Ultrasonographic Findings of Median Nerve Change according to the Wrist Position

ABSTRACT

OBJECTIVE: To assess the changes of ultrasonographic findings of median nerve according to wrist position change in normal and carpal tunnel syndrome hands. METHOD: We studied 31 carpal tunnel syndrome and 34 normal hands that were diagnosed by nerve conduction study and evaluated crossectional area, flattening ratio and distance to ulnar artery with diagnostic ultrasound. The parameters were tested according to the change of wrist position with neutral, extension and flexion in normal control and carpal tunnel syndrome. RESULTS: Crossectional area of carpal tunnel syndrome was larger than that of control. Flattening ratio of carpal tunnel syndrome was larger than that of control at extended position. Flattening ratio was greater in neutral and extended position than flexed position in carpal tunnel syndrome. Distance to ulnar artery were greater in flexed position than other positions in carpal tunnel syndrome. Frequency of least flattening ratio at flexion position in carpal tunnel syndrome was 64.52% and frequency of longest distance to ulnar artery at flexion position was 58.05%. CONCLUSION: Ultrasonography of median nerve showed no consistent findings according to change of wrist position between control and patients. Ultrasonographic diagnosis of carpal tunnel syndrome need further study for anatomical variations.