Bi-hemispheric repetitive transcranial magnetic stimulation for upper limb motor recovery in chronic stroke: A feasibility study

Background:

The emerging crucial role of non-primary and contralesional motor areas in the recovery of upper extremity (UE) after acute strokeled to the proposal ofthe “bimodal-balance recovery model”, with the hypothesis that the contribution of ipsi-and contralesional primary and secondary motor areas might vary according to the structural reserve of the ipsilesional cortico-spinal tract. This model offers itselfto novel non-invasive brain stimulation approaches for improving the effects of neurorehabilitation, targeting bilateral, wide motor cortical regions rather than focusing on the ipsilateral or contralesional M1.

Objective:

To test the safety, feasibilityand efficacy of simultaneous high-frequency rTMS of bilateral motor/premotor areas using the H5-coil, associated with unilateral motor training of the paretic UE.

Methods:

Twentypatients with UE motor involvement fromfirst-ever chronic stroke underwent11 sessions of 30 minutes of upper limb motor training (MT) of the paretic UE, each followed by rTMS with thesymmetric H5-coil, designed to stimulate both hemispheres simultaneously(40 2s-trains at 20 Hz, 20 sec inter-train interval, 1600 pulses), at 90% of resting motor threshold (RMT). Clinical measurements were collectedbefore thefirst (T0) and after the last treatment session (T1), plusone-month follow-up (T2) and included: FM-UE score, modifiedAshworth scale (MAS) global score as the sum of shoulder, elbowand wrist scores (range 0-12), handgrip strength (JAMARdynamometer).

Results:

In this study that included participants with mild to severe-moderate UE motor impairment, bilateral high-frequency rTMS ofmotor/premotor areas, following motor training, was associatedwith greater and more sustained motor improvement comparedwith motor trainingfollowed by sham. Such improvement was clinically relevant (FM-UE6 point) for 70% of subjects in the real group (vs 10%of the sham group).Interestingly, the investigators found that bilateral stimulation of motor/premotor areas was associated with a greater FM-UE improvement in more severely impaired patients, opposite to what observed in the sham group.

Conclusions:

It is possible that the wide bilateral, simultaneous stimulation may improve functional intra-and interhemispheric synchronization between motor and premotor areas and promote the unmasking of cortico-cortical and descending pathways

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