The primary objective of the study is to evaluate the long-term safety and tolerability of BIIB074 in participants with neuropathic Pain From Lumbosacral Radiculopathy (PLSR). A secondary objective is to investigate the maintenance of effect during long-term treatment with BIIB074 in participants with neuropathic PLSR. For all efficacy assessments, baseline will be prior to randomization into Study 1014802-203. Another secondary objective is to evaluate the impact of treatment with BIIB074 on quality of life (QoL).