A role for peripheral nerve ultrasound in differentiating conduction‐slowing diabetic sensorimotor polyneuropathy and chronic inflammatory demyelinating polyradiculoneuropathy

AIMS/INTRODUCTION: Differentiating chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) from conduction-slowing diabetic sensorimotor polyneuropathy (DSPN) is clinically challenging due to overlapping electrophysiological findings and frequent lack of responsiveness in nerve conduction studies (NCS). This study aimed to evaluate the role of high-resolution nerve ultrasound in distinguishing CIDP from conduction-slowing DSPN. MATERIALS AND METHODS: We retrospectively enrolled 22 CIDP and 24 conduction-slowing DSPN patients. All underwent comprehensive NCS and high-resolution nerve ultrasound. Cross-sectional areas (CSA) of multiple peripheral nerves were measured, and composite scores including the ultrasound pattern sum score (UPSS) were calculated. Statistical analyses, including logistic regression and receiver operating characteristic (ROC) curve analysis, were performed to assess diagnostic performance. RESULTS: Significant differences were found between CIDP and conduction-slowing DSPN in both NCS and ultrasound parameters. Patients with CIDP demonstrated greater prolongation of distal latencies of NCS and F-wave latency, reduced conduction velocities, and larger nerve cross-sectional areas compared with those with conduction-slowing DSPN. However, approximately 4.5%-54.5% of patients with CIDP showed no response in NCS. A UPSS score greater than 6 achieved a sensitivity of 0.77, specifically of 0.92, and an area under the curve (AUC) of 0.89 for distinguishing CIDP from conduction-slowing DSPN. CONCLUSION: High-resolution nerve ultrasound, particularly the UPSS, serves as a valuable adjunct for differentiating CIDP from conduction-slowing DSPN, especially when NCS results are inconclusive.