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The role of nerve transfers for C5-C6 brachial plexus injury in adults.

Introduction

The upper brachial plexus roots (C5-C6) innervate proximal arm muscles controlling shoulder abduction, elbow flexion and contribute to the innervation of distal muscles controlling limb function. Upper root avulsions are devastating injuries because the patient loses the critical functions of shoulder abduction and elbow flexion. Even if distal innervation is unaffected (C7-T1), without shoulder and elbow stability the wrist and hand cannot perform daily activities. Repairing these avulsed roots presents a challenging scenario to any surgeon due to the complexities of nerve regeneration, nerve transfer, and the surgical techniques themselves. The first brachial plexus nerve transfer occurred in 1948. With the advent of improved microsurgical technique, instrumentation, coupled with further understanding of nerve anatomy, significant strides have been made to improve nerve transfer outcome.

History of Brachial Plexus Injuries and Reconstruction

Brachial plexus injuries have been a reported directly or indirectly for the last 2800 years. The first mention of a brachial plexus injury in literature occurs in Homer's The Iliad around 800BC. (1)

Although sporadic mention of plexus injuries is scattered in the early literature little anatomical dissection or description took place during the next thousand years.

In 1507 Leonardo DaVinci performed a detailed dissection of a 100 year old man who had died of natural causes. This initial experience led him to sketch the now famous illustrations entitled "del Vecchio" and perform over 30 detailed human dissections.

DaVinci's impact on modern anatomy differed from prior investigators in three ways. First, DaVinci approached the human cadaver in a methodical fashion, noting every anatomical nuance. Secondly, his mechanical prowess led him to postulate on the function of that which he was dissecting. Finally and most importantly he used his artistic talent to create a detailed and vibrant anatomical reference for future work.

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In 1824 French physiologist Marie Jean Pierre Flourens was the first to theorize that an injured nerve could be bypassed, "joining the superior end of one nerve with the inferior end of the other and visa versa." (3-4)

But it wasn't until 1948 when Alexander Lurje, a Russian surgeon, performed the first brachial plexus reconstruction using nerve transfers on a 20 year old female injured by a Nazi bomb blast. (5) Remarkably he was able to perform the procedure prior to the advent of microsurgical equipment, instruments, or technique.

Over the last 20 years our improved understanding of nerve pathophysiology, anatomy, and repair has led to advances in the treatment options for upper brachial plexus trauma.

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Anatomy

Understanding the anatomy of the brachial plexus is important in order to perform a nerve transfer. It originates from the C5-T1 spinal nerve roots (ventral rami). It is further divided into three trunks, six divisions (three anterior and three posterior), three cords, and finally into five terminal nerve branches. Medical students keep these components straight using the acronym "Robert Taylor Drinks Cold Beer." The five terminal nerve branches are the musculocutaneous, axillary, radial, median, and ulnar nerves. Other nerves originate from various locations on the plexus.

The pertinent anatomy for this paper includes the roots, the superior trunk, the suprascapular nerve, and the terminal branch nerves. Please see figures 3 and 4 for an anatomical diagram and table summarizing nerves and function.

Brachial plexus injuries usually involve either pre-ganglionic avulsion or post-ganglionic rupture. Avulsion occurs when the nerve root is torn from the spinal cord. Rupture occurs when the nerve is damaged or transected distal to the dorsal root ganglion but its attachment to the spinal cord is intact. There are classifications of nerve injury from Sunderland and Seddon beyond the scope of the review. (6,7)

[FIGURE 3 OMITTED]

Physical Exam

Supraclavicular rupture or avulsion accounts for about 70% of brachial plexus injuries and among these the upper roots are involved 70% of the time. Most of these injuries occur in motorcycle or other high speed personal transportation accidents in which the head is forcefully distracted from the ipsilateral shoulder. (8) This manner of forceful separation typically results in pre-ganglionic root avulsion or post-ganglionic rupture of the upper roots (C5-C6) while sparing the lower roots (C7, C8, T1). By performing a detailed physical exam an operative plan based on what functions have been lost and what functions are most critical to regaining the highest quality of life can be established.

The physical exam is one of the best diagnostic tools to formulate the exact pattern of injury. The patient's strength and range of motion should be observed and a Tinel's test performed. (8) Serial electromyelographs (EMG) and CT myelograms are required prior to brachial plexus exploration. Typically the first EMG is performed three months following trauma and a second EMG is performed five months following injury. If no progress is identified on the EMG or during the physical exam then a CT myelogram is obtained and plexus exploration performed.

