RESUMEN
A 41-year-old Japanese female was admitted to our hospital with a history of right abducens nerve palsy, right gaze diplopia, right eye pain and double vision. Thyroid function, thyroid autoantibody levels, and tests for other pathologies were normal. Orbital contrast-enhanced short-TI Inversion Recovery-magnetic resonance imaging before treatment showed contrast-enhanced, severe lateral rectus and rectus superior muscle swelling in the right eye. We therefore diagnosed this patient as orbital myositis. Intravenous glucocorticoid pulse therapy with methylprednisolone (mPSL) was initiated. After prescribing a daily dose of 1,000 mg of mPSL three times a week, all symptoms, including physical abnormalities, disappeared. The patient was discharged on day 14 after hospitalization and was prescribed oral PSL (30 mg/day). This report indicates that early and initial adequate treatment with a high dose of mPSL is very effective for orbital myositis treatment. However, the possibility of recurrences must be always considered at subsequent follow-up.