Brachial Plexus Clinic
A multidisciplinary, comprehensive center for the study of brachial plexus and peripheral nerve injuries in the pediatric population places particular emphasis on children who suffer these types of injuries during the birth process or via other types of trauma. A regional, centralized comprehensive clinic offers the expertise in the evaluation and treatment for these children. Further programming through education and clinical and basic science research allows the center to be on the forefront in the understanding of the pathophysiologyof brachial plexus and peripheral nerve injuries and their treatment.
To provide the highest level of expertise, the members of the multidisciplinary service include pediatric neurosurgery, plastic surgery/microsurgery, neurology, social work, radiology, trauma surgery, and physical and occupational therapy. The patients are evaluated by the combined disciplines and electrophysiologic evaluation and imaging (both anatomic and functional) are able to be coordinated through the resource centers for these modalities. Treatment options including surgical intervention or physical or occupational therapy is decided following a comprehensive review of the evaluative information amongst the members of the center using established principles.
A brachial plexus and resultant upper extremity injury due to a difficult birth is one of the most common injuries during the birthing process. The incidence rate is 0.3 to 2 per 1,000 births, with most brachial plexus injuries identified immediately in the acute setting.
Brachial relates to the arm and plexus pertains to a network of nerves. The brachial plexus forms a network of nerves that conduct signals that control the muscles of the shoulder, arm, elbow, wrist, hand and fingers.
The mechanism(s) by which the brachial plexus is injured is most often attributed to severe lateral flexion of the neonate's neck when the shoulder is stopped most often at the pubic bone ("shoulder dystocia") during delivery. The extent of the traction on the brachial plexus may result in various types of injuries to the nerves, from a simple mild stretch injury up to and including avulsion (separation) of the nerves from the spinal cord.
Although a vertex delivery with a shoulder dystocia is the most common cause, brachial plexus injuries can also occur following cesarean section delivery, probably due to intrauterine forces. Other predisposing factors associated with a brachial plexus injury include a mother who has given birth at least two times, high infant birth weight, prolonged labor, premature birth and breech delivery.
Although the results of studies involving recovery without intervention vary widely, the Collaborative Perinatal Study of 1973 documented a 90% to 95% rate of spontaneous good recovery, leaving approximately 5-10% of infants at risk for permanent functional disability. Those that recovered showed some evidence of improvement by 4 months of age. A study from St. Louis found similar results. The challenge for physicians and families is to determine whether surgical intervention would be helpful to improve the function of the limb.
It is clear that the absence of any sign of recovery by 3-4 months of age is most predictive of an extremely poor functional prognosis with significant residual deficits. As a rule of thumb, the rate of spontaneous recovery dictates the final functional outcome. Those infants who are slower to begin recovery and have slow progression of returning function are less likely to achieve complete functional use of the extremity.
Approximately 75% of birth-related brachial plexus injuries involve the 5th-7th cervical nerve roots, including the upper and middle trunks of the plexus, and are clinically recognized as an "Erb’s palsy". The affected extremity is positioned in the classic "waiter’s tip" pose, adducted, internally rotated with elbow extension, forearm pronation and wrist and finger flexion. Up to 20-25% involves the entire brachial plexus (C5-T1), which is manifested by a completely flaccid upper extremity. Only 2% of injuries are isolated to C7-T1, also known as Klumpke’s palsy. With this type of injury, the flexors of the brachium are spared while the flexors and extensors of the fingers and wrist are weak or flaccid. A Horner’s syndrome may be associated with injuries that involve the C8-T1 levels due to injury of the sympathetic chain of the thoracic spinal cord. Most series cite a 4% incidence of bilateral injuries.
The diagnosis of brachial plexus injuries relies heavily upon the clinical evaluation, which can be challenging in neonates and young children. The child’s functional use of the upper extremity, assessed clinically, is the most important indication for surgery. Ideally, children are first evaluated between birth and 6 weeks of age with physical and/or occupational therapy starting at 3-4 weeks of age; at 6 weeks, if there is a fracture to allow for adequate healing. Follow-up evaluations then occur at three-month intervals. Early evaluation is important in establishing a baseline physical examination and assessment of patient and family needs. This can often be accomplished by the pediatrician or family practitioner. Continued weakness of the limb or questions regarding the injury or function should be referred to a specialist for further evaluation.
