Echographic characterization of extraocular muscles in pediatric patients with thyroid dysfunction

To characterize the size of extraocular muscles (EOMs) in a pediatric population with thyroid dysfunction using orbital echography.

Patients under age 18 with thyroid dysfunction who presented to an academic ophthalmology department from 2009 to 2020 and received orbital echography were included in this IRB-approved retrospective study. Data collected included age, clinical activity score (CAS), thyroid stimulating immunoglobulin (TSI), and extraocular recti muscle thickness on echography. Patients were organized into three age cohorts, after which statistical analysis compared recti measurements to previously reported normal ranges.

Twenty patients with thyroid dysfunction were included. When comparing average recti muscle thicknesses of study patients to those of previously published normal children in similar age ranges, the levator-superior rectus complex was significantly increased in all age groups of children with thyroid dysfunction (p-values = <.004), and the levator-superior rectus complex was most frequently enlarged compared to published normal values (78% of eyes). CAS was not correlated with EOM size in the youngest group (5-10 years old, p-values >.315) but was significantly correlated in older groups (11-17 years old, p-values <.027). TSI was not correlated with EOM size in any group (p-values >.206).

Echographic reference ranges for EOMs in children with thyroid dysfunction were established. There are increased rates of levator-superior rectus complex enlargement in children with TED compared to adults with TED, and EOM size is correlated with CAS in children older than 10 years. Though limited, these findings may serve as an additional tool for ophthalmologists to ascertain disease activity in pediatric patients with thyroid dysfunction.