Birth-Related (Obstetrical) Brachial Plexus Injuries 

Updated: May 10, 2018
Author: Alison Snyder-Warwick, MD; Chief Editor: Jeffrey D Thomson, MD 

Overview

Background

The term birth-related brachial plexus palsy (BRBPP) refers to injury noted in the perinatal period to all or a portion of the brachial plexus.[1, 2] The term obstetrical brachial plexus palsy (OBPP) has also been used but has negative implications; accordingly, other terms, such as birth-related brachial plexus injury (BRBPI), are often preferred, particularly in the United States.[3]  Injuries associated with the upper brachial plexus are classically termed Erb palsies, and those associated with the lower plexus are traditionally termed Klumpke palsies.

In 1768, Smellie described bilateral arm paralysis in a newborn.[4]  In 1872, Guillaume Duchenne coined the term obstetrical paralysis.[5]  Erb described C5-C6 paralysis in 1874,[6]  and in 1885, Klumpke described paralysis of the lower plexus. The first description of operative management for obstetrical brachial plexus lesions was reported in 1903.[7]  Poor outcomes and reports by Sever recommending nonoperative management[8, 9]  led to little interest in surgical management of OBPP until the microsurgical era brought renewed interest. In the 1980s, Gilbert popularized the most common indication for surgical reconstruction of obstetrical brachial plexus injuries.[10, 11]

Management of children with BRBPP remains challenging. Technological and surgical advancements have improved patient outcomes, but room for improvement remains. Previous controversy regarding surgical timing has been replaced with evidenced-based results. Outcomes analysis would benefit from a universal outcome measurement tool to allow comparison among institutions. Given the small number of patients who require surgical management, meta-analyses would allow better trend analysis.

Continued experience with direct nerve transfers may eventually minimize interpositional grafting procedures. Basic science research continues for methods of enhancing peripheral nerve regeneration and target muscle protection. The future of management of patients with OBPP continues to benefit from a multidisciplinary approach for delineating optimal treatment methods.

Anatomy

The brachial plexus provides the nerve supply to the upper extremity, from roots C5 to T1 (see the image below).[12]  An anatomic study of 100 cadavers demonstrated that the suprascapular nerve most frequently originates from the posterior division of the upper trunk and the lateral pectoral nerve most commonly branches from the anterior divisions of the upper and middle trunks.[13]

Schema of the brachial plexus. Schema of the brachial plexus.

Pathophysiology

BRBPP arises from an increase in the infant’s neck-shoulder angle, which results in a traction force to the brachial plexus.[14, 15] This force on the brachial plexus can cause varying degrees of nerve injury, ranging from neurapraxia to complete root avulsion. Clinically, this injury results in disruption of the sensory and motor function of the injured nerve. Seddon and Sunderland each described a classification for nerve injuries.[16, 17] The classification of nerve injury described by Seddon consisted of neurapraxia, axonotmesis, and neurotmesis. Sunderland expanded the classification system into five degrees of nerve injury, as follows.

A first-degree injury, or neurapraxia, involves a temporary conduction block with demyelination of the nerve at the site of injury. Electrodiagnostic studies elicit normal results above and below the level of injury, and no denervation changes are present within the muscle. No Tinel sign is present. Once the nerve has remyelinated at that area, complete recovery occurs. Recovery may take up to 12 weeks.

A second-degree injury, or axonotmesis, results from a more severe trauma or compression. This causes Wallerian degeneration distal to the level of injury and proximal axonal degeneration to at least the next node of Ranvier. In more severe traumatic injuries, the proximal degeneration may extend beyond the next node of Ranvier. Electrodiagnostic studies demonstrate denervation changes in the affected muscle(s), and in cases of reinnervation, motor unit potentials (MUPs) are present.

Axonal regeneration after second-degree injury occurs at a rate of 1 mm/day or 1 in./month and can be followed with an advancing Tinel sign. The endoneurial tubes remain intact, and the recovery, therefore, is complete with axons reinnervating their original motor and sensory targets.

