Afferent dysgraphia after right cerebral stroke: an autonomous syndrome?
Afferent dysgraphia is an acquired writing deficit characterized by deletions and duplications of letters and strokes. The commonly accepted interpretation states that afferent dysgraphia is associated with three main clinical features: production of spatial writing errors; the presence of left unilateral neglect; and no deterioration in performance when writing blindfolded. In order to test whether these symptoms necessarily co-occur with afferent dysgraphia, we studied the writing performances of a series of eight right brain-damaged patients. In sentence copying, spontaneous handwriting, and writing to dictation they showed afferent dysgraphia. However, signs of left neglect and spatial dysgraphia were evident only in some cases. Furthermore, the frequency of afferent errors increased when patients were required to write without vision. The present study demonstrates that afferent dysgraphia is an autonomous clinical entity and that it results from a selective impairment of a mechanism whose function is that of comparing the information about the number of letters and strokes specified at the level of letter motor programs and the actual number of movements already realized.