Children with large heads: a practical approach to diagnosis in 557 children, with special reference to 109 children with megalencephaly.

Among 557 children who presented a diagnostic problem of a large head, 109 had megalencephaly as the primary diagnosis. A clinical approach to the differentiation of this numerically important group from the various other causes of large head is outlined. The group is characterised by a familial incidence of large head in at least 50 per cent of cases; a male to female preponderance of four to one; an above-normal rate of head growth in 80 per cent of the children in the first four months after birth, and in a further 12 per cent in late infancy. The vast majority of these children were normal. Only seven children were retarded, and they also had a variety of neurological and other somatic abnormalities.