A third-degree injury, introduced by Sunderland, is similar to second-degree injury in that Wallerian degeneration occurs; electrodiagnostic studies demonstrate denervation changes with fibrillations in affected muscles. In reinnervation, MUPs are present. Regeneration occurs at a rate of 1 mm/day, and progress may be followed with an advancing Tinel sign. With the increased severity of the injury, the endoneurial tubes are not intact, thus the regenerating axons may not reinnervate their original motor and sensory targets.

The pattern of recovery after third-degree injury is mixed and incomplete. Reinnervation occurs only if sensory fibers reach their sensory end organs and motor fibers reach their muscle targets. Even within a sensory nerve, recovery can be mismatched if sensory fibers reinnervate a different sensory area within the nerve's sensory distribution. If the muscle target is far from the site of injury, nerve regeneration may occur, but the muscle may not be reinnervated completely, due to the long period of denervation.

A fourth-degree injury results in a large area of scar at the site of nerve injury and precludes any axons from advancing distal to the level of nerve injury. Electrodiagnostic studies reveal denervation changes in the affected muscles, and no MUPs are present. A Tinel sign is noted at the level of the injury, but it does not advance beyond that level. No improvement in function is noted, and the patient requires surgery to restore neural continuity, thus permitting axonal regeneration and motor and sensory reinnervation.

A fifth-degree injury is a complete transection of the nerve. As with a fourth-degree injury, surgery is required to restore neural continuity. Electrodiagnostic findings are the same as those for a fourth-degree injury.

Mackinnon popularized a sixth-degree injury classification to describe a mixed-nerve injury with a combination of the other degrees of injury in one patient.[18] This injury pattern commonly occurs when some fascicles of the nerve are working normally while other fascicles may be recovering. Other fascicles may require surgical intervention to permit axonal regeneration.

Spontaneous recovery may occur with Sunderland type I, II, +/- III injuries. In cases of severe nerve injury (Sunderland III, IV, or V) and /or avulsion, however, spontaneous recovery does not occur, and surgical intervention is warranted.

Glenohumeral dysplasia (GHD) occurs with BRBPP. Imbalances in muscle, other soft tissues, and bone at the shoulder may lead to asymmetric growth, contractures, and deformation at the cartilaginous joint surfaces.[19, 20]  The glenoid becomes progressively retroverted and inferiorly oriented, resulting in posterior displacement or subluxation of the humeral head.[21, 22]  Predictors of GHD associated with BRBPP include increasing age and muscular imbalance, but GHD may occur without restricted shoulder movement.[19]  At a median age of 16 weeks, 74% of infants undergoing surgical exploration of the brachial plexus had GHD on magnetic resonance imaging (MRI).[19]

Etiology

BRBPI may result from a multitude of causes. Positioning may lead to an increase in the neck-shoulder angle, producing a stretch injury, rupture, or avulsion if forces exceed neural tensile strength. Injury may also result from compression due to hematoma, clavicular fracture, uterine contraction, or instrumentation or manipulation.

Factors associated with BRBPI include large birth weight (>4000 g),[23, 24] large fetal weight deviation at 32 weeks estimated gestational age or large birth weight,[25, 26, 27] long or difficult labor or delivery, breech delivery, and shoulder dystocia.[28, 29, 30, 31, 32, 33] Shoulder dystocia is associated with a 100-fold increased risk of brachial plexus injury.[23] Brachial plexus injury was noted in 5-11% of shoulder dystocia cases in retrospective studies.[34]

Persistent neonatal brachial plexus injury is possible after cesarian or vaginal delivery.[35]  Persistence of brachial plexus injury beyond 1 year occurred in 85% of infants with BRBPI at one institution, and persistence of symptoms was more likely in patients with cephalic presentation, induction or augmentation of labor, birth weight greater than 9 lb, and Horner syndrome.[36]

