2009 Volume 40 Issue 4 Pages 69-80
To investigate the effects of dominant-hand hemiparesis on writing, handwriting movement analysis was conducted with 20 right-handed subjects with mild right hemiparesis following cerebrovascular accident and 13 age-matched right-handed control subjects. Subjects were required to write, without restriction of handwriting form, the Hiragana character “Fu” in frames of three different sizes with their right and left hands. Three-dimensional coordinates at three points, namely, the pen tip, the index finger base and the wrist were measured by Fastrak® (POLHEMUS) during writing. The following handwriting parameters were calculated and compared between the right and left hands for the different sizes of writing.
1) Time required to write the character did not differ between the right and left hands in the control subjects, but was significantly increased for the hemiparetic right hand.
2) Mean correlation coefficients of the tangential velocity profiles of the three points (reflecting consistency of writing movement) revealed that writing movement was more consistent for the right hand than for the left hand in both the control subjects and the hemiparetic subjects with normal sensation; however, it was less consistent when the joint position sense was impaired.
3) Ratio of the track radii of the index finger and the wrist to that of the pen tip (reflecting how separately the pen tip moves viewed from the finger and the wrist) revealed that the pen tip moved more separately than the finger and wrist in both the control subjects and the hemiparetic subjects with normal sensation, but that they moved in parallel when the joint position sense was impaired. The characteristics of handwriting movement by the dominant hand were preserved in subjects with mild dominant-hand hemiparesis when joint position sense was intact, but were lost in those with loss of position sense.