Infantile Brachial Plexus Injury

Original Editor - Robin Tacchetti based on the course by Krista Eskay
Top Contributors - Robin Tacchetti, Jess Bell and Kim Jackson

Introduction

Neonatal brachial plexus palsy (NBPP) is a closed nerve traction injury of the brachial plexus (C5-T1) predominately occurring during labour which can limit arm function. NBPP presents with flaccid paralysis or weakness in the upper extremity and is diagnosed soon after birth. The global incidence of NBPP is reported to be between 1-4 per 1000 live births with rates varying depending on study setting and availability of fetal and maternal care. The overall incidence of NBPP is decreasing.

The mechanism of brachial plexus injury includes obstetric, maternal and infants factors that apply traction to this vulnerable location. The most common cause of NBPP is shoulder dystocia where the mother's public symphysis restricts the baby's anterior shoulder during delivery. This additional traction widens the angle between shoulder and neck resulting in an overstretched ipsilateral brachial plexus.

Many infants spontaneously recover or gain close to normal upper extremity function. For those whose motor recovery is incomplete, close monitoring and expert interventions are critically important to optimising outcome.

Risk factors

1. Neonatal

• Large birth weight
• Breech presentation (caesarean section appears as a protective factor)
• Congenital anomalies

2. Maternal

• Age > 35 years
• Cephalopelvic disproportion
• Obesity
• Gestational diabetes mellitus (macrosomia)
• Previous child with NBPP

3. Labor-related factors

• Shoulder dystocia
• Increased duration of second stage of labor (>60 minutes)
• Operative vaginal deliveries
• Vacuum extraction
• Direct compression of fetal neck during delivery by forceps

Classification

There are several ways to classify NBPP. One classification system is based on which portion of the brachial plexus is injured. The "upper trunk" refers to nerves C5C6. The middle trunk refers to C7 nerve injury. Lastly, the lower trunk affects nerves C8 and Ti. If there is a complete severing of the brachial plexus then all nerve roots between C5-T1 nerves would be distrubed.

Another classification system is based on the degree of lesion of the nerve. Categories within this network are seen below:

• preganglionic and postganglionic: near the dorsal root ganglion and distant from the dorsal root ganglion respectively
• neurotmesis: complete tear of the axon and connective tissue with no chance of recovery
• axonotmesis: axon interruption with no/or partial interruption to myelin and connective tissue with gradual recovery
• neuropraxic: momentaneous physiological blockage with spontaneous recovery; no nerve rupture with full recovery
• neuroma: blocking of nerve impulse to muscle by injured nerve scar tissue

Mallet Classification

The Mallet classification system assesses

he Mallet classification was initially described in 1972 to classify performance of upper extremity movements that reflect those used in activities of daily living (abduction, hand to mouth, etc.) among children with BPBI36 and was subsequently modified with a sixth position (hand to belly).37 Administration of the modified Mallet classification involves observing the child positioning his/her upper extremity in standard positions unaided by compensation and scoring the observed movement on a scale between I (no function) and V (full function) using objective criteria for each score (Appendix A). The Mallet classification has demonstrated good intra-observer reliability, inter-observer reliability, and internal consistency.38 The Mallet classification is one of only a few tools validated for the BPBI population35,38, 39, 40, 41 and is easy to implement in a clinical setting.

CLASSIFICATION, TYPE OF INJURY, AND CLINICAL PRESENTATION

linical presentation can range from transient weakness to global paresis, with passive greater than active range of motion. Infants with total plexus injury (groups III and IV) who show no signs of recovery will need reconstructive microsurgery to repair the injured plexus and improve outcome. Infants with neuropraxic injury who fully recover by 1 month of age are managed conservatively. However, a ‘gray zone’, where optimal therapy (i.e., the decision whether to intervene surgically) is unclear, certainly exists for infants with NBPP. This gray zone includes infants with a deficit that has been managed conservatively but who may be considered for surgery based on select criteria, such as no recovery of biceps function at 3 months of age, or a failed cookie test at 9 months.

Also termed Duchenne-Erb syndrome, upper brachial plexus palsy (C5–C6) is characterized by impaired abduction and external rotation of the shoulder and elbow flexion, while hand function is preserved. Also known as Dejerine-Klumpke syndrome, lower brachial plexus palsy (C7–T1) impairs hand and wrist function. In the case of a complete brachial plexus palsy (C5–T1), the function of the entire arm is impaired, presenting with a completely flaccid arm without sensitivity, and sometimes with ocular impairment. This combination of symptoms is known as Horner’s Syndrome [9,10,11,12,13].

Rehabilitation

With NBPP, prognosis and outcomes depend on the extent of the injury. The rehabilitation options depend on the type of injury and the regeneration evidenced by spontaneous recovery of the affected limb [12].

