Neonatal brachial plexus injury (NBPI) is paralysis of either all or portions of the upper extremity caused by a traumatic injury to the brachial plexus incurred at birth.
The cause of NBPI is direct trauma to the plexus during labor and/or delivery. It involves one or more cervical (C) and thoracic (T) roots (C5 to T1), or other anatomic regions of the plexus (commonly trunks). The most common location of injury is the upper trunk with involvement of both C5 and C6 neural elements.
Epidemiology including risk factors and primary prevention
- The incidence of NBPI is 1 to 2 per 1000 live births, with studies suggesting a slight decrease over the years.
- The primary risk factors associated with NBPI include
- shoulder dystocia (100 times greater risk)
- birth weight greater than 4.5 kilograms (14 times greater risk)
- maternal diabetes
- previous children with NBPI
- Upper trunk and C5-6 root level injuries account for approximately 80% to 90% of all injuries; lower trunk injuries account for <1%; global injuries account for less than 10%.
- Appropriate preventive obstetric maneuvers should be undertaken to reduce the dystocia during delivery once it is identified.
- NBPI is generally considered to be secondary to excessive traction applied to nerves.
- In cases involving shoulder dystocia, the mechanics of maternal pelvic size and the fetal size and position during delivery all contribute to the injury. Subsequent traction applied to the shoulders during dystocia is a well-established and known mechanism of injury.
- NBPI also can occur during deliveries in which there is no documented dystocia, as well as during cesarean sections. Factors considered to be playing a role in these cases include maternal expulsive forces and intrauterine contractile forces.
- The majority of injuries (70% to 80%) are neuropraxic and will resolve within 2 to 3 months. Axonotmetic injuries account for approximately 15% to 20 % of all NBPI and demonstrate variable degrees of recovery over the first 18 months of life. The remainder of injuries (less than 5%) are either avulsions or root/trunk ruptures. Recent studies have shown that the incidence of “complete recovery” may be lower than previously thought as residual shoulder deficits can be overlooked.
Disease progression including natural history, disease phases or stages, disease trajectory (clinical features and presentation over time)
- Extent and severity of the injury influence prognosis.
- Neuropraxic injuries should completely resolve within the first 2 to 3 months of life.
- Axonotmetic injuries demonstrate slow progression of improvement with variable degrees of recovery over the first 18 months of life; recovery is never complete.
- Root avulsions and ruptures should be suspected if there is no motor function noted in affected myotomes by 3 to 4 months of age.
- The risk of contracture development and glenohumeral osseous deformity is highest in children with axonotmetic injuries and root ruptures/avulsions, and can begin to evolve within the first 4 to 12 months of life.
Specific secondary or associated conditions and complications
- Diaphragmatic paralysis can occur in any case of NBPI due to the proximity of the phrenic nerve to the plexus.
- Torticollis may occur and should warrant evaluation for intramuscular hematoma
- Osseous deformities of the glenohumeral joint can occur due to muscle imbalance leading to posteriorly directed forces across the joint, and include glenohumeral dysplasia, and posterior glenohumeral subluxation/dislocation.
- Upper extremity limb length difference is common and can approach 5% to 10% when compared to the unaffected extremity.
- Contractures of the muscles of internal rotation across the shoulder joint occur due to residual muscle imbalance
- Sensation and proprioception can be altered.
- Abnormal contraction, specifically co-contraction coupling of agonist and antagonist muscles, can lead to atypical movement patterns.
- Flexible, upper thoracic scoliosis may be seen in unresolved BPI.
2. ESSENTIALS OF ASSESSMENT
- Flaccid weakness of the involved extremity is noted immediately after delivery.
- Shoulder dystocia during the delivery is commonly reported.
- Apgar scores and birth weight should be recorded.
- Previous history of NBPI should be noted as the incidence of recurrent cases in the same mother can approach 14%.
- The initial assessment of the neonate should focus on determining the anatomic location of the injury.
- C5-6/upper trunk injuries present as absent shoulder abduction, external rotation, elbow flexion, and wrist extension.
- C5-7/upper and middle trunk injuries present the same as C5-6 injury plus absent elbow extension.
