視覚探索および到達運動障害によるタイピング障害を呈した左頭頂葉損傷例

A case of left parietal lobe damage with typing disorder due to impairments in visual search and reaching movement

　左頭頂葉脳梗塞発症後にタイピング障害を呈した症例を経験した．神経心理学的検査の結果，ワーキングメモリの低下や選択性注意低下，処理速度の低下があると考えられた．病前は視鍵法タイピストであり，入力方法からタイピングの処理過程について言語処理過程と視覚-運動処理過程を想定し評価を行った．仮名やローマ字の書字や音読は良好であったが，実際のキーボードを使用したタイピングは困難であり動作が停滞していた．キーボード上で見える範囲を限定してタイピングを行うと，手指の逡巡や打鍵位置の空間性の誤りを認めたが自己修正をしながらタイピングが可能となった．本例は頭頂間溝近傍を含む上頭頂小葉の梗塞により，視覚探索障害と到達運動障害による視鍵法タイピング障害を呈したと考えられた．

　We report a case of typing disorder after a left parietal lobe cerebral infarction. In this case, it was thought that there was a decrease in working memory, selective attention, and processing speed. The patient was a hunt- and-peck typist before the illness. His typing process was evaluated based on language processing tasks and visual-motor processing tasks. Hand writing and reading aloud of both kana and roman letters were good, but typing on the keyboard was difficult with noticeable pauses and stagnation of movement. When the visible area of the keyboard was limited, he showed hesitant finger motions and spatial errors in typing position, but was able to type with self-correction. In this case, the infarction of the superior parietal lobule, including the area near the interparietal sulcus, is thought to have caused impairments in visual search and reaching movement, which resulted in hunt-and-peck typing disorder.