Rehabilitation treatment for neonatal brachial plexus palsy includes conservative treatment, started as soon as possible with passive movements, sensory stimuli and guidance to the child’s relatives, instead of surgical treatment, which implies surgical techniques, and is performed only after spontaneous recovery, usually at 3 months of age [

Presentation

number 3 referecne chartpresentation and deficits

Segment involved:

Segment Involved	Muscular Deficits	Arm Position
C5- deltoid	abduction of shoulder	adducted
C5- supra and infraspinatus	external rotation of shoulder	internally rotated
C5 C6 bracioradialis	flexion of elbow	extended
C5 C6 supinators	supination of forearm	pronated
C6 C7 extensors of wrist	wrist extensors	flexed
C6 C7 extensors of fingers	finger extensors	flexed

Detection or "presentation" of the condition is generally in the immediate neonatal period when parents or health care providers observe deficits or absence of motor function of the hand or arm. The right upper extremity is more commonly affected due to the left occipital anterior vertex presentation at the time of birth. Breech presentation has an association with C5 to C6 root avulsions and may be bilateral. Physical exam signs depend on the severity and level of nerve root involve- ment. C5 involvement will affect the axillary nerve, leading to deltoid and teres minor weakness; the suprascapular nerve, leading to supraspinatus and infraspinatus weakness; and the musculocutaneous nerve, leading to biceps and brachialis weak- ness. C6 involvement affects the radial nerve, leading to bra- chioradialis and supinator weakness. The classic physical exam finding associated with a C5 to C6 neuropraxia, or an “upper lesion" or "upper trunk lesion," is seen when the child's arm is

held in an adducted, internally rotated posture due lack of shoulder abduction and external rotation (ER) motor function. When C7 is also involved, wrist and finger flexion is preserved, but the paralysis of deltoid, biceps, and wrist/finger extension creates a "waiter's tip" appearance, with the wrist and fingers flexed and facing laterally or posteriorly. Although seen in adult injuries, the isolated C8 and T1 injury is rarely seen in birth injuries and signifies a "lower lesion," "lower trunk lesion," or Klumpke palsy, characterized by ulnar and median nerve defi- cits, among others. In this scenario, weakness of the intrinsic muscles of the hand and wrist flexors leads to wrist hyperexten- sion, metacarpophalangeal hyperextension, and flexion of the interphalangeal joints, collectively creating a "claw hand" appearance. When both upper and lower nerve roots have been affected, a total plexus palsy (C5 to T1) will present as a flaccid upper extremity throughout. These more severe injuries are less likely to recover by natural history alone.In addition to which nerve roots are affected, the mechanical injury sustained and precise location along the nerve root's course are also critical, with neuropraxia (Sunderland I lesions) representing an intact but stretched nerve root, whereas axo- notmesis (intact root, intraneural fascicle rupture, Sunderland II to IV), neurotmesis (postganglionic tear with extraforaminal root or trunk rupture, Sunderland V), or preganglionic avul- sion of the root from the spinal cord represents increasingly severe injuries.The associated motor palsies themselves are generally pain- less, such that any suggestion of pain with passive upper extremity motion warrants radiographic workup of a clavicle or humerus fracture, although these fractures can occur in con- junction with BPBP. Assessment of the Moro reflex, in which an infant will reflexively abduct both arms in response to sudden loss of support or lowering of the head relative to the trunk, is an important test for BPBP. Upper extremity motor deficits will also cause an abnormal asymmetric tonic neck reflex, which is the normal phenomenon, up to 6 months of age, of abduction of the arm on the side to which an infant's head is turned, withconditions occuring same time

Conditions that are associated with BPBP include neonatal clavicle and humerus fractures, which are also common birth injuries with similar risk factors, as well as infantile torticollis, progressive glenohumeral dysplasia, and flexion contracture of the elbow. The glenohumeral dysplasia associated with BPBP develops over time and is characterized by a spectrum of sever- ity of glenoid retroversion, humeral head deformity/flattening, and posterior glenohumeral instability, with unopposed shoul- der internal rotation and evolving contracture playing the prin- cipal etio39

