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Effect of Force, Posture, and Repetitive Wrist Motion on Intraneural Blood Flow in the Median Nerve
Author(s) -
Ehmke Samantha,
Farias Zuniga Amanda,
Keir Peter J.
Publication year - 2021
Publication title -
journal of ultrasound in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 91
eISSN - 1550-9613
pISSN - 0278-4297
DOI - 10.1002/jum.15467
Subject(s) - wrist , medicine , carpal tunnel syndrome , median nerve , thumb , carpal tunnel , blood flow , ultrasound , anatomy , physical medicine and rehabilitation , surgery , radiology
Objectives Pinching, deviated wrist postures, and repetitive motion are risk factors for carpal tunnel syndrome. Hypervascularization of the median nerve and increased intraneural blood flow proximal to the carpal tunnel result in finger force and deviated wrist postures. The purpose of this study was to determine the effects of pinching with and without force, wrist posture, and repetitive wrist motion on intraneural blood flow in the median nerve. Methods Eleven healthy and 11 carpal tunnel syndrome–symptomatic individuals completed 3 sections of this study: 15 pinch posture force trials, 3 repetitive wrist motion trials, and 3 static wrist posture trials. Intraneural blood flow (centimeters per second) was measured with pulsed wave Doppler ultrasound during each trial. Transverse B‐mode images obtained from static trials were used to calculate the median nerve cross‐sectional area and circumference. Results An analysis of variance statistical analysis revealed significant main effects of pinch posture force ( F 4,80 = 21.397; P < .001) and wrist posture ( F 2,40 = 14.545; P < .001). Intraneural blood flow velocities were significantly greater when 6 N of force was applied by the thumb, finger, or pinch compared to no applied force in the same postures. Intraneural blood flow velocities were higher at 30° wrist flexion (mean ± SD, 2.24 ± 0.42 cm/s) than neutral (2.06 ± 0.45 cm/s) and 30° wrist extension (1.97 ± 0.46 cm/s). No changes were found in response to repetitive wrist motion. Conclusions Flexed wrists as well as applied finger and thumb forces increase median nerve blood flow at the entry to the carpal tunnel, which may negatively affect the median nerve.