Facilitating robot-assisted training in MS patients with arm paresis A procedure to individually determine gravity compensation H. Bastiaens, G. Alders, P. Feys Rehabilitation Research Center - REVAL PHL University College, Dpt. Healthcare Hasselt, Belgium pfeys@mail.phl.be P. Feys Biomedical Research Institute - BIOMED Hasselt University Diepenbeek, Belgium peter.feys@uhasselt.be S. Notelaers, K. Coninx Expertise Centre for digital Media - EDM Hasselt University – tUL – IBBT Diepenbeek, Belgium karin.coninx@uhasselt.be L. Kerkhofs, V. Truyens Dept. Occupational Therapy Rehabilitation & MS Centre Overpelt, Belgium R. Geers Centre of Expertise in Rehabilitation and Audiology Adelante Revalidatie Hoensbroek, The Netherlands r.geers@adelante-zorggroep.nl A. Goedhart Dept. Fysiotherapy Revalidatiecentrum Blixembosch Eindhoven, The Netherlands a.goedhart@blixembosch.nl Abstract—Gravity compensation (GC) of the arm is used to facilitate arm movements in conventional therapy as well as in robot-assisted rehabilitation of neurologically impaired persons. Positive effects of GC on Range of Motion (ROM) have been demonstrated in stroke. In Multiple Sclerosis (MS), research regarding this topic is lacking. Since an active participation of the patient is required for effective training, full support of the arm might not be advisable. The present study reports on the development of a procedure to measure actively the individual need for GC and to estimate the influence of GC on ROM during reaching, lifting and transporting in severely affected Persons with MS (PwMS). Ten PwMS were tested with the procedure for determination of GC. Maximal reaching movements were performed in a 3D space in three conditions: No support (NS), with GC by the HapticMaster (GC-HM) and with GC by the HapticMaster combined with a sling suspension system (GC- HMS). For the total sample, significant correlations were found between the amount of GC and clinical tests for upper limb function. In four subjects with severe arm dysfunction it was found that mean ROM is larger in the GC-HMS condition compared to the GC-HM condition, and in the GC-HM condition compared to the NS condition, suggesting positive effects of GC on active ROM in PwMS. Therefore, GC could have a positive effect on arm rehabilitation by enabling the PwMS to actively reach a larger ROM during training. Keywords-multiple sclerosis; gravity compensation; haptic robot I. INTRODUCTION Multiple Sclerosis (MS) is a chronic progressive disease which affects the central nervous system resulting in neuromotor disorders such as muscle weakness and spasticity and difficulties with coordination and balance. Also visual, cognitive and sensory dysfunctions are common in this group of patients [1]. As the disease progresses, the upper limbs get more affected which may lead to accumulated disability. A Swedish study found that 76% of a Swedish sample, consisting of 219 Persons with MS (PwMS), showed at least some disability regarding manual dexterity, leading to a significantly negative impact on the performance of activities of daily life in half of all patients [2]. Robotic devices are getting more and more familiar as a therapeutic medium to augment rehabilitation outcomes in neurologic disorders, such as stroke and MS, when being used as an additional therapy [3]. Reviews in stroke, using different types of robotic devices for different degrees of arm dysfunction, have demonstrated overall effects on arm motor function in both (sub)acute and chronic stroke patients [4-6]. These studies made use of different types of robots and electro-mechanical devices for the upper limb, mostly differentiated into exoskeletons and end-effectors. Gravity compensation (GC) of the arm is often used in conventional therapy as well as in robot-assisted rehabilitation, to facilitate active training in neurologically impaired persons. The use of GC by robotic devices has already shown This project was sponsored by the INTERREG program of the EU, indicated with IVA-VLANED-1.14, “Rehabilitation Robotics II”. 2011 IEEE International Conference on Rehabilitation Robotics Rehab Week Zurich, ETH Zurich Science City, Switzerland, June 29 - July 1, 2011 978-1-4244-9861-1/11/$26.00 ©2011 IEEE 1100