Acknowledgments:

The author wishes to recognize the work of previous authors, Drs. Robert Leffert, Vincent R. Hentz, and Michelle James, for their contributions to Green’s Operative Hand Surgery and this chapter. The outstanding assistance of Emily Reiff and Emily Eismann was instrumental to complete it.

This chapter discusses the diagnosis, treatment, and long-term expected outcomes of infants and children with neonatal brachial plexus palsies. Because the type and severity of neural injuries are variable, treatment and outcome are not uniform for all infants. In those children with mild neurapraxic lesions, spontaneous recovery is to be expected over the first several months of life, with complete recovery evident by age one. In contrast, children with severe avulsion injuries experience a lifetime of disability despite extensive therapy and surgical management. Although there have been many advances since Duchenne’s (1872) and Erb’s (1874) classic descriptions of infantile paralysis, many difficult challenges still remain. For instance, the treatment of severe injuries involving the entire brachial plexus with a combination of nerve ruptures and nerve avulsions remain insurmountable. Microsurgical reconstruction of the plexus in the first 3 to 9 months of life can improve the natural history. However, inability to directly repair avulsions of nerve roots from the spinal cord and the resulting relative paucity of donor nerves for reconstruction results in persistent and permanent impairment.

Fortunately, the incidence of these multilevel avulsion and/or rupture injuries is relatively low (between 8% and 25%) for all brachial plexus birth palsies. In addition, secondary musculoskeletal deformities are common in children with incomplete recovery in the first 1 to 3 years of life. Although nonoperative and operative intervention, such as contracture releases, tendon transfers, and osteotomies, may improve function, none can normalize limb function. The goal of this chapter is to explain the nature of the neurologic injury and its effect on the developing child. This knowledge will guide decision making regarding the initial neurological injury and its secondary musculoskeletal manifestations. Issues and controversies with incomplete evidence for decision making will also be addressed.

Pertinent Anatomy

Essential to any discussion of the natural history and treatment of a brachial plexus lesion is a thorough understanding of the anatomy. Therefore, a brief review of the pertinent anatomy is described ( Figure 40.1 ).

Normal anatomy of the brachial plexus.

The brachial plexus most commonly receives contributions contiguously from the fifth cervical (C5) through the first thoracic (T1) ventral spinal nerve roots. Prefixed cords (22%) receive an additional contribution from the C4 nerve root, whereas the much less common postfixed cords (1%) receive a contribution from T2. The C5-6 nerve roots join to form the upper trunk, the C7 nerve root continues as the middle trunk, and the C8-T1 nerve roots combine to form the lower trunk. Each trunk bifurcates into anterior and posterior divisions. The posterior divisions of all three trunks make up the posterior cord. The anterior divisions of the upper and middle trunks form the lateral cord. Finally, the anterior division of the lower trunk forms the medial cord.

The major nerves of the upper extremity are terminal branches from the cords, with the ulnar nerve arising from the medial cord, the radial and axillary nerves from the posterior cord, the musculocutaneous nerve from the lateral cord, and the median nerve from branches of the medial and lateral cords. The other nerves to the upper extremity arise sequentially throughout the brachial plexus as illustrated in Figure 40.1 . Of note, the dorsal scapular nerve arises from the C5 nerve root along with a branch to the phrenic nerve, the suprascapular nerve arises from the upper trunk, and the long thoracic nerve arises from the C5-7 nerve roots. In addition, the lateral pectoral nerve originates from the lateral cord and the medial pectoral from the medial cord. Finally, the thoracodorsal nerve and the upper and lower subscapularis nerves arise from the posterior cord. The proximal-to-distal orientation of the brachial plexus is nerve roots, trunks, divisions, cords, and terminal branches. The divisions are located behind the clavicle. Every muscle in the upper limb is innervated by the brachial plexus.

Surgical exploration and reconstruction of the brachial plexus require a thorough understanding of its three-dimensional anatomy. As noted, the brachial plexus extends proximally from the C5 to the T1 ventral nerve roots of the spinal cord and distally to the terminal branches in the upper brachium. In the neck, it is located between the anterior and middle scalene muscles. The plexus extends beneath the clavicle, superficial to the first rib, as it passes into the axilla. The plexus is divided into supraclavicular and infraclavicular portions. The brachial plexus is joined by the major blood vessels of the arm beneath the clavicle. As the plexus courses medial to the coracoid, the nerves are surrounded by the axillary artery. The relationship of the cords to the artery gives them their appropriate medial, lateral, and posterior designations. Complete exposure of the brachial plexus often requires retraction or osteotomy of the clavicle, release of the muscular insertions to the coracoid, and release of the clavicular origin of the pectoralis major muscle.

Preoperative Evaluation

Brachial plexus birth palsy has an incidence of 0.38 to 1.56 per 1000 live births. The difference in incidence may depend on the type of obstetric care and the average birth weight of infants in different geographic regions. Perinatal risk factors for brachial plexus palsy include large size for gestational age (macrosomia), maternal diabetes, multiparous pregnancies, previous deliveries resulting in brachial plexus birth palsy, prolonged labor, breech delivery, shoulder dystocia, and assisted (vacuum or forceps) and difficult deliveries.

Maternal body mass index is on the rise in the United States and other well-developed countries of the world, and this is leading to increasing fetal size and a rising incidence of gestational diabetes. Both are risk factors for brachial plexus birth palsy. Unfortunately, shoulder dystocia is often an unanticipated and unpredictable obstetric emergency. Fetal distress may contribute to muscle hypotonia and provide less protection of the plexus from stretch or compression injury during delivery.

Mechanically, shoulder dystocia in vertex deliveries and difficult arm or head extraction in breech deliveries increase the risk for nerve injury. The increased incidence of delivery by cesarean section may in part be due to an attempt to avoid dystocia and brachial plexus injuries. However, cesarean section does not guarantee prevention of a brachial plexus birth injury, although it decreases the incidence 100-fold. Further complicating the etiology are reports citing evidence of intrauterine onset of paralysis. Thus, prevention of the injury remains elusive, underscoring the importance of optimal treatment of the sequelae.

