Intermanual transfer using mental imagery in prosthetic training

People with an upper extremity amputation often choose to have fitted a
prosthesis to restore the functionality for as best as possible. Nevertheless,
about 30% of upper extremity amputees do not use their prosthesis at all due to
a low degree of functional use (Biddiss, Chau 2007, Dudkiewicz, Gabrielov et
al. 2004, Kyberd, Davey et al. 1998, Plettenburg 2002). The functional use of
upper extremity prostheses is not only determined by its function, the
technical possibilities, but also by its functionality, the way the amputee is
able to handle the prosthesis. In an earlier study of our research group is
shown that prosthetic skills can be improved when using intermanual transfer
(Romkema, Bongers et al. 2013).

Intermanual transfer implies that when you learn a motor task with one arm, not
only that arm improves, but also the arm at the other side becomes better in
the specific task (Hicks, Gualtieri et al. 1983, Karni, Meyer et al. 1998,
Kumar, Mandal 2005, Lee, Hinder et al. 2010, Mier, Petersen 2006, Pereira, Raja
et al. 2011). The untrained side thus benefits from the trained side. The
effect of intermanual transfer is shown to be present in prosthetic use, as
well in body-powered (Weeks et al., 2003) as in myo-electric prosthesis
(Romkema et al., 2012). We showed that after training of the *unaffected* side
using the simulator, the level of skills at the start of the prosthetic use
with the *affected* side was increased. This effect can be useful in
rehabilitation after an upper limb amputation, because the training can be
started earlier.

It is found that it is of great importance to start to train in the first month
after the amputation to achieve maximum success in prosthetic use (Atkins 1992,
Dakpa, Heger 1997, Gaine, Smart et al. 1997). But in this period often the
wounds are not healed yet and the prosthesis is not finished. To be able to
start to train within these weeks, in our last study (NL 35268.042.11) we used
a prosthetic simulator on the unaffected limb. A prosthesis simulator is an
upper limb prosthesis that can be applied to a sound arm. With the prosthesis
simulator the effects of a myo-electric prosthesis can be mimicked. In
myo-electric prostheses the hand is opened and closed by a motor that is
activated by electrical signals produced by the muscles. The simulator can be
used in the same way. It is applied over the arm, where the prosthetic hand is
placed in front of the sound hand (see figure 1 of the research protocol).
Therefore the training with the simulator is comparable. With an upper limb
prosthetic simulator training can start with the unaffected hand. Because of an
intermanual transfer effect a higher starting level can be reached at the time
the prosthetic training is started on the amputated side.
From our earlier study we know that after training functional and force control
tasks with the simulator on one arm, the movement times in the other arm
decreased. Though the effect is minimal en we would like to enlarge it by using
mental imagery.

The objective of this study is to determine the surplus value of mental imagery
on myo-electric prosthesis training Here fore we plan to execute two
experiments.

The goal of the first experiment is to test if intermanual transfer effects of
able-bodied adults using the simulator can be increased. There will be two
training groups. The participants in these groups learn to use the simulator on
one arm (training arm). The other arm (test arm) is tested to find out if there
is an intermanual transfer effect. One group will only obtain intermanual
transfer training while the other group obtains intermanual transfer training
extended with mental imagery. Both training groups will get a functional
training and a training focused on force control. The control group receives a
sham training not consisting of motor learning. All training programs take 45
minutes per session and are executed on five consecutive days.

In the second experiment, it will be revealed if the transfer effects are not
only present in prosthetic simulators but also in real prostheses. For
rehabilitation it is of great importance to find out if the effects found in
prosthetic simulators are also present in prosthetic users. At the moment a
study on the intermanual transfer effects in a small amount of patients using a
myo-electric prostheses (maximal eight) takes place (NL 35268.042.11 and NL
43335.042.13). Because in the end our study focuses on these patients we would
like to include them also in this study. These two patients will follow the
training where intermanual transfer and mental imagery are compared.

The results of these patients can afterward be compared with the patients that
did not followed a training and with patients that trained using intermanual
transfer only. These patients were measured in the earlier studies and this is
to burden the patient group as less as possible.

Voor elk van de doelen wordt een experiment uitgevoerd met een eigen design
(zie tabel 1-2 uit het onderzoeksprotocol). Voor alle tests worden de zelfde
taken en metingen gebruikt.

In het eerste experiment wordt gekeken wat het additionele effect van mental
imagery is. Er zijn twee trainingsgroepen en een controle groep. De
proefpersonen in de trainingsgroepen leren de simulator aan één hand
(trainingshand) te gebruiken. De andere hand (testhand) wordt gemeten om te
kijken of hier vooruitgang is. De eerste groep traint intermanuele transfer en
mental imagery, de tweede groep traint alleen intermanual transfer en de
controle groep krijgt een sham training. De trainingen zijn gericht op
functionele en krachtscontrole taken. En alle trainingsprogramma*s worden
uitgevoerd gedurende 45 min uitgevoerd op 5 opeenvolgende dagen.

De meetmomenten bestaan uit een een pretest, posttest en een retentietest (zes
dagen na afronding van de training), waarmee wordt bekeken of er leereffecten
aanwezig zijn en tevens of deze behouden blijven.

Het tweede experiment is bedoeld om bovenstaande resultaten te kunnen
generaliseren naar de patiënten. Voor dit deel worden patiënten met een
armamputatie die in aanmerking komen voor een eerste myo-electrische prothese
geïncludeerd. Het design van het experiment is gelijk aan die van de hierboven
beschreven experimenten met uitzondering van de pretest, die wordt weggelaten,
omdat deze vanwege de amputatie niet uitvoerbaar is.

In experiment 1 , three groups of 16 participants train to use an prosthetic
simulator on 5 consecutive days for 45 minutes. One group trains, beside
intermanual transfer also mental imagery, where using mirror therapy and motor
imagery, movements are learned by imagining these. In experiment 2 patients
with an upper limb amputation train the unaffected hand with the prosthetic
simulator. The prosthetic simulator mimics a real prosthesis, though can be
worn on the sound arm. The prosthetic hand of the simulator is placed in front
of the sound hand.

Performing tasks with a prosthetic simulator and mental imagery don't have any
risks.