restores incomplete arm and hand strength.
test in infants can reliably
identify which portion of the injured brachial plexus requires resection and repair
with nerve graft.
It is important to remember that in the great majority of patients, although surgical repair will result in improved function of the arm, it will not restore complete muscle strength. Because of this, and the fact that many patients will improve to varying degrees without surgery, great care is needed when selecting patients for surgical treatment.
Optimal timing for
surgical intervention depends on the severity of the brachial plexus injury. For
example, infants with suspected nerve root avulsion or ruptured brachial plexus require early
surgical exploration. On the other hand, infants with less extensive injury will
show clinical improvement during the first 3-6 months and thus require more time
before a decision can be made regarding the need for surgery.
In a given patient, direct surgical repair of the brachial plexus depends on the location and extent of the nerve injury. Reconstruction using nerve grafts is carried out in a number of ways, and the surgeon should make decisions based on his/her experience.
A unique problem in
brachial plexus surgery in infants is that no neurophysiology test allows reliable
identification of the portion of the brachial plexus that requires resection and
repair with nerve grafting. We base our decision on the result of direct electrical
stimulation of the brachial plexus, the severity of neuromas seen at the time of exploration,
and infant's muscle weakness prior to surgery.
The complete absence
of improvement results from a severe injury, including nerve root avulsion or
rupture of the brachial plexus. These infants would require early brachial plexus
repair surgery.
Horner’s syndrome includes droopy eye and small pupil; the presence of this
sign indicates injury to the lower brachial plexus (C8-T1) close to the spinal
cord; it can be associated with avulsion of the nerve roots. Pseudomeningocele
is a finding on MRI scan which suggests possible avulsion of the particular
nerve root.
If infant shows some contraction in muscles at the age of 2-3 months, we recommend
continuous physical therapy until 4-6 months.
Muscle strength in the arm and hand is measured and documented by physicians and therapists. Changes in muscle strength are noted after surgery and in follow-up examinations.
Chest x-ray
is taken primarily to check for diaphragm paralysis due to phrenic
nerve injury.
| Cervical spine MRI is obtained to determine the presence of pseudomeningocele (pocket of cerebrospinal fluid) along the spinal nerve root, which may indicate detachment of the nerve root from the spinal cord. |
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of muscles. The test provides information about the distribution and severity of
the brachial plexus injury and associated nerve root avulsion. It can also be used
for postoperative follow-up of patients. A major drawback is that it is a qualitative
rather than a quantitative analysis of innervation.
Videotape is
used prior to surgery, at 6 months after surgery, and at subsequent follow-up visits
to document the clinical course of each patient.
Injury to the phrenic nerve, which is adjacent to the upper trunk of the brachial plexus, can cause diaphragm paralysis. Reconnecting the nerve allows the paralysis to eventually resolve.
Injury to the lung
will cause pneumothorax.
Injury to the subclavian
artery and vein is also possible.
Wound infection can occur around the incisions in the neck or the legs.
Additional injury
to the brachial plexus is possible but can be easily avoided. It should be noted,
however, that a decrease in muscle strength can follow reconstruction of the brachial
plexus with nerve grafts. This occurs because a functioning nerve root is sometimes
cut and connected to the other part of the brachial plexus using nerve grafts. The
muscle strength will most likely return with time, and the risk of such complications
is very small.
Three basic operative procedures are performed:
of severely injured part of the brachial plexus
(removal of scar tissue surrounding
the injured nerve).
We do not perform
neurolysis alone. All of our patients will need neurolysis, and removal
of injured parts of brachial plexus, and reconstruction of the brachial plexus
with placement of nerve grafts. Nerve grafts are harvested from the calf
on one side or both sides.
A skin incision is
made along the neck and sometimes extended to the shoulder. When a nerve graft
procedure is needed, additional incisions are made on the posterior aspect
of one or two legs in order to harvest the sural
nerve for nerve grafts.
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For upper brachial
plexus injury (Erb's palsy), the brachial plexus above the clavicle is exposed. For total brachial
plexus injury, the entire brachial plexus is exposed above and below the clavicle.
Neuromas are almost invariably present, and additional pathology such as scar tissue
surrounding the brachial plexus, avulsed nerve root, and ruptured trunk of the brachial
plexus may also be present.
Once the abnormal brachial
plexus has been exposed, muscle contractions in response to direct electrical stimulation
of the nerve root and the other part of the brachial plexus are examined. Nerve action potential
study is impossible in infants because of the small operative field and has not been
validated for brachial plexus surgery in infants.
In any event, no or
minimal muscle contraction during electrical stimulation to a given nerve root is
a strong indication for nerve grafting procedure. On the other hand, good muscle
contraction during electrical stimulation can be produced by only a small number
of intact axons,
which are insufficient for functional recovery without nerve grafts.
Thus, we take into account the extent of a neuroma and an infant's preoperative muscle strength when making decisions about the need for nerve grafts. In general, we prefer resection of the neuroma combined with nerve grafting, especially for upper and middle trunk injuries. But nerve graft for the lower trunk injury is done only when the infant has no muscle contraction in the wrist and hand preoperatively or has avulsed nerve roots. Otherwise, we tend to do neurolysis of the lower trunk. This conservative approach is based on the fact that the functional outcome of nerve grafting of the lower trunk is not as good as on the upper and middle trunk.
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The spinal nerve root,
trunk (black arrow), and other parts of the brachial plexus most often are surrounded
by nonneural
scar tissue (blue arrow). This is removed to free up the brachial plexus. When the
neuroma is not extensive, the infant has some muscle strength, and electrical stimulation
elicits strong muscle contraction, neurolysis alone is performed. Also, neurolysis
is a part of the nerve grafting procedure. In other words, neurolysis needs to be
done before nerve grafts are placed.
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Reconstruction of the
brachial plexus with nerve graft can produce gratifying results, particularly in
infants with upper trunk injury. This operative photograph illustrates a form of
nerve grafts used for brachial plexus surgery. A number of variations of nerve grafting
procedures are utilized, depending on the location and extent of brachial plexus
injury. It is important to note that nerve grafting offers the best chance for infants
whose injury is extensive and for whom the probability of spontaneous recovery is
minimal.
Improvement in deltoid
and biceps
muscle strength is detectable around 6 months after surgery, although some infants
show improvements sooner. Muscle strength will increase gradually over the next 18
months. Improvement of the forearm and hand muscles is detectable around 8 months
and continues for 3-4 years.
Outcomes reported in the literature
Our own study described outcomes in the first series of patients who underwent brachial plexus surgery at the St. Louis Children's Hospital.
,
nerve grafting, or a combination of those procedures were performed on the patients.
Our initial experience is encouraging, and we conduct ongoing analysis of the outcomes of surgery at our Center.
Another study of 241 children who underwent repair of brachial plexus for birth injury reported the following results:
