Three-Dimensional Movement Analysis of Handwriting in Subjects With Mild Hemiparesis  Takako Harada, MD, Yasutomo Okajima, MD, PhD, Hidetoshi Takahashi, MD, PhD  Archives of Physical Medicine and Rehabilitation  Volume 91, Issue 8, Pages 1210-1217 (August 2010) DOI: 10.1016/j.apmr.2010.01.023 Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 1 Experimental apparatus. (A) A 3-D coordinate measuring machine.a (B) A transmitter producing a constant magnetic field. (C) A ballpoint pen in which a position sensor is installed. (D) Position sensors, 2.8×2.2×1.5cm, fixed at the metacarpophalangeal joint of the index finger and at the distal radius. Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 2 Writing tracks of a healthy right-handed young subject and correlation in writing speed. (A) An example of Fu, a Japanese syllabary character, handwritten by a healthy young subject. Tracks of movement of the pen tip, metacarpal head of the index finger (index finger base), and distal end of the radius (distal forearm) after 10 trials of writing in a 6-cm square are layered. Solid lines are tracks while the pen tip is in contact with the table, and dotted lines are those while the pen tip is off the table. It is shown that the index finger base and the pen tip draw nearly consistent tracks. (B) Changes in the speed at the pen tip, index finger base, and distal forearm during 10 trials of writing (A). It is shown that the speed-time graph is nearly consistent over time and that the speeds at the pen tip, index finger base, and distal forearm are positively correlated with each other. Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 3 Proximo-distal separation of writing tracks in healthy subjects. The ratios of the track radius of the index finger base or distal forearm to that of the pen tip in (A) healthy young subjects (n=15) and (B) healthy elderly subjects (n=10) were compared between the right (R) and left (L) hands and between writing in 6-cm and 15-cm squares. In both young and elderly subjects, the ratio was significantly lower in right-hand than left-hand writing (P=.02 for the index base/pen tip in part A, P=.009 for the radial end/pen tip in part A, and P<.001 for both separations in part B) and significantly increased as character size was larger. (P<.001 for both separations in both part A and part B. *P<.05 (analysis of variance). Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 4 Proximo-distal separation of writing tracks in hemiparetic patients. (A) Patients without sensory deficit (n=15), (B) patients with sensory deficit (n=10). The same comparison as in figure 3 was performed in patients. The results in patients with normal joint position sense (A) were similar to those in healthy subjects; the ratio was significantly smaller in right (R) –hand than left (L) –hand writing, (P=.01 for both index base/pen tip and radial end/pen tip in part A) and the ratio significantly increased as character size increased (P<.001 for both separations in part A). In patients with impaired joint position sense (B), neither right-left nor character size–related difference in the ratio was significant (P=.12∼.47). *P<.05 (analysis of variance). Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 5 Proximo-distal linkage of writing movement in healthy subjects. The instantaneous speeds at the pen tip, the index finger base, and the distal forearm were plotted against time from the start to the end of writing, and the correlation coefficients between the speed of the pen tip and that of the index finger base or distal forearm were calculated for both (A) healthy young (n=15) and (B) elderly (n=10) subjects. No significant right (R)–left (L) difference in the correlation coefficient was found except for correlation between the pen tip and the index finger base in the elderly subjects (P=.03 for the index base/pen tip correlation in part B and P=.19∼.43 for other correlations.). The correlation coefficient significantly increased as the size of the character increased in both subjects.(P<.005 for the index base/pen tip correlation in part B and P<.001 for other correlations.) *P<.05 (analysis of variance). Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions

Fig 6 Proximo-distal linkage of writing movement in hemiparetic patients. (A) Patients without sensory deficit (n=15), (B) patients with sensory deficit (n=10). The same comparison as in figure 5 was performed in patients. In patients with normal joint position sense (A) and without (B), no significant right (R)–left (L) difference in the correlation coefficient between the pen tip and either the index finger base or the distal forearm was found (P=.14∼.47). Size-related differences in the coefficient were significant in these patients (P=.006 and P=.002 for the index base/pen tip correlation in part A and B, and P<.001 and P=.03 for the radial end/pen tip correlation in part A and B), similar to the control subjects in figure 5. However, these differences were less significant in patients with sensory impairment. *P<.05 (analysis of variance). Archives of Physical Medicine and Rehabilitation 2010 91, 1210-1217DOI: (10.1016/j.apmr.2010.01.023) Copyright © 2010 American Congress of Rehabilitation Medicine Terms and Conditions