Nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies

October 2023

Abstract

Purpose of review

The purpose if this review is to provide an overview of the available data on the use of nerve ultrasound for the diagnosis and follow-up of peripheral neuropathies.

Recent findings

During the last decade, nerve ultrasound has been established as a complementary tool for the evaluation of morphological changes mostly for immune-mediated polyneuropathies. Through the development of ultrasound protocols for evaluation of disease-specific sites, nerve ultrasound has proven to be a practical, widely available, reproducible diagnostic tool with no relevant contraindications.

Summary

Cross-sectional area, echogenicity, morphology of the individual nerve fascicles, thickness of the epineurium, vascularization and mobility of the nerve are the main parameters evaluated with nerve ultrasound in polyneuropathies. Patients with typical chronic inflammatory demyelinating polyneuropathy show multifocal nerve enlargements easily visible on the upper extremities and the brachial plexus, whereas its variants show focal nerve enlargements. On the other hand, axonal neuropathies including diabetic neuropathy present with isolated nerve enlargement mostly in compression sites.

What is CIDP?

Chronic inflammatory demyelinating polyneuropathy (CIDP) can be thought of as the chronic form of AIDP. It is primarily distinguished both by its time course—by definition, symptoms must persist for at least 8weeks—and its responsiveness to corticosteroid treatment (AIDP, you may recall, is not steroid responsive). It tends to be monophasic, with a relatively gradual onset and even more gradual recovery, but some patients can present with a relapsing and remitting course. Otherwise, CIDP closely resembles AIDP, with predominantly distal, symmetric, ascending motor weakness and decreased or absent reflexes. Albuminocytologic dissociation in the CSF is a hallmark finding, as with AIDP. IVIG, PLEX, or pulse high- dose corticosteroids are first- line treatment.

There are several CIDP variants, including sensory- predominant and pure motor forms, that can be harder to recognize and diagnose. CSF analysis and electrophysiologic testing are helpful.