The kinematics of handwriting movements as expression of cognitive and sensorimotor impairments in people with multiple sclerosis

Abstract

Handwriting is an important activity of daily living, which requires sensorimotor and cognitive skills that could deteriorate in presence of neurological diseases. Handwriting impairments are common in people with multiple sclerosis (PwMS). Aims of the present study were to characterize handwriting movement features of PwMS in comparison with those of healthy adults, and to evaluate the relationship between kinematic parameters of handwriting movements and the results of the assessment of cognitive and motor domains. A new handwriting evaluation methodology was applied to quantify handwriting features of 19 PwMS and 22 age-matched healthy controls who were required to write a sentence on a digitizing tablet. Kinematic parameters of the sentence and of the strokes were used to evaluate handwriting performance. PwMS showed an altered handwriting kinematics with respect to healthy controls: higher movement duration, fragmented velocity profile and higher jerk. Furthermore, motor abilities and cognitive status of PwMS were related to handwriting parameters in accordance with the evidence that MS is a multifactorial disease affecting different domains. These results suggested that the proposed methodology might be a valuable tool to quantitatively assess handwriting impairments and the efficacy of handwriting treatments in PwMS.

Figure 1

Handwriting kinematic parameters of healthy controls (HC – grey circles) and people with multiple sclerosis (PwMS, red circles). The first line shows the sentence parameters: duration of the sentence (A), words (B), and spacing between words (C). The second and third lines show stroke parameters: number of strokes (NoS - D), stroke duration (E) and length (F), number of inversion in the velocity profile (NIV - G), normalized jerk (H). Each circle represents the average value for a single subject. The horizontal line indicates the group average, and the error bars show the standard error value. * and **indicate p < 0.05 and p < 0.01, respectively.