Article

PURPOSE: To investigate the effect of inhibitory low frequency repetitive
Transcranial Magnetic Stimulation (rTMS) applied to the non-lesioned hemisphere
on kinematics and coordination of paretic arm reach-to-grasp (RTG) actions in
individuals with stroke. RELEVANCE: This study is designed as a phase I trial to
determine the feasibility and efficacy of low frequency rTMS applied to the
non-lesioned hemisphere for the recovery of reach-to-grasp actions in individuals
with hemiparesis secondary to stroke. The results have important implications for
the use of rTMS in parallel with complex paretic arm skill practice.
PARTICIPANTS: Nine adults, anterior circulation unilateral stroke. Their average
age was 59 years, the average time since stroke was 4.8 years. METHOD AND
ANALYSIS: Two TMS treatments were performed on two separate days: active rTMS and
sham rTMS. Cortico-motor excitability (CE) of the non-lesioned hemisphere as well
as RTG kinematics of the paretic hand as participants reached for a dowel of 1.2
cm in diameter was assessed before and after the rTMS treatments. In the active
condition, rTMS was applied over the "hot spot" of the extensor digitorum
communis muscle (EDC) in primary motor cortex (M1) of the non-lesioned hemisphere
at 90% resting motor threshold. TMS pulses were delivered at 1 Hz for 20 min. In
the sham condition, a sham coil was positioned similar to the active condition;
TMS clicking noise was produced but no TMS pulse was delivered. DEPENDENT
MEASURES: CE was measured as peak-to-peak amplitude of the motor evoked potential
at 120% of resting motor threshold. RTG kinematics included movement time, peak
transport velocity, peak aperture, time of peak transport velocity and time of
peak aperture. RTG coordination was captured by cross correlation coefficient
between transport velocity and grasp aperture size. RESULTS: While 1 Hz rTMS
applied over non-lesioned M1 significantly decreased the MEP amplitude of
non-paretic EDC, sham TMS did not have a significant effect on MEP amplitude.
Active rTMS significantly decreased total movement time and increased peak grasp
aperture. There were no changes in peak transport velocity or the time of peak
transport velocity or the time of peak aperture after application of active rTMS.
Additionally, the participants completed RTG actions with a more coordinated
pattern after undergoing active rTMS. Following sham TMS, there were no changes
in CE, RTG kinematics or coordination. While there were no significant
correlation between changes in cortico-motor excitability and RTG kinematics, the
decrease in cortico-motor excitability of the non-lesioned hemisphere showed a
strong correlation with an increase in cross-correlation coefficient. CONCLUSIONS
AND IMPLICATIONS: The findings demonstrate the feasibility and efficacy of low
frequency rTMS applied to the non-lesioned hemisphere for the recovery of
reach-to-grasp actions in individuals with hemiparesis secondary to stroke. The
inhibitory effect of low frequency rTMS resulted in improved paretic hand
reach-to-grasp performance with faster movement time and more coordinated
reach-to-grasp pattern. These results have important implications for the use of
rTMS for stroke rehabilitation.

Langue : ANGLAIS