Post-ganglionic rupture injuries are amenable to grafting whereas pre-ganglionic avulsion injuries require nerve transfer. Pre-ganglionic root avulsion is not amenable to direct repair and nerve transfer remains the best option. Some injuries avulse or rupture 80-100% of the plexus roots. These patients are not good candidates for nerve transfer due to the loss of the lower motor roots typically used for transfer. Often these are treated with nerve grafts from the phrenic, intercostal, or contra-lateral brachial plexus. (8)

Concepts of Brachial Plexus Reconstruction

Many studies document nerve regeneration following injury; however the absolutes regarding recovery remain elusive. We know that once the nerve begins to regenerate it moves at about 1-1.5 mm daily. (9) The motor endplates with which the nerve communicates will eventually cease to function in 12-18 months. If a proximal plexus injury occurs, then the regenerated nerve may not reach the motor end plate in time to be effective.

Salvage of critical motor end plates and their corresponding muscles may be facilitated with the transfer of nerve fascicles from uninjured nerves. This nerve re-routing essentially converts a proximal nerve injury into a distal nerve injury closer to the motor endplate. By shifting the injury closer to the target muscle, regeneration of the proximal nerve stump can reach the motor endplate before degradation. This is the essence of nerve transfer.

[FIGURE 5 OMITTED]

The three important criteria for primary brachial plexus reconstruction are patient selection, timing to reconstruction, and prioritizing the restoration of function.

Patient selection

Multiple studies have shown that younger patients recover from nerve transfer faster and ultimately have a better outcome. Typically patients under 40 years of age have the best functional outcome following nerve transfer. (10)

Tobacco use and compliance should also be considered. It is critical that the patient adheres to an occupational therapy and physical therapy program before surgery. Even if function is restored, if the joints have ceased working then the reconstruction is for naught.

Timing of reconstruction

Just as important for optimal functional outcome is timing to surgery. Studies have shown that nerve transfers performed within 6 months post-trauma yield results superior to transfers performed after 6 months post-trauma. (11) It is important to have the patient evaluated by a neurologist and upper extremity surgeon as soon as possible following trauma.

Restoration of Function

When contemplating brachial plexus reconstruction, one must have a specific plan since each patient's injury pattern is inherently different. The two most important actions which need to be restored in the high plexus injury are elbow flexion and shoulder abduction. (9)

Elbow flexion is critical to human interaction with the environment and its restoration is the principal goal of brachial plexus reconstruction. This is particularly true in C5-C6 injuries where the musculocutaneous nerve has been compromised. The musculocutaneous nerve innervates the brachialis and biceps which are the elbow flexors. Restoration of elbow flexion can significantly improve the activities of daily living for the patient.

Restoration of shoulder stabilization and abduction is the second most important priority in primary reconstruction of high brachial plexus injuries. (9-10) The axillary and suprascapular nerves may also be compromised in C5-C6 injuries. The axillary and suprascapular nerves innervate the deltoid and the suprascapular muscles, respectively. These muscles abduct and stabilize the shoulder, providing a solid platform for hand function.

Nerve transfer options for C5-C6 brachial plexus injuries

The current nerve transfer used for the restoration of elbow flexion is the Oberlin transfer which was first described by Christophe Oberlin of Paris in 1994. He described the transfer of a single redundant fascicle from the ulnar nerve directly coapted to the biceps motor fascicle. (12) This transfer restores elbow flexion following loss of the musculocutaneous nerve, a branch of the lateral cord. In 2004 he reported that 20 of 32 patients who underwent the procedure recovered active motion against gravity and resistance (M4). (12) This procedure was validated by Leechavengvongs in Thailand who reported his experience with 26 of 32 patients who had regained M4 elbow flexion following the Oberlin transfer. (13) In both studies none of the patients displayed any sequelae from sacrificing an ulnar nerve fascicle as a donor. (12,13)

Unfortunately some patients in the French and Thai studies required further muscle origin transfers (Steindler Flexorplasty) to improve elbow flexion. Researchers found that when the brachialis muscle was re-innervated the patient achieved better elbow flexion than biceps reinnervation alone. (12-15) In search of a procedure which would eliminate the need for additional muscle transfer, Oberlin along with Susan MacKinnon in St. Louis, described the Oberlin double nerve transfer in 2003. (14,15) In this repair one redundant fascicle from the ulnar and median nerves are coapted directly to the motor braches of the biceps and brachialis muscles. The additional re-innervation of the brachialis, a strong elbow flexor, has improved outcome following loss of the musculocutaneous nerve. In 2005 Oberlin reported 15 of 15 patients recovered M4 strength and MacKinnon reported 6 of 6 recovering M4 strength. (14,15) No patients from either study exhibited motor or sensory loss from the donor nerves. The addition of the median nerve coaptation has increased the success of the procedure without sacrificing native residual hand function. (14,15)

[FIGURE 6 OMITTED]

