A BIG HEAD
History
Sami, a 9-month-old boy, has been referred to the community paediatric clinic by his health visitor because his head circumference is on the 99.6th centile. He was born at 38 weeks’ gestation by spontaneous vaginal delivery, following an uneventful pregnancy to a Samoan woman. His birth weight was 4.3 kg (91st centile) and his head circumference at birth was 38 cm (98th centile). This is the mother’s third baby, but the other two children have a different father. Sami doesn’t sleep very well, waking up to three times per night, and this was the main reason his mother went to see her health visitor. Sami is otherwise well and has not had any previous medical problems. He has been able to sit unsupported for the last 2 months, he crawls, he can use either hand to pick up raisins or grains of rice. His mother has no concerns about his vision or hearing and he passed his newborn hearing screen. He is still breast-feeding but also eats purées and finger foods. The mother, her partner and the three children live in a two-bedroom flat. The growth chart in his parent-held child health record is shown in Figure 63.1.
Figure 63.1 Sami’s growth chart (reproduced with permission of the Child Growth Foundation).
Examination
Sami is a well-looking child, who smiles and babbles continuously. He is not dysmorphic. His weight is 10.5 kg (91st centile), his length is 76.2 cm (98th centile) and his head circumference is 49.7 cm (99.6th centile). Cardiovascular and respiratory examinations are normal. His anterior fontanelle is almost closed. Neurological examination reveals normal tone, power and reflexes in the upper and lower limbs.
Questions
• What features in the history help to distinguish between the causes of a big head?
• What other features should be sought on examination?
• What is the most likely explanation for the large head circumference?
Medicine
A large head may be a normal variant, often with a familial tendency, or may be caused by pathological processes. In an infant, rising intracranial pressure will cause the skull with unfused sutures to expand rapidly. If possible, it should be determined from previous measurements whether the head circumference is enlarging and crossing centiles (a worrying feature) or whether it is just growing steadily along the same centile. There may be other symptoms of raised intracranial pressure: vomiting, lethargy, irritability, poor feeding. Developmental delay or regression (loss of previously attained developmental milestones) suggests metabolic, genetic and syndromic causes. Social concerns about a family raise the possibility of a subdural haematoma from non-accidental injury. Parents should be asked whether they or the siblings have large heads – do they have difficulty buying hats to fit them? The causes of a large head (macrocephaly) are listed below. When performing the examination, these should be borne in mind. The shape of the head, and the size, shape and patency of the fontanelles and cranial sutures should be assessed. The presence of dysmorphic features, birthmarks or other congenital anomalies should be sought. Central and peripheral nervous systems should be examined and development assessed. Weight and height should be measured and plotted on a centile chart, as should parental head circumferences.
Causes of macrocephaly
Possible examination finding
Hydrocephalus Tense fontanelle, distended scalp veins
Vascular malformations Cranial bruit
Tumour Abnormal neurology
Subdural haematoma Bruising, other injuries
Fragile X syndrome Developmental delay, large ears
Neurofibromatosis Café-au-lait patches, axillary freckles
Overgrowth syndrome, Developmental delay, large hands/feet
e.g. Soto’s syndrome
Metabolic, e.g. mucopolysaccharidoses Developmental delay, coarse features
Familial macrocephaly Parent has large head circumference
Sami has normal development and his growth chart shows that he has always been a large baby with a large head. The change from the 98th centile to 99.6th centile is not concerning, considering the slow rate of change and the likelihood of small errors in measurement. The cause of his large head size is likely to be familial and this was supported by his mother’s head circumference lying on the 98th centile.
KEY POINTS
• The commonest cause of a large head is familial macrocephaly.
• Check the growth chart and developmental history for a child with a big head.
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