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Selective kana jargonagraphia following right hemispheric infarction
R Hashimoto1, Y Tanaka, M Yoshida
1Department of Neurology, Jichi Medical School, Tochigi, Japan.
Brain and Language
|June 27, 1998
Summary
A right-brain stroke caused a unique writing impairment in a Japanese man, affecting kana but not kanji writing. This selective kana jargonagraphia suggests specific brain damage impacting grapheme buffer and motor writing functions.
Area of Science:
- Neuroscience
- Neurolinguistics
- Cognitive Psychology
Background:
- Right hemispheric strokes can cause complex neurological deficits.
- Aphasia, particularly Broca-type aphasia, is typically associated with left hemisphere damage.
- Writing disorders (agraphia) can manifest differently depending on the nature of brain injury and linguistic system.
Observation:
- A right-handed Japanese man with Broca-type aphasia post-right hemispheric infarction exhibited fluent writing.
- His agraphia disproportionately affected kana (syllabograms) compared to kanji (ideograms).
- Kana errors included substitutions, intrusions, transpositions, and deletions, increasing with word length.
Findings:
- Phonological analysis revealed kana substitutions were largely dissimilar to target sounds.
- Error distribution was similar for familiar and novel words, and asymmetric within words (more errors at the end).
- The patient presented with kana jargonagraphia, characterized by fluent yet disordered kana writing.
Implications:
- Findings suggest selective damage to a hypothesized kana graphemic buffer due to right hemisphere injury.
- Disinhibition of motor writing engrams may also contribute to the observed fluent output despite agraphia.
- This case highlights the intricate relationship between right hemisphere function, writing systems, and language processing.