Most commonly, a brachial plexus birth palsy involves the upper trunk (C5-6 or Erb’s palsy), potentially in combination with injury to C7 (extended Erb’s palsy); less often, the entire plexus (C5-T1 or global palsy) is injured. Injuries are described classically as neurapraxia (Sunderland type I), axonotmesis (Sunderland types II to IV), neurotmesis (Sunderland type V), or avulsion ( Figure 40.2 ). Mechanically, lesions have been described as stretch (Sunderland type I), varying degrees of rupture (Sunderland types II to V), and avulsion. Upper trunk extraforaminal ruptures are more common with vertex delivery and shoulder dystocia. The right upper limb is involved more often because of the more frequent left occiput anterior vertex presentation, which places the right shoulder behind the symphysis pubis. C5-6 root avulsions are particularly frequent with breech presentation and can at times be bilateral . When the entire plexus is involved, a combination of stretch, rupture, and avulsion injuries can occur in various portions of the plexus.

A severe traction injury to the brachial plexus may cause nerve injuries of varying severity in the same plexus. Such injuries include avulsion of the nerve root from the spinal cord (cannot be repaired), extraforaminal rupture of the root or trunk (can be surgically repaired), intraneural rupture of fascicles (some spontaneous recovery possible), and neurapraxia (recovery certain).

A mechanical cause of infantile paralysis is the predominant theory on the etiology of brachial plexus birth palsy. The theory is based on extensive work that began with original descriptions of brachial plexopathy during delivery by Smellie and Duchenne and anatomic studies by Metaizeau. However, there are rare reports of possible congenital causes of a birth palsy such as hypoplastic plexus. In addition, it has been postulated that there may be abnormal in utero forces (maternal propulsive forces) acting on the posterior shoulder region and the plexus as the fetus passes over the sacral promontory before obstetric delivery. The pushing forces of uterine contractions in a dystocia situation have been studied to determine their contribution to neonatal nerve injury in these deliveries.

Increased in utero pressure and subsequent traction across the plexus have been proposed as a possible root cause. In addition, the presence of an anomalous uterus, such as a bicornuate or fibroid one, may decrease the space available for the infant and lead to compression across the brachial plexus. These alternative causes have become contentious issues in a litigious society because the presence of a brachial plexus birth palsy may result in a malpractice suit against everyone participating in the birth of that infant, including the obstetrician, midwife, labor nurse, hospital, and others.

The diagnosis of a brachial plexus birth palsy is predominantly by physical examination. The differential diagnosis includes pseudoparalysis as a result of fracture or, less commonly, infection; injury to the central nervous system or cervical spinal cord; neuromuscular disorders; and congenital anomalies of the upper limb that result in limited motion and strength. Because fracture of the clavicle can occur concomitantly with a birth palsy, radiographs are clinically indicated. A humeral shaft fracture can mimic a brachial plexopathy, although the two injuries do not tend to coexist in the same limb. Instead, a severely displaced humeral shaft fracture results in an isolated radial nerve palsy.

Generally, the diagnosis of a brachial plexus palsy is readily apparent. The spectrum of clinical findings is dependent on the extent of nerve injury and the timing of examination. The presence of Horner syndrome (i.e., ptosis, myosis, enophthalmos, anhidrosis) is worrisome for an avulsion injury in the lower roots and a poor prognosis ( Figure 40.3 ). The recovery after birth is often dynamic with changing physical findings over the first few weeks and months of life. Patience is required to perform a reliable examination of an infant (Video 40.1 ). Observation of spontaneous movement, testing of neonatal reflexes, and stimulation of motor activity are necessary for an accurate examination. The most important aspect of the examination is to determine the prognosis for recovery. Therefore, serial examinations on a 1- to 3-month basis during infancy are critical for prediction of outcome and determination of indications for surgical intervention.

A 4-month-old child with left global brachial birth palsy and Horner syndrome.

(Courtesy of Shriners Hospitals for Children, Philadelphia.)

Narakas and Slooff attempted to clinically categorize the continuum of brachial plexus palsy into four groups. The mildest clinical group (I) is represented by the classic upper trunk C5-6 (Erb’s) palsy, with initial absence of shoulder abduction and external rotation, elbow flexion, and forearm supination. Wrist and digital flexion and extension are intact. Successful spontaneous recovery is believed to occur in as many as 90% of infants in this group. Group II represents an extended upper trunk lesion and includes additional involvement of C7, with the absence of wrist and digital extension added to the limitations noted for group I. These infants have the classic “waiter’s tip” posture of their hand and wrist. The prognosis is worse with C5-7 involvement. Group III consists of a flail extremity but without a Horner syndrome. The most severe involvement (group IV) is manifested as a flail extremity with a Horner syndrome. These infants may have an associated phrenic nerve palsy with an elevated hemidiaphragm. This is best assessed via dynamic study such as a chest fluoroscopy or ultrasound during breathing. These infants have limited chance of meaningful spontaneous recovery.

For prognostic reasons, it is important to determine whether the level of injury is preganglionic or postganglionic (see Figure 40.2 ). Because of the proximity of the ganglion to the spinal cord and the fact that the motor cell body is in the spinal cord, preganglionic lesions are avulsions from the cord that will not spontaneously recover. By assessing the function of several nerves that arise close to the midline and the ganglion, one can frequently determine the level of the lesion by physical examination ( Table 40.1 ). Specifically, the presence of Horner syndrome (sympathetic chain), an elevated hemidiaphragm (phrenic nerve), and a winged scapula (long thoracic nerve) and the absence of rhomboid (dorsal scapular nerve), all raise concern about a preganglionic lesion.

