eMedicine Specialties > Orthopedic Surgery > Trauma

Brachial Plexus Injuries, Traumatic

Author: Mark R Foster, MD, PhD, FACS, President and Orthopaedic Surgeon, Orthopaedic Spine Specialists of Western Pennsylvania, PC
Coauthor(s): Christopher Chaput, MD, Assistant Professor of Orthopedic Surgery, Texas A&M Health Science Center; Consulting Surgeon, Department of Orthopedic Surgery, Scott and White Memorial Hospital; Robert A Probe, MD, Associate Professor of Orthopedic Surgery, Texas A&M University Health Science Center; Chairman, Department of Orthopedic Surgery, Scott and White Clinic and Memorial Hospital
Contributor Information and Disclosures

Updated: Sep 26, 2008

Introduction

History of the Procedure

The treatment of lesions of the brachial plexus has changed from shoulder fusion, elbow bone block, and finger tenodesis following World War II to far greater functional restoration by advances in nerve repair and microsurgery.  The natural history of becoming "one handed" within 2 years has been replaced by early exploration, neurolysis, nerve grafting, neurotization, and free muscle transfers, as well as tendon transfers, for shoulder and elbow function and for wrist or hand prehension. Recent advances in diagnostic imaging, nerve transfers, electrophysiologic testing, nerve root repair, nerve rootlet replantation, and free muscle transfers make this a dynamic but highly specialized field.^1,2,3

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Specialty Site Orthopaedics
Orthopaedics CME and News

Related eMedicine topics:
Brachial Plexus Injuries, Obstetrical
Tendon Transfers

Problem

High-energy trauma to the upper extremity and neck can cause a variety of lesions to the brachial plexus. Most common are traction injuries, in which the head and neck are moved away violently from the ipsilateral shoulder; injuries may also be caused by compression between the clavicle and first rib, penetrating injuries, or direct blows. Recognition may be delayed by other injuries, particularly to the spinal cord and head.^4,5 Because this topic is complex, this article focuses primarily on traction injuries, the most common injuries in adults. Such injuries usually are catastrophic for the affected individual. Loss of useful function of the upper extremity is common, but early repair and reconstruction are providing far greater restoration than was possible a few years ago.

Related Medscape topic:
Resource Center Trauma
Resource Center Spinal Disorders

Related eMedicine topic:
The Polytraumatized Patient 

Frequency

Reliable information on the incidence of traumatic brachial plexus injuries is difficult to find; the exact incidence is not known. Goldie and Coates suggested that 450-500 closed supraclavicular injuries occur each year in the United Kingdom.⁶ Young males are disproportionately affected, mostly between 15 and 25 years of age, as in other types of trauma.

Narakas developed his rule of "seven seventies " in his experience over 18 years with 1068 patients⁷ :

• Approximately 70% were motor vehicle accidents (MVAs).
• Of the MVAs, 70% were motorcycles or bicycles.
• Of the cycle riders, 70% had multiple injuries. 
• Of the multiple injuries in cycle riders, 70% were supraclavicular injuries.
• Of the supraclavicular injuries, 70% had at least one root avulsed.
• Of the avulsed roots, 70% were lower C7, C8, T1. 
• Of the 70% avulsed roots, 70% of those were associated with chronic pain. 

Etiology

The common mechanism for traction injuries of the brachial plexus is violent distraction of the entire forequarter from the rest of the body. These injuries usually result from a motorcycle accident or a high-speed motor vehicle accident. A fall from a significant height may also result in brachial plexus injury, either traction type or from a direct blow; penetrating injuries and low- or high-velocity gunshot wounds also are seen.

In traction-type injuries, the crucial prognostic factor is whether the injury is proximal (preganglionic) or distal (postganglionic) to the dorsal root ganglion. A preganglionic root avulsion means that the cell bodies of the sensory nerves are pulled from the cord, diminishing the possibility of recovery or surgical reconstruction. These are differentiated from distal ruptures — postganglionic stretch injuries — in which cell bodies are still in continuity with their axons.  

