A Selective Ideational Apraxic Agraphia for Consonants


Abstract: Aim: The proposed graphemic area in the dominant hemisphere contains letter representations that are responsible for guiding the skilled movements required for writing and for recognition of the physical features of letters. Dysfunction in this system may cause apraxic agraphia. In this study, writing performance of a right-handed, left hemisphere damaged, 12-year old apraxic agraphic patient with a native language of shallow ortography is analysed. Methods: Writing performance was evaluated with several different word lists, each holding same amount of letters, novel words (non-word), words, functors, and high-imagery and low-imagery words. Non-words were derived from words by changing a single letter. Results: A selective writing impairment limited to the left hand was observed. Her deficit was graphemic in nature; she made no phonological errors during spontaneous speech and oral naming. Writing was not affected by lexical factors (grammatical class, word length, or abstract quality) or lexicality (word, non-word, functor). In the entire corpus of responses, she wrote 2 of 154 vowel letters (1.3%) and 51 of 232 consonant letters (22.0%) incorrectly. Conclusions: It is proposed that the corpus callosum carries the interhemispheric control of praxis and writing at different levels, praxis for writing carried separately from praxis in general and within praxis for writing vowels and consonants are handled separately.

Keywords: Agraphia, apraxia, corpus callosum

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