Different neurophysiological methods such as evoked potentials (EP), testing of 
the autonomic nervous system (ANS) or polysomnography have the potential to 
detect clinically silent lesions or to confirm the existence of an association 
between a clinical symptom and multiple sclerosis (MS); previously undetected by 
MRI. Therefore, in the most recent MRI criteria for the diagnosis of MS (MAGNIMS 
consensus guidelines), neurophysiological confirmation of optic nerve 
dysfunction (slowed conduction on visual EP), support dissemination in space 
and, in patients without concurrent visual symptoms, dissemination in time. In 
this chapter we will review the existing evidence regarding the role of 
different neurophysiological tests (specifically the role of EPs, autonomic 
nervous system testing and sleep testing in MS) in the diagnosis and management 
of MS.