Investigations in Microcephaly: How often do they Aid Diagnosis?

Aims/Background: Microcephaly is defined as a head circumference less than 2 SD compared to a cohort of the same age/sex. Causes include genetic disorders, congenital infections, and rarely metabolic conditions. It can be associated with abnormal neurodevelopment and disability.

Objectives: We conducted an audit to analyse the yield of investigations in children identified to have Microcephaly, as well as the long term outcomes of these children.

Methods: A retrospective case note review of 20 children identified to have Microcephaly from a coding database since 2010.

Results: 50% were diagnosed within the 1^st year of life. 25% children were incorrectly labelled as having Microcephaly, when their head circumferences were within normal range.

80% had a MRI, of which 50% showed positive findings. 5/8 showing non-specific white matter changes. 85% had genetic studies, of which 47% came back positive. 5 of these were copy imbalances of unknown significance.

75% had metabolic investigation and 45% had a CK sent – none of which had any positive results. 30% had TORCH screening, and 55% had TFTs – all were negative.

95% of our children went on to have developmental delay. 60% had visual problems, 45% had seizures. 40% had behavioural problems.

The majority of children were also being followed up regularly by other professionals (e.g. 80% by SALT, 70% by Physio/Orthopaedics, 30% by Opthalmology).

Conclusion: 45% of our children had an identified clear cause for their Microcephaly. 25% were incorrectly diagnosed and were unnecessarily investigated for their head size.

MRI and Genetic testing have good yields, but frequently have positive results which are of unknown significance, which can result in parental anxiety.

Metabolic testing rarely yields positive results, and often required multiple samples to be sent due to sample deterioration.

These children often need following up as the majority in our sample ended up having developmental delay. They often need multidisciplinary involvement for their ongoing management.