Preganglionic lesions can be reconstructed only by nerve transfers, most commonly with the thoracic intercostal nerves, a branch of the spinal accessory nerve, or partial peripheral nerve transfers. Postganglionic ruptures have reconstructible proximal and distal nerves beyond the zone of injury. Thus, a postganglionic injury is a complex peripheral nerve lesion that can be reconstructed with intercalary nerve grafts. Peripheral nerve transfers can also be used to reconstruct these injuries. However, functional spontaneous recovery is also possible in postganglionic injuries, likely due to partial ruptures and redundant innervation pathways present at birth. Narakas group I and those in Narakas II with complete biceps recovery by 4 months have a high likelihood of full function. Infants in groups III and IV are unlikely to achieve full function without surgical intervention.

The majority of neonatal brachial plexus injuries involve the upper trunk. The classic Erb palsy involves C5-6 (46%). The next most common injury (an extended upper trunk lesion or extended Erb’s palsy) involves C5-7 (29%); with these injuries, the pattern is most frequently postganglionic. When the lower plexus is involved, preganglionic avulsions of C8-T1 are most common. The exception to this situation is an upper trunk lesion seen with a breech delivery. These nerve injuries tend to be preganglionic C5-6 avulsions from the spinal cord.

Most authors use the timing of specific motor function recovery and the absence of recovery as an indication for surgical intervention. Wyeth and Sharpe in 1917 advised surgical intervention if no recovery was seen by 3 months of life. Gilbert and Tassin concurred with the 3-month time interval and used recovery of antigravity biceps function as the key indicator of spontaneous recovery of the brachial plexus. Waters similarly found biceps recovery to be statistically reliable. Laurent and colleagues advised monitoring biceps, triceps, and deltoid function.

Clarke and associates described the timing of return of elbow flexion and elbow, wrist, finger, and thumb extension as discriminators of outcome and used a combined threshold score of motor recovery of these muscles as an indication for nerve surgery. Ultimately, Clarke advised that recovery at 9 months be assessed with a “cookie test” (i.e., inability to bring a cookie to the mouth with the arm at the side) to predict outcome and determine the need for microsurgical intervention in difficult cases.

Grading recovery of specific muscles in an infant is difficult. Many centers use the Medical Research Council (MRC) muscle grading system to define results. The schema classifies muscle strength as 0 (no contraction), 1 (trace contraction), 2 (active motion with gravity eliminated), 3 (active motion against gravity), 4 (active motion against gravity and resistance), and 5 (normal power). However, this system requires volitional contraction, which is not feasible in an infant and difficult in a young child. Understanding this, Gilbert and Tassin modified the MRC grading system to a four-grade one of 0 (no contracture), 1 (contracture without movement), 2 (movement with gravity eliminated), and 3 (complete movement against the corresponding weight of the extremity). The modified Mallet classification ( Figure 40.4 ) provides a more global motor function of the upper trunk as opposed to isolated muscle testing.

Mallet modified classification system for grading shoulder function in a child.

(From Mallet J: [Paralysie obstetricale du plexus brachial: traitement des sequelle: primaute du traitement de l’epaule: method d’expression des resultants.] Rev Chir Orthop Reparatrice Appar Mot 1972;58(Suppl 1):166–8.)

A sixth category of “internal rotation” has been added to better balance the Mallet classification with regard to external and internal rotation. This global abduction system assesses external rotation of hand-to-mouth, hand-to-neck, hand-to-spine, and hand-to-belly activities on a scale of 1 to 5. A score of 1 is no function, 5 is normal function, and grades 2 to 4 denote progressive improved strength, as shown in Figure 40.4 . The majority of late 20th century papers on infantile brachial plexus have used these classification schemes to determine the results of spontaneous recovery and surgical intervention.

More recently, Clarke and coworkers advocated use of the Hospital for Sick Children Active Movement Scale (AMS) ( Table 40.2 ), a grading system that divides muscle strength into movement with gravity eliminated (grades 0-4) and movement against gravity (grades 5-7). This system requires that full active motion with gravity eliminated occur (grade 4) before scoring antigravity muscle strength (5-7). Thus, the presence of contractures that limit joint passive range of motion can limit the progression from grade 4 to grade 5 despite the muscle strength being adequate to move the limb against gravity. The Toronto Test Score is a similar grading of specific muscle functions at the elbow, wrist, and hand, is used only in infancy to predict the need for surgical nerve reconstruction, and is not designed to track progressive recovery over time ( Table 40.3 ). Thus, no scoring system is without limitations.

The Mallet, Toronto Test Score, and AMS are statistically reliable in terms of interobserver and intraobserver analyses. As might be expected, intraobserver reliability is better than interobserver, and less complicated systems (Mallet) have higher reliability than more complicated schemes (AMS). The Pediatric Outcomes Data Collection Instrument (PODCI), which assesses parent and patient-reported function, has also been shown to be a reliable tool for measuring baseline function in children with chronic brachial plexus injuries against normative per age data, as well as for assessing postoperative changes in these children. However, parent reports of their child’s function can be confounded by litigation against the delivery team, as this injury carries with it a strong emotional component that affects perceptions of function. This information is critical for comparing results and for assessing multicenter studies of therapeutic interventions for brachial plexus birth palsy.

Recently, the recognition that objective measurements and legacy measures may not correlate with enhanced function has resulted in a paradigm shift in outcome assessments. The initiative toward patient- or caregiver-reported outcomes has resulted in the development of reliable subjective measures. For children with brachial plexus palsy, Shriners Hospitals for Children has invested millions of dollars into patient-reported outcomes using the computer adaptive test (CAT) approach. This methodology has been shown to correlate with legacy measures, discriminate among brachial plexus impairment levels, possess minimal floor and ceiling effects, and be less burdensome compared to previous measurement systems.