Pathophysiology

In traction-type brachial plexus injuries, the head and neck are moved away violently from the ipsilateral shoulder. Upper plexus injuries (C5 and C6) usually predominate if the arm is at the side because the first rib acts as a fulcrum to direct the traction forces preferentially in line with the upper plexus. When the arm is moved violently and abducted overhead, the lower elements (C8-T1) typically are injured, as the force is directed in line with C7. A lower plexus lesion predominates when the arm is raised because the coracoid acts as a fulcrum in a similar fashion. Lower plexus lesions may be more common, in part, because of the well-formed transverse radicular ligaments that help resist traction forces at C5, C6, and C7; C8 and T1 lack these ligaments.

Traction forces can result in preganglionic or postganglionic injuries. Preganglionic injuries refer to lesions proximal to the dorsal root ganglion, which is in the spinal canal, and foramen. Preganglionic ruptures may be central or direct from the spinal cord or intradural. Preganglionic lesions do not cause wallerian degeneration or neuroma formation because the axons remain in continuity with the cell bodies in the dorsal root ganglion. Postganglionic lesions are defined as any lesions distal to the spinal ganglion and are physiologically similar to other peripheral nerve injuries.

Presentation

History

The index of suspicion for a brachial plexus injury is much higher for severe shoulder girdle injuries, particularly motorcycle and motor vehicle accidents. The mechanism of injury should be considered, as these may occur in polytrauma. Other injuries requiring sedation indicate that detailed follow-up examination of the upper extremity may needed.

The patient may present with the following symptoms:

• Pain, especially of the neck and shoulder. Pain over a nerve is common with rupture, as opposed to lack of percussion tenderness with avulsion
• Paresthesias and dysesthesias
• Weakness or heaviness in the extremity
• Diminished pulses, as vascular injury may accompany traction injury.

Physical examination

The standard advanced trauma life support (ATLS) protocol should be followed. Abrasions to the head, helmet, or tip of the shoulder suggest supraclavicular injury. Ptosis (lid droop), enophthalmos (sinking of the eye into the orbit), anhydrosis (dry eye), and miosis (small pupil) or Horner syndrome suggest a complete lower plexus lesion (see Image 1), as the sympathic ganglion for T1 is in close proximity to the brachial plexus.

Swelling about the shoulder can be dramatic. Diminished or absent pulses suggest vascular injury, and special consideration should be given to rupture of the subclavian vessels. Clavicle fractures often are palpable. Careful inspection and palpation of the axial skeleton may reveal concomitant injuries. Examine each cervical root individually for motor and sensory function as soon as circumstances allow.

Some special considerations are warranted for the neurologic examination, as follows:

• Sensory examination: This examination is extremely important. Deep pressure sensation may be the only clue to continuity in a nerve with no motor function or other sensation. Apply full pinch to the nail base and pull the patient's finger outward. Any burning suggests continuity of the tested nerve. When no burning is elicited, these examination findings are less helpful because a neuropraxia can persist for more than 6 months. Table 1. Deep Pressure Test

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  Table

  Location of Deep Pressure Test	Affected Spinal Nerve	Nerve	Affected Cord
  Thumb	C6	Median nerve	Lateral cord
  Middle finger	C7	Median nerve	Lateral cord
  Little finger	C8	Ulnar nerve	Medial cord

  Location of Deep Pressure Test	Affected Spinal Nerve	Nerve	Affected Cord
  Thumb	C6	Median nerve	Lateral cord
  Middle finger	C7	Median nerve	Lateral cord
  Little finger	C8	Ulnar nerve	Medial cord