Assessment

HCPs experienced in newborn assessment should undertake a detailed review of maternal history and delivery details to identify risk factors for NBPP (e.g., shoulder dystocia or presence of humeral or clavicular fracture). They should perform a detailed physical musculoskeletal and neurological examination, including active and passive range of motion, and assess normal reflexes. This exam should include assessing for clavicular or humeral fracture, which can mimic NBPP due to pain limiting range of motion. When concern is raised for bony injury, a chest and humeral x-ray should be obtained. Assess respiratory status and check symmetry of chest movements promptly to assess for phrenic nerve injury. An elevated hemi-diaphragm may be seen on chest x-ray or detected on ultrasound. The presence of Horner’s syndrome and diaphragmatic paralysis suggest an avulsion injury, which is a persistent, definitive deficit. Detailed documentation should be part of the newborn record and included in the referral form (Table 2). Differential diagnoses to be considered include: pseudoparesis (i.e., pain secondary to humeral fracture or to an infection of the bone, joints, soft tissue, or vertebra); myotonia congenita (a form of arthrogryposis multiplex congenita); anterior horn cell injury (e.g., congenital cervical spinal atrophy, congenital varicella syndrome); and pyramidal tract or cerebellar lesions

de a thorough history (including gestational and birth history) and a careful and complete physical examination.11-14 History and physical examination should be directed toward the following goals: • Assessment of any associated nonneurologic injuries. • Localization of the neurologic injury. • Determining the severity of the injury. • Delineating the risk factors for persistence. • Monitoring for spontaneous recovery on sequential examination. A variety of scales have been developed for the assessment • Cookie test When the infant is 9 months old, a cookie is placed in his or her hand and the elbow is then held against his or her side. The test is considered successful if the infant is able to get the cookie to his or her mouth without flexing the neck beyond 45 degrees. • Towel test A towel is placed over the infant’s eyes and the test is considered successful if he or she can take away the towel from the eyes with the involved limb versus the unaffected limb.

Resources

• Brachial Plexus Injury
• Erb's Palsy
• Horner's Syndrome
• Klumpke's Paralysis

Recommendations

• 1) Neonatal care providers should evaluate newborns for NBPP when delivery has been complicated by shoulder dystocia, a humeral or clavicular fracture, or when asymmetrical upper extremity movement is apparent.
• 2) All newborns with NBPP and incomplete recovery by 1 month of age should be referred immediately to a multidisciplinary health care team to optimize outcomes and minimize residual deficits. The referral should include detailed information on the risk factors, severity of injury, and course of recovery.
• 3) For infants receiving ongoing nonoperative therapy in their community, continuous dialogue among the child’s multidisciplinary health care team, community health care providers, and nonoperative therapists is required to identify issues of growth and development and facilitate specialized assessments.

Most of the authors agree that 80 to 96% of the patients with NBPP recover completely in the first year of life.1-6 • Most authors agree that infants with global/pan plexus palsies or flail and Horner syndrome should undergo surgical intervention at the earliest, preferably within 2 or 3 months after birth.1-6,11-15 • About 70 to 80% of the patients with NBPP have Erb’s palsy or extended Erb’s palsy. There is no consensus on the timing of surgical intervention in these cases. However, intervention after 9 months yielded poorer results, especially with regard to the hand function. Therefore, majority favored operative intervention, if there is no recovery of shoulder external rotation and/or elbow flexion/extension by 4 or 5 months of age.1-6

Treatment

These professionals use rehabilitation techniques and resources in a complementary way, such as electrostimulation, botulinum toxin injection, immobilizing splints, and constraint induced movement therapy of the non-injured limb. Professionals and family members work jointly. Surgical treatment includes primary surgeries, indicated for children who do not present any type of spontaneous rehabilitation in the first three months of life; and secondary surgeries, recommended in children who after primary surgery have some limitation of injured limb function, or in children who have had some spontaneous recovery, yet still have significant functional deficits. Treatment options for NBPP are defined by clinical evaluation/type of injury, but regardless of the type of injury, it is unanimous that conservative treatment is always started as early as possible.

Surgical interventions can be divided into categories: Primary reconstruction is the initial surgical management and may include nerve surgery/reconstruction (e.g., direct repair, neurolysis, nerve grafting, nerve transfers) and/or soft tissue procedures (e.g., functioning free muscle transfer, tendon transfers). Secondary reconstruction is considered when the desired functional outcome can be improved or refined further with surgical intervention or when there has been no further improvement/recovery after primary surgical intervention. This includes soft-tissue reconstruction (e.g., tendon/muscle transfer, FFMT, capsulotomies) and osseous procedures (e.g., arthrodesis, osteotomy). • The rate of nerve regeneration is estimated to be around 1 mm/day or 1 in/month. Therefore, clinical results may not be seen for 1 to 2 years after the surgical intervention.3-5 • The shorter the distance to the target muscle, the lesser the time for reinnervation. While waiting for reinnervation to occur, regular physiotherapy should be done to prevent contracturesThe infant’s upper body is placed in a prefabricated cast, to limit movements of the neck and the affected arm, for a week or two. Gentle range of motion can be allowed after 2 to 3 weeks. Regular physiotherapy and follow-up in a rehabilitation center for a minimum period of 5 years is recommended for assessment of recovery and determination of potential secondary reconstructions to improve function

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