P.041 Guillain Barre syndrome could be a rare presenting finding of nodal and paranodal autoantibodies in immune-mediated neuropathies (IMN): A clinical utility of Cell based Assay

Abstract

Background: Guillain Barre Syndrome (GBS) and chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) are the two most common forms of treatable IMNs. Antibodies targeting proteins at paranodal cell-adhesion molecules such as contactin-1 (CNTN1), neurofascin-155 (NF155), contactin-associated protein 1 (CASPR1), and nodal neurofascins-NF140 and NF186, have been discovered in CIDP patients. Methods: Between August 2021 and January 2023, at BC Neuroimmunology laboratory, Vancouver we screened a total of 214 sera of patients for detecting nodal and paranodal antibodies with a fixed CBA. These patient sera were assayed for the presence of NF140, NF155, NF186, CNTN1, plus Caspr1 antibodies. The final diagnosis and response to therapy of positive cases were evaluated by a questionnaire requested from their physicians. Results: 10 cases were positive for nodal/paranodal antibodies by CBA (mean age 52.4 ± 15.4 years). Two cases were NF155 Ab positive CIDP with good response to conventional therapies. Three cases were double positive for NF140 and 186 Abs, three were double positive for CNTN1 and CASPR1 Abs. Interestingly, two cases were triple positive with GBS presentation. Conclusions: We identified a subgroup of nine patients with CIDP nodal and paranodal antibodies. Among them, two cases had triple positive antibodies with GBS presentation and poor response to plasma exchange and IVIg.