[Medical problems of handedness].

Handedness is one example of many forms of behavioral lateralization seen in humans. In the present review the practical relevance and the problems of left-handedness are discussed. Left-handedness has existed in a small subset of the human population, approximately 8%, since the origin of man. The incidence of left-handedness as usually defined is consistent among human populations. An understanding of handedness may lead to valuables clues as to how the brain becomes organised in the way it does. Several authors suggested a pathological handedness explaining the origin of laterality in man. There is a general agreement that sinistrality can occur as a result of pre- or perinatal damage to the left hemisphere. A disproportionate number of sinistrals is found in clinical populations. The review indicates that there is no sure evidence to suggest that left-handedness is a pathological sign.