CHAPTER 241 Early Management of Brachial Plexus Injuries
Surgical treatment of BP injury includes end-to-end neurotization, interpositional nerve grafting, intraplexus/extraplexus nerve transfer, and in rare instances, neurolysis alone. Secondary surgery is often performed at a later date and may include free muscle transfer, tendon transfers, and muscle/tendon releases. Management of BP injuries is complex, and there is still ongoing debate about the optimal timing of surgery, determination of whether surgery is indicated, and the type of repair to perform.1,2
Historical
The first surgical repair of the BP was attempted in the last decade of the 19th century after successful attempts at nerve suturing,3,4 experimental work on nerve grafts,5 and the introduction of this method to clinical surgery.6 The repair techniques commonly applied were neurolysis, direct repair with epineural sutures, and coaptations wrapped in a membrane. Over the years, surgeons have used different kinds of suture material for nerve repair, including animal and human hair, animal tendon, fascia, linen, silk, cotton, and polyester. Various aqueous or gel media have been used for adherence of nerve ends difficult to suture. BP lesions became a separate clinical entity among peripheral nerve lesions in the first half of the 19th century. At autopsy, Flaubert described rupture of the C5 spinal nerve with avulsion of C6 through T1 caused by reduction of a dislocated shoulder.7 Subsequently, BP management of 8 cases in wounded soldiers during the American Civil War8 and 24 European cases9 was reported.
Secondary suture of a traction injury to the BP 7 months after trauma was initially carried out in the beginning of the 20th century.10 The first nerve transfer consisted of implanting the distal stump of the damaged spinal nerve C5 into the healthy C6.11 Unfortunately, the results of these first surgical attempts at repair are not known. At that time, however, the results of surgery were inconsistent and often poor. BP surgery was performed only by a small group of surgeons,12–15 and several deaths related to surgery occurred.14,16 Before and during World War I, nerves were regarded as simple cord-like structures. Severed nerves were repaired by simply restoring continuity in the expectation that nerve regeneration would then restore function. Procedures to close large gaps under considerable tension were still preferred over nerve grafting. Throughout this period, infection remained a problem, and the results of nerve repair continued to be disappointing.
During the first half of the 20th century, reconstructive surgical procedures were developed to treat the sequelae of poliomyelitis and could also be applied to BP lesions. These musculotendinous transfers had the approval of surgeons because they produced more predictable results and were more readily available than the demanding, time-consuming nerve repair surgery. BP lesions remained uncommon before World War II because the violent trauma needed to cause avulsion or rupture often resulted in life-threatening lesions as well. During the 1930s, BP lesions became more common, and the role of motorcycle accidents as an important cause of BP lesions was recognized by Bonola.17
The Second World War produced a large number of patients with BP lesions who were thoroughly studied and operated on by the team of Sir Seddon (Barnes, Bonney, Brooks, and Yeoman). They reported on the use of autologous nerve grafts in five patients with success in two.18,19 The accumulation of World War II victims stressed the necessity of intensifying the search for better treatment modalities and led to a breakthrough in nerve repair. For the first time these patients were referred to special centers to receive specialist attention and to be available for thorough investigation and study. Antibiotics made effective control of wound infection possible. Studies at a basic level revealed the complexities of the internal structure of nerves. Then came the realization that restoration of continuity is just the first step in restoration of function. Disorderly regeneration and loss of regenerating axons at the suture line were recognized as important factors that complicated and adversely affected recovery. The central objective of nerve repair finally emerged, namely, to reduce the loss of axons that occurs during regeneration and to assist regenerating axons to reestablish useful functional connection with the periphery such that the new pattern of innervation approximated the original as closely as possible. Procedures and techniques were developed to create optimal conditions for regeneration and improve the repair. Among these was the suggestion that microsurgical techniques might be used to improve the repair of severed nerves.20 The significance of the data emerging from basic studies filtered through to the clinical level in the 1960s.
