We report on a right-handed, deaf, life long signer who suffered a lef
t posterior cerebral artery (PCA) stroke. The patient presented with r
ight homonymous hemianopia, alexia and a severe sign comprehension def
icit. Her production of sign language was, however, virtually normal.
We suggest that her syndrome can be characterized as a case of 'sign b
lindness', a disconnection of the intact right hemisphere visual areas
from intact left hemisphere language areas. This case provides strong
evidence that the neural systems supporting sign language processing
are predominantly in the left hemisphere, but also suggests that there
are some differences in the neural organization of signed vs spoken l
anguage within the left hemisphere.