Two nerve transfers, the radial to axillary and spinal accessory to the suprascapular, are currently used to restore shoulder stabilization and abduction in upper plexus avulsions. These transfers can be used independently, but they have been shown to provide better results when performed in combination. (16,17) Good outcome ([greater than or equal to] M3) has been reported in 86% of patient undergoing concurrent transfer to both the axillary and suprascapular nerve. (16,17)

Transferring the radial to axillary nerve was originally described in 1948 by Alexander Lurje from Russia. (5) However his initial description was through an anterior approach which was a difficult dissection for the surgeon, not well tolerated by the patient, and required an interpositional graft. The transfer was essentially abandoned for other options until 2003 when Leechavengvongs from Thailand described the posterior approach. (18)

Through a single longitudinal incision the anterior branch to the axillary nerve is isolated in the quadrilateral space. Subsequently the radial nerve is dissected in the triangular interval just distal to the teres major. At this point the motor nerve to the long head of the triceps is identified and coapted to the anterior branch of the axillary nerve restoring innervation to the deltoid muscle.

The posterior approach was revolutionary because the ease of dissection, no interpositional graft was required, and it places the donor close to the motor endplate of the recipient. (18) Additionally the nerve transfer can improve shoulder stability and abduction because it is additive with the spinal accessory to suprascapular nerve transfer. Leechavengvongs reported that 7 of 7 patients achieved deltoid function against gravity (M4) with a mean of 124 degrees of shoulder abduction. (19) There was no reported shoulder subluxation or loss of triceps function. (19)

The spinal accessory to suprascapular nerve transfer is an older yet reliable option for restoration of glenohumeral stability and shoulder abduction. (8,11,20) The spinal accessory nerve is a cranial nerve which serves to innervate the trapezius muscle distal in its course. Originally this transfer required a large supraclavicular Millesi incision for access however recent advances in technique have permitted much smaller and more aesthetic incisions. This transfer has been successful largely due to its consistent anatomy, and close proximity to the donor nerve which negates the need for interpositional grafting. Terzis reported that in 118 spinal accessory transfers outcomes were good to excellent in 79% of patients. (11) These results were echoed by Spinner who reported a good outcome in 74% of his 577 transfers. (21)

When considering brachial plexus reconstruction for C5-C6 root avulsions these three nerve transfers have been shown to be effective both individually and in combination. This "bundled" transfer when performed prior to six months following injury in patients under 40 years of age has achieved excellent results. (16,17) The bundle is successful because it concentrates on two critical areas, elbow flexion and shoulder stability. Additionally it provides similar motor to motor nerve coaptation without interpositional grafts which speeds re-education. A recent study from Thailand reported 13 of 15 patients with complete C5-C6 avulsion regained M4 elbow and shoulder abduction. (16) This series used the older single Oberlin transfer and more recent experience suggests that elbow flexion can be further improved.

Conclusion

Injury to the brachial plexus is a devastating and life altering event for the patient as well as a challenging reconstructive dilemma for the surgeon. Recent strides have been made in the diagnosis, management, and treatment of upper brachial plexus root avulsion. Nerve transfers have evolved into a valuable option; however, a thorough understanding of clinical anatomy and timing to coaptation are crucial for optimal outcome. A combined three nerve transfer consisting of the Double Oberlin, radial to the axillary, and the spinal accessory to the suprascapular has been shown to be an effective primary reconstruction for adult C5-C6 injuries.

References

(1.) Aydn A, et. al. Three-thousand-year-old written reference to a description of what might be the earliest brachial plexus injuries in the Iliad of Homer. Plast ReconstrSurg. 2004 Oct.;114(5):1352-3.

(2.) da Vinci, Leonardo. The brachial plexus. c.1508. The Royal Collection. [C] 2005, Her Majesty Queen Elizabeth II. Available online: http://www.universalleonardo.org/ work.php?id =355. August 5, 2008.

(3.) Kennedy, Robert. On the restoration of coordinated movements after nerve-crossing, with interchange of function of the cerebral cortical centers. Philosophical Transactions of the Royal Society of London, Series B, Containing Papers of a Biological Character. 1901;194:127-162.

(4.) Langley JN, Anderson HK. The union of different kinds of nerve fibres. J. Physiol. 1904 Aug.;31(5):365-91.

(5.) Lurje A. Concerning surgical treatment of traumatic injury of the upper division of the brachial plexus. Annals of Surgery. 1948 Feb.;127(2):317-26.

(6.) Seddon HJ: Three types of nerve injury. Brain. 1943 Dec.;66(4):237-88.

(7.) Sunderland S. A classification of peripheral nerve injuries producing loss of function. Brain. 1951 Dec.;74(4):491-516.

