first voluntary destabilizing behaviours observed in the development of a locomotor pattern as the whole body centre of mass (COM) transitions from a large to small base of support (from a bipedal to a monopedal position related to gait) This task represents a challenge to the postural control system due to the volitional transition from a condition of relatively static stable support to one of continuously unstable posture during locomotion [8,9,10,11] and one that has been shown to be a sensitive indicator of balance dysfunction [11]

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