2nd application of low-energy shock waves has a cumulative effect on free nerve

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Clin Orthop Relat Res. 2006 Feb;443:315-9.

Second application of low-energy shock waves has a cumulative effect

on free nerve endings.

Takahashi N, Ohtori S, Saisu T, Moriya H, Wada Y.

Department of Orthopedic Surgery, Graduate School of Medicine, Chiba

University, Chiba, Japan.

Some physicians recommend treating tendinopathies with multiple

sessions of shock waves. Some evidence, however, suggests shock wave

application can induce nerve fiber degeneration. We questioned

whether repeated shock wave application provides a cumulative effect

on nerve fibers compared with the effect of one application. One

thousand shock wave impulses of an energy flux density of 0.08 mJ/mm

were applied to the foot pad of 32 rats. After 14 days, 16 rats

received a second application. The foot pads were resected on Days 7,

14, 28, and 42. Sections were processed immunohistochemically using

antibodies for sensory nerve.

We compared the number of epidermal nerve fibers in rats that

received one application of shock waves with the fibers in rats that

received two applications. During the first 4 weeks, there was nearly

complete degeneration of epidermal nerve fibers in both groups. By

the end of 6 weeks, reinnervation of the epidermis began in the

single-treatment group. Reinnervation occurred slower in the repeated-

treatment group. These data show that a second application has a

cumulative effect on nerve fibers.

Our data suggest multiple applications of low-energy shock waves

might a provide longer-lasting antinociceptive effect.