Some consider intrauterine pressure neuropathy to be a cause of BRBPP, on the basis of the high pressures exerted between the brachial plexus and the mother's pelvis with labor and on the occurrence of BRBPP in uneventful cesarean deliveries and in vaginal delivery without significant mechanical difficulty. Gonik et al suggested that spontaneous endogenous uterine and maternal expulsive forces are four to nine times greater than the force calculated for clinician-applied forces.[37]

Vertex presentation accounts for most BRBPP cases (94-97%); breech presentations account for 1-2% of cases; and cesarean deliveries account for 1% of cases. Mothers with diabetes, obesity, or preeclampsia, as well as mothers who are multiparous and previously had large babies, are also considered to be at higher risk for their children to have BRBPP.

Epidemiology

BRBPIs occur in 0.5-5 infants per 1000 live births.[26, 25, 32] The incidence ranges globally from 0.2% to 4% of live births. According to the World Health Organization, prevalence is generally 1-2% worldwide, with the higher numbers being in underdeveloped countries.

Prognosis

Most patients with BRBPP recover spontaneously and do not require surgical intervention. For those patients with more severe neural injuries requiring surgical management, outcomes are hopeful. The assessment of clinical functional outcomes, however, is limited by the lack of a universal outcome measure in the evaluation of patients with BRBPP.

The Brachial Plexus Outcome Measure has been proposed as an effective and consistent outcome assessment tool.[38]  Different centers use different scales for evaluation of motor function, change scales depending on patient age, use different scales for different body regions, use two scales to describe motion and strength, or describe range of motion as degrees of joint angle, limiting the capacity for comparison studies or meta-analyses.

The Canadian OBPI Working Group published a meta-analysis, however, comparing outcomes of children younger than 2 years who underwent either operative nerve repair or nonoperative management of BRBPP.[39]  Nerve repair reduced functional impairment significantly as compared with nonoperative management. In 222 patients, there were no deaths, major adverse events occurred in 1.5%, and minor adverse events occurred in 5%. With nonoperative management, 27% of patients exhibited residual impairment.

With neuroma excision and grafting, reported outcomes demonstrate a relationship with the extent of the brachial plexus lesion.

O’Brien et al[40]  reviewed their series of 52 patients with BRBPP treated with brachial plexus neuroma resection and interpositional sural nerve grafting at an average age of 9.8 months. A Medical Research Council score of greater than or equal to 3/5 was demonstrated in the setting of C5-C6 injury in biceps function in 92% of children, triceps function in 92%, and deltoid function in 83%. In the setting of C5-C7 injuries, children scored greater than or equal to 3/5 on the Medical Research Council scale in the biceps in 76%, triceps in 76%, and deltoid in 72%. Children with a C5-C8 and T1 lesion achieved and Medical Research Council score greater than 3/5 in the biceps in 73%, triceps in 53%, and deltoid in 67%.

Gilbert et al[41]  reported their 20-year experience with neuroma excision and grafting in patients with no biceps function by age 3 months. They reported “good or excellent” shoulder function after 4-year follow-up in 80% of children that had C5-C6 lesions. Only 61% of patients achieved this function with C5-C7 injuries. Children with complete brachial plexus lesions achieved “average, good, or excellent results” in 77% of cases at 8 years postoperatively. They reported better outcomes in elbow function, with 81% of children achieving “good or excellent” results at 8 years. Hand function was reported as “useful” in 76% of children.

AFter reconstruction with neurolysis, neuroma excision and grafting, and/or nerve transfers, El-Gammal et al[42]  reported good or excellent outcomes for elbow flexion and extension in 77% of children, but they reported achieving this same level of function for thumb extension in only 28% of patients and for wrist extension in only 31% of patients.

