Encyclopedia of Health and Medicine

trigger-point injection 385
be painful, there is no risk for electrical shock
from TENS. It is important to keep the electrode
pads covered with gel. The main SIDE EFFECT with
TENS is irritation to the skin from the adhesive
that holds the electrodes in place or from using
the electrodes without adequate gel. People who
have an implanted PACEMAKER or IMPLANTABLE CAR-
DIOVERTER DEFIBRILLATORS (ICD) cannot use TENS
because the electrical current of the TENS interferes
with the pacing signals.
See ACUPUNCTURE; DERMATOME; MALDYNIA; NERVE;
NEURON; NOCICEPTOR; TRIGGER-POINT INJECTION.
trigger-point injection An injection of local
anesthetic into an area of MUSCLE that has tightened
into a knot that constricts or pressures a
NERVE, causing severe PAIN. Trigger points are
highly sensitive to touch or other stimuli and may
form after musculoskeletal injuries and in CHRONIC
PAIN conditions such as myofascial pain syndrome
and FIBROMYALGIA.
Typically a pain specialist, often an orthopedic
surgeon (specialist in musculoskeletal conditions)
or a neurologist (specialist in conditions that affect
the NERVOUS SYSTEM), administers the trigger-point
injection. Depending on the cause of the damage,
the injection may combine a local anesthetic with
a corticosteroid medication to directly target
INFLAMMATION in the area. The injection is an office
procedure that causes brief discomfort from the
insertion of the needle. Complete relief from pain
immediately follows as the anesthetic numbs the
nerves. After the numbness wears off pain relief
often lasts several months and for some people is
permanent.
The main risks of trigger-point injection are discomfort
at the time of injection and bruising at the
site that may cause superficial (surface) tenderness
for several days. Ice to the site lessens the risk for
bruising and relieves its discomfort. Other specific
risks depend on the injection site.
See also ANESTHESIA; CORTICOSTEROID MEDICATIONS.