1st Joint ESMAC-GCMAS Meeting - Análise de Marcha

O-59
AUDITORY-PACED WALKING FOLLOWING STROKE
Roerdink, Melvyn, MSc 2 , Lamoth, Claudine, PhD 1 , Kwakkel, Gert, PhD 1,2 , van Wieringen, Piet,
PhD 2 , Beek, Peter PhD 1
1 Institute for Fundamental and Clinical Human Movement Sciences, Faculty of Human
Movement Sciences, Vrije Universiteit, Amsterdam, The Netherlands
2 Department of Physical Therapy, Vrije Universiteit Medical Centre, Amsterdam, The
Netherlands
Summary/conclusions
Gait coordination is usually compromised following stroke. Auditory pacing seems to be an
expedient means to improve hemiplegic gait coordination, although, to date, detailed studies of
the temporal coupling between pacing signal and gait characteristics have been lacking. In the
present study this coupling was studied in both healthy and hemiplegic participants walking on a
treadmill. Hemiplegics predominantly coordinated the movements of their non-paretic lower limb
to ipsilateral auditory pacing stimuli. This instance of perceptual-motor anchoring may provide
promising possibilities for future therapeutic interventions.
Introduction
Stroke patients’ gait coordination is often hampered by a marked interlimb asymmetry, impaired
timing of thoracic-pelvic rotations, and altered coordinative variability [1-2]. The use of auditory
pacing as a therapeutic technique may positively affect hemiplegic walking, e.g., in terms of
walking velocity, stride length and gait symmetry [2]. Unfortunately, the temporal coupling
between pacing signal and gait has not been studied thus far, in spite of the fact that a detailed
analysis of auditory-motor coordination might provide valuable information about the underlying
motor control processes. The purpose of this study was to examine auditory-motor coordination
in paced walking following stroke, in particular the coordination between footfalls and the
auditory pacing signal.
Statement of clinical significance
A better understanding of auditory-paced walking in both unimpaired and pathological gait
coordination might lead to both evidence- and theory-based rehabilitation goals, cf. [2].
Methods
Six individuals with chronic post-stroke hemiparesis and six age-matched healthy controls
volunteered in the study. First, the stride frequency was determined when participants walked at
their comfortable velocity on a treadmill. Subsequently, while keeping velocity constant, stride
frequency was manipulated by means of auditory pacing. The pacing frequency increased in three
steps from 90%, via 100%, to 110% of the stride frequency observed in unpaced comfortable
treadmill walking. Participants were instructed to synchronize heel strikes with ipsilateral
auditory pacing stimuli, that is, heel strikes of the left (right) foot had to be synchronized with
auditory beeps presented at the left (right) ear. Auditory-motor coordination (i.e., mean absolute
error between pacing frequency and stride frequency | ∆f| and variability of the relative phase
between ipsilateral instants of auditory pacing and heel strikes σ) was compared between groups.
Results
All control participants and four stroke patients coupled their stride frequency to the prescribed
auditory pacing frequency. On average | ∆f | was 0.05 strides/min. In Figure 1, individual
spectrograms are shown. The two patients with poor frequency coupling made more strides in the
90% pacing condition and fewer strides in the 110% pacing condition than prescribed (Figure 1,
lower panel). Note that stroke patients’ spectrograms exhibited larger stride-frequency variability
as well. This tendency was statistically significant at the group level, i.e., stride interval
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