[Lhermitte's sign].

Besides Babinski's, Lhermitte's sign is likely the eponym mostly used in the neurological literature. We review here the history of this eponym as well as recent advances on its pathophysiology and treatment. Lhermitte's phenomenon is, on one hand, a symptom as it is spontaneously explained by patients, and, on the other hand, a sign as it may be triggered by flexion of the nape. Initially described after head and cervical spine trauma, firstly by Marie and then by Babinski, it was Jean Lhermitte who recognized on it an etiological specificity, namely, a demyelinating sign of cervical spinal posterior cords. He also made a pathophysiological interpretation of the phenomenon, namely, a stretching of posterior cords during flexion of the neck. All authors agree that this phenomenon is more common in multiple sclerosis, although it has been descibed in many other conditions. The history of how this sign was hatched, whose pathophysiology remains a mystery, is fascinating. And it is fascinating the fact that patients compare the phenomenon with a current, especially if we bear in mind that few people may have suffered an electrocution, mainly in that time when just a few ones could actually enjoy domestic electricity.