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Brachial
Plexus (Erb's Palsy)
The brachial plexus is a
network of nerves that originate near the neck and shoulder. These
nerves begin at the spinal cord in the neck and control the hand, wrist,
elbow, and shoulder (see Figure 1). Nerves are the electrical wiring
system in all people that carry messages from the brain to the rest
of the body. A nerve is like an electrical cable wrapped in insulation.
Motor nerves carry messages from the brain to muscles
to make the body move. Sensory nerves carry messages to the brain from
different parts of the body to signal pain, pressure, and temperature.
The brachial plexus has nerves that are both motor and sensory.
The
network of nerves is fragile and can be damaged by pressure, stretching,
or cutting. Stretching can occur when the head and neck are forced
away from the shoulder, such as might happen in a fall off a motorcycle.
If severe enough, the nerves can actually avulse, or tear out of, their
roots in the neck. Pressure could occur from crushing of the brachial
plexus between the collarbone and first rib, or swelling in this area
from injured muscles or other structures.
Injury to a nerve can stop signals to and from the brain, preventing
the muscles of the arm and hand from working properly, and causing
loss of feeling in the area supplied by the injured nerve. When a nerve
is cut, both the nerve and the insulation are broken. Pressure or stretching
injuries can cause the fibers that carry the information to break and
stop the nerve from working, without damaging the cover.
When nerve fibers are cut, the end of the fiber farthest from the
brain dies, while the insulation stays healthy. The end that is closest
to the brain does not die, and after some time may begin to heal. If
the insulation was not cut, new fibers may grow down the empty cover
of the tissue until reaching a muscle or sensory receptor.
Some brachial plexus injuries are minor and will completely
recover in several weeks. Other injuries are severe enough that some
permanent disability involving the arm can be expected.
Many brachial plexus injuries can recover
with time and therapy. The time for recovery can be weeks or months.
When an injury is unlikely to improve, several surgical techniques can
be used to improve the recovery. To help decide which injuries are likely
to recover, your physician will rely upon multiple examinations of the
arm and hand to check the strength of muscles and sensation. Additional
testing, such as an MRI scan, or CT scan/myelography, may be used to
visually evaluate the brachial plexus. A Nerve Conduction Study/Electromyogram
(NCS/EMG), a test that measures the electrical activity transmitted
by nerves and muscles, may also be performed. In some cases, repair
of the nerves or transfer of undamaged nerves from other areas of the
body can be performed. In other cases, transfer of functioning muscles
(tendon transfer) to take over areas of lost function can be performed.
The patient must do several things to keep up muscle activity
and prevent the joints from getting stiff. Your doctor may recommend
therapy to keep joints flexible. If the joints become stiff, they will
not work even after muscles begin to work again. When a sensory nerve
has been injured, the patient must be extra careful not to burn or
cut fingers since there is no feeling in the affected area. After the
nerve has recovered, the brain gets lazy and a procedure called sensory
re-education may be needed to improve feeling in the hand or finger.
Your doctor will recommend the appropriate therapy based on the nature
of your injury.
Factors that may affect results after brachial plexus injury include
age and the type, severity, and location of the injury. Though brachial
plexus injuries may result in lasting problems for the patient, care
by a physician and proper therapy can maximize function.
The brachial plexus is a network of nerves that originate
near the neck and shoulder, whose branches form the nerves that go
into the arm, forearm, and hand.
© 2006 American Society for Surgery of the
Hand
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