Transfer of the spinal accessory nerve to the suprascapular nerve has shown similar functional outcomes compared to nerve grafting from C5 to the suprascapular nerve. A retrospective review of suprascapular nerve reconstruction with either spinal accessory nerve transfer or C5 nerve root grafting found no difference in external shoulder rotation after 3 years of follow-up.[43]

Similarly, Terzis and Kostas[44]  saw no significant differences in outcome in patients undergoing suprascapular nerve reconstruction via either direct neurotization (spinal accessory or intraplexus) or nerve graft. They reported good or excellent results in supraspinatus function in 96% of patients and in infraspinatus function in 75%. Forty-one of 50 patients achieved Mallet grade III or IV external shoulder rotation, and the authors described a trend towards increased range of shoulder abduction in patients with direct nerve transfers.

Pondaag et al[45]  also found no differences in glenohumeral rotation, passive external rotation, and Mallet hand-to-head movement after nerve transfer versus grafting.

Nerve transfers have demonstrated functional improvements. In 54 patients with no external shoulder rotation, but otherwise spontaneous recovery, the spinal accessory–to–suprascapular nerve transfer resulted in Mallet score IV external rotation in 40 patients, Mallet grade III in 10 patients, and unchanged function in 4 patients.[46]

Intercostal nerve transfers to the musculocutaneous nerve resulted in Medical Research Council grade M4 biceps function in 84%[47]  and good or excellent elbow flexion in 93.5%.[48]  Oberlin transfer was reported to achieve Medical Research Council grade M4 or M5 biceps function in 4 of 7 patients[49]  and Medical Research Council grade M5 in two of two patients[50]  in separate studies.

Secondary surgical procedures involving tendon and muscle transfers and releases are available to patients with functional limitations.[51, 52]  Limited shoulder function can be enhanced at a later age with procedures to release the subscapularis muscle or transfer the teres major and latissimus dorsi muscles.[53, 54, 55, 56]  Recovery of elbow flexion can be augmented at a later date, if necessary, with muscle or tendon transfers.

Limb-length discrepancy between the unaffected and affected arms is a consequence of BRBPP.[57]  Delayed bone age in the affected upper extremity may account for the decreased growth.[58]

Children with BRBPP score lower on health-related quality-of-life scales and have higher problem scores and maternal distress as compared with age-matched controls.[59, 60]  Children who have undergone surgical repair of BRBPP commonly report pain, which is often low in intensity and episodic.[61]

Children affected with BRBPP demonstrate lower scores for global and upper-extremity function compared with pediatric norms, but they participate in organized sports at the same rate as their unaffected peers. As many as 42% of these children perceive a disability related to their sport, but they do not experience higher injury rates and do participate in multiple sports compared with their unaffected peers.[62]

The ability of children with BRBPP to perform self-care activities without significant limitation compared with their peers is determined by the presence of impairment of hand function, as assessed by the Pediatric Evaluation of Disability Inventory (PEDI).[63]

 

Presentation

History

Infants are evaluated as early in the postnatal period as possible. A careful history is necessary to elicit risk factors, establish chronology, and differentiate brachial plexus and nonbrachial plexus etiologies of upper-extremity motor weakness.

Physical Examination

The evaluation of an infant with suspected birth-related brachial plexus palsy (BRBPP) should be performed by a multidisciplinary team, including physical and occupational therapy, to appropriately assess motor function and competency with activities of daily living. The patient’s chest and upper extremities should be disrobed to allow proper motor evaluation. Presence of confounding injuries should be assessed, such as shoulder dislocation; clavicular, humeral, or rib fractures; ecchymoses; or scarring suggestive of previous fat necrosis and injury.

Upper-extremity posturing may provide clues to the level of injury within the plexus. The classic “waiter’s tip” positioning of the arm suggests an upper-plexus injury, including the roots of C5, C6, and occasionally C7. This upper plexus pattern is known as Erb palsy, and the patient keeps the arm adducted, shoulder internally rotated, elbow extended, forearm pronated, and wrist and fingers flexed.