By the late 1950s and into the 1960s, intercostal nerve (ICN)–to–musculocutaneous nerve (MCN) transfers were performed.21 Several other surgical teams also contributed to the understanding and treatment of BP lesions.22–26 Unfortunately, during the 1960s, repair of traction injuries remained disappointing, and direct surgery was discontinued in favor of nonoperative treatment.27–32 Above- or below-elbow amputation was advised in many cases.33
Surgeons involved in reconstructive work on the upper extremity often explored the BP mainly to determine the diagnosis and obtain a prognosis. The discouragement widely felt culminated at a meeting of the International Society for Orthopaedic Surgery and Traumatology in Paris in 1966, where the following consensus was reached: (1) surgical exploration of BP injuries, particularly at the supraclavicular level, was of no real benefit to diagnosis and prognosis, and (2) repair was mostly impossible and, when performed, did not achieve substantial results.34 The introduction of microscopic magnification in the same period offered new opportunities in the surgical management of BP injuries.35 In the mid-1960s, a major step forward was made independently by Millesi and Narakas, who used microsurgical technique for nerve grafts coapted to ruptured trunks and cords. Both men were in disagreement with Fletcher, who favored amputation of the limb in severe cases and fitting of a prosthesis.36 Their first reports stirred much interest but were also met with skepticism.37–40 Gratifying results were achieved in a sufficient number of patients to encourage other surgeons to pursue early surgical reconstruction after injury. The efforts of Millesi and Narakas were soon complemented by those of other surgeons such as Allieu, Alnot, and Sedel in France, Brunelli in Italy, Kline in the United States, and Hudson in Canada.
Knowledge of nerve regeneration broadened as diagnostic tests became available, including electromyography (EMG)41 and cervical myelography.42 Refinements included the use of evoked nerve action potentials (NAPs)43 and the association of computed tomography (CT) and myelography.44 Seddon’s18 and Sunderland’s20 classifications of nerve injury could be applied with more clarity, and the distinction between patients who should or should not undergo surgery became less vague. In the 1970s, survival after motorcycle trauma increased because of the use of helmets and improvement in lifesaving procedures. From 1975 onward, regular exchange of knowledge was established between European teams motivated by the steady increase in the number of patients with BP lesions. In similar fashion, groups of peripheral nerve experts became established in various parts of the world and published articles on a variety of topics related to peripheral nerves. Surgical repair of the peripheral nervous system has become commonplace in most major medical centers. A comment made in 1951 by Sir Sydney Sunderland, “it is no longer a question of what can be done, but of establishing what should be done,”20 would appear to have been addressed.
History of Brachial Plexus Birth Injury Management
One of the he first description of a birth-related brachial plexus injury (BRBPI) was provided by the obstetrician Smellie in 1768.16,45–47 He reported on a spontaneously resolving paralysis of both arms lasting several days. In 1851, the first pathologic description of an 8-day-old infant was presented. At autopsy, extensive hemorrhagic infiltration was found in the entire BP that strongly suggested that a laceration had taken place.16 Duchenne described infants in 1872 and Erb described adults in 1874 with the distinct clinical entity of a flaccid palsy in which abduction and external rotation of the arm were paralyzed, together with absent elbow flexion and supination of the forearm.47,48 The condition is frequently referred to as Erb-Duchenne paralysis or Erb’s palsy. Other authors have probably described the occurrence of BRBPI at an earlier date than Duchenne and Erb did.16,47
The first nerve surgery for BRBPI was reported by Kennedy from the University of Glasgow in February 1903. Kennedy described 2 patients who were selected for surgery because of the absence of spontaneous recovery and muscle responses at the age of 2 months. One baby was treated surgically at 2 months and the other at 6 months of age.48 The surgical procedures were well documented with scarring of the superior trunk described. The upper trunk was resected, and three distal targets (suprascapular nerve [SSN], anterior division and posterior division) were sutured with a central suture of “fine chromotized catgut” to the fifth and sixth nerves. Because resection of the upper trunk resulted in a gap, the shoulder of the infant was pushed upward and the head tilted to the side operated on to perform a tension-free nerve suture. Kennedy claimed that 4 to 8 months after surgery, the infants had fairly good use of their arm.48 One year later, Kennedy had extended his surgical series to 5 infants with BRBPI.49 Only 2 months after Kennedy, on the other side of the Atlantic Ocean, the American surgeon Taylor performed his first surgical procedure in New York.16 The surgical technique that he and his colleagues described is approximately the same as Kennedy’s, although the actual nerve suture was done by “lateral sutures of fine silk involving the nerve sheaths only.” Taylor operated mainly on older children (4.5 to 11 years), but he did operate on some infants: the 3 youngest were 8, 16, and 25 months. Of these 3 infants, 2 died within days after the operation. In a 1921 paper, Taylor described his surgical experience in treating 76 patients with BRBPI. In his last 25 patients (surgically treated from 1914 to 1921), only 1 “died of hemorrhage on table,” and in 1 patient the surgery was stopped because of hemorrhage.50 Surgery for an obstetric BP injury was apparently performed quite commonly in those years. William Sharp (who was trained by Cushing) reported his neurosurgical procedures in 146 patients with BRBPI operated on between 1913 and 1923 in the New York Polyclinic Hospital.51 The length of surgery was short because of lack of proper anesthesia, adequate illumination, and magnification. The surgical results were, however, were quite good.
