Disease activity in chronic inflammatory demyelinating polyneuropathy: A comparative study of clinical and skin biopsy markers

Introduction/aims: Epidermal nerve fiber involvement in chronic inflammatory demyelinating neuropathy (CIDP) has been reported in a limited number of patients. We quantified small-fiber involvement in a mixed cohort of patients with typical CIDP and CIDP variants to evaluate relationships with clinical outcome measures at different disease stages.

Methods: Intraepidermal nerve fiber densities (IENFDs) were evaluated by skin punch biopsies of 23 patients with CIDP and 13 healthy controls at the forearm, thigh, and distal leg. Skin sections were optimally interpreted in all three regions in 16 CIDP patients and 10 age- and sex-matched healthy controls. Statistical analysis was performed in these subjects.

Results: The IENFDs in forearm, thigh, and distal leg were similar among seven typical CIDP and nine CIDP variants. IENFDs in those regions were significantly reduced in CIDP compared with healthy controls, with a moderate negative correlation with scores on the International Neuropathy Cause and Treatment (INCAT) Upper Limb Functional Disability Scale. The reduction in IENFD compared with controls was more remarkable in the distal leg. In clinically unstable CIDP patients, the IENFDs of distal leg and forearm were significantly reduced compared with stable CIDP patients and controls. Stable CIDP patients had significantly reduced IENFDs in distal leg and forearm compared with controls.

Discussion: In this exploratory study, we confirm that small fibers are also affected in CIDP. Larger studies are needed to explore longitudinal changes of IENFD in CIDP and its relation to disease stage.