A winged scapula indicates injury to the long thoracic nerve (C5, C6, C7). Injury to the C7 root in isolation may result in an elbow-flexed posture. A flail limb with no motor function suggests a pan–brachial plexus injury, including roots C5, C6, C7, C8, with or without T1. Horner syndrome (eyelid ptosis, pupillary miosis, and anhidrosis) indicates injury to the lower plexus with injury to the T1 root proximal to the separation of the sympathetic fibers from the somatic motor fibers. Isolated injuries to the lower brachial plexus, referred to as Klumpke paralysis, typically do not occur with BRBPP.[64]

Motor evaluation of the patient with BRBPP is essential as it is indicative of prognosis and guides therapy. This examination can be challenging owing to the age of the patient and the complexity of the injury. Several classification systems have been described to categorize motor function, particularly in the setting of BRBPP.

The Active Movement Scale (see Table 1 below) developed at the Hospital for Sick Children in Toronto[65, 66]  is a universally applicable, validated scale for motor assessment. Fifteen movements (shoulder abduction, flexion, internal and external rotation, elbow flexion and extension, forearm pronation, and wrist, finger, and thumb flexion and extension) are scored from 0 to 7. Advancement in score requires full range of motion (ROM) before strength against gravity can be assessed.

Table 1. Active Movement Scale (Open Table in a new window)

Observation

Score

Converted Score

Gravity eliminated

 

 

-No contraction

0

0

-Contraction, no motion

1

0.3

-Motion ≤ ½ range

2

0.3

-Motion > ½ range

3

0.6

-Full motion

4

0.6

Against gravity

 

 

-Motion ≤ ½ range

5

0.6

-Motion > ½ range

6

1.3

-Full motion

7

2.0

The Medical Research Council scale[67]  and the Mallet scale[68]  are other commonly used classification systems, but they require active patient cooperation and therefore are not applicable to patients of all ages[69]  and are not useful for all injury scenarios.[70]

 

Workup

Laboratory Studies

Before any lengthy surgical procedure in the vicinity of large vessels, a hemogram should be obtained and coagulation factors checked.

No specific laboratory studies are helpful in diagnosing patients with birth-related brachial plexus palsy (BRBPP).

Imaging Studies

Computed tomography (CT) myelography or magnetic resonance imaging (MRI) is useful to help predict locations of nerve root avulsion. Diaphragmatic ultrasonography (US) is used to evaluate phrenic nerve function.

Glenohumeral dysplasia (GHD) is assessed by means of US, radiography, MRI, or CT.[71, 72] Three-dimensional (3D) imaging provides a more comprehensive view of glenohumeral deformation than two-dimensional (2D) radiography does.[21, 73]

Other Tests

Electromyography (EMG) and nerve conduction studies are less useful for patients with BRBPP than they are for adults with brachial plexus injuries.

With EMG, fibrillations are associated with denervation and become apparent approximately 4-6 weeks following injury. Motor unit potentials suggest collateral sprouting, indicating recovery, but may not appear on EMG testing until 12 weeks after injury. In general, EMG findings may be misleadingly optimistic.[74] Most surgeons believe that clinical examination is a better prognostic indicator than EMG.

 

Treatment

Approach Considerations

Most infants with birth-related brachial plexus palsy (BRBPP) demonstrate spontaneous improvement in upper-extremity function and do not require surgical management. Spontaneous complete recovery rates have been reported to be as high as 93% by age 4 months.[75]  Recovery rates and extent depend on the injury type and severity. Mild injuries with rapid recovery clearly do not require surgery. Similarly, injuries involving a flail upper limb and Horner syndrome require operative management.

Discerning the conditions between these two extremes that would benefit from operative management is more challenging. Historically, absence of elbow flexion by age 3-4 months has been used as a predictor of benefit from operative management. Poor shoulder function at age 5 years and increased need for secondary procedures were noted by Gilbert and Tassin in infants who had no biceps function at age 3 months and received no surgery.[76, 77]

The timing for surgical intervention has since been debated in the literature.[78, 40, 79]  When absence of elbow flexion alone was used to predict outcome, Michelow et al[23]  reported poor recovery was incorrectly reported 12% of the time. When evaluation of elbow, wrist, finger, and thumb extension were added to assessment of elbow flexion at age 3 months, poor recovery was incorrectly predicted only 5.2% of the time.

