A study on handedness and cerebral speech dominance in right-handed Chinese

The handedness of Chinese schoolchildren and adults was examined with nine test items; the former group was also surveyed using a questionnaire. The prevalence rate of left-handers was about 3.5% for both schoolchildren and adults. This result strongly suggests that handedness is established in childhood. A study of cerebral speech dominance in 94 right-handed Chinese by means of a Wada test showed that the dominant hemisphere was on the left side in 92 patients and on the right in the remaining two. Thirty of the 94 patients with surgical lesions in the sylvian region were operated upon, and the reliability of the Wada test was demonstrated in each case. It is concluded that in the great majority, but not all, of right-handers the left cerebral hemisphere is dominant for speech. A study of 55 right-handed aphasic patients with surgically verified lesions showed the following:1.The lesions were invariably found around the sylvian fissure, on the left in 53 and on the right in two.2.Nominal aphasia was most frequent (32/55), with lesions any where around the Sylvian fissure.3.Motor aphasia was relatively frequent (20/55), with lesions solely in the anterior sylvian region.4.Sensory aphasia was rare (3/55), with lesions in the posterior sylvian region. In this study the patients undergoing the Wada test were all, right-handed. No satisfactory explanation for this absence of left-handers has yet been found.