The primary objective of the study is to evaluate the efficacy of two dose regimens of BIIB074 on neuropathic pain in participants with pain from lumbosacral radiculopathy (PLSR). Secondary objectives are to evaluate the efficacy of 2 dose regimens of BIIB074 on additional neuropathic pain measures and assessments of low back pain, disability, and quality of life; To investigate the safety and tolerability of 2 dose regimens of BIIB074 and To characterize the pharmacokinetics (PK) of BIIB074 in this population.