Quantitative muscle ultrasound as a biomarker in Charcot-Marie-Tooth neuropathy

Objective The utility of quantitative muscle ultrasound as a marker of disease severity in Charcot-Marie-Tooth (CMT) disease subtypes was investigated. Methods Muscle ultrasound was prospectively performed on 252 individual muscles from 21 CMT patients (9 CMT1A, 8 CMTX1, 4 CMT2A) and compared to 120 muscles from 10 age and gender-matched controls. Muscle ultrasound recorded echogenicity and thickness in representative muscles including first dorsal interosseus (FDI) and tibialis anterior (TA). Results Muscle volume of FDI and thickness of TA correlated with MRC strength. Muscle echogenicity was significantly increased in FDI (65.05 vs 47.09; p < 0.0001) and TA (89.45 vs 66.30; p < 0.0001) of CMT patients. In TA, there was significantly higher muscle thickness (23 vs 18 vs 16 mm; p < 0.0001) and lower muscle echogenicity (80 vs 95 vs 108; p < 0.0001) in CMT1A compared to CMTX1 and CMT2A. This corresponded to disease severity based on muscle strength (MRC grading CMT1A vs CMTX1 vs CMT2A: 59 vs 48 vs 44; p = 0.002). Conclusion In CMT, quantitative muscle ultrasound of FDI and TA is a useful marker of disease severity. Significance The current findings suggest that quantitative muscle ultrasound has potential as a surrogate marker of disease progression in future interventional trials in CMT.