[100 years of the Babinski sign].

In 1896 Joseph Francois Felix Babinski described for the first time the phenomenon of the toes. In his first paper he simply described extension of all toes with noxious stimulation of the sole of the foot. It was not until 1898 that he specifically described the extension of the hallux with stimulation of the lateral border of the sole. Babinski was probably not aware at the time that E. Remak, a German physician, had previously described the sign. In his third paper of 1903 Babinski concludes that if other authors had described the abnormal reflex before him, they found it fortuitously and did not realize its semiologic value. Babinski probably discovered it by a combination of chance, careful observation and intuition. He also had in mind practical applications of the sign particularly in the differential diagnosis with hysteria and in medico-legal areas. Several of his observations and the physiopathological mechanism proposed by him are still valid today. He realized since 1896 that the Babinski reflex was part of the flexor reflex synergy. He observed that several patients during the first hours of an acute cerebral or spinal insult had absent extensor reflexes. He realized that most patients with the abnormal reflex had weakness of the toes and ankles. He found a lack of correlation between hyperactive myotatic reflexes and the presence of an upgoing hallux. He discovered that not all patients with hemiplegia or paraplegia had the sign. He thought erroneously that some normal subjects could have an upgoing toe. His dream of a practical application of the sign has been fully achieved. The motto of Babinski was Observatio summa lex. Perhaps there is no better dictum in clinical neurology.