Follow‐Up Studies of Nerve Ultrasound and Motor Conduction in Patients With Autoimmune Nodopathy

INTRODUCTION/AIMS: This study aimed to investigate long-term ultrasound and electrophysiological follow-up findings and their associations with antibody (Ab) titers in patients with autoimmune nodopathy. Longitudinal data correlating imaging, electrophysiological changes, and Ab dynamics remain scarce. METHODS: A total of 16 patients with autoimmune nodopathy were prospectively recruited between August 2016 and July 2025. Patients underwent follow-up clinical, electrophysiological, and ultrasound assessments at intervals of approximately 6-12 months. Bilateral nerve ultrasound was performed on the median nerve, ulnar nerve, and brachial plexus in all patients, and nerve conduction studies (NCS) were performed concurrently. The median follow-up duration was 13.5 months. RESULTS: Cross-sectional area (CSA) changes were significantly associated with Ab titer changes (p = 0.010). The CSA changes were not associated with those of motor conduction velocity (MCV) (p = 0.171). No significant associations were observed between MCV changes and Ab titer changes (p = 0.853). Five patients exhibited a reduction in nerve CSA: four of these converted to seronegative status, and one showed a decrease in Ab titer during follow-up. Among the six patients with increased nerve CSA, five had unchanged or higher Ab titers, while the remaining patient was seronegative at follow-up. The changes in CSA and Ab titer were consistent with one another in individual patients throughout follow-up. DISCUSSIONS: Changes in nerve CSA were closely associated with those of Ab titers, even during long-term follow-up of individual patients. These findings suggest that nerve ultrasound may serve as a supplementary biomarker for disease activity in patients with autoimmune nodopathy.