NeuroRehabilitation 33 (2013) 621–629 DOI:10.3233/NRE-131002 IOS Press 621 Robot-aided neurorehabilitation in sub-acute and chronic stroke: Does spontaneous recovery have a limited impact on outcome? R. Colombo a,b,∗ , I. Sterpi a , A. Mazzone b , C. Delconte c and F. Pisano c a “Salvatore Maugeri” Foundation, IRCCS, Service of Bioengineering, Pavia, Italy b “Salvatore Maugeri” Foundation, IRCCS, Service of Bioengineering, Veruno (NO), Italy c “Salvatore Maugeri” Foundation, IRCCS, Division of Neurologic Rehabilitation, Veruno (NO), Italy Abstract. BACKGROUND: Robotic neurorehabilitation, thanks to high dosage/intensity training protocols, has the potential for a greater impact on impairment. OBJECTIVE: We aimed to analyze how time since the acute event may influence the motor recovery process during robot-assisted rehabilitation of the upper limb. METHODS: A total of 41 patients after stroke were enrolled: 20 in subacute phase, i.e. ≤ 6 months elapsed since their unilateral cerebrovascular accident (CVA), and 21 at chronic stage, i.e. > 6 months since CVA. All subjects underwent 30 minutes of robot- aided rehabilitation twice a day, 5 days a week for at least three weeks of training. Patients were evaluated at the start and end of treatment using the Fugl-Meyer and Modified Ashworth clinical scales and by a set of robot measured kinematic parameters. The time interval from stroke was considered as a grouping factor to analyze its impact on time course of recovery. RESULTS: After training both groups significantly improved their impairment (F = 44.25, p < 0.001) but sub-acute patients showed a greater improvement on the Fugl-Meyer scale than chronic patients. The time course of recovery of the kinematic variables showed higher time constants of motor improvement in the sub-acute than chronic group, but they were one order lower than spontaneous recovery time constants. CONCLUSIONS: Spontaneous recovery seems to have a limited impact on the improvement of sub-acute patients, most of their changes being likely due to re-learning during rehabilitation. In addition, a longer recovery time was required to maximize outcome in sub-acute than in chronic patients. Keywords: Robotic therapy, motor recovery, stroke, spontaneous recovery, neurorehabilitation 1. Introduction Despite the significant advances in prevention and acute treatment protocols, stroke remains the most important cause of adult disability worldwide (Langhorne, Sandercock, & Prasad, 2009). Motor ∗ Address for correspondence: Ing. R. Colombo, Fondazione Sal- vatore Maugeri, Via Salvatore Maugeri 10, 27100 Pavia, Italy. Tel.: +39 0382 592207; Fax: +39 0382 592081; E-mail: roberto. colombo@fsm.it. impairment, restricting function in arm and leg move- ments and mobility, is the most widely recognised impairment caused by stroke. About half of stroke survivors have impaired hand-arm, and often remain disabled for the remainder of their life (Broeks, Lankhorst, Rumping, & Prevo, 1999; Timmermans, Spooren, Kingma, & Seelen, 2010). Strong evidence shows that repeated task-oriented practice can assist the natural pattern of functional recovery (Levin, Kleim, & Wolf, 2009). Robotic neurorehabilitation, thanks to 1053-8135/13/$27.50 © 2013 – IOS Press and the authors. All rights reserved