Comparison between Clinical Disabilities and Electrophysiological Values in Charcot-Marie-Tooth 1A Patients with PMP22 Duplication

Abstract

Background and PurposeCharcot-Marie-Tooth disease (CMT) type 1A (CMT1A) is the demyelinating form of CMT that is significantly associated with PMP22 duplication. Some studies have found that the disease-related disabilities of these patients are correlated with their compound muscle action potentials (CMAPs), while others have suggested that they are related to the nerve conduction velocities. In the present study, we investigated the correlations between the disease-related disabilities and the electrophysiological values in a large cohort of Korean CMT1A patients.MethodsWe analyzed 167 CMT1A patients of Korean origin with PMP22 duplication using clinical and electrophysiological assessments, including the CMT neuropathy score and the functional disability scale.ResultsClinical motor disabilities were significantly correlated with the CMAPs but not the motor nerve conduction velocities (MNCVs). Moreover, the observed sensory impairments matched the corresponding reductions in the sensory nerve action potentials (SNAPs) but not with slowing of the sensory nerve conduction velocities (SNCVs). In addition, CMAPs were strongly correlated with the disease duration but not with the age at onset. The terminal latency index did not differ between CMT1A patients and healthy controls.ConclusionsIn CMT1A patients, disease-related disabilities such as muscle wasting and sensory impairment were strongly correlated with CMAPs and SNAPs but not with the MNCVs or SNCVs. Therefore, we suggest that the clinical disabilities of CMT patients are determined by the extent of axonal dysfunction.

Association of social support with quality of life in patients with polyneuropathy

“…We found that changes on NCS are not related either to QoL or symptoms in our group of patients. This has been shown previously in other neuropathies such as Charcot‐Marie‐Tooth disease (Kim et al ., ) .…”

Molecular and clinical features of inherited neuropathies due to PMP22 duplication

“…Clinical deficits correlate more with decrease in compound motor action potential (CMAP) and sensory nerve action potential (SNAP) amplitudes as a consequence of axonal loss, than motor or sensory NCVs which reflects the degree of demyelination [5,36,40,81]. Verhamme et al [78] observed that CMAP amplitude reduced over time with disease progression, while NCV remained fairly constant in adults with CMT1A.…”

Severe phenotypes in a Charcot–Marie–Tooth 1A patient with PMP22 triplication

“…10,11 Here, we identified a CMT1A family with wide phenotypic difference. Subsequent genetic study identified that a patient with severe clinical symptoms had unusual PMP22 triplication.…”