Expanded Access Study Amifampridine Phosphate in Lambert-Eaton Myasthenic Syndrome (LEMS),Congenital Myasthenic Syndrome

Primary: The primary objective of this study under the original protocol was to provide neuromuscular specialists and neurologists access to amifampridine phosphate therapy for their patients with LEMS, CMS or downbeat nystagmus until the product became commercially available. Secondary: The secondary objective of this study under the original protocol was to provide additional long-term safety data on amifampridine phosphate in patients. Primary The primary objective of this study after its fifth amendment was to provide access to amifampridine phosphate therapy to pediatric patients with LEMS, and pediatric and adult patients with CMS until the product became commercially available for these indications or development of the product for the indication was terminated. Secondary: The secondary objective of this study after its fifth amendment was to assess the long-term safety of amifampridine phosphate in pediatric patients with LEMS, and pediatric and adult patients with CMS.