Bimodal aphasia and dysgraphia: Phonological output buffer aphasia and orthographic output buffer dysgraphia in...

We report a case of crossmodal bilingual aphasia-aphasia in two modalities, spoken and sign language-and dysgraphia in both writing and fingerspelling. The patient, Sunny, was a 42 year-old woman after a left temporo-parietal stroke, a speaker of Hebrew, Romanian, and English and an adult learner, daily user of Israeli Sign language (ISL). We assessed Sunny's spoken and sign languages using a comprehensive test battery of naming, reading, and repetition tasks, and also analysed her spontaneous-speech and sign. Her writing and fingerspelling were assessed using tasks of dictation, naming, and delayed copying. In spoken language production, Sunny showed a classical phonological output buffer (POB) impairment in naming, reading, repetition, and spontaneous production, with phonological errors (transpositions, substitutions, insertions, and omissions) in words and pseudo-words, and whole-unit errors in morphological affixes, function-words, and number-words, with a length effect. Importantly, her error pattern in ISL was remarkably similar in the parallel tasks, with phonological errors in signs and pseudo-signs, affecting all the phonological parameters of the sign (movement, handshape, location, and orientation), and whole-unit errors in morphemes, function-signs, and number-signs. Sunny's impairment was selective to the POB, without phonological input, semantic-conceptual, or syntactic deficits. This shows for the first time how POB impairment, a kind of conduction aphasia, manifests itself in a sign language, and indicates that the POB for sign-language has the same cognitive architecture as the one for spoken language. It may also indicate similar neural underpinnings for spoken and sign languages. In writing, Sunny forms the first case of a selective type of dysgraphia in fingerspelling, orthographic (graphemic) output buffer dysgraphia. In both writing and fingerspelling, she made letter errors (letter transpositions, substitutions, insertions, and omissions), as well as morphological errors and errors in function words, and showed length effect. Sunny's impairment was selective to the orthographic output buffer, whereas her reading, including orthographic input processing, was intact. This suggests that the orthographic output buffer is shared for writing and fingerspelling, at least in a late learner of sign language. The results shed further light on the architecture of phonological and orthographic production.