Microcephaly in Australian infants: A retrospective audit.

Aim: To describe clinical characteristics, outcomes and causes of microcephaly in children whose condition was identified within the first year of life.

Methods: Retrospective review of medical records of microcephalic children born between 2008 and 2018 and admitted for any reason during the same period to a tertiary paediatric hospital. Microcephaly was defined as occipitofrontal circumference (OFC) more than two standard deviations below the mean (>-2 SD).

Results: Between January 2008 and September 2018, 1083 medical records were retrieved. Of the children, 886 were ineligible and 197 were confirmed cases of microcephaly. Of cases, 73 (37%) had primary microcephaly (at birth) and 72 (37%) had severe microcephaly (OFC > -3 SD). Of microcephalic children, 192 (98%) had congenital anomalies, of whom 93% had major anomalies, mostly cardiovascular or musculoskeletal. Neurological signs or symptoms were reported in 148 (75%), seizures being the most common. Of the 139 children with abnormal central nervous system (CNS) imaging, one or more structural brain abnormalities were identified in 124 (89%). Failure to reach developmental milestones was observed in 69%, visual impairment in 41% and cerebral palsy in 13%. Microcephaly was idiopathic in 51% and 24% had diagnosed genetic disorders. There was no association between developmental outcomes or structural brain anomalies and severity of microcephaly or timing of diagnosis.

Conclusion: Our results suggest the need for a systematic investigative approach to diagnosis, including a careful history, examination, genetic testing and neuroimaging, to determine the underlying cause of microcephaly, identify co-morbidities, predict prognosis and guide genetic counselling and therapy.