• Examination of wrist and finger sensation and motion with respect to the median, ulnar, and radial nerves may help start to locate the lesion within the brachial plexus. 
• Motor examination: Significant variations occur among the spinal nerves within the cord and account for most of the anomalous patterns of innervation. These variations may make identifying the levels involved challenging. In addition, C4 may contribute a branch to the plexus up to 60% of the time. When C4 makes a significant contribution to the plexus, the plexus is called prefixed. A prefixed cord can explain recovery in the distribution of a nerve root clinically presumed to be avulsed. When performing the motor examination, keep in mind that most individual muscles have contributions from multiple cervical levels (see Image 2). Table 2. Guide to Motor Testing

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  Table

  Cervical Root	Clinically Relevant Gross Motor Function
  C5	Shoulder abduction, extension, and external rotation; some elbow flexion
  C6	Elbow flexion, forearm pronation and supination, some wrist extension
  C7	Diffuse loss of function in the extremity without complete paralysis of a specific muscle group, elbow extension, consistently supplies the latissimus dorsi
  C8	Finger extensors, finger flexors, wrist flexors, hand intrinsics
  T1	Hand intrinsics

  Cervical Root	Clinically Relevant Gross Motor Function
  C5	Shoulder abduction, extension, and external rotation; some elbow flexion
  C6	Elbow flexion, forearm pronation and supination, some wrist extension
  C7	Diffuse loss of function in the extremity without complete paralysis of a specific muscle group, elbow extension, consistently supplies the latissimus dorsi
  C8	Finger extensors, finger flexors, wrist flexors, hand intrinsics
  T1	Hand intrinsics

• Elbow flexion and extension determine musculocutaneous and high radial nerve function. Shoulder abduction tests the axillary nerve, which comes off the posterior cord. The posterior cord may also affect deltoid function by the radial nerve. The latissimus dorsi is innervated by the thoracodorsal nerve off the posterior cord, and may be tested by palpation of the muscle while the patient coughs. Pectoralis muscles can be palpated as the patient adducts the arm against resistance (the medial pectoral nerve to the sternal head comes off the medial cord, the lateral pectoral nerve to the clavicular head comes off the lateral cord). The long thoracic nerve innervates the serratus anterior, and the dorsal scapular nerve innervates the rhomboids; thus, winging of the scapula may help localize the injury.

Related Medscape topics:
Resource Center Trauma
Resource Center Vascular Surgery

Related eMedicine topics:
The Polytraumatized Patient
Horner Syndrome
Peripheral Vascular Injuries
Clavicle Fractures

Indications

Formerly, most brachial plexus lesions were treated conservatively. Patients were monitored over 12-18 months for recovery of significant voluntary motor control, and any residual deficit was pronounced permanent. Leffert suggested that after 9-12 months, any residual deficit at the level of the shoulder can be considered permanent.⁸ However, recovery of more distal function may occasionally be observed more than a year after injury. The customary treatments were shoulder fusion, elbow fusion, wrist and finger tenodesis and transhumeral amputation.

The 3 crucial factors in restoration of upper arm function after brachial plexus injury are patient selection, timing of surgery, and prioritization of restoration. Open injuries from a sharp object may benefit most from immediate exploration and, if possible, direct, end-to-end repair. With an open injury from a blunt object, a 3- to 4-week delay in repair, after initial debridement and tagging, allows injured nerve ends to demarcate. Low-velocity gunshots injuries may be neuropraxic, and may be observed. High-velocity gunshot injuries need early exploration for significant soft-tissue damage.

Stretch injuries present the most complex issues. Early surgery may preclude opportunities for spontaneous recovery; delayed surgery may allow failure of end plates and reinnervation. Suspected avulsions may be explored at 3-6 weeks, and, generally, failure of adequate reinnervation may be explored at 3-6 months.

Surgical options include nerve (primary) and soft-tissue (secondary) reconstruction. External neurolysis alone may benefit a nerve in continuity that exhibits a nerve action potential (NAP). Postganglionic neuromas or ruptures may benefit from nerve grafting. From an overall perspective, such grafts include C5 for shoulder abduction, C6 for elbow flexion, and C7 for elbow and wrist extension.

