Axonal damage determines clinical disability in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP): A prospective cohort study of different CIDP subtypes and disease stages

Abstract

Background and purpose Monitoring of patients with chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is challenging in daily medical practice because the interrelationship between clinical disability, CIDP subtype, and neuronal degeneration is still elusive. The aim of this prospective cohort study was to investigate the role of different electrophysiological variables in CIDP monitoring. Methods Comprehensive bilateral nerve conduction studies (NCS) and structured clinical examinations were performed in 95 patients with typical CIDP and CIDP variants (age at inclusion 58.6 ± 11.6 years; median [range] inflammatory neuropathy cause and treatment overall disability score (INCAT‐ODSS) 3 [0–9]), at time of first diagnosis in 25 of these patients (based on data from the prospective Immune‐mediated Neuropathies Biobank registry). After 12 months, 33 patients underwent follow‐up examination. Typical CIDP patients and patients with CIDP variants were characterized electrophysiologically and each individual NCS variable and the overall sum score for axonal damage and demyelination were then correlated to clinical disability scores (INCAT‐ODSS, modified Medical Research Council (MRS) sum score, and INCAT sensory score). Results As opposed to demyelination markers, the NCS axonal damage variable correlated strongly with disability at both first diagnosis and advanced disease stages in cross‐sectional and longitudinal analyses. Distal compound muscle action potential amplitudes of the upper limbs were found to have the strongest correlation with overall clinical function. Typical and atypical CIDP variants had distinct electrophysiological characteristics but, in typical CIDP, axonal degeneration markers were more strongly associated with clinical disability. Conclusions Total disability is largely determined by the degree of axonal damage, especially in typical CIDP. Although most patients have symptoms predominantly in the legs, NCS of the upper limbs are essential for the monitoring of patients with CIDP and CIDP variants.

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

“…In these cases, secondary axonal damage has occurred, so that primarily the nerves of the lower extremities, can no longer be evaluated adequately through the NCS. When the axonal damage has progressed so far at the beginning of treatment, the question arises as to how to adequately evaluate the course of the disease [42][43][44].…”

The impact of the SARS-CoV-2-pandemic on patients with chronic inflammatory neuropathies: results from the German INHIBIT register

“…Preventive measures to protect hospital staff and patients, such as mandatory testing, made it more difficult for patients to attend hospital and outpatient appointments. However, electrophysiological evaluation requiring direct physician-patient contact is essential since progressive axonal damage was shown even in asymptomatic limbs correlating with overall clinical disability [14,15].…”

Prevalence and determinants of pain in chronic inflammatory demyelinating polyneuropathy: Results from the German INHIBIT registry

“…The individual degree of axonal damage was defined by the number of nerves with reduced distal compound muscle action potential (CMAP) amplitudes during electrophysiological nerve conduction studies (NCS) as recently reported [26] and compared to published reference values [27]. The axonal damage was rated on an ordinal scale: no damage in any limb (0), sensory involvement of the lower limbs (mild, 1), sensorimotor involvement of the lower limbs (moderate, 2), sensorimotor involvement of the lower limbs plus sensible involvement of the upper limbs (severe, 3) and sensorimotor involvement of the upper and lower limbs (very severe, 4).…”