The examination consists of a motor evaluation that scores both individual muscle groups (using the five-point British Research Council Grading System) and functional muscle group activities, including abduction, external rotation, and hand-to-head, hand-to-back and hand-to-mouth movements as well as sensory and reflex exams. Physicians should compare clinical assessments on subsequent visits every three months.
Children who recover partial function between examinations should continue to be followed at three-month intervals. Children who fail to improve on subsequent visits or who improve initially but then plateau at a nonfunctional level should be evaluated, initially via electromyography (EMG). This will assess the levels of injury and determine if there is evidence of early reinnervation.
Electrophysiologic studies, including EMG and somotosensory evoked potentials (SSEP) and imaging such as CT scans and MRI, are useful in confirming clinical diagnosis and extent of the injury. Electrodiagnostic tests, however, do not offer any prediction of ongoing or potential recovery. These studies are usually obtained at 4 to 6 months of age following non-progression of recovery.
In evaluating the possibility of a nerve root avulsion from the spinal cord, the standard had been a CT myelogram. With improved MRI formats, this non-invasive evaluation is more desirable for children. A pseudomeningocele or nonvisualization of the nerve roots is indicative of a preganglionic injury which at this time cannot be repaired with conventional techniques. Unfortunately, root avulsions have a poor prognosis for recovery and restoration of function to the extremity with current reparative techniques. If imaging does not reveal evidence of nerve root avulsion and the child has not had a significant partial or full return of function by 4 to 6 months of age, surgical intervention should be considered.
It has been determined that early evaluation and intervention are important because functional results following surgery before 6 to 9 months are significantly better than those with intervention in older children (12 to 18 months). Children as young as 4 months of age can be considered for operative brachial plexus repairs. Though reparative surgery up to 18 to 24 months of age is possible, numerous studies have shown that children at that age are less likely to have good outcomes, though other operative interventions are available to improve outcome.
All of the surgical procedures are performed under general anesthesia. In the primary surgery, the initial phase consists of exploration, visualization and identification of the different elements of the brachial plexus. Following exposure, intra-operative EMG/SSEP studies are used to test the damaged segments. This is critical in determining the type of repair most suitable. The most common injury found through these means is an axontomesis or stretch injury. This damage involves only the perineurium (connective tissue cover surrounding a bundle of nerve fibers) and the axons. Though the nerve is viable, degeneration has disconnected it from the muscle. The natural regenerative effort of the nerve against scar results in a neuroma when the pathway of the regenerating axons is blocked by the scarring, and the axons are prevented from successfully extending across the injured segment. The fibrotic scarring is most likely formed in response to hemorrhage and damage at the time of the initial injury and can partially or completely block conduction to the distal muscle groups. The EMG/SSEP studies confirm the extent of physiologic function passing through the neuroma as well as the existence of an avulsion if it was not diagnosed preoperatively.
The goal of all reparative procedures is to create an adequate pathway for the regenerating axons to reach their motor units and restore maximal function. The intervention following exploration is a neurolysis or the careful microsurgical dissection of the epineurial and perineurial scar tissue. With a neurolysis, the scar tissue compressing the injured segment of the nerve is released, allowing improved conduction of the existing neural elements and a wider conduit for improved regeneration.
Nerve grafts are used when there is minimal or no conduction across the scarred segment following the neurolysis. A "cable" or interpositional graft is performed by resecting the severely damaged segment of nerve and replacing it with a segment of the patient’s sural (relating to the calf of the leg) nerve. The "donor" sural nerve is a purely sensory nerve. It is obtained from the lateral aspect of the leg, just above the ankle, and leaves the patient with a small area of anesthesia on the lateral aspect of the foot. This area becomes smaller in children as they get older, due to ingrowth from surrounding areas. This graft is then sutured in line (end to end) following the resection of the damaged segment of nerve. The graft serves as a new conduit for the regeneration of axons across the scarred region into the distal end of the nerve. When reasonable electrophysiologic conduction across the damaged segment remains, the surgeon can use newer graft techniques that do not sacrifice the intact fibers. More recently, we have used end to side nerve grafts which preserves potentially intact fibers and lessens/eliminates any decrement in baseline function since the nerve is not cut. Results have been similar to the published literature.
