Olfactory bulb volume and asymmetry as predictors of executive dysfunction in adolescents with congenital heart disease

Neurodevelopmental disabilities are common sequelae in patients with congenital heart disease (CHD), although limited research has investigated the mechanistic underpinnings of these findings. Our study investigates whether olfactory bulb (OB) anomalies predict neurodevelopmental outcomes in adolescents with CHD.

A prospective, observational study of 54 CHD and 75 healthy subjects, ages 6–25 years old, was completed under the supervision of a senior pediatric neuroradiologist. T2 3D Space and T2 Blade 2 MM MRI images were manually segmented to extract volumetric bilateral regions of the OB and cerebrospinal fluid (CSF) using ITK-SNAP. Imaging metrics were correlated to OB asymmetry, CSF to OB ratio, total CSF volume, total OB volume, and independent left and right CSF and OB volumes. Executive function was determined by the NIH Toolbox Cognitive Battery, Behavioral Rating Inventory of Executive Function (BRIEF) and Delis-Kaplan Executive Function System (D-KEFS).

No statistically significant results were reported between cohorts for asymmetry of OB, CSF to OB ratio, total CSF volume, total OB volume, nor between independent left and right CSF and OB volumes. Increased OB volume and asymmetry of the OB were associated with worse outcomes on the BRIEF Parent Report.

Our findings identify adolescents who are at risk for executive dysfunction, particularly those showing increased OB volume and/or asymmetry of the OB. This is especially concerning for the CHD population with atypical OB morphology, as they show significantly poorer outcomes on the BRIEF Parent Report and face a higher overall risk.