The Toronto Test Score consists of the sum of converted scores from the Active Movement Scale (see Table in Clinical) for these five movements at age 3 months. Operative management is indicated for a test score of less than 3.5. Fisher et al[80]  reviewed 209 patients with OBPP managed over a 4-year period at the Hospital for Sick Children. Groups were divided by presence or absence of elbow flexion at age 3 months, as well as surgical or nonsurgical management. At 3-year follow-up, no differences in upper extremity function were noted among the groups, indicating that elbow flexion alone is a poor predictor of functional prognosis and need for surgical intervention.

Clarke et al at the Hospital for Sick Children developed a general algorithm that includes motor assessment at birth and then age 3, 6, and 9 months.[81]  Patients with a flail arm and Horner syndrome may proceed to early surgical management. Horner syndrome is a poor prognostic sign.[82]

The Toronto Test Score is performed at age 3 months. A score of less than 3.5 predicts poor spontaneous recovery and is an indication for surgical management. For infants who scored greater than 3.5, the motor examination is again completed at age 6 months. Failure to improve from low scores on the Active Movement Scale at age 6 months may indicate a need for surgical intervention.

At age 9 months, the child again undergoes motor evaluation and assessment with the “cookie test,” which involves placing a lightweight cookie in the affected upper extremity with the humerus adducted against the chest wall. The child passes the test if he or she is able to flex the elbow sufficiently to reach the cookie to the mouth without flexing the neck more than 45°. In cases of a passed cookie test, nonoperative management is usually recommended. Operative intervention for C5-6 neuroma excision and sural nerve grafting has been suggested for patients who have elbow flexion at 9 months but who have deficits in shoulder motion or forearm supination.[81, 83]

There is a small subset of patients who, despite passing these previous milestones, may benefit from primary nerve surgery to treat poor shoulder function, particularly external rotation.[81]

It should be noted that no single algorithm is universally applicable, and management decisions must be achieved based on individual circumstances and performance over time.

Brachial plexus reconstructions are complex, lengthy procedures that require skill, appropriate equipment, and a well-prepared team. The patient’s overall health status must be included in the consideration for operative management. The patient must be sufficiently healthy for a prolonged surgical procedure. The brachial plexus is in the vicinity of critical structures such as the great vessels and thoracic cavity. Systemic conditions such as coagulopathies may be contraindications for surgery.

Medical Therapy

Physical therapy is used to maintain passive range of motion (ROM) of the affected joints. Some believe that in patients with BRBPP, transcutaneous electrical nerve stimulation (TENS) is useful in waking up muscles that have been successfully reinnervated over a period of time.[84] However, no scientific studies support this conclusion, and the authors do not routinely employ this modality.

Glenohumeral dysplasia (GHD) with shoulder instability (dislocation or subluxation) may be managed with chemodenervation of internal shoulder rotators, closed reduction, and shoulder spica casting.[85]  

Surgical Therapy

Once the need for operative intervention has been determined, many reconstructive options are available, depending on the intraoperative findings, including the type of neural lesion encountered, the resulting neural gap, and the amount of available neural donor tissues. Surgical treatment involves brachial plexus exploration, neuroma excision, and nerve grafting or nerve transfer.

Preparation for surgery

Given the complexity and length involved with brachial plexus reconstruction procedures, appropriate preoperative planning can improve efficiency and outcomes. Safety measures, such as suturing the nasotracheal tube to the nasal septum and placing a clear plastic drape over the patient’s face, may prevent disastrous and avoidable airway complications. The patient should be appropriately positioned, with all pressure points effectively padded and protected. Throughout the process, communication among all caregivers is essential to minimize complications.

