Unilateral dysgraphia of the dominant hand in a left-hander: a disruption of graphic motor pattern selection.

This paper reports the case of an English speaking, fully left-handed patient (DS) with a left unilateral writing deficit occurring after a subarachnoid hemorrhage due to the rupture of an anterior communicating aneurysm. DS's performance in spelling and in right-handed writing was entirely preserved while his left-handed writing was characterized by the production of errors which could generally be spontaneously self-corrected. Errors produced with lower-case letters differed from the ones produced with upper-case letters: The former usually corresponded to letter substitutions which were characterized by a high degree of physical similarity between the target letter and the one produced. The latter tended to result in the production of aborted letters. This impairment is discussed in the context of cognitive models of writing. It is suggested that graphic motor patterns for lower-case letters and for upper-case letters are different in nature and consequently that production processes may also differ.