Impairment of letter formation: the case of "ideomotor" apraxic dysgraphia

this paper we describe a patient with an apraxic agraphia following encephalitis. A.G., a 37-year-old right-handed man, showed a selective deficit in handwriting with normal intellectual, linguistic and visuo-constructional abilities. Reading was intact. Oral spelling and assembling block letters were flawless. A.G. was able to write single letters and digits, but he was severely impaired in writing words and numbers. Most errors consisted of incomplete and poorly formed letters and letter substitutions. The number of errors increased with the length of the stimuli. Word copying was as impaired as writing to dictation. According to current models of writing, the pattern of performance of A.G. is consistent with a specific impairment of the temporary buffer in which the graphic motor patterns are maintained for neuromuscular execution. We propose to define this deficit ‘ideomotor apraxic’ agraphia opposed to the ‘ideational apraxic’ agraphia which consists in a deficit in writing single letters with preservation of copying abilities.