Operative details

Neuroma excision has been shown to have superior long-term results compared with neurolysis alone in children with birth-related brachial plexus lesions. Neurolysis alone for the surgical management of neuroma-in-continuity provides functional improvements at 12-month follow-up for patients with upper-plexus, but not total-plexus, lesions.[86]  After neuroma excision and interpositional nerve grafting, patients with BRBPP regain their preoperative functional levels by 3-6 months postoperatively,[87]  indicating no downgrade of function for patients selected as operative candidates via the previously outlined algorithm.

In a long-term comparison of 108 patients receiving either neurolysis alone or neuroma excision and interpositional grafting, patients with upper-plexus lesions who received only neurolysis had no functional improvements 4 years postoperatively, whereas those with upper-plexus lesions receiving neuroma resection and grafting achieved significant functional gains in seven tested movements.[88] In the same study, patients with total-plexus lesions treated with neuroma resection and grafting demonstrated significant functional improvements in 11 of 15 tested movements at 4-year follow-up, whereas the corresponding group treated with neurolysis alone showed no significant functional improvements.

Because neuroma resection and grafting yields improved outcomes in BRBPP patients requiring surgical management, sural nerve grafts can be harvested as the first stage of the procedure. This sequence allows initial prone patient positioning to facilitate sural nerve graft harvest, followed by supine positioning for brachial plexus exposure and reconstruction. Sural nerve harvest for graft material results in minimal donor-site morbidity but does create a permanent insensate patch at the lateral foot, which, though measurable, often goes unnoticed by patients.[89]  When the sural nerve is harvested proximally, from its branch point from the tibial nerve, up to 13-15 cm per leg may be obtained from a 10-kg infant.

Many approaches to brachial plexus exposure may be used, but the authors typically use a supraclavicular approach with a V-shaped incision coursing along the posterior border of the sternocleidomastoid (SCM) and the superior edge of the clavicle. As dissection proceeds to expose the plexus, the clavicular head of the SCM and the external jugular vein may have to be divided. The supraclavicular sensory nerves may be required as additional graft material and therefore should be divided distally during the exposure to preserve length. The transverse cervical artery and omohyoid are also divided.

Once exposed, the fat pad of Brown is swept laterally to expose the brachial plexus. The suprascapular vessels are divided to increase exposure of the brachial plexus neuroma. The phrenic nerve, coursing from lateral to medial, is carefully dissected away from the neuroma. Each of the roots of the brachial plexus is then systematically identified as the neuroma is dissected to determine the level and nature of the lesion. The C4 root is located as a landmark for identifying the C5 root by following the supraclavicular nerves proximally. Dissection of the neuroma proceeds in a cranial-to-caudal direction. An empty foramen suggests root avulsion.

Once the proximal extent of the neuroma is identified, dissection proceeds distally to identify healthy nerve. The nerve trunks are identified and dissected. The dorsal scapular artery, located between either the upper and middle trunks or the middle and lower trunks, requires division for adequate plexus visualization. Infraclavicular exposure can usually be achieved with inferior traction on the clavicle rather than clavicular resection. Care should be taken to avoid injury to the subclavian artery during dissection of the C8 and T1 roots. The T1 root lies adjacent to the parietal pleura and can be adherent depending on the extent of the neuroma.

A saline pool test should be performed after dissection is completed to assess pleural integrity. The neuroma should be dissected in its entirety. The nerve roots are stimulated to ascertain functional upper extremity results.

Once the neuroma is completely exposed, it is divided in its midportion. Distally, nerves are divided at healthy, soft-appearing nerve, distal to the neuroma. Distal neural ends are sent to pathology as frozen sections for histologic examination. Proximally, nerves should also be transected in healthy regions and samples sent for frozen section. The frozen sections are then reviewed with a neuropathologist to ensure absence of fibrosis or scarring and the presence of a normal fascicular pattern to ensure reconstruction outside of the zone of injury. Management should incorporate information from preoperative imaging, histologic appearance, and intraoperative appearance and stimulation.

