CD40LG and Waldenstrom macroglobulinemia: ACDF: anterior cervical discectomy and fusion; EMG: electromyography; NCS: nerve conduction studies; MRI: magnetic resonance imaging; IVIG: intravenous immunoglobulin; SPEP: serum protein electrophoresis; IgM: immunoglobulin M; WM: Waldenström macroglobulinemia