Postoperatively, it has been determined that children quickly resume their usual routines and only remain on the hospital’s neurosurgical floor for one to three days for observation. Normally, they are discharged when they are eating well and no longer have significant need for pain medication.
If a graft was placed, the arm is kept in a sling for four weeks after the child is discharged. The main purpose of the sling is to remind the family to limit activity. Otherwise, movement of the limb is important to limit rescarring. Parents are able to remove the sling to change the dressing and inspect the incision.
The return of function is monitored one month postoperatively and every three to six months afterward. Following two or four weeks of recovery, children begin a physical and occupational therapy program. Though seen initially by therapists twice a week, the family is instructed to perform the range-of-motion interventions and other exercises each day. The goal is to maintain the musculature and joint movement until reinnervation.
Because regenerating axons grow approximately one millimeter per day, the reinnervation of a 10-centimeter nerve segment to the deltoid and/or biceps may take approximately three to four months. More distal reinnervation will take longer. Once the nerve reaches its target, there is a gradual refinement of its connections and a period of "retraining" that is required for maximal recovery of function. Recovery should be expected to continue 12 to 24 months postoperatively.
When a child has made some but not yet either a "functional" recovery (able to get their hand to their mouth) or less than "optimal" functional recovery, the secondary surgery can be considered. This has included possible operative interventions such as nerve decompression, tendon releases and/or transfer, etc. to try to improve the outcomes in these children. Usually performed after 9 months of age up to 5-6 years old (or sometimes older), the goal is to improve the use of the extremity by improving nerve conduction and range of motion. Again, at our institution, the type of surgery is dependant on the affected segments and depends on the optimal approach either at one sitting or multiple procedures over time. The children postoperatively are either casted or splinted in a "statue of liberty" position with little overall discomfort.
To date, the results of brachial plexus injury repairs have been rewarding. Results in the Center for Brachial Plexus and Peripheral Nerve Injuries at Children’s Hospital and the few other institutions performing this work show that between 40% and 80% of patients will have improvement of one grade in at least two of three major muscle groups following the primary surgery neurolysis with or without grafting. Improvement of at least one grade translates into significant functional improvement in the use of the extremity, allowing children with brachial plexus injury to lead more normal and independent lives. While those with C5 and/or C6 injuries show better outcomes, gains in other neural territories remain promising.
For the secondary surgery, all of the patients will have some level of improvement, best in the patients who are functional but not optimal. Improvement usually involves better shoulder abduction/flexion and external rotation. There is a bit less improvement in supination. This poor response in supination is usually addressed later with tendon transfers.
Complications are few (less than 3%) and primarily include infection, bleeding and a worsened neurological condition. There is rarely a decrement in function with neurolysis alone. The risk of worsening functional status depends on the need for an interpositional graft. Given the natural history of these injuries, these risks may well be outweighed by the possible benefits. These children may achieve significant improvement and long-term functional use of the limb.
Since the summer of 1995, the Center for Brachial Plexus and Peripheral Nerve Injuries at Children’s Hospital of Pittsburgh has evaluated and treated over 800 children with more than 200 undergoing surgery with all types of brachial plexus and peripheral nerve injuries, utilizing a multidisciplinary approach that includes professionals who specialize in neurosurgery, micro/hand surgery, neurology, physical and occupational therapy, neuroradiology and social work. Each of these specialties is available during an office visit to maximize the efficiency of a patient’s evaluation and to facilitate the collaboration among the different specialists. Patients with injuries to the brachial plexus and peripheral nerves due to all types of trauma are able to benefit from this approach by receiving comprehensive medical, surgical and psychosocial options throughout their ongoing evaluation.
For more information on the Brachial Plexus Clinic, please call (412) 692-3433 or visit the clinic's webpages on the Children's Hospital of Pittsburgh website.