Median nerve deformation in differential finger motions: Ultrasonographic comparison of carpal tunnel syndrome patients and healthy controls

Abstract

PURPOSE We investigated the median nerve deformation in the carpal tunnel in patients with carpal tunnel syndrome and controls during thumb, index finger, middle finger and a four finger motion, using ultrasound. METHODS Both wrists of 29 asymptomatic volunteers and 29 patients with idiopathic carpal tunnel syndrome were evaluated by ultrasound. Cross-sectional images during motion from full extension to flexion were recorded. Median nerve cross-sectional area, perimeter, aspect ratio of the minimal enclosing rectangle, and circularity in extension and flexion positions were calculated. Additionally, a deformation index was calculated. We also calculated the intra-rater reliability. RESULTS In both controls and patients, the median nerve cross sectional area became significantly smaller from extension to flexion in all finger motions (p<0.05). In flexion and extension, regardless of the specific finger motion, the median nerve deformation, circularity and the change in perimeter were all significantly greater in CTS patients than in controls (p<0.05). We found excellent intra-rater reliability for all measurements (ICC>0.84). CONCLUSIONS With this study we have shown that it is possible to assess the deformation of the median nerve in carpal tunnel syndrome with ultrasonography and that there is more deformation of the median nerve in carpal tunnel syndrome patients during active finger motion. These parameters might be useful in the evaluation of kinematics within the carpal tunnel, and in furthering our understanding of the biomechanics of carpal tunnel syndrome in the future.

High-resolution ultrasonography of cross-sectional area of median nerve compared with electro-diagnostic study in carpal-tunnel syndrome

“…These percentages were higher in previous studies such as Chen et al and van Doesburg et al [14][15][16][17]. This difference might be due to the use of different instruments or methods.…”

“…This difference might be due to the use of different instruments or methods. Although electrodiagnostic tests are accurate and the gold standard for diagnosing carpal tunnel syndrome, 10% to 25% of cases would be missed using this test, depending on disease severity or method of performance [17]. Yesildag et al demonstrated that a median nerve circumference of more than 10.5 mm is sensitive (89%) and specific (94.7%) for CTS [6].…”

Median Nerve Deformation During Finger Motion in Carpal Tunnel Syndrome: Correlation Between Nerve Conduction and Ultrasonographic Indices

“…In a previous study, 8 it was suggested that the deformation indices of the area, perimeter, and circularity could be used to distinguish the CTS patients from the controls. In this study, the perimeter and circularity were consistent with the results of the previous study.…”

“…7 It was suggested that several ultrasound indices can be used to estimate the condition of the disease. 8 Using this technique, we assessed the potential of ultrasound indices to determine the severity of CTS. The objective of this study was to compare the median nerve ultrasonographic indices of CTS patients and healthy controls, and to assess the potential correlation between median nerve deformation indices and the clinical severity of CTS.…”

2G2-3 Metacarpophalangeal Joint Flexion and the Deformation of Median Nerve

“…Active gliding of the extrinsic finger flexors is known to cause compression stress and deformation of the median nerve at carpal tunnel region. [2] Both flexor digitorum superficialis and flexor digitorum profundus contribute to the flexion of interphalangeal joints (IPJ) and metacarpophalangeal joint (MCPJ). Moreover, intrinsic hand muscles such as lumbricals are considered as the main contributor to the flexion of the MCPJ.…”