[Optic nerve swelling and gadolinium contrast enhancement on magnetic resonance imaging in the subacute stage of Leber's hereditary optic neuropathy: a case report].

We report the case of a 50-year-old man with subacute onset of bilateral visual field loss and visual acuity loss. His visual acuity was 0.07 OD/0.09 OS and Goldmann perimetry showed central scotomas. The optic fundi were normal bilaterally. Magnetic resonance imaging (MRI) showed hyperintensity in the right optic nerve on T(2) weighted imaging and swelling of the optic chiasm with slight enhancement of the bilateral optic nerves and the optic chiasm on gadolinium-enhanced imaging. Since sensory disturbance in the left hand and leg was noted in addition to the visual problem, multiple sclerosis (MS) was suspected initially. The patient was treated with intravenous methylprednisolone (1,000 mg/day), plasma exchange therapy, and immunosuppressant therapy. However, his visual disturbance did not improve. He had a history of deafness and family history of visual disturbance, because of which we performed an analysis of mitochondrial DNA. G11778A point mutation was found, and a diagnosis of Leber's hereditary optic neuropathy (LHON) was made. Although gadolinium contrast enhancement and swelling of the optic nerve are rare, this case shows that these findings are not in conflict with LHON. The present case also suggests that mitochondrial dysfunction may trigger the onset of MS-like extraocular symptoms in patients with LHON.