Autoimmune nodopathy associated with contactin-2 antibodies manifesting as Guillain–Barré syndrome: a case report

Abstract

Abstract

BACKGROUND: The autoimmune nodopathy affecting the node of Ranvier was formerly classified within the spectrum of chronic inflammatory demyelinating polyradiculoneuropathy. However, as a result of comprehensive pathological and immunological investigations conducted in recent years, it has increasingly been recognized as a distinct clinical entity. To date, there have been no reported cases linking autoimmune nodopathy at the node of Ranvier with anti-CNTN2 antibodies. This paper presents a case study demonstrating such an association, detailing the clinical and electrophysiological features, and thereby contributing to the global understanding and recognition of this condition. CASE PRESENTATION: The patient, a 48-year-old female of Han nationality, was admitted to the intensive care unit (ICU) after experiencing a period of unconsciousness, accompanied by a high-grade fever lasting over 4 h. Diagnostic evaluations, including blood tests and imaging studies, indicated the presence of heat stroke and coagulation dysfunction. The therapeutic interventions administered included endotracheal intubation and mechanical ventilation, continuous cooling with electric ice blankets and ice caps, treatments to correct coagulopathy, and aggressive fluid resuscitation. Following these interventions, the patient regained consciousness, and her body temperature returned to normal. However, upon cessation of mechanical ventilation, she exhibited limb weakness and produced indistinct vocalizations, although she was capable of sound production. Routine electromyography identified peripheral nerve injury of the axonal type, while cerebrospinal fluid analysis revealed protein-cell dissociation. Laboratory assays of both blood and cerebrospinal fluid samples tested positive for the anti-CNTN2 antibody IgG. Given the limited availability of effective therapeutic research for this condition at the time, intravenous immunoglobulin therapy was administered with the patient's informed consent, although it did not result in significant improvement of her symptoms. CONCLUSION: Clinically, impairments in limb motor abilities, dysarthria, respiratory insufficiency, protein-cell dissociation within the cerebrospinal fluid, and early axonal degeneration as evidenced by electromyography are critical diagnostic criteria for autoimmune nodopathy of the Ranvier nodes in patients who test seropositive for anti-CNTN2 antibodies. For individuals presenting with these phenotypes and suspected of having Guillain-Barré syndrome or chronic inflammatory demyelinating polyradiculoneuropathy, it is essential to conduct comprehensive assessments for node, paranode, and juxtaparanode antibodies, along with their specific subtypes, to refine therapeutic strategies.