[A case of pure agraphia due to left parietal lobe infarction]

We reported a case of an 86-year old woman with pure agraphia due to the left parietal lobe infarction. The characteristics of agraphia were as follows. Most errors in Kana and Kanji writing to dictation and copying were no response. She was able to write only numerals from 1 to 12 precisely. Most errors in numerals were substitution. One unrecognizable numeral was found. She succeeded in pointing to nine among ten single Kana letter named by the examiner with the systematic table of the Japanese syllabary, but missed in pointing to Kana words. It took more time for the patient to point to single Kana letter than the control. Magnetic resonance imaging showed a cerebral infarction in the left parietal lobe which included a part of superior parietal lobule and supramarginal gyrus. We classified pure agraphia with parietal lobe infarction into two types in our previous report. In one type (type 1), letters in writing are poorly formed, but the ability to make words with the methods other than writing are reserved. The only deficit of graphic motor pattern could cause Type 1 agraphia. In another type (type 2), letters in writing were well-formed, but spelling with anagram or typing was disturbed. The deficits of writing process other than graphic motor pattern could cause Type 2 agraphia. This typing seems to be effective not only in Kana but also in Kanji. In this report, we investigated the differences of lesion between two types out of some references. Type1 agraphia seems related to lesion of left superior parietal lobule, while Type 2 agraphia seems related to lesion of left supramarginal gyrus. This case had the features of type 2 agraphia at least, and the compatible lesions.