Invasive radiographic studies, such as myelography, combined myelography and computed tomography (CT), and magnetic resonance imaging (MRI), have been used in an attempt to distinguish between preganglionic avulsion injuries and postganglionic extraforaminal ruptures. Kawai compared all three techniques with operative findings in infants. Myelography had an 84% true-positive rate with 4% false-positive and 12% false-negative rates. The addition of CT to myelography increased the true-positive rate to 94%. The presence of small diverticula was only 60% accurate in diagnosing an avulsion; however, the presence of large diverticula or frank meningoceles was universally diagnostic. MRI had a true-positive rate similar to that of CT myelography but also allowed extraforaminal assessment of the plexus. MRI allows evaluation for possible double-crush injuries. High spin echo MRI, MR myelography, and MR neurography improve the resolution of MR analysis. MRI has the potential advantage of sedation only inasmuch as myelography requires general anesthesia for an infant. These radiographic studies may improve the quality of preoperative planning, but the final decision regarding the presence or absence of an avulsion injury is determined at the time of surgery.

Electrodiagnostic studies with electromyography (EMG) and nerve conduction velocity (NCV) have also been used in an attempt to improve diagnostic accuracy of the severity of the nerve injury. The presence of normal sensory nerve conduction in the absence of motor nerve conduction is diagnostic of root avulsion. Absence of reinnervation at 3 months is suggestive of an avulsion. The H-reflex has been shown to help prognosticate outcome. Unfortunately, the presence of motor activity in a muscle has not been accurate in predicting an acceptable level of clinical motor recovery in that muscle. With EMG, the presence of partial reinnervation can confuse the clinical picture.

Studies have shown that nearly normal findings on EMG can be seen in infants with a severe lesion or even root avulsion. Frequently, there are substantial discrepancies between preoperative electrodiagnostic testing (EMG and nerve conduction), intraoperative somatosensory evoked potential testing, and surgical findings. A potential source of this discrepancy is the plasticity of the infantile nervous system. For example, Slooff documented innervation of the deltoid and biceps from C7 in the presence of avulsions of C5 and C6. At this stage, it is clear that neurophysiologic studies may underestimate the severity of injuries and provide a false optimism regarding recovery. It has been estimated that 20 to 25% of infants with a brachial plexus birth palsy will require microsurgical intervention and that the clinical information is the decisive factor in determining indications for surgery. At present, most centers and brachial plexus microsurgeons ultimately rely on the physical examination findings over time to assess recovery and decide on surgical intervention.

Natural History

The natural history of neonatal brachial plexus palsy was initially thought to be uniformly favorable; however, recent studies portend a more guarded prognosis. Assessing history is complicated by the lack of true natural history studies. In a systematic review of 76 studies discussing the natural history of BPBP, no paper met all four established criteria for an unbiased study, and only two studies met even two criteria; in these papers, residual neurological deficits existed in 20 to 30% of children. Subsequently, the rate of permanent neurological deficit has been found to be as high as 40%. A true natural history likely may never be elucidated as doing so would require withholding treatment that has become recognized as beneficial for optimal outcomes. Despite limitations in natural history studies, there is sufficient evidence to draw certain conclusions, as follows.

• •
  

  The majority of brachial birth palsies are transient. Infants who recover partial antigravity upper trunk muscle strength during the first 2 months usually have a full and complete recovery over the first 1 to 2 years of life.

  
  
• •
  

  Infants who do not recover antigravity biceps strength by 5 to 6 months of life should undergo microsurgical reconstruction because successful surgery would result in a better outcome than the natural history alone.

  
  
• •
  

  Infants with partial recovery of C5-7 antigravity strength during months 3 to 6 of life will have permanent, progressive limitations in motion and strength, as well as risk for the development of joint contractures in the affected limb.

  
  
• •
  

  Infants with global injuries and avulsion injuries of the lower trunk with have the worse prognosis and most limitations with lifelong dysfunction in the arm and hand.

The major clinical dilemma resulting from the uncertainty regarding spontaneous neurologic recovery is to determine whether infants without antigravity return of C5-7 function at 3, 4, 5, or 6 months of age warrant surgical exploration and nerve reconstruction. These infants have varying degrees of rupture (Sunderland types II to IV), and their ultimate neuromuscular recovery without intervention or with just tendon transfers has still not been compared with their recovery after microsurgery plus tendon transfers. Ideally, this question would be addressed in a prospective randomized clinical trial with sufficient enrollment ; however, such a study has been difficult to perform due to varying clinical practices and beliefs among surgeons at different centers.

Parents, primary care physicians, and therapists are under substantial emotional pressure to do what they believe is best for the affected infant. Unfortunately, despite strong opinions and at times solicitous pressure from specific medical centers, data are still insufficient to definitively answer the question. Comparative analysis has shown that elbow flexion alone is an insufficient criterion to warrant nonoperative care and that useful motor function has been observed in patients without elbow flexion at 3 months of age.

Disagreement among surgeons is common regarding surgical indications. This lack of clarity creates large regional variations in care and makes decision making difficult for parents. Accessing information from support groups and the Internet is common. This input affects parents’ decision making regarding care of their child. The quality of that information, however, can be variable. The long-term outcome with regard to function, activities of daily living, pain, career choice, and personal life is limited. The minimal data collected by support groups infer ongoing difficulties in performing activities of daily living. Pain, as evidenced by self-mutilating behavior, is rare in infants, occurring about 3 to 4% of the time. Chronic pain in adulthood is thought to be uncommon but the true incidence has yet to be documented.

