The brain MRI didn't show typical MS lesions. Other diagnoses must be considered. NMO, Neuromyelitis Optica, is in most cases not painless as described by this patient. The fact that there was no recovery is also suspect for another disease.

Besides, a spinal cord scan in case of NMO would probably show longitudinally extensive lesions of at least three vertebrae. The lesions shown in this scan were short.

For example Sarcoidosis and Leber's hereditary optic neuropathy remain possible.

DNA examination brought the solution: Leber's hereditary optic neuropathy.