Nerve Ultrasound in Pediatric Polyneuropathies: A Systematic Review.

The diagnosis of peripheral polyneuropathy in children and the differential diagnosis among its various forms often present a challenge, also because electrodiagnostic studies can be painful and sometimes yield inconclusive results. This systematic review examines the role of nerve ultrasound (n-US) in the diagnosis and follow-up of pediatric polyneuropathies. We searched PubMed and Embase from 1975 to April 1, 2025. Included studies assessed patients aged ≤ 18 years with clinically and neurophysiologically confirmed polyneuropathy, providing pediatric-specific qualitative or quantitative n-US findings. Eighteen studies met the inclusion criteria. Six focused on acquired inflammatory polyneuropathies (three on Guillain-Barré Syndrome [GBS], three on Chronic Inflammatory Demyelinating Polyneuropathy [CIDP]), eight on Charcot-Marie-Tooth disease (CMT), two on lysosomal storage disorders, one on Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS), and one on mixed etiologies. Most (n = 7) were case reports. Cross-sectional area and nerve enlargement (NE) distribution were the main parameters evaluated. Marked, diffuse NE was found in demyelinating CMT and lysosomal disorders; CIDP showed diffuse and multifocal NE; GBS presented mild and proximal NE. No NE was reported in axonal CMT or ARSACS. Few studies assessed echogenicity or fascicular structure; none evaluated vascularization. n-US shows promise in differentiating demyelinating conditions such as CMT, CIDP, GBS, and certain metabolic syndromes in children. However, further age-matched control studies are needed, given that nerve growth and myelination peak between 15 and 17 years. Future research should explore n-US as an early diagnostic, screening, and follow-up tool.