Today’s standard technique of autologous nerve grafting to bridge the defect was not commonly used in the early days of BRBPI surgery.52 Nerve transplantation had been performed in 1892: a dog’s sciatic nerve was sutured in place of a defect of the external popliteal nerve. The results of nerve transplantation were poor, and therefore nerve grafting was not widely applied in clinical practice. Other surgical techniques that were reported consisted of nerve transfer (which was then alternatively called nerve crossing), fascicular transfer, and end-to-side repair.52
In 1916, the orthopedic surgeon Sever downplayed the use of nerve surgery in a paper on 471 nonoperatively treated patients.53 He followed with a second publication along the same lines.47 He concluded that “In regard to the operation on the plexus in the usual upper arm type of case, it might be said that in the experience of this clinic it has not been found necessary…. It cannot be too strongly emphasized that no operation on the plexus will be of any great use in restoring functional activity to the arm, unless contracted and restricting muscles are divided, and careful after-treatment persisted in for a long period.”47 The neurosurgeon Sharpe added that “there is not one case of complete recovery of function” in his series of 146 patients.51 This belief was shared by Jepson a few years later: “There has been no case yet…which has shown an anatomic and physiologic cure from the plexus operation. Even marked improvement is usually lacking…. Many times the nerve is so badly damaged that it is beyond repair.”54 Both Sever and Jepson advised that orthopedic operations be performed for BRBPI.54 For improvement in shoulder function, Sever recommended release of the restricted shoulder mobility, followed by muscle and tendon transfers. Jepson performed a rotation osteotomy of the humerus. Modifications of these surgeries are still performed today.55
The high mortality rates and the limited results in the young infants may have contributed to the relative abandonment of BRBPI surgery.16 In the 1920s, even Taylor, who had considerable operative experience, preferred to wait as long as any improvement was taking place.56 Fifty years later, after development of the surgical microscope, improvements in surgical tools, creation of fine suture materials, and the use of autologous nerve grafts together with improved safety of anesthesia, nerve surgery for infants was reintroduced in 1978 by Alain Gilbert and associates.57 The field has progressed to the point that even with total or pan-BRBPI lesions, a useful hand can be obtained.58
Anatomy
Although numerous variations in formation of the BP have been reported, the following common form can be taken as a point of departure. The BP is composed of five spinal nerves that join to form three trunks, each of which divides into an anterior and posterior division that lead to the three cords from which all the major nerves to the arm subsequently arise. The five spinal nerves are C5, C6, C7, C8, and T1. Commonly, there is a contribution to the BP from C4. The C5 and C6 spinal nerves merge (Erb’s point) to form the upper trunk. The C8 and T1 nerves merge to form the lower trunk, and the C7 nerve continues into the middle trunk. Each trunk terminates in an anterior and posterior division. The posterior divisions come together into the posterior cord. The anterior divisions of the upper and middle trunks form the lateral cord, and the anterior division of the lower trunk forms the medial cord. Each cord has two main terminal branches: the lateral cord provides the MCN and the lateral component of the median nerve, the medial cord leads to the ulnar nerve and the medial component of the median nerve, and the posterior cord provides the axillary nerve and the radial nerve. Over its entire trajectory, smaller nerves to the shoulder and upper limb muscles leave the plexus. Variations in anatomy may hamper clinical efforts to localize the site of a lesion.59
Pathophysiology and Classification
Despite the numerous ways to injure a nerve, the pathologic reactions are similar. After axonal injury, responses are at first degenerative and later regenerative. An increase in traction force applied to a peripheral nerve results in stepwise rupture of the peripheral nerve elements moving from inside to outside. Anatomic rupture begins with the axon or its coverings and then proceeds to the basal membrane, endoneurium, perineurium, and finally the epineurium. Based on these sequential events, the severity of the nerve lesion is graded in relation to the degree of neural damage. The most frequently applied classification scheme is Seddon’s classification of neurapraxia, axonotmesis, and neurotmesis.18 Sunderland introduced a classification based on five grades of progressive pathologic events.20
Clinical
The clinical history, physical examination, and adjuvant testing provide insight on localizing the injury and determining the extent of injury. The physical examination requires a detailed motor and sensory examination of the affected limb. The grading system of the Medical Research Council of Great Britain (MRC) dates back to the early treatment of poliomyelitis and war injuries and is at present the most commonly used strength-grading system.60,61 Evaluation of both passive and active range of motion of the joints may reveal contractures requiring management.
The term magnetic resonance neurography (MRN) applies to novel MRI techniques that have greatly improved the ability to visualize peripheral nerves.62 Thus far, this technique has been more valuable in evaluating compression syndromes and tumors than traumatic injury. Notwithstanding, with improvement in the resolution of MRN will come added ability to localize nerve injury and characterize the underlying pathophysiology.
