A large head is a feature of a large number of neurological conditions of childhood. These include:
- hydrocephalus and subdural effusions;
- abnormalities of venous drainage;
- skeletal dysplasias;
- brain malformations; for example, agenesis of the corpus callosum and hemimegaloencephaly;
- early onset tumours;
- neurocutaneous syndromes, including neurofibromatosis, tuberous sclerosis and haemangiomatosis, and Proteus syndrome;
- dysmorphic syndromes, particularly Sotos and Beckwith- Widemann;
- metabolic diseases, particularly GM2 gangliosidosis, mucopolysaccharidosis and Canavan's and Alexander's leucodystrophy.
It may be an isolated primary abnormality, with or without cerebral impairments. Since head circumference measurements are part of the physical examination of young children, it may be the presenting feature, despite its non-specific nature.