The enlarged extraocular muscle: to relax, reflect or refer?

PurposeExtraocular muscle enlargement (EOME) is most commonly associated with thyroid eye disease, but there are other causes. We report our outcomes of investigating and managing non-thyroid-related EOME (NTR-EOME).MethodsRetrospective consecutive case series. Sixteen patients identified by clinical features and orbital imaging. Patient demographics, radiological features, and adjuvant tests including biopsy and final diagnosis were recorded.ResultsMean age at presentation 59.3 years (range 24-89 years). Mean follow-up 3.2 years (range 3 months to 5.5 years). Superior rectus (SR) was most commonly involved muscle (8/16 cases) followed by lateral rectus (4/16). Of the 16 cases, 14 were associated with underlying systemic neoplasia (5 lymphoma, 5 metastatic carcinoma, and 4 presumed paraneoplastic syndrome). All SR enlargement was associated with underlying neoplasia. All patients underwent orbital imaging followed by systemic imaging based on clinical index of suspicion (14/16 patients (13 full body CT (FBCT), 1 mammography)). Positive systemic radiological findings were detected in 12/14 cases. Of the remaining 2 patients, 1 underwent full body positron emission tomography-computed tomography (FBPET-CT), which detected thyroid carcinoma, and the second patient underwent FBCT for staging following orbital biopsy showing lymphoma. Four patients (25%) died within 3 years of follow-up due to disseminated systemic malignancy.ConclusionsAll cases of NTR-EOME should be viewed with a high level of clinical suspicion for systemic neoplasia, especially when the SR is involved. FBCT can help to identify a primary systemic cause. FBPET-CT is best reserved for cases negative on FBCT or for staging and monitoring systemic disease. NTR-EOME can be associated with significant mortality (25%), hence warrants prompt and thorough systemic investigation.