A 72-year-old woman developed a lower motor neuron syndrome (MNS) 4 months
before the appearance of breast cancer. Monoparesis progressed to quadripar
esis despite high-dose IV immunoglobulins, plasma exchange, and azathioprin
e, and high-dose IV methylprednisolone. The patient improved only after the
,removal of the tumor. MRI demonstrated hyperintensities in the cervical sp
inal cord. The patient had antibodies that reacted with axonal initial segm
ents and nodes of Ranvier. The findings suggest that in this patient lower
MNS may be a paraneoplastic condition associated with breast cancer.