A case misdiagnosed as bilateral abducens palsy

A 66-year-old male was admitted to our neurosurgical floor because of double vision and gait disturbance. Neurological examinations revealed bilateral 6th nerve palsy with both eyes pointing toward the midline. Initially, using a tentative diagnosis of intracranial mass lesions, especially localized at the base of the skull, computerized tomography of the head, cerebral angiography, orbital venography, and metrizamide CT cisternography were performed; the findings were normal. An orbital CT scan showed an enlargement of the bilateral medial rectus muscles, and the thyroid functions of T3 and T4 and the T3 uptake were all elevated, which was compatible with the diagnosis of Graves' disease. The limitations of both eyeballs were considered to be due not to the 6th nerve palsy, but to the hypertrophy of the bilateral medial rectus muscles. We neurosurgeons should recall Graves' disease as well as intracranial lesions, cerebrovascular disease, and post-traumatic sequelae when examining a patient who presents limitations of external ocular movement. (author)