Various case series of patients with autoimmune demyelinating disease affecting both the central and peripheral nervous system (CNS and PNS) have been reported for decades. Frequently, demyelination starts within PNS, but later CNS pathology develop, in some cases with a relapsing–remitting course. The potential mechanisms of concomitant damage of the myelin from the PNS and CNS remain unclear. We studied 80 patients with ‘’classical” PNS demyelination (25 with acute inflammatory demyelinating polyneuropathy (AIDP) and 55 with chronic inflammatory demyelinating polyneuropathy (CIDP)) and 80 with “classical” CNS demyelination – multiple sclerosis (MS). The goal of the research was to study the clinical, electrophysiological and neuroimaging interrelations of impairment of the central and peripheral nervous system in diseases with pollard demyelinating manifestations: central and peripheral. The research revealed the existence of a clinical-neurophysiological continuum of central and peripheral demyelination. The extremes of this clinical-neurophysiological continuum were occupied by AIDP and CIDP on one limit and MS on the other. The intermediate part of the mentioned spectrum was occupied by a syndrome of combined central and peripheral inflammatory demyelination. The subclinical impairment of the CNS in demyelinating polyneuropathies could be detected by means of electrophysiological and neuroimaging investigations. In cases of AIDP subclinical signs of pyramidal tract impairment were established based on conduction in the pyramidal pathway by means of motor evoked potentials (MEP). The clinical impairment of the CNS was established within the CIDP pattern of symmetric proximal and distal weakness (Dimachkie MM, Saperstein DS, 2014). This form develops mainly in females, in remitting-relapsing course of the disease, with expressed degree of the motor and sensory deficit, and resistant to conventional immunosuppression treatment. The study demonstrated that in a significant number of patients with MS subclinical signs of peripheral nerve impairment occurred. The sensory fibers of the sural and motor fibers of the peroneal nerves were more frequently involved.