Peripheral neuropathy in limbic encephalitis with anti‐glutamate receptor antibodies: Case report and systematic literature review

INTRODUCTION Autoantibodies to the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor and N-methyl-d-aspartate (NMDA) receptor are known to be the causes of autoimmune encephalitis particularly limbic encephalitis. The involvement of the peripheral nervous system is rarely reported. METHODS We analyzed the serial nerve conduction studies of a previously reported case of anti-AMPA receptor encephalitis, who was presented with conscious disturbance and quadriplegia. Initial nerve conduction studies (NCS) revealed motor axonal polyneuropathy with active denervation. We also performed systematic review of similar cases with overlapped peripheral neuropathy and glutamate receptor encephalitis through Embase, PubMed, and MEDLINE. RESULTS Follow-up NCS of the patient with anti-AMPA receptor encephalitis found reverse of the acute neuropathy, which was compatible with clinical recovery of quadriplegia. The systematic review identified 10 cases with overlapping peripheral neuropathy with anti-AMPA or NMDA receptor encephalitis. Motor or sensorimotor neuropathies were more common than pure sensory neuropathies. Anti-Hu, anti-amphiphysin, or anti-gnaglioside antibodies coexisted in some cases and might be associated with the peripheral symptoms. CONCLUSIONS Both anti-AMPA and anti-NMDA receptor encephalitis could overlap with acute peripheral neuropathy. It is important to consider peripheral symptoms and perform diagnostic tests.