Radiotherapy in the management of thyroid orbitopathy. Computed tomography and clinical outcomes
S. C. Kao, D. L. Kendler, R. A. Nugent, J. S. Adler and J. Rootman
Department of Ophthalmology, University of British Columbia, Vancouver, Canada.
OBJECTIVE--We investigated the long-term outcome of patients with thyroid
orbitopathy treated with orbital radiotherapy using quantitative clinical
measurements and orbital computed tomographic morphometric changes.
DESIGN--Patients who had undergone orbital radiotherapy for thyroid
orbitopathy at least 1 year previously were retrospectively recalled for
follow-up examination and computed tomography. Controls were patients with
similar disease activity but who had not undergone radiotherapy.
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 radiotherapy (12
orbits). INTERVENTION--Standardized, super-voltage, orbital radiotherapy.
MEASUREMENTS--Five clinical indexes of orbitopathy and six computed
tomographic indexes were examined for interval changes. RESULTS--The
orbital computed tomographic muscle-diameter index enlargement ratio did
not change in either group (radiotherapy group, 1.54 to 1.51, not
significant; nonradiotherapy group, 1.37 to 1.36, not significant). The
mean (+/- SEM) number of muscles with low-density areas increased in both
groups (radiotherapy group, 1.1 [+/- 1.9] muscles per orbit; P < .001).
Soft-tissue signs improved significantly with lesser improvements in
extraocular muscle function in both groups. Proptosis, visual acuity, and
intraocular pressure rise on upgaze did not improve significantly in either
group. CONCLUSIONS--No changes in muscle size measured 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-tissue signs, improved on
follow-up, but this was not influenced by the method of treatment.
