What is a clinically isolated syndrome (CIS)?
Clinically isolated syndrome is the first presentation of signs and symptoms that show characteristics of inflammatory demyelination that could be Multiple Sclerosis but is only a single monophasic event (not disseminated in time).
An example of a clinically isolated syndrome would be an episode of either optic neuritis or transverse myelitis or other single isolated event.
If such patients have abnormal magnetic resonance imaging (MRI) showing other (asymptomatic) lesions characteristic of Multiple Sclerosis, it is highly likely that a clinically isolated syndrome is actually the initial attack of Multiple Sclerosis.
