EP05.12: Prenatal imaging and clinical outcomes in isolated congenital aqueductal stenosis: a single‐centre retrospective cohort study

Congenital aqueductal stenosis (CAS) is a known cause of obstructive hydrocephalus, with implications for poor neurodevelopmental outcomes. However, isolated CAS remains relatively understudied. Our objective is to investigate the prenatal imaging measures, clinical course and outcomes associated with isolated CAS. We conducted a retrospective cohort study using our institutional database in the period of 2010-2023. We included patients with isolated CAS confirmed postnatally who were imaged prenatally and had ≥1 year of clinical follow-up. Patients with additional intracranial and/or extracranial structural anomalies, or genetic anomalies were excluded. Neurodevelopmental outcomes were verified by developmental-behavioural pediatricians, and imaging findings underwent standardised measurement of ventricular sizes and Frontal Occipital Horn Ratio (FOHR) by a pediatric neuroradiologist. Twenty-two patients were prenatally diagnosed with CAS via Ultrasound/MRI, at a median gestational age (GA) of 19.8 weeks. Overall, 14/15 patients exhibited a FOHR >0.5, indicating clinically significant ventriculomegaly in initial MRI at 18-32 weeks GA. There was significant increase in median size of the third ventricular coronal width from 7.5mm in prenatal imaging to 12mm in postnatal imaging prior to postnatal treatment (p = 0.01). Twenty-one patients (95.4%) required shunting or endoscopic third ventriculostomy and bilateral choroid plexus cauterisation (ETV/CPC), with 11 undergoing multiple CSF diversion procedures during follow-up. Among these patients, 9 experienced epilepsy, 1 developed cerebral palsy, 8/10 aged <5 years exhibited global developmental delay, and 6/12 aged ≥5 years required special education. Our findings indicate a progressive increase in ventricular sizes from initial imaging to delivery, with most children requiring CSF diversion procedures and experiencing neurodevelopmental impairment.