Nerve Surgery

The role, timing, and technique for nerve reconstruction are controversial issues. The original surgical interventions on the brachial plexus at the turn of the 20th century consisted of resection of the neuroma and direct repair. Kennedy initially described three cases in 1903 with subsequent reports by Wyeth and Sharpe in 1917 and Taylor in 1920. In a report on 1100 infants with brachial plexopathy in 1925, Sever was uncertain of the benefit of surgical intervention. By the 1930s, brachial plexus nerve surgery had fallen out of favor. The advent of microsurgical techniques and extensive work in the 1970s and 1980s by Narakas, Millesi, and Gilbert in Europe, Kawabata and others in Asia, and Boome and Kaye in South Africa led to the resurgence in brachial plexus microsurgical reconstruction. At this time, medical centers throughout the world have plastic surgery, neurosurgery, and orthopedic surgery subspecialty brachial plexus centers actively performing brachial plexus nerve reconstruction.

The spectrum of nerve surgery includes neurolysis, neuroma resection and nerve grafting, and nerve transfers. Direct repair is rarely performed because of the extensive nature of the lesion and inability to achieve a tension-free nerve repair without grafting. Although neurolysis has been performed extensively, most centers have abandoned its independent use. Clearly, there is no role for neurolysis in the presence of an avulsion injury. Neurolysis has been shown to have results no different from the natural history following total plexopathy, and the evidence is similar (although less conclusive) for injuries involving upper trunk rupture.

Gilbert and Whitaker strongly believe there is no role for neurolysis alone. Laurent and colleagues advocated its use in conjunction with intraoperative electrodiagnostic studies. A neuroma-in-continuity was maintained if greater than 50% of a muscle action potential was found after neurolysis. Otherwise, the neuroma was resected and grafted. However, recovery of muscle strength following nerve grafting was greater than with neurolysis despite the fact that the preoperative status of the neurolysis patients was better compared to those patients who underwent nerve grafting.

Capek and associates described better long-term results after resection and grafting of both conducting and nonconducting neuromas than with neurolysis despite initial worsening of the situation with resection and grafting. Superiority of nerve grafting over neurolysis has also been shown by others. The topic of neurolysis has been recently revisited, although without clear evidence that neurolysis alone affects the natural history as many children would have improved spontaneously without surgery. Based on the present information, neurolysis alone is viewed as having little therapeutic benefit.

The standard nerve reconstruction strategy is resection of the neuroma and sural nerve grafting with extraforaminal ruptures. In an upper trunk (C5-6) rupture with an extraforaminal neuroma-in-continuity, resection of the neuroma and sural nerve grafting are performed from the C5 and C6 roots to the most proximal healthy nerve tissue of (1) the upper trunk anterior division, lateral cord, or musculocutaneous nerve; (2) the suprascapular nerve; or (3) the upper trunk posterior division, posterior cord, or axillary or radial nerves ( Figure 40.5, A ). If C7 is involved, additional grafting is necessary from C7 to the posterior cord ( Figure 40.5, B ). Nerve transfers are becoming more popular for reconstruction of C5-6 and C5-7 injuries, with transfer of (1) the intercostals or partial ulnar nerve to the biceps motor branch, (2) a branch of the spinal accessory nerve to the suprascapular nerve, and (3) the radial nerve long head of the triceps motor branch to the axillary motor branch. Results of nerve transfers for upper plexus lesions appear to be equivalent to nerve grafting at the shoulder and elbow.

A, B, Nerve grafting strategies for upper trunk rupture. ax , Axillary; m , median; mc , musculocutaneous; r , radial; u , ulnar.

In the case of ruptures and avulsions, nerve transfers in conjunction with nerve grafting are performed by using the thoracic intercostals (T2-4) ( Figure 40.6 ) or a branch of the spinal accessory nerve (cranial nerve XI) after it innervates the trapezius ( Figure 40.7 ). The spinal accessory can be harvested from an anterior or posterior approach ( Figure 40.8 ). With total plexus avulsions, nerve transfers are the only reconstructive option and may include the intercostals, spinal accessory, contralateral C7, and even the hypoglossal nerve. Carlstedt and coworkers have done experimental and limited clinical work on direct reimplantation or grafting into the spinal cord, but at present, the suboptimal results and the risk of causing cervical instability as a result of the laminotomy or injury to the nerves to uninvolved limbs does not warrant its use.

Nine-month-old with harvest of three intercostal nerves prior to transfer.

(Courtesy of Shriners Hospitals for Children, Philadelphia.)

Nerve grafting strategies for nerve transfers and grafts.

Schematic representation of a distal spinal accessory nerve transfer to the suprascapular nerve using the posterior approach. The proximal fibers innervating the superior and middle aspect of the trapezius muscle have been preserved, thus preventing a drooped shoulder.

Gilbert and Whitaker as well as Slooff advocated that priority be given to microsurgical reconstruction of the hand in infants with extensive avulsions and limited nerve options. Unlike adults, infants with brachial plexopathy have the potential to regain hand function after nerve grafting or nerve transfers, due to the shorter distance from the injury to the target muscles in the infant’s upper limb. In each microsurgical case, the plan must be individualized depending on the time from injury, extent of the palsy, and available reconstructive options.

Although there is ongoing debate about the timing of microsurgical intervention, the most common criterion is the absence of return of biceps muscle function associated with (1) total plexopathy and Horner syndrome at 2 to 3 months or (2) an upper trunk lesion at 5 to 6 months. Reconstruction is performed between 3 and 9 months of age at various centers. The degree of muscle recovery is open to debate and interobserver error makes comparative analysis difficult. Gilbert and others advocated for microsurgery when recovery of antigravity biceps function is not seen by 3 months of life. The reasons for early intervention include less risk for irreversible loss of motor endplates because of prolonged denervation and better parental acceptance of surgical intervention if performed while the limb is still flail or has minimal motion.

