Facilitating robot-assisted training in MS patients with arm paresis: a procedure to individually determine gravity compensation

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 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 persons with MS were tested with the procedure for determination of GC. Maximal reaching movements were performed in a 3D space in three conditions: without GC (NS), with GC by the HapticMaster (GS) and with GC by the HapticMaster combined with a sling suspension system (GSS). For the total sample, significant correlations were found between the amount of GC and clinical tests (MI, FM, ARAT). In four subjects with severe arm dysfunction it was found that mean ROM is larger in the GSS condition compared to the GS condition, and in the GS condition compared to the NS condition, suggesting positive effects of GC on active ROM (aROM) in PwMS. Therefore, GC could have a positive effect on arm rehabilitation by enabling the PwMS to actively reach a larger ROM during training.