Functional Capacity and Motor Performance of Upper Limbs in Individuals with Cerebellar Disorders: A Pilot Study

In simple daily activities carried out by the upper limbs, the cerebellum is responsible for the adaptations required for the accurate movement based on previous experiences and external references. This paper aims to characterize the performance of the upper limbs after a cerebellar disease. We evaluated the digital and handgrip strength, dexterity, and function of the upper limbs. The motor performance of the upper limbs was assessed through the use of a digitizing tablet by performing aiming movements with the upper limb most affected by cerebellar disease and the paired limb of the healthy group. The results showed differences between groups: the cerebellar group had higher latency to movement onset, was slower, and presented less smooth trajectories and higher initial direction errors. Moreover, the movement direction influenced the peak velocity and the smoothness for both groups (contralateral directions were slower and less smooth). We concluded that cerebellar disorder leads to movement planning impairment compromising the formulation of an internal model. Alterations on movement execution seem to be a consequence from disruptions in the anticipatory model, leading to more adaptations. These findings are compatible with the roles of the cerebellum on the control of voluntary movement.

VOLUME OF CONVEX HULL: A TECHNIQUE FOR QUANTIFYING HUMAN POSTURAL STABILITY

Many disorders, such as nervous system disorders, can affect orientation of the body segments in 3D space negatively. Patients with these disorders often show body segments instability during stance tasks. Nowadays, 3-axis gyroscopes are about to be used to measure postural stability. The main objective of the paper is to describe a method which would be suitable for quantifying postural stability and 3D movement as a whole using a cheap 3-axis gyroscope. New method based on the volume of a 3D convex hull (CH) obtained by plotting pitch, roll and yaw angles versus each other was proposed for quantitative evaluation of 3D trunk sway. The sway was measured while patients with degenerative cerebellar disorder (Pts) and eleven healthy subjects (HSs) performed quiet stance on a firm surface (FiS) and foam surface (FoS) with open eyes (OE) and closed eyes (CE). The CH was used to identify differences in balance control, and there were significant differences found between the two groups. The median (Mdn) of the volume of Pts with OE on FiS is four times larger than the Mdn of the volume of HS with OE on FiS. The Mdn of the volume of Pts with CE on FoS is 80 times larger than the Mdn of the volume of HS with CE on FoS. It was therefore found that the volume of CH is suitable for quantifying postural sway and identifying differences in balance control.