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Ultrastructural analysis of the nerve grafts 3 weeks after the injury rev-
ealed that not only were there more regenerated and well-myelinated axons
in the ESWT nerves, but also the endoneurium was free from reactive cells
and degenerated myelin profiles, which were present in abundance in the
untreated nerves (
Fig. 3.3
;
Hausner et al., 2012
). These findings indicated
that the improved rate of axonal regeneration and the clearing-up of the
degenerated structures in the denervated nerves are strongly related. It
remains for future studies to establish whether either of these processes
enjoys priority over the other in the temporal sequence of events.
5. CONCLUSION
Shock waves were introduced into the arsenal of modern human med-
ical therapy some 30 years ago (
Shrivastava and Kailash, 2005; Thiel, 2001
).
Following the initial treatment trials on urolithiasis, extracorporeal shock
waves were introduced both preclinically and clinically for the treatment
of acute and chronic soft and hard tissue healing problems (
Ogden et al.,
2001
). In most cases, improvements in the soft and hard tissue healing pro-
cesses were found to be associated with increased levels of vascularization,
and this mechanism of action was therefore considered to be a general,
but not overall scenario for shock wave-induced improvement (
Wang
et al., 2004; Yan, Zeng, Chai, Luo, & Li, 2008; Zimpfer et al., 2009
). How-
ever, it has subsequently been demonstrated that other nonvascular mech-
anisms contribute to the tissue repair (for details, see
Fig. 3.1
).
numbers of myelinated axons in the graft and distal to the grafting site are much higher
in the ESWT animals than in the controls. There was no significant difference between
the controls and the ESWT animals in the numbers of myelinated axons distal to the
graft 3 months after axotomy and grafting (right).
*
Significant difference (p
<
0.05)
between the control and the ESWT groups by ANOVA, computed by using Tukey's
all pairwise multiple comparison procedures. (B-F) Photographs of semithin cross-
sections from the proximal stump (B), the middle of the graft (C, D), and the distal stump
(E, F) 3 weeks after axotomy. The shock wave-treated peripheral nerves (ESWT) contain
more myelinated axons, while the control nerves display far fewer regenerated axons
(arrows) and are full of degenerated myelin sheaths and reactive cells. (G, H): Photo-
graphs of semithin cross-sections from the distal stump 3 months after axotomy. There
is no striking difference between the ESWT and control nerves, although the myelin
sheaths of the regenerated axons appear thinner than those seen in the intact proximal
stump (B). Methylene blue-thionin staining according to Rüdeberg, scale bar
¼
25 mm.
This figure is reproduced from the publication by
Hausner et al. (2012)
, with the kind per-
mission of Elsevier/Rightslink.
