In Patients with Dysimmune Motor and Sensorimotor Mononeuropathies, the Degree of Nerve Swelling Correlates with Clinical and Electrodiagnostic Findings

In non-vasculitic immune-mediated neuropathies, imaging studies demonstrate an enlargement not only of clinically involved but also of clinically intact nerves. The present study aimed to present a pattern of nerve swelling and its relation to nerve function. In a group of patients with dysimmune motor and sensorimotor mononeuropathies, nerve cross-sectional areas (CSAs) were measured using ultrasonography (US) and compound muscle action potential (CMAP) amplitudes using electrodiagnostic (EDx) studies. Nerve CSAs were compared in (1) clinically involved, (2) swollen and clinically uninvolved, and (3) non-swollen (clinically uninvolved) nerves. Patients’ non-swollen nerves were also compared to those of controls. In swollen nerves, the correlation between nerve CSA and CMAP amplitude was calculated. Twenty-two patients (12 men) and 50 controls (28 men) were included in the study. Clinically involved nerves were thicker than swollen segments of clinically intact nerves (p < 0.001). The patients’ non-swollen (clinically uninvolved) nerves were thicker than the controls’. In swollen nerves, CSA was strongly negatively correlated with CMAP amplitude (r = −0.54, p < 0.001). In patients with immune-mediated mononeuropathies, nerve swelling correlates with clinical and EDx findings. Patients’ clinically uninvolved nerves were also swollen, but to a lesser degree.