Behavioral and neurophysiological effects of an intensified robot-assisted therapy in subacute stroke: a case control study

BACKGROUND: Physical training is able to induce changes at neurophysiological and behavioral level associated with performance changes for the trained movements. The current study explores the effects of an additional intense robot-assisted upper extremity training on functional outcome and motor excitability in subacute stroke patients. METHODS: Thirty moderately to severely affected patients < 3 months after stroke received a conventional inpatient rehabilitation. Based on a case–control principle 15 patients were assigned to receive additional 45 min of robot-assisted therapy (Armeo(®)Spring) 5 times per week (n = 15, intervention group, IG). The Fugl-Meyer Assessment for the Upper Extremity (FMA-UE) was chosen as primary outcome parameter. Patients were tested before and after a 3-week treatment period as well as after a follow-up period of 2 weeks. Using transcranial magnetic stimulation motor evoked potentials (MEPs) and cortical silent periods were recorded from the deltoid muscle on both sides before and after the intervention period to study effects at neurophysiological level. Statistical analysis was performed with non-parametric tests. Correlation analysis was done with Spearman´s rank correlation co-efficient. RESULTS: Both groups showed a significant improvement in FMA-UE from pre to post (IG: + 10.6 points, control group (CG): + 7.3 points) and from post to follow-up (IG: + 3.9 points, CG: + 3.3 points) without a significant difference between them. However, at neurophysiological level post-intervention MEP amplitudes were significantly larger in the IG but not in the CG. The observed MEP amplitudes changes were positively correlated with FMA-UE changes and with the total amount of robot-assisted therapy. CONCLUSION: The additional robot-assisted therapy induced stronger excitability increases in the intervention group. However, this effect did not transduce to motor performance improvements at behavioral level. Trial registration The trial was registered in German Clinical Trials Register. Clinical trial registration number: DRKS00015083. Registration date: September 4th, 2018. https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00015083. Registration was done retrospectively