Handedness and progressive hydrocephalus in spina bifida patients.

Hand preference and functional hand-dominance of 45 spina bifida patients (aged 13 to 25 years) were assessed by means of self-reports on an ordinal scale and a tapping task. Non-right-handedness was more frequent among patients with accompanying progressive hydrocephalus. Left-hand preference was significantly more frequent in this group than in patients without shunts. Non-right-handedness in hydrocephalic patients correlated positively with the estimated degree of pre-operative progress of the hydrocephalus. The apparent failure to establish right-handedness in these patients seemed to reflect a developmental disorder of lateralization, related to a more advanced degree of progressive hydrocephalus at an early age. It is suggested that the disorder may be attributable to dysfunction of the corpus callosum, caused by delay in the development of callosal white matter when the hydrocephalus is in a progressive state.