Ultrasound-guided hydrodissection decreases gliding resistance of the median nerve within the carpal tunnel

Abstract

Introduction: The aim of this study was to assess alterations in median nerve (MN) biomechanics within the carpal tunnel resulting from ultrasound-guided hydrodissection in a cadaveric model.

Methods: Twelve fresh frozen human cadaver hands were used. MN gliding resistance was measured at baseline and posthydrodissection, by pulling the nerve proximally and then returning it to the origin. Six specimens were treated with hydrodissection, and 6 were used as controls.

Results: In the hydrodissection group there was a significant reduction in mean peak gliding resistance of 92.9 ± 34.8 mN between baseline and immediately posthydrodissection (21.4% ± 10.5%; P = 0.001). No significant reduction between baseline and the second cycle occurred in the control group: 9.6 ± 29.8 mN (0.4% ± 5.3%; P = 0.467).

Discussion: Hydrodissection can decrease the gliding resistance of the MN within the carpal tunnel, at least in wrists unaffected by carpal tunnel syndrome. A clinical trial of hydrodissection seems justified. Muscle Nerve 57: 25-32, 2018.

Keywords: carpal tunnel; gliding resistance; hydrodissection; injection; nerve; ultrasound.

Conflict of interest statement

Disclosures: No conflicts of interest to report.

© 2017 Wiley Periodicals, Inc.

Figures

Figure 1

A) Median nerve and tendons in closest proximity to the median nerve exposed 2.5 cm proximal to the proximal wrist crease (arrow). Median nerve exposed distal to the carpal tunnel outlet, approximately 5cm distal to the proximal wrist crease depending on hand size. B) Three palmar digital branches (dotted arrows) and motor branch (solid arrow) of the median nerve identified. C) Branches of the median nerve sutured together: the neutral position of the nerve identified by markers at the same level of the nerve and underlying FDS3 tendon (arrow).

Figure 2

Experimental set up.

Figure 3

Flow chart describing testing sequence.

Figure 4

Transverse ultrasound image of the carpal tunnel. Left=ulnar. A 27-gauge needle (dotted arrow) penetrated the TCL (down pointing arrows) on the ulnar side of the carpal tunnel A) freeing the median nerve (MN) from the transverse carpal ligament B) separating the nerve from the underlying subsynovial connective tissue and flexor tendons (FT).

Figure 5

Difference in A) peak gliding resistance and B) energy absorption between baseline (cycle 1) and second cycle for both groups. The boxplots show the distribution of peak gliding resistance and energy absorption for the two groups. The boxes represent the 25th, 50th, and 75th percentiles. The whiskers show the range and points represent the data values.

Figure 6

A) Mean peak gliding resistance at baseline, during repetitive motion testing, post-TCL transection and post-neurolysis of the median nerve. Error bars represent standard deviations. B) Energy absorption at baseline, during repetitive motion testing, post-TCL transection and post-neurolysis of the median nerve. Error bars represent one standard deviation.