Overview of Brachial Plexus Management

Gerald Stark, BSME, CP, FAAOP


Management of the Brachial Plexus Injury or BPI is one area where the device created is intended to satisfy both orthotic and prosthetic goals, blurring the lines between support of the limb and functional need. Treatment by the orthotist and prosthetist often differ, but requires a blending of the different philosophies and componentry developed independently in each respective field. The primary goals of a device is ordered in most to least significance: 1) Prevent deformity, 2) Correct deformity, 3) Fix position to obtain maximum function. 1 The main deformity is shoulder subluxation due to muscular flaccidity at the shoulder. Added goals are to treat edema, maintain bimanuality, and ease pain caused by traction.1 These functional goals are influenced by the unilateral/ bilateral involvement, gadget tolerance, donning/ doffing, and wear time. 1 While rejection rate for upper extremity prostheses can be as high as 50 %, the acceptance rate for a brachial plexus orthosis has been estimated as high as 70% after one year of use. 4

Brachial plexus may be divided into closed or open trauma to nerve branches at the shoulder. In children, 90% of brachial plexus injury is a closed Erb's Palsy which results from birth injury. Injury of the lower brachial plexus is referred to as Kumpke's palsy. This affects nearly 5,000 children per year with an estimate of one to two per 1,000 births. 6 Of those, one in ten require some form of treatment and often involve malpractice litigation. 6 In adults, brachial plexus injury is often the result of traction on the nerve roots C5-C6 as the head is distracted from the shoulder. 4 Lower trauma to nerve roots C8-T1 occur as the arm is brought over the head. 4 These injuries follow Narakus' "law of seven seventies": 70% of traumatic BPI are due to motor vehicle accidents, 70% involve bicycles or motorcycles, 70% have multiple injuries, 70% have subclavicular nerve lesion, 70% have one nerve root avulsed, 70% have lower root (C7, C8, T1 or C8, T1) avulsed, 70% with lower root avulsed experience persistent pain. 4 Other causes for traumatic BPI can be a penetrating stab wound, gunshot, or other open trauma which involves the nerve roots (which may heal faster because there is distinct borders of trauma rather than distraction or tearing). Most patients with traumatic BPI are males, 15-25 years of age. 4

The first concern with BPI is shoulder subluxation due to muscular flaccidity. As the humeral head subluxes distally it places increasing traction since the nerve roots are held by the clavicle and scaline muscles. 4 Second is the functional positioning of the limb and preservation of extremity function. After WWII this was accomplished surgically with shoulder fusion, elbow bone lock, and finger tenodesis. 4 In the 1960's shoulder fusion in slight abduction and flexion combined with transhumeral amputation with "good" to "fair" functional results. 4 Today surgical management of nerve root avulsions focuses on early, aggressive microsurgical reconstruction of the brachial plexus using nerve donors, grafts, and free vascularized and neurotized muscles. 7 This often results in significant return especially in young patients. Amputation results only when these microsurgical techniques have failed. 7 Surgically the injury is divided into preganglionic or postganglionic. Tendon transfers, pectoralis transfer, and latissimus dorsi transfers cannot be used with C5-C6 avulsions since these muscles are not functional. Transfer of the triceps to biceps is possible only when there is some elbow flexion existing. The nerve tissue for preganglionic injury is not reconstructable and can benefit from an intercostals motor nerve transfer at the 4 rib in which the nerve is routed subcutaneously to the musculocutaneous nerve if 6-12 months post injury. If after 12 months post injury, a gracilis transfer is recommended in which the (Continued from page 7) entire biceps is excised and replaced with the gracilis muscle with the obtuator nerve, artery, and vein. The motor nerves of the 3 rd , 4 th , and 5 th ribs then innervate the gracilis. 4 Postganglionic has shown some recovery up to 3 months after which nerve grafting for the upper trunk is recommended after patient has plateaued. Nerve grafting of the lower trunk presents with mixed results and may require a tendon transfer later. 4 Often stabilization of the humerus in the anesthetic upper limb cannot be achieved due to the weight of the arm, so shoulder fusion is recommended for many patients. 1,4 The recommended position for the shoulder fusion is approximately 20 degree abduction, 30 degree flexion, and 40 degree of internal rotation. 1

Orthotic/prosthetic management often follows an understanding of the functional levels. C5-C6 presents with a complete loss of shoulder and elbow control. Some wrist extension using finger extensors and extensor carpi ulnaris are still available. 1,4 Thumb and index finger sensation in impaired. C5-C7 also adds radial palsy, increased hand sensory loss, and loss of wrist, hand, and finger extension. 1,4 C7- C8 shows good shoulder and elbow function, but finger flexor weakness, extensors, and intrinsics of the hand. Surgical intervention is fairly successful at this level. Patients do not usually have myosites below the elbow because forearm innervation is lost. 1,4 C8-T1 has lost finger flexors and hand intrinsics, but has good hand sensation except for the 4 th and 5 th finger. This level has the greatest orthotic success. Complete plexus injury has the least amount of success since the arm is completely flail and insensate. Pain is also often present due to nerve traction. 4 Often amputation is recommended for the best functional outcome although not often pursued. Orthotic benefits at this level are limited to: 1) Protection of the limb, 2) Support to minimize pain, 3) Edema prevention. 1 The following table is presented as a functional guide, but injuries are usually case dependent especially when incomplete. 1

Orthotically the first goal is to prevent the subluxation of the shoulder so the weight of the arm must be supported is often supported with the use of a shoulder saddle and an inverted "Y" strap to support the lower forearm also referred to as a hemisling. This is made of padded polyethylene or can be constructed of 2" straps, Spenco Æ , or leather. There is no device as of yet to provide the active shoulder motion although the Rancho Los Amigos Orthosis does aid in flexion/extension and rotation with straps if shoulder movements are poor to trace. 1 A shoulder cap may be used for additional axial support and cable installation, but increases skin coverage and overall bulk. If additional support is required a "gunslinger" or pelvic hemi-girdle variation may be used to support the arm inferiorly. The mechanism is attached to a lower LSO support or to a wheelchair and the positioning joints are mounted inferiorly to provide translational movement.

