Walsh & Hoyt: Subacute Motor Neuropathy

Patients with subacute motor neuropathy usually have an underlying systemic lymphoma that has been diagnosed by the time symptoms of the neuropathy occur. This syndrome has rarely been described in patients with other malignancies. Affected patients have no significant sensory symptoms or signs. Instead, they develop painless progressive weakness that may be proximal or distal, symmetric or asymmetric, usually affecting the legs more than the arms. The weakness is associated with findings of lower motor neuron dysfunction, including fasciculations, reduction in muscle stretch reflexes, and eventual atrophy of affected muscles. The bulbar and respiratory muscles are often spared, but when they are affected the damage is usually not severe. Unlike other forms of paraneoplastic peripheral neuropathies, subacute motor neuropathy usually stabilizes or may even improve spontaneously after months or even years, independent of the course of the underlying neoplasm.