Hemispheric control of the writing hand: the effect of callosotomy in a left-hander.

We report a case of a left-hander with left hemispheric language. After callosotomy, he could use the left hand to write only random letters and digits, and he became right-handed for writing. Therefore, writing by left-handers with left hemispheric language dominance may be accomplished by transcallosal transmission of the linguistic content from the left hemisphere to the right.