Human T-cell lymphotropic virus type-I associated myelopathy complicated by optic neuritis

A 48-year-old Japanese woman from Kyushu was admitted to the Nippon Medical School First Hospital with complaints of numbness in both legs, gait disturbance, and urinary problems. On examination, her lower extremities were spastic with increased reflexes and positive Babinski sign. Sensation was absent below the T4 spinal level. The cerebrospinal fluid contained HTLV-I antibodies and she was diagnosed with HTLV-I associated myelopathy. Her symptoms were resolved with prednisolone, but six months later a visual disturbance of the left eye edema developed. Orbital CT scans showed that left optic nerve was edematous. T2 enhanced MRI revealed a high intensity lesion of the left optic nerve. ERG was normal and no VEP was detected in response to flashing stimulation to the left eye. The HTLV-I antigen titer of CBF was very high. Her optic neuritis improved following oral administration of prednisolone and retrobulbar injections of dexamethasone. This is the first case report of HTLV-I associated myelopathy complicated by optic neuritis.