Prospective studies by Al-Qattan and Waters, however, have indicated that recovery of antigravity biceps function by 4 and 5 months of age, respectively, results in outcomes that are equivalent to those of microsurgery, especially when combined with secondary tendon transfers to improve shoulder motion. Similarly, others have demonstrated functional results equivalent to nerve grafting in 12 to 55% of children treated conservatively despite lacking biceps function at 3 months old. Finally, Clarke advocated microsurgery as late as 9 months for infants who fail the “cookie test” and thus have less than grade 6 biceps strength on the AMS. Microsurgical reconstruction at that relatively late time was overwhelmingly positive. Therefore, either the motor endplates of infants may be more resilient to irreversible demise than those of adults, or incomplete denervation of the affected muscles due to redundant innervation preserves motor endplate integrity.

Ultimately, the best time for microsurgical intervention in children with extraforaminal nerve rupture is still unknown. Comparative analysis indicates that biceps function alone is an insufficient criterion for operative management as some patients without biceps function by 3 months old recover useful limb function without microsurgery. There is little consensus regarding the timing and type of procedures performed. Economic analysis indicates that microsurgical intervention at 3 months for nerve rupture is unlikely to be successful enough to produce cost savings for the payor. Most centers and surgeons recommend that nerve surgery be indicated at 3 months for total plexus lesions and rarely indicated for an isolated rupture of the upper plexus.

The problem with reviewing the results of microsurgery is that few patients (1) have long-term follow-up or (2) undergo microsurgery alone. Gilbert and Tassin’s original study compared microsurgery with spontaneous recovery. For C5-6 lesions, 100% recovered grade III shoulder motion spontaneously. In the nerve surgery cohort, 37% regained grade III and 63% obtained grade IV. With C5-7 lesions, 30% recovered grade II and 70% grade III with observation. With nerve surgery, 35% were grade II, 42% were grade III, and 22% were grade IV. Later, Gilbert and Whitaker reported 81% shoulder function following C5-6 reconstruction in children with Mallet scores of III, IV, or V for abduction and 64% shoulder function in children who underwent total plexus reconstruction with Mallet scores of grade III or IV at greater than 2-year follow-up.

When combined with secondary shoulder reconstruction, at 5 years these results increased to 70% shoulder function following C5-6 reconstruction with Mallet abduction class IV or V. Similarly, with total plexopathy reconstructions in which the hand was prioritized, at 2-year follow-up there were only 25% with grade III or IV shoulder function; 70% with grade III, IV, or V elbow function; and 35% with grade III or IV hand function using Gilbert’s classification scheme. With the addition of secondary shoulder and hand procedures, this increased to 77% in the shoulder and 75% in the hand at 6-year follow-up. Gilbert maintains that nerve surgery not only improves function over natural history in selected patients but also increases the possibility for secondary tendon transfers. Long-term data from Sweden indicate that microsurgical patients still have deficiencies that may require assistance in activities of daily living. The more severe the original injury, the more likely there will be permanent deficiencies.

These results should be compared to the natural history data available. Smith and coauthors published a study of 170 patients to assess the natural history of brachial plexopathy with regard to timing of biceps recovery. Twenty-eight patients with absent biceps at 3 months of age were followed long term. Biceps contractions were observed in 20 patients (71%) by 6 months of age. Ultimately, 27 out of 28 had at least antigravity biceps muscle function. Patients who regained biceps between 3 and 6 months had better Mallet scores than patients who achieved biceps muscle function after 6 months of age. Twelve (55%) of the 22 patients who did not have brachial plexus surgery had class IV shoulder function. The authors concluded that the long-term function was favorable for the majority of C5-6 infants without nerve surgery.

Zancolli and Zancolli found that 82% of affected infants monitored from birth had recovery of biceps function and that recovery in 75% began between months 4 and 5. Waters addressed the same issue and found that of the 49 infants with no biceps recovery at 3 months, 42 recovered biceps function by 6 months. By assessing function at 2 years of age, infants with recovery of biceps function between 3 and 6 months had a progressive decrease in Mallet grades for abduction, external rotation, hand-to-mouth, and hand-to-neck activities stratified by month of biceps recovery. In infants with biceps recovery between 3 and 6 months of age, recovery of function by Mallet grade was as follows: global abduction II (3%), III (52%), and IV (45%); global external rotation II (54%), III (31%), and IV (15%); hand-to-neck II (39%), III (33%), and IV (28%); and hand-to-mouth II (33%), III (24%), and IV (43%). These results are similar to Gilbert’s published microsurgical results.

In addition, in both natural history and nerve surgery patients, secondary shoulder transfer and osteotomies improve function. For patients with recovery of biceps function between 3 and 6 months of life and later shoulder reconstruction, there will be an expected improvement to an average grade IV for all Mallet movements that involve external rotation and abduction. However, in both natural history and nerve surgery patients with incomplete recovery, there may be some deterioration in function with time. A driving question is how different are patients who undergo nerve surgery at 3 months from those who recover biceps function between 3 and 6 months and undergo secondary reconstruction? This answer is critical to resolve the question as to whether unnecessary surgery is being performed or whether some centers are failing to perform nerve surgery at a young age. This controversy is presently unresolved because of lack of comparable data.

The increasing use of nerve transfers further complicates the indications for nerve grafting. Nerve transfers utilize direct neurorrhaphy at a site closer to the target muscle. The more distal location of the neurorrhaphy allows a shorter regeneration time, faster recovery, and a longer window of time to await spontaneous recovery before fearing irreversible motor endplate demise. Therefore, surgeons may prolong the decision to intervene when viable nerve transfer options are available. Ladak et al reported results of 10 patients treated with three nerve transfers (i.e., spinal accessory to suprascapular, radial to axillary, and ulnar or median fascicle to musculocutaneous) at 10 to 18 months of age. Recovery of function progressed between 6 and 24 months postoperatively, with ultimate function equivalent to published results of nerve grafting despite being performed at a later age.

