Chronic motor axonal neuropathy: pathological evidence of inflammatory polyradiculoneuropathy

Chronic immune and inflammatory motor neuropathies may resemble motor neuron disease, and the distinction may be particularly difficult if conduction block or GM1 antibodies are absent. The pathology of this axonal type of chronic motor neuropathy has not been characterized except in a few cases associated with paraproteinemia. We describe the clinical, electrophysiological, and pathological findings in a patient with a chronic motor axonal neuropathy, normal immunoelectrophoresis, and no GM1 antibodies. At autopsy the spinal cord was normal with the exception of chromatolytic motor neurons. All the ventral roots were greatly thinned. Of 10 mixed nerves and numerous spinal roots sampled, five showed areas of perineurial, perivascular lymphocytic infiltration. There was severe axonal loss in the motor roots that was not as evident in mixed nerves, and the sensory nerves and roots were virtually unaffected. Our findings suggest that a chronic motor axonal neuropathy without paraproteinemia or GM1 antibodies may, in some cases, result from an inflammatory process.