152 Canine Sports Medicine and Rehabilitation
Finally, TENS can be safely used for pain
relief for an extended period of time without
significant side effects (Cherian et al., 2016).
Therapeutic effects on tissue healing
and protection
TENS can have positive effects toward wound
healing and tissue protection, possibly by
affecting local blood flow through neural acti
vation. Atalay and Yilmaz (2009) found that
post‐mastectomy skin flaps that were treated
with TENS showed significantly less necrosis
as compared to those that received standard
postoperative care. TENS may also be effective
in treating chronic wounds, even those that
have failed to heal despite consistent routine
care (Yarboro & Smith, 2014). Additionally,
TENS can reduce tissue edema, including lower
extremity lymphedema, potentially protecting
against the progression to chronic lymphedema
and possible development of cellulitis and
chronic skin ulcers (Choi & Lee, 2016). Finally,
Zotz and Paula (2015) found that the anti‐
inflammatory effects of TENS appear to reduce
development of heterotopic ossification.
Therapeutic effects on tissue flexibility
and joint ROM
When used in conjunction with a stretching
program, TENS promotes greater muscle
flexibility gains as compared to stretching
alone (Karasuno et al., 2016). Studies have
also demonstrated that subjects with myofas
cial pain in the upper trapezius muscle who
received TENS in addition to the standard
care program had greater cervical spine ROM
improvements when compared to those who
received standard care only (Azatcam et al.,
2017; Dissanayaka et al., 2016). TENS can
have immediate positive effects on joint
ROM, especially if limitations are related to
pain (Valenza et al., 2016).
Patients with spasticity can also gain mobil
ity with TENS treatment due to spasticity
reduction (Fernández‐Tenorio et al., 2016),
leading to improved function (Karakoyun et al.,
2015; Laddha et al., 2016). Of note, a review by
Mills and Dossa (2016) showed better spasticity
reduction may occur when TENS treatment is
combined with active therapy.
Therapeutic effects on muscle strength
There are some studies that indicate sensory
level TENS may have beneficial effects toward
muscle function. However, the results may be
more from facilitation rather than direct
strengthening. For example, a literature review
by Harkey and colleagues found that TENS
was significantly more effective than NMES,
cryotherapy, or manual therapy in addressing
the quadriceps muscle inhibition often seen
with knee injuries. In the studies reviewed,
TENS was applied to the knee joint rather than
the quadriceps muscle but was hypothesized to
still have a positive effect on muscle contraction
by targeting the presynaptic reflex inhibitory
mechanisms that are believed to cause quadri
ceps dysfunction (Iles, 1996; Harkey et al., 2014).
A more recent study has supported these find
ings (Son et al., 2016) and followed with an
additional study to demonstrate direct transla
tion of improved quadriceps function to better
quality gait (Son et al., 2017).
There is evidence that TENS may promote
improved muscle function in neurologically
involved patients as well. Jung and colleagues
demonstrated improved trunk muscle activa
tion and improved motor control in patients
with stroke when TENS was added to conven
tional physical therapy treatment (Jung et al.,
2016), especially when treatment included
task‐related training (Chan et al., 2015).Considerations for clinical applicationTo ensure safety, muzzling may be recom
mended, at least for the first ES treatment, to
allow assessment of the patient’s tolerance for
the modality. However, one author (K.N.) has
not found a need for additional restraint if ES is
introduced slowly and the patient’s response to
the initial sensation is monitored closely. It is
the author’s opinion that if a patient appears to
be distressed by the sensation of ES, the treat
ment should be discontinued and a different
therapeutic technique pursued.
The general procedure for providing NMES
is to place the electrodes over the muscle to be
stimulated (Figure 7.14). A coupling medium is
needed to transmit the current from the elec
trode to the skin. Some electrodes are coated