Can MS show lesions only in the brain and not in the spinal cord? And what type of MS would this be?

See below. If you have optic neuritis and suspicious lesions in the brain, you have a very high chance of having multiple sclerosis. The absence of lesions in spinal cord is not exclusionary. Although other disorders may cause your issues, would get diagnosis confirmed, and start a potent MS agent ASAP, if that seems to be answer.

Related Questions

Is it unusual to have MS lesions only in the spinal cord, but not in the brain?

Does happen. Far less common presentation, but several patients may have initial lesions in spinal cord. However, here's the main challenge: a condition called neuro-myelitis optica might present this way also, and the drugs for ms would make things worse, so get an aquaporin 4 study to make things more precise. Read more...