A Case of Congenital Idiopathic Enlargement of Extraocular Muscles.

The purpose of this case report is to report a case of congenital idiopathic enlargement of extraocular muscles. A four-month-old girl showed limitation of adduction and supraduction in the right eye. A computerized axial tomography (CAT) scan revealed hypertrophy of the lateral rectus muscle and inferior rectus muscle of the right eye. Thyroid hormone and antibody levels were normal. No inflammatory findings on magnetic resonance imaging (MRI). A traction test under general anesthesia revealed a strong limitation of supraduction and a mild limitation of adduction. Therefore, the inferior rectus muscle was recessed 4.5 mm at the age of six months. A partial biopsy of the inferior rectus showed no inflammatory cell infiltration. After the first surgery, the patient's limitation of supraduction improved, but the limitation of adduction persisted. So, a 5 mm recession of the right lateral rectus muscle was added at one year and one month. However, the hypertropia of the sound eye became stronger after treatment of amblyopia. Because of the strong limitation of supraduction, tenotomy of the inferior rectus was performed at the age of six years. Postoperatively, no impairment of infraduction occurred, and the limitation of supraduction was mildly improved. Since the findings on MRI were not changed through our observation period, we concluded that the patient had idiopathic external ophthalmoplegia.