Valenstein E, Heilman K M
Arch Neurol. 1979 Aug;36(8):506-8. doi: 10.1001/archneur.1979.00500440076016.
Agraphia may result from the loss or unavailability of the memory of movements necessary to form written letters. For this mechanism to be invoked, it must first be demonstrated that there is no language deficit and that there is no disconnection between language and motor areas. A left-handed patient demonstrated bilateral agraphia and apraxia, but not aphasia, following a right parietal infarction. Preservation of the ability to type with the left hand demonstrated that the right hemisphere was not disconnected from language input. In addition, paragraphic errors while typing were shown to be secondary to left hemispatial neglect.
失写症可能源于形成书写字母所需动作记忆的丧失或无法获取。要调用这一机制，首先必须证明不存在语言缺陷，且语言区和运动区之间不存在联系中断。一名左利手患者在右侧顶叶梗死之后出现双侧失写症和失用症，但无失语症。左手打字能力的保留表明右半球与语言输入未脱节。此外，打字时的逐段错误被证明是左侧半侧空间忽视的继发症状。
