Atypical chronic inflammatory demyelinating polyradiculoneuropathy: recent advances on classification, diagnosis, and pathogenesis

October 2021

Abstract

Purpose of review

In recent years, there has been an intense debate in literature regarding the definition of the individual variants of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), their possible pathogenetic mechanisms, and impact in the diagnosis of CIDP.

Recent findings

The 2021 European Federation of Neurological Societies/Peripheral Nerve Society (EFNS/PNS) guidelines revised the definition of the individual CIDP variants and implemented their diagnostic criteria. Diagnosis of atypical CIDP is challenging and misdiagnosis is frequent, leading to diagnostic delay and consequent greater accumulation of disability and treatment dependency. Recent studies suggest that patients with typical CIDP have an antibody-mediated mechanism of neuropathy whereas in those with Lewis--Sumner syndrome (LSS) neuropathy is preferentially mediated by macrophages and T cells.

Summary

Although the validity of the 2021 EFNS/PNS diagnostic criteria for atypical CIDP is unknown, they will hopefully lead to greater uniformity in the selection of patients to be enrolled in future studies and to a greater diagnostic accuracy. New data are emerging on the possible pathological mechanisms of individual variants and this could result in the discovery of specific diagnostic biomarkers and new therapies.

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.