A Trial to Assess the Long-term Safety and Efficacy of Lacosamide in Subjects With Painful Diabetic Neuropathy

The purpose of this study is to determine if lacosamide (SPM 927) is safe if taken for a longer period of time and whether it continues to work well to treat pain. Subjects will receive lacosamide at a dose that will be individually determined to be the one that provides most pain relief with the least side effects. The maximum dose will be 600mg/day. Subjects may participate in this trial until October 2007. This time may be extended to allow them to participate until lacosamide is commercially available. If a subject meet the requirements for the study at Visit 1 and after a two weeks phase without trial medication, s/he enters a Titration Phase to determine the personal optimal dose of lacosamide. When this dose is reached s/he will enter the Maintenance Phase and will be asked to return for visits every 4 weeks for the first 24 weeks and every 12 weeks thereafter.