- C5-T1 injuries present with paralysis of whole arm and hand.
- Sensation to pinprick should be tested in C5-T1 dermatomes. Absent sensation is more consistent with an avulsion or rupture type injury.
- Ipsilateral Horner sign (ptosis and meiosis) is suggestive of C8-T1/ lower trunk injuries with sympathetic chain involvement.
- Assessment for diaphragm paralysis is essential in all cases of NBPI.
- Passive range of motion should be assessed in all planes of motion across the glenohumeral joint, with specific attention paid to shoulder external rotation, flexion, and abduction. Passive supination, wrist and finger flexion, and elbow extension should be tested as well.
- Observation of tone and reflexes in the involved extremity is essential in order to rule out central causes of upper extremity weakness.
- In infancy and childhood, functional observation should focus on whether the arm is appropriately incorporated into developmental skills.
- In older children, assessment should focus on how the affected extremity is incorporated into self-care skills, play, and other functional activities, with particular observation of compensatory patterns of movement.
Routine laboratory studies are not needed in NBPI.
- Plain radiographs of the involved extremity, shoulder, and chest should be obtained in the neonate to rule out humeral and clavicular fractures, and diaphragmatic paralysis.
- Magnetic resonance imaging (MRI) is generally not indicated in the initial assessment of NBPI in a neonate or infant, but can play a role in assessing the shoulder for residual sequelae such as glenohumeral osseous deformity and subluxation.
Supplemental assessment tools
Electrodiagnostic studies may be helpful for pre-surgical decision making and prognostication, but are not necessary for nonsurgical clinical decision making.
Early predictions of outcomes
- The most widely accepted early predictor of outcome is emergence of biceps movement. If biceps contraction/elbow flexion is not noted by 4 months of age, further spontaneous recovery is unlikely without surgical intervention, and functional outcome will be poor.
- Other indicators of poor prognosis include the presence of a total plexopathy, Horner’s syndrome, and nerve root avulsions.
Some cases of NBPI will lead to civil legal action against the delivering obstetrician. Careful, complete, and detailed notes are encouraged since the physiatrist may be called to testify.
3. REHABILITATION MANAGEMENT AND TREATMENTS
Available or current treatment guidelines
There are presently no accepted, standardized treatment guidelines.
At different disease stages
- Management of the neonate with a diagnosed NBPI begins with the initiation of gentle passive range-of-motion exercises across the shoulder joint and elbow starting at 7 days of age.
- Prior to that, the affected extremity should be supported for protective purposes only and should not be ranged. Family members should be instructed not to hold infants under the arms as this can increase stress to the recovering plexus and shoulder joint.
- Splinting is not recommended in this initial period.
- Occupational therapy should focus on developmentally based incorporation of the arm into activity, either passively or actively. Additionally, the parents should be educated in home based stretching, strengthening, and developmental incorporation of the arm.
- Outpatient therapy and home-based programming continues as above, with the focus on contracture prevention, strengthening, and developmental incorporation and function.
- Taping may be applied to the shoulder and upper arm to facilitate improved upper extremity and scapular position, to influence scapulohumeral kinematics and to facilitate supination.
- Constraint induced movement therapy principles may be considered to facilitate improved incorporation of the affected extremity into activity.
- If, by 4 months of age, no more than trace movement is noted in elbow flexion or shoulder abduction, then referral to a trained hand surgeon or neurosurgeon for surgical exploration and repair is recommended.
- The optimal timing of surgery is controversial, though it is generally accepted that surgery be accomplished between 4 and 10 months of age to optimize outcomes.
- Outpatient therapy and home-based programming continues as above, with the long-term management focusing on prevention of contracture development (with development of subsequent osseous abnormalities) and facilitation of functional skills through the use of adaptive equipment and compensatory strategies.
- In appropriate patients, secondary surgical interventions can improve active range of motion and function, and include
- muscle-tendon transfers to achieve active motion in a functional plane
- internal rotation contracture releases to improve active range of motion
- humeral osteotomies to improve upper extremity positioning and subsequent function
Coordination of care
A multidisciplinary or interdisciplinary approach to management is recommended given the complex nature and variable recovery patterns of NBPI. This becomes even more critical when viewed in the context of the developing child.