Tse demonstrated equivalent restoration of shoulder external rotation between patients treated with nerve grafting from C5 to the suprascapular nerve and those treated with a spinal accessory nerve to suprascapular nerve transfer; note that the latter patients had more severe brachial plexus injuries overall. Similar encouraging results of spinal accessory-to-suprascapular nerve transfer have been found by others, even in patients treated as late at 30 months of age. Elbow flexion can also be restored by nerve transfer in properly selected patients. Little and colleagues, in a multicenter study, outlined the expected results and indications for ulnar and/or median fascicle transfer to restore elbow flexion and supination in neonatal brachial plexus palsies. Elbow flexion could be reliably restored in children as old as 18 months of age, with supination recovery more dependent on age and with better supination following double-fascicle transfer (median and ulnar to both biceps and brachialis) over single-fascicle transfer to the biceps alone.

Ultimately, the decision between nerve grafting and nerve transfers should be individualized for each patient. Clearly, C5-6 avulsion injuries that cannot be treated with grafting are ideal candidates for nerve transfers. Similarly, dissociative recovery can occur, where only some of the muscles innervated by the upper trunk have recovered sufficient function, and the surgeon’s goal is to restore innervation of the remaining paralyzed muscles without resecting the upper trunk and losing function of the muscles that have already recovered. In such cases, a la carte nerve transfers can be targeted to specific distal motor nerves. Nonetheless, precise indicators for nerve transfers remain unclear at the present time.

Surgical Technique: Nerve Grafting

The extent of surgical exposure depends on the level and severity of the injury. All microsurgical procedures in infants are performed under general anesthesia without the use of neuromuscular blocking agents. Both lower extremities are prepared for sural nerve graft harvest in cases of global palsies, although one sural nerve is generally sufficient for grafting isolated C5-6 injuries, so the other leg may be left undraped for venous access. Alternatives to nerve autograft, such as allograft and nerve conduits, have not yet been proven safe or effective in pediatric brachial plexus surgery. The shoulder girdle, chest, and neck are prepared for exposure of the brachial plexus and all possible planned nerve grafting and nerve transfer procedures (i.e., intercostals, spinal accessory, partial ulnar nerve, contralateral plexus).

The infant is placed supine, head tilted to the unaffected side, in a slight reverse Trendelenburg position to improve venous outflow from the head. For upper trunk ruptures, exposure can be performed through a transverse incision in the supraclavicular region. Dissection is carried out through the platysma and supraclavicular fascia to the plexus. The omohyoid muscle can be transected or retracted inferiorly. At times, the transverse cervical artery is transected ( Figure 40.9 ). The phrenic nerve is identified, usually in a scarred position on the anterior scalene muscle or the anterior surface of the upper trunk neuroma ( Figure 40.10 ), following the phrenic leads to the C5 root ( Figure 40.11 ). The C5, C6, and C7 roots are sequentially exposed between the anterior and middle scalene muscles and labeled with Silastic loops. A decision is made regarding the integrity of each nerve root.

Key anatomic landmarks include the omohyoid muscle and the pectoralis minor muscle, which are divided between ligatures for later reapproximation. The C8 root is located just above and posterior to the subclavian artery, whereas the T1 root is almost directly posterior to the artery. With dissection of the deltopectoral groove, the lateral cord is the most superficial structure. In this example, the superior trunk and the C7 root are ruptured and the C8 root is avulsed (note the rootlets attached to the swollen dorsal root ganglion).

(Copyright © Elizabeth Martin.)

Phrenic nerve is isolated and protected. The nerve runs along anterior aspect of the anterior scalene. Patient is supine and head is to the right.

(Courtesy of Shriners Hospitals for Children, Philadelphia.)

Additional landmarks helpful in identifying the various roots include the phrenic nerve contributions from the C5 root and the transverse cervical (scapular) artery, which frequently crosses over the C7 root.

(Copyright © Elizabeth Martin.)

Electrophysiologic studies, inspection of the transected nerve under the microscope, and rapid histologic staining may all be factors in decision making. Generally, the upper roots are intact at the level of the foramina, and there is an extraforaminal neuroma at the junction where the C5 and C6 roots form the upper trunk (Erb’s point). Distal dissection beneath the clavicle leads to identification of the divisions, cords, and major nerves. The axillary artery should also be identified and protected. In infants, the clavicle can often be left intact and mobilized with a Penrose drain or retractor for adequate exposure. If necessary, the clavicle can be transected obliquely and repaired with a suture through drill holes along with periosteal repair at the end of the operation.

Sequentially the major nerves are identified. The suprascapular nerve is exposed and labeled with a Silastic loop, usually as it exits the upper trunk neuroma and passes posterior toward the suprascapular notch. The musculocutaneous nerve is identified, labeled, and exposed from distal to proximal for the lateral cord to the anterior division of the upper trunk until the neuroma is encountered. Similarly, the radial and axillary nerves are exposed and dissected to the posterior cord and posterior divisions of the upper, middle, and lower trunks. The posterior division of the lower trunk is generally intact, but the posterior division of the upper trunk and at times the middle trunk are usually encased in the neuroma. Intraoperative evoked potentials and nerve conduction are performed to determine the integrity of the nerve roots proximally and the peripheral nerves distally.

Some centers still advocate neurolysis if at least 50% of a normal action potential is generated across the neuroma by electrical stimulation. However, Gilbert, Meyer, Laurent, Clarke, and their colleagues have all reported suboptimal results with neurolysis. Therefore, transection of the fibrous neuroma proximally and distally and reconstruction of the defect with sural nerve grafts in an end-to-end fashion is frequently performed ( Figure 40.12 ). The graft can be secured to the proximal and distal nerve ends using epineural sutures, fibrin glue, or both. The use of fibrin glue alone can dramatically decrease operative time and has become standard practice for many authors. Fibrin glue is particularly useful for the proximal neurorrhaphy given the difficulty of suturing within or adjacent to the neural foramen. With either neurorrhaphy technique, however, it is important to cut the graft cables sufficiently long to avoid tension on the neurorrhaphy.

