The effect of forward arm extension on gait initiation in patients with Parkinson*s disease

Walking of patients suffering from Parkinson*s disease (PD) is characterized by
small steps, loss of arm swing and starting problems. Impaired function of the
Supplementary Motor Area (SMA), which is an important output target of
striato-thalamic projections, is argued to play a causal role in this
disturbance of both motor initiation and organization of multi-limb movements.
By applying forward arm extension as a cue for gait initiation, we hypothesize
that starting to walk will improve due to (i) facilitating SMA activity to fuel
the cyclic motor program of gait and (ii) a forward shift of the patient*s
axial center of gravity, stimulating the natural response of a forward foot
placement.

To assess whether forward extension of both arms improves gait initiation in
patients with PD, measured by faster coverage of the initial two meters of
walking. Secondary objectives are to determine whether this change in
performance can be measured accurately using only a stopwatch and distance
markers and to what extent the use of inertial measurement units (IMUs) adds
essential information. Moreover, the relationship between these parameters and
the patient*s subjective assessment of gait initiation will additionally be
assessed.

Observational study

During the tasks gait initiation performance will be measured using IMUs
(integrating accelerometers, gyroscopes and magnetometers in a matchbox-like
container) on both shanks and both thighs and a stopwatch and distance markers.
The IMUs can be used to determine bilateral step size and gait velocity
objectively and accurately. Gait will be assessed over a distance of six meters
with timing passage of the initial two meters distance and the full six meters.
For future clinical application, we will additionally investigate whether
measurement of gait velocity using only a stopwatch and distance markers is
sufficiently accurate, as well. After measurement preparation and task
instruction, the participant has to perform the following tasks:
1. 6 meter walk test (repeated 3 times, initiated at a verbal signal of the
examiner) without arm extension
2. 6 meter walk test (repeated 3 times, initiated at a verbal signal of the
examiner) with simultaneous arm extension at gait initiation

The six gait trials will be executed semi-randomly; the first trial will always
be gait initiation without arm extension. After executing all trials patients
will be asked about their subjective assessment of their performance using a
questionnaire.

Other parameters of interest (Hoehn & Yahr stage, MDS-UPDRS part III score,
side of symptom dominance) will be collected from the patient*s file.
The study will consist of a pilot study and a cross-sectional study in which
gait initiation performance with and without arm extension will be compared in
PD patients.

Forward arm extension at gait initiation

There are no risks or benefits, and the burden is limited to the time invested
in the test (approximately 30 minutes, with breaks if necessary).