RADIOTHERAPY IN THE MANAGEMENT OF THYROID ORBITOPATHY - COMPUTED-TOMOGRAPHY AND CLINICAL OUTCOMES

Objective.-We investigated the long-term outcome of patients with thyr oid orbitopathy treated with orbital radiotherapy using quantitative c linical measurements and orbital computed tomographic morphometric cha nges. Design.-Patients who had undergone orbital radiotherapy for thyr oid orbitopathy at least 1 year previously were retrospectively recall ed for follow-up examination and computed tomography. Controls were pa tients with similar disease activity but who had not undergone radioth erapy. Setting.-Subspecialty clinic in a university teaching hospital. Patients.-Twenty-one patients (42 orbits) who underwent radiotherapy and six clinically comparable patients who had not undergone radiother apy (12 orbits). Intervention.-Standardized, supervoltage, orbital rad iotherapy. Measurements.-Five clinical indexes of orbitopathy and six computed tomographic indexes were examined for interval changes. Resul ts.-The orbital computed tomographic muscle-diameter index enlargement ratio did not change in either group (radiotherapy group, 1.54 to 1.5 1, not significant; nonradiotherapy group, 1.37 to 1.36, not significa nt). The mean (+/-SEM) number of muscles with low-density areas increa sed in both groups (radiotherapy group, 1.1 [+/-1.9] muscles per orbit ; P<.001). Soft-tissue signs improved significantly with lesser improv ements in extraocular muscle function in both groups. Proptosis, visua l acuity, and intraocular pressure rise on upgaze did not improve sign ificantly in either group. Conclusions.-No changes in muscle size meas ured with computed tomography were found in either patients undergoing radiotherapy or patients not undergoing radiotherapy after long-term follow-up. Clinical indexes of thyroid orbitopathy, especially soft-ti ssue signs, improved on follow-up, but this was not influenced by the method of treatment.