# Exploring Ultrasonographic Atypical Aspects in Drug‐Resistant Multifocal Chronic Inflammatory Demyelinating Polyneuropathy

## TL;DR

This study shows how ultra-high-frequency ultrasound can reveal nerve structure changes in severe CIDP, helping guide treatment decisions.

## Contribution

The study introduces the use of ultra-high-frequency ultrasound to detect internal nerve changes in multifocal CIDP.

## Key findings

- UHF-US revealed altered echogenicity and fascicular architecture in enlarged nerves.
- Changes in nerve structure correlated with severe electrophysiological findings.
- UHF-US guided treatment escalation in three patients with multifocal CIDP.

## Abstract

Chronic inflammatory demyelinating polyneuropathy (CIDP) and its variants are characterized by nerve enlargement (NE), particularly in the proximal segments of the median nerve (MN) and cervical roots, as assessed by ultrasound (US). NE is typically moderate and seldom exceeds double the normal size of the cross‐sectional area (CSA). Furthermore, limited knowledge exists regarding the changes in the internal structure of nerves evaluated with high‐frequency ultrasound. This study describes three cases of significant CIDP‐NE assessed with an ultra‐high‐frequency probe (UHF‐US; 33 MHz) showing how changes in US‐nerve images may guide treatment choice.

Three patients diagnosed with multifocal CIDP and followed for several years in our department were studied. Clinical evaluations, electrodiagnostic studies (EDX), laboratory analyses, and UHF‐US of the nerves were performed.

Nerve conduction studies (NCS) revealed severe demyelinating neuropathy with conduction blocks, reduced motor conduction velocities (MCV) in all cases, and secondary axonal degeneration in two cases. Ultrasound showed NE in the roots and nerves, with altered echogenicity and modification of internal nerve structure. A second‐line treatment was successfully started in three patients.

UHF‐US allows for the evaluation of structural changes in the nerve. NE and alterations in internal structure can be considered ultrasound markers of disease severity, guiding therapeutic decisions.

This study highlights the potential of ultra‐high frequency ultrasound (28–33 MHz) to detect internal structural changes in enlarged nerves in multifocal CIDP. In three patients, altered echogenicity and fascicular architecture were associated with severe electrophysiological findings and guided treatment escalation. These findings support the role of UHF‐US as a tool to monitor disease severity and tailor therapy.