Central or conduction aphasia in a Japanese patient

Yamadori A, Ikumura G. Cortex 1975; 11:73-82.

Notes on Japanese language: the basic unit of Japanese similar to a syllable is called a haku. All haku (unlike syllables) have equal temporal duration. A kanji can have any number of haku, but a kana always has one haku. There are 46 kana characters for 46 basic haku. Using diacritical marks all 112 kana can be transcribed with 46 kana. Word length is proportional to the number of haku.

The patient had fluent speech and good understanding but had verbal paraphasias and anomias. Repetition was poor. Written comprehension was good in silent reading but worse in aloud reading. Copying words and sentences was without error.

Repetition was worse with increasing number of syllables. Naming was worse with increasing number of syllables. Cueing did not help. Kana was read better than kanji (but recall that kana only has one haku and so word length was shorter). In writing, word length was an issue with more errors with longer words. That the patient had superior transcription of kanji than kana (due to absent phonology when writing) and superior oral reading of kana was expected (kana has less haku).

The authors thought the problem was the stability of the acoustic word image and not in concept (blogger note: a Luria idea). However the author credits Saussure (1916) and Dubois (1964) that conduction aphasia is "an efferent disturbance." The ability to represent a distinct acoustic image is lost in the first phase of the motor encoding process. They criticize the term "conduction" aphasia noting errors of naming, oral reading and dictation. The authors suggest "central" aphasia as used by Goldstein (1948) and Conrad (1948). "anomia has never been considered as an integral part, except by Conrad"

Notes: alternative explanations of conduction aphasia include disconnection of the motor speech area from Wernicke's area (Wernicke; Geschwind; Benson); degradation of the concept formation (Goldstein; Conrad, Hacaen); disturbed receptive function (Lieppmann and Pappenheim, 1915) and disturbed auditory short term memory(Warrington and Shallice).

References:
Benson DF, Sheremata WA, Bouchard R, Segarra JM, Price JM, Geschwind N. Conduction aphasia Arch Neurol 1973; 28: 339-346.

Conrad K. Strukturanalysen birnpathologischer Falle. Zum problem der leitungsaphasie. Dtsc Z Nervenheilk 159:188-228.

Dubois J, Hacaen H, Angelergues R et al. Etude neurolinguistique de l'aphasie de conduction. Neuropsychologia 2:944 (1964).

Geschwind.. disconnection syndromes etc.

Goldstein K. Language and language disturbances New York, Grune and Stratton, 1948.

Sasanuma S , Fujimora O (1971). Selective impairment of phonetic and non-phonetic transcripton of words in Japanese aphasic patients: kana v. kanji in visual recognition and writing. Cortex &: 1-18.

ibid. An analysis of writing errors in Japanese aphasic patients. Kanji v. kana words. Cortex 8:265-282 (1972) note-- see other post.

Warrington EK , Shallice T (1969). The selective impairment of auditory verbal short-term memory Brain 92: 885-896.