- The Narakas categorization and Sedden classification systems are used to describe initial clinical severity and neuropathoanatomy, respectively.
- The Modified Mallet classification, the Toronto Score Test, and the Active Movement Score are tools commonly used in the older child to describe upper extremity movement and to standardize the clinical examination.
While there continues to be some controversy over the timing and type of surgery offered, consensus has begun to grow. Infants with clearly severe injuries, indicated by the presence of Horner’s Syndrome or flail arm, are recommended for early surgical exploration and intervention at 3 months. Infants with no antigravity biceps functionality by 5-6 months are generally offered surgery as well. The controversy of early surgery lies in the question of how long to wait in hopes of improvement. Some recently published animal model studies argue that increased survival of injured motor neurons and decreased neuroinflammation in the spinal cord can occur with earlier surgical intervention. Retrospective reviews of NBPI patients have even led to new prediction algorithms to help with making the decision of surgery vs no surgery.
- Botulinum toxin A (BTX-A) has been used to improve flexibility of shoulder rotators and to treat co-contractions. The toxin is injected into the normal functioning muscle/muscle groups to allow the weakened muscles/groups to strengthen.
- A meta-analysis by Buchanan et al supported the use of BTX-A to treat muscle co-contractures. The analysis included 325 patients over 10 studies.
- Outcome measures and BTX-A dosing varied between studies. Injections were also performed in conjunction with PT/OT, reconstructive surgery, and serial casting.
- 77% of 220 with internal rotation and adduction contractures of the shoulder, improved functional mobility (passive extension, abduction, external rotation). Injections sites included only pectoralis major or pectoralis major with latissimus dorsi, subscapularis, and teres major in some studies.
- 92% of 60 with flexion and extension lag of the elbow, experienced improved mobility and resolution of co-contractures following triceps injection.
- All 45 with pronation contracture of the forearm, improved supination and mobility post pronator teres injection.
- Older participants, over 7.5 years found by Basciani and Intiso, experienced poorer responses to BTX-A.
- Overall BTX-A effect persisted past its short half-life. Results included improvement of functional mobility and co-contractures even in cases refractory to other interventions like casting, PT/OT, and surgery.
Translation into practice: practice “pearls”/performance improvement in practice (PIPs)/changes in clinical practice behaviors and skills
- Deficits in passive lateral rotation of the shoulder, with the shoulder placed in full adduction, may be suggestive of pending posterior glenohumeral dislocation, especially in children under the age of 9 months.
- Deficits in active range of motion, when associated with full passive range of motion, may be caused by underlying abnormal co-contraction coupling between agonist-antagonist muscle groups.
4. CUTTING EDGE/EMERGING AND UNIQUE CONCEPTS AND PRACTICE
Cutting edge concepts and practice
Quality of Life
Quality of life throughout the lifetime of NBPI patients is a question often discussed with new parents. Recent research provides a surprisingly bright perspective on this topic. A variety of studies have shown that in early years and as adolescents and adults that quality of life measures are actually similar compared to the general population. While having a child with NBPI does impact parents from a worrying perspective and there are obvious affects to participation, work and education choices in the long run, this should provide hope to any parent. There are clear issues of psychological development that need to be addressed by the treatment team of any NBPI patient, including healthy coping strategies and how to interact with those unfamiliar with their injury. Further research into specific sub areas of quality of life affected in this population is ongoing should help continue to improve treatment management.
5. GAPS IN THE EVIDENCE-BASED KNOWLEDGE
Gaps in the evidence-based knowledge
- Continued research is needed to assess the long-term effects NBPI has on quality of life looking at a variety of different indicators other than simple health.
- A Controversy continues over the optimal timing of and indications for microsurgical repair of plexus lesions, as well as the type of repair provided. New techniques, including rapid MRI in the first 12 weeks of life, may help in surgical planning, but further research data is needed to confirm these methods.
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Original Version of the Topic
Robert Rinaldi, MD. Neonatal Brachial Plexus Injury. 11/10/2011.
Charles Taylor, II, MD
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Sheena Pillai, BS
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Robert Rinaldi, MD
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