Paediatrics: Macrocephaly and microcephaly

Macrocephaly and microcephaly

Macrocephaly

Macrocephaly is defined as a head circumference above the 99.6th centile. The majority of such children will have a benign and familial cause for this condition. However, hydrocephalus and degenerative disorders need to be considered.

History

·  Take a full history including developmental progression.

·  Are there any features of autism or degenerative disorders?

·  Are there signs of raised intracranial pressure?

Examination

·  Perform a thorough examination.

·  Plot OFC on a growth chart along with previous measurements.

·  Look at the skin for signs of neurofibromatosis.

Findings and investigation

·  Abnormal: if there are any abnormalities these will need further investigation.

·  Normal: if the examination is normal, try and compare the child’s head circumference with parental head circumferences. If they are all large, then the likely diagnosis is familial macrocephaly. If the parents’ head circumferences are normal, then the child’s condition is probably benign, but it would be appropriate to follow measurements for the next 12mths. If there is crossing of centiles then perform a CT scan, looking for hydrocephalus.

Some children, boys more than girls, present with macrocephaly, mild developmental delay/hypotonia. If there is nothing else in the history and examination then manage as above. They will, however, need to be inves-tigated for the developmental delay.

Microcephaly

Microcephaly is defined as a head circumference below the 0.4th centile. It is associated with a small brain. The majority of these children will have developmental and neurological abnormalities.

History

·  Take a full history including developmental progression and infection during pregnancy.

·  Was Guthrie screening done (phenylketonuria)?

Examination

·  Perform a thorough examination.

·  Plot OFC on a growth chart along with previous measurements.

Look for features of craniosynostosis—spiral CT head if likely.

Investigation

·Repeat PKU screening.

·Obtain a karyotype, plasma lactate, maternal and child’s TORCH infection screen, plasma and urine for amino and organic acidaemias.

·MRI scan.

Management

Obtain genetic advice. There may be a recurrence risk of up to 25% (auto-somal recessive microcephaly) if no cause is found.

Hydrocephalus

Hydrocephalus may be present irrespective of whether there is obstruction to cerebrospinal fluid flow. The causes are:

·Obstructive (non-communicating): aqueduct stenosis, posterior fossa and other tumours.

·Communicating: meningitis, subarachnoid haemorrhage, IVH.

Clinical features

·History: older children may present with a history of headache and vomiting; babies usually present because there is concern about head growth (i.e. crossing centiles) and delay in development.

·Examination: plot OFC on a growth chart along with previous measurements; macrocephaly or bulging fontanelle in those with open sutures; ‘sunsetting’ of the eyes; papilloedema; hyperreflexia; spasticity; poor head control.

·Diagnosis: cranial imaging looking for enlarged ventricles. Imaging may also reveal associated congenital abnormalities such as Arnold–Chiari malformation.

Treatment

·Neurosurgical referral for placement of ventricular shunt system or other surgery urgently.

·Children with shunt systems in place are at risk of shunt blockage, infection (e.g. ventriculitis), and subdural haematoma. Acute changes in behaviour, new onset headache, or persistent fever will need to be assessed with these problems in mind. Again, referral to the neurosurgical team for imaging and CSF sampling will need to be carried out.