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(
Gigo-Benato et al., 2010
). However, TENS was shown to impair axonal
regeneration after crush lesion (
Baptista et al., 2008
). This result was con-
firmed by a second study demonstrating that TENS to the tibialis anterior
muscle first administered 3 days after sciatic nerve crush and then every
second day for a 14-day-period inhibited functional recovery of the neuro-
muscular system (
Gigo-Benato et al., 2010
).
That instead continuous percutaneous stimulation with a low intensity
could be advantageous for nerve regeneration has been reported also from
a crush injury model (
Mendonca, Barbieri, & Mazzer, 2003
).
On the opposite, percutaneous electrical stimulation 15 min/day starting
1 week after nerve repair did reduce the macroscopic regeneration across
10-mm nerve gaps bridged with silicone tubes. However, within the nerves
that successfully bridged the gap, the morphometrical parameters for nerve
regeneration were significantly increased in comparison to nonstimulated
nerves (
Chen et al., 2001
).
Comparison of different percutaneous stimulation protocols of pulse
current versus direct current stimulation revealed that pulse stimulation
increased nerve fiber density and direct current stimulation decreased nerve
fiber density (
Cheng & Lin, 2004
). It has further been demonstrated that
percutaneous stimulation can support axonal regeneration and maturation
only when stimulation protocols are well controlled and stimulation is
restricted to minimal repetitions and minimal intensities, otherwise the
treatment could be detrimental (
Lu et al., 2009
). Recently, a percutaneous
electrical stimulation protocol (15 min every second day) has been described
to improve peripheral nerve regeneration across silicone tube-bridged nerve
gaps (10 mm) in a diabetic rat model (
Yao et al., 2012
). However, a single,
brief and more controlled stimulation protocol directly applied to the
reconstructed nerve at the time of peripheral nerve reconstruction has been
developed over the past decade and is described in the following.
2.2. Direct, brief, low-frequency electrical stimulation
Direct low-frequency (20 Hz) electrical stimulation of the proximal
nerve stump for 1 h (two to threefold threshold current) together with nerve
reconstruction surgery has been established as the standard procedure
(
Gordon, Sulaiman, & Ladak, 2009
). It has been evidenced that the treat-
ment accelerates axonal outgrowth across the suture sites after end-to-end
coaptation or small gap reconstruction and that functional motor recovery
is supported as well (
Ahlborn, Schachner, & Irintchev, 2007; Al-Majed,
Neumann, Brushart, & Gordon, 2000; Brushart et al., 2002; Gordon,
Sulaiman, & Ladak, 2009; Vivo et
al., 2008
). Furthermore,
a
