Derakhshan Iraj
Case Western Reserve and Cincinnati Universities, Ohio, USA.
Brain Inj. 2009 Aug;23(9):770-4. doi: 10.1080/02699050903120373.
A right handed man with trauma to the head was admitted with headache and seizures. A severe right sided weakness was noted after a blunt trauma to the right side of his head.
MRI of brain revealed a right-sided subdural hematoma and a normal left hemisphere and downstream motor pathways. Bimanual simultaneous drawing and manual reaction times indicated that the patient was right hemispheric in laterality of his major hemisphere.
The right sided weakness in this patient was due to temporary transcallosal disconnection (diaschisis) of the minor hemisphere (left, in this case) from the excitatory signals arising from those structures of his major hemisphere devoted to movements occurring on nondominant side, transmitted via the corpus callosum to his left hemisphere. This case draws attention to disparity between neural and behavioral handedness (laterality of major hemisphere versus that of the preferred hand). Drawing longer lines by the left hand in simultaneous bimanual tasks and a slower simple reaction time to central visual stimuli by the ostensible dominant hand permitted lateralization of the major hemisphere to the right. Thus, the neurally nondominant side (right) lagged behind the dominant (left) by an interval equal to interhemispheric transfer time.
一名头部受伤的右利手男性因头痛和癫痫发作入院。其头部右侧受到钝器伤后出现严重的右侧肢体无力。
脑部MRI显示右侧硬膜下血肿，左侧半球及下行运动通路正常。双手同时绘图及手动反应时间表明，该患者优势半球的偏侧性为右侧半球。
该患者右侧肢体无力是由于非优势半球（在本例中为左侧）与优势半球中负责非优势侧运动的结构产生的兴奋性信号暂时经胼胝体离断（交叉性小脑失联络），这些信号通过胼胝体传递至其左侧半球。该病例提醒人们注意神经学上的利手（优势半球的偏侧性）与行为学上的利手（优势手的偏侧性）之间的差异。在双手同时进行的任务中，左手绘制的线条更长，且表面上的优势手对中央视觉刺激的简单反应时间更慢，这使得优势半球定位于右侧。因此，神经学上的非优势侧（右侧）比优势侧（左侧）落后一个等于半球间传递时间的间隔。
