Outcome of partial agenesis of corpus callosum

Abstract

The diagnosis of corpus callosum anomalies by prenatal ultrasound has improved over the last decade due to improved imaging techniques, scanning skills and the routine implementation of transvaginal neurosonography. Our aim was to investigate all cases of incomplete agenesis of the corpus callosum and to report the sonographic characteristics, the associated anomalies and the perinatal outcome. We performed a retrospective analysis from January 2007 to December 2017 of corpus callosum anomalies, either referred for second opinion or derived from the prenatal ultrasound screening program in a single tertiary referral center. Cases with complete agenesis were excluded from analysis. Standardized investigation included detailed fetal ultrasound including neurosonogram, fetal karyotyping (standard karyotype or array CGH) and fetal MRI. Pregnancy outcome was collected and pathological investigation in case of termination of pregnancy or fetal/neonatal loss was compared with prenatal findings. The pregnancy and fetal/neonatal outcome are reported. The neurological assessment was conducted by a pediatric neurologist using Bayley scales of infant development-II and standardized Child development Inventory investigation when Bayley investigation was unavailable. Corpus callosum anomalies were diagnosed in 148 cases during the study period, 62 (41.9%) of which were excluded due to complete agenesis, remaining 86 fetuses with partial agenesis (58.1). In 20 cases partial agenesis (23.2%) was isolated whereas 66 (76.7%) presented with different malformations in which 29 cases (43.9 %) were only CNS lesions, 21 cases (31.8 %) were non CNS lesions and in 16 cases (24.3%) a combination of CNS and non CNS lesions was found. The mean gestational age at diagnosis for isolated and non-isolated cases was comparable: 24.29 (SD 5.05) and 24.71 (SD 5.35) weeks respectively. Of the 86 pregnancies with partial agenesis, 46 patients opted for termination of pregnancy .Neurological follow-up was available for 35 children. The overall neurological outcome was normal in 21/35 children (60%); 3/35 (8.6%) showed mild, and 6/35 (17.1%) moderate impairment. The remaining 5/35 (14.3%) had a severe impairment. The median duration of follow-up for the isolated form was 45.6 months (range 36-52 months) and 73.3 months (range 2-138 months) for non-isolated form. Partial corpus callosum agenesis should be accurately investigated by neurosonography and fetal MRI to describe its morphology and associated anomalies. Genetic anomalies are frequently present in non-isolated cases. Efforts must be taken to improve ultrasound diagnosis of partial agenesis and confirmation of its isolated nature in order to enhance parental counseling. Although children with prenatal diagnosis of isolated agenesis have favorable prognosis later in life in 60%, they have often mild to severe disabilities including speech disorders at school age and behavior and motor deficit disorders that can emerge at a later age.