Novel Presentation of Contactin-1 Autoimmune Nodopathy as a Lumbosacral Radiculoplexus Neuropathy
Objective:
We describe a case of contactin-1 autoimmune nodopathy presenting as a subacute, painful lumbosacral radiculoplexus neuropathy (LRPN) in a patient with smoldering Waldenström’s macroglobulinemia.
Background:
Contactin-1 autoimmune nodopathy is a rare autoimmune disorder targeting paranodal proteins at the node of Ranvier. Clinically, it is known to present as a severe, motor predominant neuropathy.
Design/Methods:
Case report.
Results:
A 79-year-old woman with smoldering Waldenström’s macroglobulinemia was for a 3-week history of progressive lower extremity pain and weakness. Neurologic examination demonstrated inability to walk or stand and severe, asymmetric flaccid paraparesis (right worse than left) with proximal and distal weakness, decreased/absent tendon reflexes, and reduced vibratory sensation and proprioception. Cranial nerves and upper extremity exam were normal. Electrodiagnostic testing demonstrated a subacute, demyelinating polyneuropathy with reduced recruitment and mildly large motor unit potentials in proximal and distal lower limb muscles. MRI of the thoracic spine, lumbar spine, and lumbosacral plexus revealed no abnormal enhancement. CSF protein was elevated without pleocytosis. Blood work-up showed strongly positive IgG4 contactin-1 antibody by cell-based assay and immunofluorescence assay. 24-hour urine study showed nephrotic-range proteinuria (3.2 grams). Renal biopsy confirmed membranous nephropathy and liquid chromatography tandem mass spectrometry identified a peptide profile consistent with contactin-1. The patient received daily 1g intravenous methylprednisolone for 5 days followed by weekly infusions for 4 weeks and rituximab induction therapy (1 g ×2, 2 weeks apart). After 3 months, she regained ability to walk.
Conclusions:
This case expands the clinical phenotype of contactin-1 autoimmune nodopathy to include LRPN. Recognition of this presentation is important given its association with IgM paraproteinemia and membranous nephropathy and different treatment strategy compared to typical LRPN.
Generative AI Usage
No, did not use generative AI in the drafting or editing in this abstract.
Disclaimer: Abstracts were not reviewed by Neurology® and do not reflect the views of Neurology® editors or staff.