The Effects of Electrical stimulation on Nerve Regeneration
in Brachial Plexus Injuries using Implantable Electrodes
Sang-Soo Kim,
M.D., Dong-Churl Kim, M.D.
Department
of Orthopaedic Surgery,
Abstract
The
purpose of this study is to review the clinical result of electric stimulus on the restoration of
motor and sensory recoveries in the brachial plexus injuries. We had evaluated
retrospectively 20 cases of brachial plexus injuries who
were treated by surgical reconstruction of their damaged nerves and electrical
stimulation. Among 20 cases, 18 cases were treated by insertion of electrode to
the nerves, and 2 cases to the motor points of muscles. For the comparison, 24
cases were selected who were received similar operation without electrical
stimulation. All cases were followed up for at least 24 months, as a rule. As a
result, we had a significant difference in the power of elbow flexor, shoulder
abductor and sensibility of forearm between two groups, suggesting that the
electrical stimulation to nerve and muscle enhanced the progress of nerve
regeneration or muscle strength retrospectively. The result suggests that the
electrical stimulation is a promising supplementary method for functional
recovery in peripheral nerve surgery.
Introduction
By
the development of microsurgical technique, surgical reconstruction of injured
peripheral nerve has been quite successful. Even in the complex plexus injury,
many promising surgical techniques were introduced recently. However, we have
several problems in the peripheral nerve surgery. The first one is that the
axonal regeneration after the nerve re-anastomosis is so slow that the patient
should wait for a long time, one or two years or more, in case of brachial
plexus injury. Another disappointing aspects of
peripheral nerve surgeons is that we have nothing to do for the motor recovery
in case of neglected cases who lost the chance of nerve reconstruction within
one year after injury. The third problem is insufficient recovery of muscles
after nerve surgery. The muscle power is trace or poor which is so weak to use
in daily life. The authors tried to use TES in case of brachial plexus injuries
with the purpose of stimulating the axonal regeneration and improving the
muscle power.
Materials
and Methods
44
patients who had had nerve surgery with or without electrical stimulation for
traumatic brachial plexus injuries participated in this study. Studied subjects
were divided into 2 groups based on treatment methods, that is, whether they
had got supplementary electrical stimulation in addition to nerve surgery or
not. We applied the TES in 20 operated cases of brachial plexus injury, for two
years from 1993 to 1995. Eighteen cases were inserted the percutaneous
electrode to the nerve during the surgery, at the proximal point of nerve
suture. In two cases, electrodes were inserted to the motor point of biceps
brachii which did not recovered useful muscle power (below fair grade) after the
nerve surgery and regular physical therapy for two years. We selected 24 cases
of brachial plexus injuries who were done nerve surgeries only (without TES),
for comparison. All the patients' ages ranged from teens to thirties. We put
the ground electrodes around the shoulder area.
The
electrode that we used is spiral-coiled, Teflon-coated stainless steel wire,
which was made in
Results
In
two cases of Biceps brachii stimulation, we had a good recovery within three
months. The muscle power were improved from trace to fair or good degree of
muscle power by the stimulation of motor points for two months.
All
patients were evaluated to compare the result of electrically stimulated group
with non-stimulated group by assessment of functional restoration in suprascapular
nerve, musculocutaneous nerve and median nerve.
In
the stimulated group of suprascapular nerve, the initial muscle power(trace
grade) were recovered in 2.7 months after nerve surgery. In the stimulated
group of musculocutaneous nerve, the
power of biceps brachii became trace
within 3.4 months. But in the nonstimulated group, the initial recovery were
started from 9.6 months in supraspinatus and 9.1
months in biceps after nerve surgery.
For
the sensory function, in the stimulated group of median nerve, initial deep
touch recovery started from 4.5 months. But in the nonstimulated group, the
initial sensory recovery started from 9 months after the surgery. The result of
long term follow up for 2 years are also superior in the stimulated group than
nonstimulated group (Fig 1, Fig 2).
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Discussion
According
to the latest experimental reports, there were a few examples that electrical
stimulation can accelerate the regeneration of axon. However, the mechanism of
biochemical effect of electricity, i.e., how the electrical stimulation effects
the regeneration of axon of damaged nerve is not known yet.
But
according to the Shen and Zhu, the electrical stimulation increase the number
of the endoneurial vessel and enlarge the vessel so that improves the ischemic
state of damaged nerve and accelerate the Wallerian degeneration. As a result,
it can provide the proper inner environment for axonal regeneration. Also the
electrical stimulation gives effects for the direction of inner electric
current so it brings the growth in quality of nerve fiber and brings the mature
effect. And those effects are main reasons to accelerate the function of
damaged nerve.
Besides,
it is not known clearly about the biomechanical effect of electrical
stimulation on the muscles until now. However, the increase of local
vascularity, the change of cellular structure of muscles, and the increase of
the neurotropic factors were proposed as hypotheses for the proofs of the
effect of electrical stimulus on muscles. Errikson and Haggma RK reported
succinate dehydrogenase is activated during the intracellular metabolism of muscle
cell by electrical stimulus, so it can prevent the decrease of activity of
oxidase. Also, according to the Goldberg and his colleagues, the electric
stimulus accelerate the active movement of certain amino acid inside of muscle
cell so it increase DNA synthesis. By the result, the muscle fiber grows and
this growth is explained as a generation of electricity which brings the
hypertrophy of muscle. Especially, Brevet reported the muscular hypertrophy and
increase of muscular power because of the increase of myosin synthesis which is
an amino-acid for muscle contraction after the electric stimulus.
References
1.
Brevet A. Pinto E. Peacock J. and Stockdale F.E. : Myosin synthesis increased
by electrical stimulation of skeletal muscle cell culture. Science, Sep.17, 193
: 1152 -1154, 1976.
2.
Erriksson E., and Haggma RK T : Comparison of
isometric muscle training and electrical stimulation supplementing isometric
muscle training in the recovery after major knee ligament surgery. Am J Sports
Med. May-June 7(3) : 169-171, 1979.
3.
Goldberg AL. Etlinger JD. Goldspink
DF., and Jablecki C. : Mechanism of work-induced
hypertrophy of skeletal muscle. Med Sci Sports.7(3) :
185-198, 1975.
4.
Handa Y. and Hoshimiya N : Functional electrical stimulation for the control of
theupper extremities. Med Prog
Techn. 12 : 561-563, 1987.
5.
Shen N. and Zhu J : Experimental study
using direct current electrical field to promote peripheral nerve regeneration.
J Reconstr Microsurg. 11 :
189-193, 1995.