MRI findings of trigeminal nerve hypoplasia in congenital corneal anesthesia: a case series

Abstract Purpose Congenital corneal anesthesia (CCA) is a rare pediatric disorder characterized by absent corneal sensation and potential for severe ocular complications. Imaging literature remains limited and radiologic awareness is low. We report MRI findings in pediatric CCA using high-resolution heavily T2-weighted sequences to characterize trigeminal nerve morphology and review the current literature systematically. Methods A descriptive case series of consecutive pediatric patients with clinical suspicion of CCA, referred to the pediatric ophthalmology service at a tertiary medical center, with one additional patient from a second institution, between March 2021 and February 2025. All patients underwent brain MRI; high-resolution heavily T2-weighted sequences (FIESTA, DRIVE, or T2 SPACE) were used where available. Results Four pediatric patients (age range 6 months to 3 years, one female) were evaluated. Trigeminal nerve abnormalities were identified in all four patients, including unilateral hypoplasia or thinning (three patients), bilateral thinning (one patient), and hypoplastic Meckel’s cave in two patients. All patients demonstrated ipsilateral corneal anesthesia and pathology, including ulceration, scarring, and neovascularization. Conclusions Trigeminal nerve hypoplasia on high-resolution T2-weighted MRI appears to be a consistent imaging finding in pediatric CCA. Dedicated high-resolution T2-weighted sequences depicting the trigeminal nerve course are essential. This series aims to increase awareness of this rare diagnosis, for which an early surgical procedure may save vision and prevent corneal blindness.