Six-month-old child with left brachial birth palsy. Supraclavicular exposure revealed ruptures at C5 and C6. Sural nerve grafts to upper trunk anterior division, upper trunk posterior division, and suprascapular nerve secured with fibrin glue. Child is supine and head is to the right.

(Courtesy of Shriners Hospitals for Children, Philadelphia.)

When avulsions are encountered, especially in the lower roots, more extensive exposure is necessary. This may include modifying the skin incision to a “Z” or using a second infraclavicular transverse incision to expose the infraclavicular area. Each nerve root is assessed closely to determine the viability of the root, which can be difficult because of partial avulsions. Electrophysiologic studies and histologic staining can augment direct microscopic observation. The C5 and C6 roots are usually intact with an extraforaminal rupture. The exception is an upper trunk lesion resulting from a breech delivery, in which case C5 and C6 are often avulsed. With severe lesions, C8 and T1 are usually avulsed and C7 is variable in integrity. Each case presents a unique intraoperative decision-making challenge. However, there are principles and general case scenarios with avulsions that can lead to the most optimal results.

• •
  

  The C5, C6, and C7 nerve roots have extraforaminal ruptures, and C8 and T1 are avulsed. With three nerve roots available for grafting, it is possible to reconstruct the entire injured plexus. In this situation, the C5 and C6 nerve roots are transected to viable nerve and coapted by sural nerve grafting to the most viable proximal aspects of the suprascapular nerve and the medial, lateral, and posterior cords (see Figures 40.5, B , and 40.12 ).

  
  
• •
  

  The C5 and C6 nerve roots have extraforaminal ruptures and C7, C8, and T1 have avulsions ( Figure 40.13, A ). This scenario means there is less viable proximal nerve. The hand receives priority with grafting from C5 or C6 to the medial (ulnar and median nerves) and lateral cords (musculocutaneous and median nerves) ( Figure 40.13, B ). Suprascapular nerve reconstruction is achieved either by nerve grafting or more commonly by transfer of the spinal accessory nerve. Reconstruction of the posterior cord may need to be abandoned or performed by transferring intercostal nerves to the musculocutaneous nerve and nerve grafting to the posterior cord.

  
  

  
  

  
  

  

  
  

  
  

  A, B, Combination grafting for a C5-7 rupture and C8-T1 avulsion.

  
  
  
  
• •
  

  C5 is the only viable nerve root. This is the most difficult situation and requires prioritizing an anatomic site. In infants, it is advised that the hand be given priority with grafts from C5. A combination of spinal accessory and intercostal nerve transfers to the suprascapular, musculocutaneous, and median nerves along with C5 grafts to the lower trunk is performed ( Figure 40.14 ). The lower plexus is mobilized as much as possible to limit the length of the nerve grafts. Use of the contralateral C7 nerve may be necessary to maximally reconstruct the plexus, but published results are variable. Reports of contralateral C7 transfer with short or no grafts through a retropharyngeal approach may prove promising in such cases, although few centers are currently performing this technique.

  
  

  
  

  
  

  

  
  

  
  

  T2, T3, and T4 nerve transfers to the musculocutaneous motor branch for biceps reconstruction.

  
  

Surgical Technique: Nerve Transfers

Nerve transfers can be performed as part of the reconstruction of an explored brachial plexus as described earlier or can be performed without formal exploration of the brachial plexus. The advantages of nerve transfers include a shorter axonal regeneration distance, no need for nerve grafts, and an operative field distant from the zone of injury and therefore no scarring. The techniques have been adequately described for transfers of the (1) spinal accessory to suprascapular nerve, (2) radial triceps branch to axillary nerve, and (3) median and/or ulnar fascicle to the musculocutaneous branches to the biceps and/or brachialis.

The spinal accessory to suprascapular nerve transfer can be performed through an anterior supraclavicular approach, although a posterior approach affords a more distal neurorrhaphy and the opportunity to free the suprascapular nerve from the suprascapular notch (see Figure 40.8 ). The radial-to-axillary transfer is performed through an incision in the posterior arm, and the elbow flexion transfers are performed through a medial brachial approach. Therefore, performance of these three nerve transfers simultaneously requires exposure of the posterior shoulder and posterior and medial brachium. Such exposures can be accomplished with the patient in the lateral decubitus position. The dependent axilla is sufficiently protected with a lateral chest wall pad, and all bony prominences are well padded, paying careful attention to the lower extremities. The entire affected arm, chest wall, and scapular region is draped. Muscle relaxant is avoided to allow nerve stimulation.

For the spinal accessory to suprascapular nerve transfer, a transverse incision is made immediately superior to the spine of the scapula ( Figure 40.15 ). The upper trapezius is elevated from the spine of the scapula and reflected superiorly to identify the supraspinatus muscle. The supraspinatus muscle is retracted inferiorly to expose the superior margin of the scapular body. The suprascapular notch is identified and its ligament is sectioned to expose the suprascapular nerve. The spinal accessory nerve is then identified on the anterior surface of the trapezius that is just medial to the scapular spine. The nerve is traced as distally as possible and then cut and rerouted superiorly and laterally, preserving as many proximal muscular branches as possible until it reaches the suprascapular nerve without tension. The suprascapular nerve is cut proximal to the notch and coapted to the spinal accessory nerve.

Only gold members can continue reading. Log In or Register to continue

Share this:

• Click to share on Twitter (Opens in new window)
• Click to share on Facebook (Opens in new window)

Related

Related posts:

Flexor Tendon Injury Chronic Elbow Instability: Ligament Reconstruction Tendinopathy Arthrogryposis Spasticity: Cerebral Palsy and Traumatic Brain Injury Rheumatoid Arthritis and Other Connective Tissue Diseases

Stay updated, free articles. Join our Telegram channel

Join