ECHOGRAPHIC MONITORING OF RESPONSE OF EXTRAOCULAR-MUSCLES TO IRRADIATION IN GRAVES OPHTHALMOPATHY

Purpose: Confirmation of the efficacy of orbital irradiation in Graves ' ophthalmopathy is needed due to the unpredictable natural history of the disease, the variation in individual clinical presentations, the contribution of other simultaneous treatments, and the lack of control led studies using objective criteria to classify and assess response o ver time. Orbital echography before and at select intervals following orbital irradiation is proposed as an objective parameter of tissue re sponse to orbital irradiation over time. Methods and Materials: From J anuary, 1983 to September, 1993, 55 patients with progressive Graves' ophthalmopathy underwent 20 Gy retrobulbar irradiation. On retrospecti ve review, standardized orbital echography was performed randomly prio r to irradiation in 37 of the 55 patients to assess the acoustic chara cteristics of the extraocular muscles and to quantitate their individu al and summed diameters. Twenty-one patients had at least one follow-u p echographic evaluation at random intervals of 0 to 27.5 months follo wing completion of irradiation, Twelve patients received steroids befo re or during irradiation, which were tapered in proximity to completio n of radiation. Follow-up ranged from 2 to 65 months with the majority followed at least 6 months (18 patients). Results: Of the 21 patients with serial studies, 18 showed an interval decrease in individual and summed muscle size over time and return of symmetry, Interval improve ment was documented as early as the 1 month follow-up study, with cont inued improvement seen during the 3-9-month studies, with stability ty pically achieved within 12 months. One patient had further changes bet ween the 21 and 27.5 month follow-up studies. Exacerbation of disease was, however, echographically demonstrated in three patients at 6.5, 8 .5, and 13 months, Follow-up studies in two of these patients again re vealed improvement, one following tapered steroids, The third patient required orbital decompression. Conclusion: Objective parameters of re sponse are needed to document both the immediate and long-term outcome of orbital irradiation on the course of Graves' ophthalmopathy and co nfirm its efficacy. Serial echography is proposed as a new technique f or providing parameters to judge response.