Preoperative diagnosis of a preganglionic or root avulsion injury indicates the need for early surgery and use of nerve transfers. One standard for the diagnosis of root avulsion is laminectomy with direct visualization of the roots. This can be modified to a minimally invasive procedure using an endoscope63; however, it has not become a commonly used technique. Clinical findings consistent with root avulsion include lack of power in the proximal muscles, presence of SNAPs with EMG denervation, Horner’s syndrome, and lack of nerve roots on imaging. When compared with intradural inspection of roots, CT myelography with 1- to 3-mm axial slices enables accurate diagnosis of the integrity of the roots in 75% to 85% of patients.64 MRI with 3-mm axial slices provided an accurate diagnosis in just 52% of patients when compared with intradural inspection.64 The presence of a pseudomeningocele, although highly suggestive of root avulsion, is not conclusive evidence. In the acute situation, an intradural blood clot can prevent filling of a pseudomeningocele. The resolution of MRI has improved enough in some institutions to trace the presence or absence of intradural nerve roots and thus negate the need for CT myelography. MRI acquisitions timed to the respiratory and cardiac cycle can improve the resolution of fine structures in cerebrospinal fluid by reducing apparent motion, although scan time may be greatly increased.
Based on his experience in treating 1068 patients with BP injuries during an 18-year span, Narakas developed his rule of “seven seventies.” He reported that approximately 70% of traumatic BP injuries occur secondary to motor vehicle accidents; of these, approximately 70% involve motorcycles or bicycles. Of the cycle riders, approximately 70% had multiple injuries. Overall, 70% had supraclavicular lesions; of these, 70% had at least one root avulsed. At least 70% of patients with a root avulsion have avulsions of the lower roots (C7, C8, or T1). Finally, of patients with lower root avulsion, nearly 70% will experience persistent pain.65
Therapy/Management
Avulsion of nerve roots may lead to the development of severe pain in the distribution of the injured nerve root. The pain is often described as a burning or crushing pain with paroxysmal burning or shooting pain. Nonoperative treatment may require polypharmacy under the guidance of a pain center. Fortunately, the natural history of avulsion pain is that about half the patients become pain free or able to cope with their pain within 1 year and the majority are pain free within 3 years. Unfortunately, in some patients avulsion-related pain can become exceedingly severe. Avulsion pain can be surgically managed by making a series of lesions at the dorsal root entry zone of the traumatized spinal cord.66
When there is evidence of a Sunderland V (rupture) injury as a result of a stretch mechanism at the site of transection, the nerve ends often need to be resected back to a more healthy region. Demarcation of the injury can be difficult to appreciate acutely, and 2 to 3 weeks is generally required for the injury to declare itself. This delay allows more effective trimming of the stumps to healthy tissue and results in better outcomes.67,68 An alternative is to explore the wound, tag the nerve ends, and then re-explore in a few weeks. For gunshot wounds, a low-velocity projectile is often associated with Sunderland grade I injuries, whereas high-velocity projectiles cause more soft tissue disruption and higher grade Sunderland injury. Most gunshot wounds leave the plexus element in continuity. If there is no improvement on EMG in the first few months, exploration, NAP recordings, and if indicated, repair are necessary.
One factor that may limit recovery is the death of neurons after axotomy. Retrograde transport of neurotrophic factors potentially derived from target organs can support the survival and regeneration of both sensory and motor neurons.69 Some neuroprotection is afforded by the presence of a nerve graft, but the amount of cell loss already present at the time of repair remains.70 It is also apparent that over time, loss of Schwann cells in the distal nerve likewise has a negative impact on regeneration. These findings suggest that earlier repair of nerve injury is likely to be associated with improved outcome.
An argument against early surgery is that it does not allow the possibility of spontaneous recovery, which may bestow a better outcome than achieved with surgery. By waiting 3 months, there is the possibility of performing intraoperative electrophysiologic studies on a lesion to help determine whether regeneration is occurring. In contrast, early surgery is easier to perform because there is less scarring. Early surgery can allow visual inspection of the acute lesion and perhaps some prediction of outcome with or without nerve repair. Although there is some clinical evidence that early surgery may be beneficial to outcome, the debate rages on.71
Surgical management is divided into the initial, or primary, surgery and delayed, or secondary, surgery. Primary surgery is aimed at repairing the nerves and is time dependent. Examples include end-to-end nerve repair, end-to-side nerve repair, nerve grafting, nerve transfer, and neurolysis. Secondary surgery is performed when primary nerve repair is not likely to result in functional improvement or when recovery after nerve repair reaches a plateau still lacking in function. Secondary surgery is focused on maximizing function by performing muscle and tendon transfers and bone or joint work.72