Motor Neuropathy Causes and Associations

Toxic/Drug-Induced Motor Neuropathy

Vincristine causes motor neuropathy in approximately 10% of patients, ranging from grade 1-3 distal weakness to rare life-threatening grade 4 motor neurotoxicity, with pre-existing axonal Charcot-Marie-Tooth disease significantly increasing vulnerability 1, 2
Bortezomib predominantly causes sensory neuropathy but motor impairment occurs in ~10% of cases with mild to severe distal weakness in lower limbs 2
Other neurotoxic chemotherapeutic agents (platinum compounds, taxanes, thalidomide) primarily affect sensory fibers but can have motor components 1, 2

Diabetic neuropathy typically presents as distal symmetric polyneuropathy affecting both sensory and motor fibers, though motor involvement is less prominent, and diabetic central neuropathy can damage motor neurons of the spinal cord 3, 4, 5

Charcot-Marie-Tooth type 1A should be ruled out in cases of severe motor neurotoxicity, particularly with vincristine exposure, as these patients present with predominant motor involvement and distinct deformities (hollow foot, stork legs) 1