Nerve transfers (neurotization) can be performed to accelerate recovery from preganglionic injuries.⁹ Such procedures, performed ideally within 6 months, reduce time to reinnervation by reducing the distance to the site of the nerve injury. Sources for transfer include the spinal accessory nerve, intercostal nerves, and the medial pectoral nerve.^10,11 The Oberlin transfer uses a fascicle of a functioning ulnar nerve, but the median nerve or others may also be used in specific cases. 

Significant recovery after nerve grafting can take more than 18 months, and maintaining joint mobility, minimizing edema, and treating deafferentation pain during this period can make postoperative care challenging.

The age of the patient also is important. The ability of nerve transfers to restore functional strength decreases dramatically with patient age. Therefore, many of the surgical options are reserved for younger patients.

Relevant Anatomy

The brachial plexus is formed from the spinal nerves or roots, the coalescence of the ventral (motor) and the dorsal (sensory) rootlets as they pass through the spinal foramen. The dorsal root ganglion contains the cell bodies of the sensory nerves; the cell bodies for the ventral nerves lie within the spinal cord.

Typically, the brachial plexus is formed from C5-T1; in some cases with there is a contribution from C4 (prefixed, 28-62%) or T2 (postfixed, 16-73%). All nerve supply to the upper extremity passes through this plexus. The brachial plexus starts at the scalenes, courses under the clavicle, and ends at the axilla. It is typically composed of 5 roots, 3 trunks, 6 divisions (2 from each trunk), 3 cords and terminal branches. 

The 5 roots are named by the level with which they correspond. The C5-7 roots give off branches to form the long thoracic nerve, and the C5 root gives branches to form the dorsal scapular nerve. C5 and C6 gives branches to form the superior trunk, C7 the middle trunk, and C8 and T1 the inferior trunk. Each trunk has 2 divisions: 1 division of each of the trunks forms the posterior cord; the anterior division of the superior trunk and the anterior division of the middle trunk form the lateral cord. The anterior division of the inferior trunk forms the medial cord. The medial, lateral, and posterior cord designations describe their relationship to the axillary artery.

The superior trunk gives off the suprascapular nerve and a nerve to subclavius. The posterior cord has the upper and lower subscapular nerves, with the thoracodorsal nerve between them. The lateral pectoral nerve emanates from the lateral cord, and the medial pectoral nerve from the medial cord but with a connection between the pectoral nerves. The posterior cord then becomes the axillary and radial nerves.

The lateral cord continues as the musculocutaneous nerve; a branch from the medial and lateral cords becomes the median nerve; and a branch from the lateral branch joins the medial cord continuation as the ulnar nerve, after the medial cord gives off the medial brachial cutaneous and the medial antebrachial cutaneous nerves. The cords and branches are distal to the clavicle; the roots and trunks proximal. The plexus lies in close proximity to the axillary artery, which exits between the anterior and middle scalenes. Knowledge of this anatomy may allow localization of lesions from the physical examination.

Many different approaches to the brachial plexus have been used. Surgeon preference is largely shaped by training and by the goals of a particular procedure. In any approach, the clavicle can be a barrier to visualization. Millesi described an approach using 3 anterior incisions with the patient in the supine position.¹² He makes a sagittal incision on the lower neck and 2 transverse incisions more distally, following skin tension lines. By moving the clavicle and looking at the plexus from both a cephalad and a caudad direction, he is able to visualize upper, middle, and lower trunks of the brachial plexus and avoid osteotomy of the clavicle. The spinal nerves of the upper plexus can also be visualized with this approach.

Contraindications

Contraindications to surgery include the following:

• Joint contractures
• Severe edema
• Advanced patient age
• Lack of patient motivation or lack of patient understanding of surgical goals

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