Neurologic Complications in Multiple Myeloma and Plasmacytoma

Neurologic complications in plasma cell malignancies are frequently seen in the practice of neuro-oncology, involving areas such as the peripheral and central nervous system. These can be the first symptoms, leading to the diagnosis of the underlying disease, or they may appear during the course of the illness. Radicular pain secondary to compressive radiculopathy is the most common neurologic complaint. Additionally, neurotoxic side-effects derived from the first-line drugs employed are frequently observed during treatment of the malignancy, particularly sensory distal polyneuropathies. Multiple myeloma (MM) is the most common malignant plasma cell disorder, accounting for approximately 10 % of all haematological malignancies. A wide spectrum of neurological complications has been described associated with MM, ranging from carpal tunnel syndrome to the life-threatening spinal cord compression. Plasmacytoma is defined as a localized proliferation of malignant plasma cells, and it may eventually turn into MM. Plasmacytoma may occur inside or outside the bone marrow, with neurologic involvement depending on the placement of the mass. The POEMS syndrome is a paraneoplastic disorder associated with the presence of a bone plasmacytoma. Peripheral neuropathy is always present in the POEMS syndrome. Moreover, clinical manifestations secondary to central nervous system involvement are being increasingly recognized, like papilloedema, stroke, and pachymeningitis. This review will focus on the neurologic complications associated with MM, plasmacytoma, POEMS syndrome, and their management. Furthermore, neurologic complications derived from treatment will also be reviewed, especially the treatment of emergent peripheral neuropathy.