Sonography of the median nerve in Charcot-Marie-Tooth disease.

OBJECTIVE: The purpose of our study was to describe the features on high-frequency sonography of median nerves in patients with Charcot-Marie-Tooth disease and determine whether sonography can help in the detection and characterization of the disease in these patients.

SUBJECTS AND METHODS: The median nerves of 24 patients with genetically proven Charcot-Marie-Tooth disease (12 patients with Charcot-Marie-Tooth disease type 1A, seven with Charcot-Marie-Tooth disease type 2, and five with Charcot-Marie-Tooth disease type X) were prospectively examined at the right mid forearm with a 12-5-MHz transducer. Image analysis for each patient included measurement of both the cross-sectional area and fascicular diameter of the nerve. Correlations then were made with genetic and electrophysiologic features and with findings in a control group of 50 subjects.

RESULTS: Sonography was found to be a reliable means of detecting the nerve hypertrophy and the fascicular swelling occurring in patients with Charcot-Marie-Tooth disease. The 1A type of Charcot-Marie-Tooth disease could be distinguished sonographically by a larger nerve area and fascicular diameter than those observed in patients with the other types of disease (including Charcot-Marie-Tooth disease type 2 and X-linked type) and the control subjects. In patients with Charcot-Marie-Tooth disease and control subjects, linear regression analysis did not show a correlation between either the cross-sectional area or fascicular diameter of the nerve and the patient's height, body mass, sex, or electrophysiologic parameters.

CONCLUSION: High-resolution sonography can be used to detect the hypertrophy of median nerves in patients with Charcot-Marie-Tooth disease. It can be helpful in defining the Charcot-Marie-Tooth type 1A on the basis of the larger nerve sizes and fascicular diameters than those occurring in patients with other types of the disease. In an affected kindred, sonography is promising as a screening tool for identifying individuals who should undergo genetic assessments.