Ultrasound therapy facilitates the recovery of acute pressure‐induced conduction block of the median nerve in rabbits

Abstract

Though the use of ultrasound for the treatment of carpal tunnel syndrome (CTS) or compression neuropathy has been described, its effect remains controversial. A test model of acute CTS was developed using rabbits. Acute median nerve compression was induced by the infusion of saline into the carpal tunnel under general anesthesia to elevate the intracarpal pressure. A reduction in the compound muscle action potential (CMAP) amplitude of the abductor pollicis was noted after intracarpal pressure increased. To investigate the efficacy of ultrasound in acute CTS, rabbits with acute median nerve compression were divided into 3 groups (10 each) and ultrasound was applied at different intensities to each group as follows: 1.5 W/cm(2) to group 1; 0.2 W/cm(2) to group 2; 0.0 W/cm(2) (sham) to group 3. A total of 10 treatment sessions were given over a period of 2 weeks. Following ultrasound application, the CMAP amplitudes showed significant improvement in group 1 compared to the other two groups (P < 0.05), indicating facilitated recovery from acute CTS in this pressure-induced median nerve compression rabbit model. The benefits of ultrasound application in a clinical setting must be verified by further clinical trials.

Comparative Anatomy of the Subsynovial Connective Tissue in the Carpal Tunnel of the Rat, Rabbit, Dog, Baboon, and Human

“…We used New Zealand White rabbits weighing 4.0-4.5 kg because the median nerve is better visualized when the rabbit is bigger, and also because there is more tenosynovium present. The rabbit has a nearly identical situation as the human regarding the osseous and connective tissue formations in the carpal canal [21,30,33], and there is extensive data available describing median nerve compression in the rabbit carpal tunnel [9,32,34,35]. We found an anatomical variation in the course of the median nerve, but this high bifurcation is similar to variations also found in humans [22,24].…”

Performance of a High-Repetition, High-Force Task Induces Carpal Tunnel Syndrome in Rats

“…Several studies document changes in nerves of rats, primates, and rabbits following chronic compression with cuffs 5,22,29,30,35 or acute infusion of saline into the carpal tunnel. 38 Repeated electrical stimulation of the muscles innervated by the median nerve led to a reduction in large fibers and slowing of conduction in rabbits. 3 As none of these models involves chronic nerve injury from voluntary repetitive motion, they fail to completely simulate human work-related CTS.…”

Effects of Pulsed Ultrasound Therapy on Sensory Nerve Conduction Parameters and the Pain Threshold Perceptions in Humans

“…The underlying pathology of the carpal tunnel syndrome is a focal demyelination by compression. In animal experiments, an artificially induced nerve conduction block could be remedied more quickly by ultrasound therapy than by placebo therapy [19].…”

“…During ultrasound therapy, absorption or reflection of ultrasound waves in the body tissue results in heating. A thermal effect of continuous ultrasound on peripheral nerves has been described in previous studies [14][15][16][17][18][19][20]. Kramer [18] showed that there is a linear relationship between an increase in the intensity (0.5 W/cm 2 , 1 W/ cm 2 , 1.5 W/cm 2 , 2.0 W/cm 2 ) and increase in nerve conduction velocity in the application of continuous ultrasound on the ulnar nerve.…”