Since the shoulder cannot be used to achieve positional control, elbow joints are available where most of the terminal positioning can be achieved. These range from bilateral friction joints, spring loaded locking joints, and unilateral ratchet joints. Where polymer systems are used, a simple overlap joint can be employed. Bilateral flail arm hinges are available that provide a spring counterbalance laterally and a reciprocating lock medially. Ratchet joints lock the arm when it is manually positioned and unlock it when the arm is flexed completely similar to a lawn chair joint. Instances where transhumeral amputation has been chosen, externally powered electric elbows with corresponding terminal devices can be utilized. Some contend transradial amputation would be a benefit even if the elbow is non-functioning and the skin over the residuum is insensate, because proprioception may be still be present to aid in arm positioning. 4 Where the BPI arm is left intact, humeral and forearm cuffs support the arm passively with elastic Velcro closures. A fairly cosmetic lightweight orthosis from the Netherlands uses a medially mounted ratchet elbow in a unilateral construction with four small cuffs that wrap from the medial on the humeral and forearm section. A modular system from England referred to as the Stanmore Orthosis incorporates shoulder, locking elbow, and terminal device function with cable control with a shoulder cap and unilateral, medial construction.

Distally the main goal is to protect the limb and hold it anteriorly. If functional prehension is desired, a smaller 9P hook terminal device may be mounted in the palmar area of the hand with an infant wrist, controlled with a standard Bowden cable system. The cabling may also be split to provide assistance lifting the forearm, where needed. Another orthotic option is to use a tenodesis splint that uses the existing hand as the manipulator with body or external power control. While more cosmetic, it must be remembered that the fingers are usually insensate with limited functional prehension. The tenodesis splint may be a metal Rancho type or a lower profile RIC polymer type. These can be cable controlled as a ratchet or to apply the pinch force. External power using myoelectric or switch control may also be employed to apply pinch, but this adds extra weight, bulk, and expense. Earlier designs used pneumatic or a "McKibben" muscle that contracted and pulled the tenodesis splint closed. 2,3 Later designs used linear actuators or rotary worm gears to provide powered pinch. 2,3 Currently only one device which is commercially available for linear actuation which is relatively light weight, uses myo or switch control, and can provide up to 14 lbs. of pinch. 2 Instances that only partially involve the loss of the distal extensors may use a low profile WHO with MP assist.

Harnessing of the "prosthosis" has usually two goals, suspension and operation of terminal device and/or elbow. This may be done with a chest strap or a figure of 8 design. A chest strap has the advantages of axillary comfort, easier donning, and works well with shoulder saddle designs. The figure of 8 captures more of the unilateral scapular abduction and resists migration. An elastic inverted "Y" strap descends distally to support the lower forearm and position it anterior to the trunk. Additional excursion for cable activation can be captured with a shoulder sling over the apex of the contralateral shoulder. While additional harnessing features may be incorporated, this increases the complexity of donning and the likelihood of rejection.

Overall the orthotic goals must first be met, but functional prosthetic goals are still possible for the motivated patient as a result of the variety of componentry.

Fillauer, Inc. Chattanooga, Tennessee

References:
1) Leffert, R., Lowe, C., and Snowden, J., Orthoses for Brachial Plexus Injuries. Atlas of Orthoses and Assistive Devices, Chapter 20, 3rd ed., Mosby Year Book, St. Louis, 1997, pp. 339-347.
2) Slack, M., and Berbrayer, D., A Myoelectrically Controlled Wrist-Hand Orthosis for Brachial Plexus Injury: A Case Study. Journal of Prosthetics and Orthotics, Vol. 4, Num. 3, 1992, pp. 171-174.
3) Benjuya, N., and Kenney, S., Myoelectric Hand Orthosis. Journal of Prosthetics and Orthotics, Vol. 2, Num. 2, 1990, pp. 149-154.
4) Michael, J., and Nunley, J., Brachial Plexus Injuries: Surgical Advances and Orthotic/Prosthetic Management. Atlas of Limb Prosthetics, Chapter 12A, 2nd ed., Mosby Year Book, St. Louis, 1992, pp. 293-310.
5) Brachial Plexus Palsy Foundation, Royersford, PA, http://membrane.com/bpp/overview.html
6) Erbs Palsy and Shoulder Dystocia Birth Injury Center, http://www.erbs-palsy-birth-injuries.com/
7) Terzis, J., Vekris, M., and Soucacos, P, Brachial Plexus Root Avulsions, World Journal of Surgery, DOI: 10.1007/s00268-001-0058-8, Societe Internationale de Chirurge, 2001.