Chronic
hemiparesis of an upper limp[sic] following stroke has been related to an
over-involvement of the ipsilateral hemisphere that inhibits use of the
affected limb. Interventions helping to shift back this altered
lateralization have been suggested to positively affect upper limp
functional recovery. One such intervention is the combination of motor
imagery (MI) supported by EEG neurofeedback. However, cortical
reorganization requires highly intensive practice. In this feasibility
study this was achieved by implementing a mobile EEG neurofeedback
system.
The training regime consisted of 14 MI sessions over a
time course of 4 weeks. Three chronic stroke patients practiced MI
neurofeedback using kinaesthetic imagination of a power grip of either
the affected or the unaffected hand. Neurofeedback was based on features
extracted from the 8-30 Hz frequency range. MI training was conducted
at the patients’ home using a fully mobile 24-channel EEG system. Before
and after the training, motor functions were assessed using a modified
version of the Fugl-Meyer Assessment (FMA) and the modified Motor
Assessment Scale (MAS). Moreover, pre- and post-training 96-channel EEG
recordings were performed for MI and movement execution (ME) of the
power grip task that was used for the MI neurofeedback training.
Event-related desynchronization (ERD) in the 8–30 Hz frequency range was
extracted offline for a region of interest analysis. Analysis focused
on contra- and ipsilateral ERD and on the lateralization of ERD, defined
as the difference between contralateral and ipsilateral ERD.
All
patients remained motivated throughout the training and completed the
training regime. During MI and ME with the unaffected hand, patients
showed stronger contralateral than ipsilateral activity in both the pre-
and the post-training sessions. For the affected hand, MI and ME were
however associated with stronger ipsilateral than contralateral
activity. Changes were observed over the course of training, that, on a
descriptive level, suggest a reduction of the altered lateralization for
the affected hand in all three patients during MI. Furthermore, for one
patient a significant improvement in the FMA score was observed, which
paralleled the changes in MI and ME induced ERD.
This study
demonstrates that home-based MI neurofeedback training is feasible and
allows for highly intensive training regimes. The observations made are
in line with the notion of an over-involvement of the ipsilateral
hemisphere during activities of the affected limb. The described changes
of lateralization with MI neurofeedback training encourage continuing
this line of research with larger sample sizes and matched healthy
controls, to see if home-based MI neurofeedback training can indeed help
to shift MI- and ME-related activation towards the expected
lateralization patterns.
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