Immunohistochemistry and electrophysiological findings in swine abattoir workers with immune-mediated polyradiculoneuropathy

Importance Workers exposed to aerosolized brain in a swine-processing plant developed immune-mediated polyradiculoneuropathy (IP) possibly triggered by an immune response. Objective Immunohistochemistry results were correlated with electrophysiological variables to examine the immunopathogenesis of this disorder. Design/setting Laboratory studies used normal nerve tissue that was exposed to sera from 12 IP patients; 10 exposed controls; and 10 unexposed controls. Clinical and electrophysiological data from IP patients were obtained from medical record reviews. Main outcome measures Analysis included electromyography results of IP patients and nerve conduction studies examining CMAP amplitude, distal motor latency, motor conduction velocity, F-wave latency, sensory nerve action potential amplitude, and sensory nerve conduction velocity. Case and control results were compared relative to distance from exposure. Results Electrodiagnostic findings revealed prolongation of the distal and f-wave latencies suggestive of demyelination at the level of the nerve root and distal nerve terminals. Immunohistochemical results identified an antibody to the peripheral nerve, with staining at the level of the axolemma. Thus, IP may be a primary axonopathy with secondary paranodal demyelination causing the conduction changes. Staining of the distal and proximal portions of the nerve appears consistent with easier access through the blood-nerve barrier. Conclusions and relevance IP is an immune-mediated neuropathy related to antibodies to an axon-based antigen on peripheral nerves. Secondary paranodal demyelination is likely. Further studies to identify the primary axonal antigenic target would be useful.