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.