Chronic Inflammatory Demyelinating Polyradiculoneuropathy: A Comparative Study of Magnetic Resonance Neurography and High-Resolution Nerve Ultrasound in the Assessment of Brachial Plexus.

Background and objectives: Magnetic resonance neurography (MRN) and high-resolution ultrasound (HRUS) are complementary diagnostic modalities in the diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). HRUS may be a cheaper bedside alternative to MRN. It is important to know their correlation with each other and with clinical severity and electrophysiology. There are no data on the normal cross-sectional area (CSA) of the brachial plexus in the Indian population. We undertook this study to establish a normative data of CSA of the brachial plexus for Indians, compare HRUS and MRN findings in CIDP, and correlate the findings with electrophysiological parameters.

Methods: A prospective, observational, cross-sectional study was done in the Department of Neurology, National Institute of Mental Health and Neurosciences, Bangalore, India from February 2020 to February 2022. Twenty adult patients with CIDP underwent clinical and electrophysiological evaluation. Their MRN and ultrasound (USG) findings were compared to those of 20 age- and sex-matched healthy controls. Correlation between disease severity, electrophysiological parameters, MRN, and HRUS was done.

Results: Controls had a median CSA of 0.06-0.07 cm2 for all 3 trunks of the brachial plexus, while CIDP patients had a median CSA of 0.11-0.14 cm2. There was a nonsignificant positive correlation between distal latency and CSA, and nonsignificant negative correlation with conduction velocity, amplitudes, and F-wave persistence. No significant correlation was seen between inflammatory neuropathy cause and treatment disability score and CSA. MRN and HRUS showed good correlation.

Conclusions: MRN and HRUS show a significant increase in CSA in CIDP. HRUS may be a cheaper bedside alternative to MRN.