Once the neuroma is adequately resected, the resulting nerve gaps should be measured. Reconstruction may consist of a combination of nerve grafts and transfers, if necessary, depending on the size of the neural gaps and the amount of nerve graft available. Priority is given to reconstruction of hand function, followed by the elbow and shoulder.

Anatomic reconstructions, or grafts from the intended target to the original root, are performed whenever possible. Cable grafts are performed with the amount of available graft. Additional graft material may be obtained from the cervical plexus if required. All grafts are reversed to minimize axonal dropoff. Neural coaptations are performed with fibrin glue with the use of the operating microscope.

Nerve transfers allow reconstruction of a nerve from a different nerve source and are useful in cases of root avulsion, late presentation, or isolated deficits. Transfers also allow reconstruction of specific motor or sensory deficits with a single nerve coaptation and can sometimes be performed in closer proximity to the target function to allow more rapid target innervation.[90]  The International Federation of Societies for Surgery of the Hand noted limitations in the literature that prevent direct comparisons of nerve grafting and nerve transfer and cautioned against overreliance on nerve transfers for patients with severe BRBPP.[91]

The spinal accessory–to–suprascapular nerve transfer is commonly performed in cases of BRBPP for restoration of supraspinatus and infraspinatus muscle function.[92, 93]  This transfer can be performed from either an anterior or a posterior approach,[94, 95]  and the posterior approach allows simultaneous release of the suprascapular ligament, which is a known compression site of the suprascapular nerve.

Reconstruction of biceps function can be performed via the Oberlin transfer, which consists of transfer of a redundant branch supplying the flexor carpi ulnar muscle to the biceps branch of the musculocutaneous nerve.[50, 49]  Humphreys and Mackinnon[96]  described transfer of redundant fascicles of both median and ulnar nerves to restore function to the biceps and brachialis branches of the musculocutaneous nerve. These transfers have been reported in patients with BRBPP.[97]  Transfer of three or more intercostal nerves can be performed to the musculocutaneous nerve for reconstruction of elbow flexion in cases of insufficient donor axons.[47]

Other nerve transfers described for use in BRBPP are the medial pectoral nerve–to–musculocutaneous nerve transfer,[98]  the radial nerve–to–axillary nerve transfer,[99]  ipsilateral C7 neurotization of the upper trunk,[100, 101]  and the contralateral C7 transfer in cases of pan-plexus root avulsions,[102]  though these transfers are less commonly used. Hypoglossal[103]  and phrenic nerve[104]  or phrenic nerve branch[105]  transfers have also been performed in patients with BRBPP, though their use is not recommended, owing to significant donor deficits.

Postoperative Care

The patient’s affected upper extremity should be maintained in a Velpeau stockinette for 3 weeks postoperatively to maintain shoulder adduction. After this 3-week immobilization period, the child may be permitted to move freely.

Complications

Complications of surgery for BRBPP include the following:

  • Infection
  • Hematoma
  • Seroma
  • Injury to nearby structures, including vascular structures and the thoracic cavity

Unique to this surgery is the possibility of further inhibiting function by injuring components of the brachial plexus that are normal or recovering. In this patient population, injury to the phrenic nerve can result in devastating pulmonary compromise that could require urgent diaphragmatic plication. In theory, an intercostal motor branch or a nerve to the rectus muscle can be transferred to the distal end of the phrenic nerve, just above the diaphragm, to provide some reinnervation of the diaphragm.

Long-Term Monitoring

Initially, patients with BRBPP are monitored for wound management. At 4 weeks following surgery, patients are referred for therapy to regain active and passive ROM of the extremity. Recovery of some motor function may be noted as early as 3 months following surgery. Baseline motor function is usually achieved by 6 months. Patients continue to improve for up to 4 years, however, following surgery. Botulinum toxin has been used for management of muscle imbalance and has shown sustained benefits for elbow movement imbalance.[106] Secondary procedures such as muscle transfers, tendon transfers, osteotomies, or shoulder releases may also be necessary to maximize function.