(8.) Terzis JK, Kostopoulos VK. The surgical treatment of brachial plexus injuries in adults. Plast Reconstr Surg. 2007 Apr.;119(4):73-92.

(9.) Weber R, MacKinnon S. Nerve transfers in the upper extremity. Journal of the American Society for Surgery of the Hand. 2004 Aug.;4(3):200-13.

(10.) Dvali L, Mackinnon S. Nerve repair, grafting, and nerve transfers. Clin Plast Surg. 2003 Apr.;30(2):203-21.

(11.) Terzis JK, Kostas I. Suprascapular nerve reconstruction in 118 cases of adult posttraumatic brachial plexus. Plast Reconstr Surg. 2006 Feb.;117(2):613-29.

(12.) Teboul F, Oberlin C. Transfer of fascicles from the ulnar nerve to the nerve to the biceps in the treatment of upper brachial plexus palsy. J Bone Joint Surg Am. 2004 July;86(7):1485-90.

(13.) Leechavengvongs S, Witoonchart K, et. al. Nerve transfer to biceps muscle using a part of the ulnar nerve in brachial plexus injury (upper arm type): a report of 32 cases. J Hand Surg Am. 1998 July;23(4):711-6.

(14.) Liverneaux PA, Oberlin C, et. al.

Preliminary results of double nerve transfer to restore elbow flexion in upper type brachial plexus palsies. Plast Reconstr Surg. 2006 Mar.;117(3):915-9.

(15.) Mackinnon SE, Novak CB, et. al. Results of reinnervation of the biceps and brachialis muscles with a double fascicular transfer for elbow flexion. J Hand Surg Am. 2005 Sep.;30(5):978-85.

(16.) Leechavengvongs S, Witoonchart K, et. al. Combined nerve transfers for C5 and C6 brachial plexus avulsion injury. J Hand Surg Am. 2006 Feb.;31(2):183-9.

(17.) Bertelli JA, Ghizoni MF. Reconstruction of C5 and C6 brachial plexus avulsion injury by multiple nerve transfers: spinal accessory to suprascapular, ulnar fascicles to biceps branch, and triceps long or lateral head branch to axillary nerve. J Hand Surg Am. 2004 Jan.;29(1):131-9.

(18.) Witoonchart K, Leechavengvongs S, et. al. Nerve transfer to deltoid muscle using the nerve to the long head of the triceps, part I: an anatomic feasibility study. J Hand Surg Am. 2003 July;28(4):628-32.

(19.) Leechavengvongs S, Witoonchart K, et. al. Nerve transfer to deltoid muscle using the nerve to the long head of the triceps, part II: a report of 7 cases. J Hand Surg Am. 2003 July;28(4):633-8.

(20.) Malessy MJ, et. al. Evaluation of suprascapular nerve neurotization after nerve graft or transfer in the treatment of brachial plexus traction lesions. Neurosurgical Focus. 2004 Sep.;101(3):377-89.

(21.) Songcharoen P, Spinner R., et. al. Brachial plexus injuries in the adult. Nerve transfers: the Siriraj Hospital experience. Hand Clin. 2005 Feb.;21(1):83-9.

Matthew J. Schessler, MS-III

West Virginia University School of Medicine

W. Thomas McClellan, M.D.

Plastic and Upper Extremity Surgeon

Morgantown Plastic Surgery Associates
Figure 4.

Summary of pertinent nerves arising from the brachial plexus,
major target muscles, and functions.

Important Nerves for Upper Brachial Plexus Injury and
Reconstruction

Nerve              Major muscles innervated

Musculocutaneous   Biceps brachii, brachialis mm.
Axillary           Deltoid m.
Suprascapular      Supraspinatus m.
Radial             Triceps brachii, wrist/hand extensors
Median             Wrist flexors, hand muscles
Ulnar              Wrist flexors, hand muscles

Nerve              Important Functions

Musculocutaneous   Elbow flexion
Axillary           Shoulder abduction & stability
Suprascapular      Shoulder abduction & stability
Radial             Elbow, wrist, & finger extension
Median             Wrist flexion, hand function
Ulnar              Wrist flexion, hand function

Figure 7.

Summary of nerve injuries, transfer options, and restored
functions for the upper plexus.

Nerve Transfer Options

Injured Nerve      Nerve Transfer     Function Restored

Musculocutaneous   Median and ulnar   Elbow flexion
                   fascicles

Axillary           Radial fascicles   Shoulder stability
                                      and abduction

Suprascapular      Spinal accessory   Shoulder stability
                   (XI) fascicles     and abduction
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Title Annotation:Scientific Article
Author:Schessler, Matthew J.; McClellan, W. Thomas
Publication:West Virginia Medical Journal
Article Type:Report
Date:Jan 1, 2010
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