Controversies were raised about the cooperation of Levi-Montalcini with the Italian pharmaceutical industry Fidia. While working for Fidia, she improved the understanding of gangliosides. Beginning in 1975, she supported the drug Cronassial (a particular mixture of gangliosides) produced by Fidia from bovine brain tissue. Independent studies showed that the drug actually could be successful in treatment of intended diseases (peripheral neuropathies). Years later, some patients under treatment with Cronassial reported a severe neurological syndrome (Guillain–Barré syndrome). As per the normal cautionary routine, Germany banned Cronassial in 1983, followed by other countries. Italy prohibited the drug only in 1993; at the same time, an investigation revealed that Fidia paid the Italian Ministry of Health for a quick approval of Cronassial and later paid for pushing use of the drug in treatment of diseases where it had not been tested. Levi-Montalcini's relationship with the company was revealed during the investigation, and she was criticized publicly.