[Nuchal-paretic sign in multiple sclerosis]

A 43-year-old patient with clinically established diagnosis of multiple sclerosis had the nuchal-paretic sign. Neck flexion caused reversible deterioration of gait and increased the weakness of the right lower extremity. Although the sign is not pathognomonic for multiple sclerosis it is a peculiar pyramidal sign suggesting demyelination especially in the cervical part of the spine. Mechanical stretching of the demyelination plaques in the cervical spine reduces probably the density of the action current generated at the nodes of the demyelinated fibres.