The brachial plexus is an intricate, complex peripheral neural unit (Gilcrease-Garcia et al, 2020). It supplies the upper limbs, allowing expression of the mind through art, writing and exercise, as well as being the most useful aid to carry out almost all aspects of daily functioning. Injuries to the brachial plexus have consequences far beyond initial structural damage. While the initial injury is to the nerves, adverse events that follow involve the muscles, bones and joints of the affected extremity.
Obstetric brachial plexus palsy in newborn babies is often associated with increased force on the neck during passage through the birth canal, putting excessive strain on the brachial plexus and causing nerve injury (Palomo-Carrion and Sanchez, 2020). Obstetric brachial plexus palsy results from injury to the cervical roots C5–C8 and thoracic root T1 (Al-Qattan and El-Sayed, 2017) (Figure 1). As a result of the nerves exiting through the anterior vertebral foreman along the clavicle and towards the upper part of the arm, they can be injured with traction. Although many infants will regain function with no long-term deficits, a large proportion of children do not regain adequate function of the limb (Frade et al, 2019).
Classification
Brachial plexus injuries can be classified in several ways, such as by severity, where the injury is categorised as avulsion, rupture, neuroma or neuropraxia (Synder-Warwick, 2021) (Figure 2).
They can also be categorised based on anatomic location. Upper plexus palsy (also called Erbs Palsy) traditionally involves C5, C6 and C7 of the brachial plexus nerves. It is the most common form of obstetric brachial plexus palsy and presents with an adducted arm, internally rotated at the shoulder. It is often characterised by the ‘waiters tip’ posture, where the wrist is flexed and the fingers are extended (Figure 3a).
Lower plexus palsy involves branches C8 and T1 of the brachial plexus system. This is the rarest form of palsy, and its main clinical features include poor hand grasp.
Total brachial plexus palsy involves all five of the primary nerves in the brachial plexus. This is the most severe injury, where infants are left with a flaccid and insensate arm. There is a strong correlation between assisted births and total brachial plexus palsy (von Heideken et al, 2020).
Narakas (1987) classified obstetric brachial plexus lesions into four groups (Table 1), highlighting increasing severity from groups 1–4, the symptoms and the prognosis for each group. Classification of brachial plexus injuries by nerve root can be a useful tool for predicting future recovery patterns and identifying treatment options (Gilcrease-Garcia et al, 2020).
Table 1. Classification of obstetric brachial plexus palsy
| Group | Name | Roots injured | Site of weakness/paralysis | Likely outcome |
|---|---|---|---|---|
| 1 | Upper Erb's | C5, C6 | Shoulder abduction/external rotation, elbow flexion | Good spontaneous recovery in over 80% of cases |
| 2 | Extended Erb's | C5, C6, C7 | As above, with drop wrist | Good spontaneous recovery in about 60% of cases |
| 3 | Total palsy with no Horner syndrome | C5, C6, C7, C8, T1 | Complete flaccid paralysis | Good spontaneous recovery of the shoulder and elbow in 30–50% of cases. A functional hand may be seen in many patients |
| 4 | Total palsy with Horner syndrome | C5, C6, C7, C8, T1 | Complete falccid paralysis with Horner Syndrome | The worst outcome. Without surgery, severe defects throughout the limb are expected |
Prevalence
Although spontaneous recovery is known, there is a large subset of newborns who do not recover and require primary or secondary surgical intervention (Shah and Coroneos, 2021). In a study by Annika et al (2019), the incidence of persisting obstetric brachial plexus palsy was calculated as 19 per 38 749 live births or 0.49 per 1000 in the UK. According to Sienas et al (2017), the prevalence in the USA is 1.5 in 1000 live births, with Yarfi et al (2019) highlighting that shoulder dystocia had 100 times greater risk, an exceptionally large baby (>4.5 kg) had 14 times the risk and forceps delivery had nine times the risk for having a child with brachial plexus birth palsy.
Aetiology
There are many factors that can lead to a child being born with obstetric brachial plexus palsy. As a result of the impact on the child's physical and psychological development, there is a need to advance preventative strategies; therefore, the importance in determining the causes is widely recognised (Van der Looven et al, 2020).
Difficulty delivering the shoulders during childbirth (shoulder dystocia) has long remained the main obstetric cause (Benedetti et al, 1978; Rouse and Owen, 1999; Narendran et al, 2022), with the risk of an obstetric brachial plexus palsy being significantly reduced with a caesarean section (Kossambe et al, 2021). The risk increases with the number and types of manoeuvres required within a shoulder dystocia (Michelotti et al, 2018); however, this can be reduced with a systematic approach to shoulder dystocia training (Dahlberg et al, 2018).
For a standard delivery of the baby's head, gentle axial traction should be applied to allow the anterior shoulder to deliver under the symphysis pubis with clear avoidance of any downward traction, which has the potential to harm the brachial plexus (Royal College of Obstetricians and Gynaecologists, 2012). It can be instinctive to apply traction to the fetal head; however, strong downward traction is largely associated with permanent brachial plexus injuries (Crofts, 2017) Any traction should be applied carefully, slowly and in an axial direction. Crofts et al (2016) investigated management and outcomes of shoulder dystocia across a 12-year period following the introduction of an obstetric emergencies training program. They found that compliance with national guidance improved with continued training and led to a reduction in brachial plexus injuries at birth.
A systematic review published by Van Der Looven et al (2020) concluded that shoulder dystocia, macrosomia, maternal diabetes, instrumental delivery and breech delivery were the main risk factors for obstetric brachial plexus palsy. Macrosomia was confirmed as the second biggest risk factor, with incidents expanding rapidly with increasing birth weight (Lipscomb et al, 1995; Van Der Looven et al, 2020).
Maternal diabetes was also a significant factor. Disproportionate growth of trunk with a smaller head to abdominal ratio is well documented in women with diabetes (Shinohara et al, 2021). A large study conducted by Freeman et al (2017) highlighted that 61% of diabetic mothers underwent a caesarean section, with Van Der Looven et al (2020) speculating that this may be related to a fear of shoulder dystocia or obstetric brachial plexus palsy.
In 2015, the landmark case of Montgomery v Lanarkshire legally reaffirmed the concept of informed consent to inform women of the risks of shoulder dystocia, after it was argued that if Nadine Montgomery had known the risks, she would have requested a caesarean section. It established a duty of care to warn patients of material risks, with the test of materiality defined as ‘a reasonable person in the patient's position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it’. Rather than being a matter for clinical judgement, the ruling assessed that a patient should be told whatever they want to know, not what is deemed relevant by professional opinion (Chan et al, 2017).
With a breech birth, there is a significant increase in the chance of developing an upper obstetric brachial plexus palsy injury or a bilateral injury (Synder-Warwick, 2021). While there is no definitive answer as to why this is the case, Kekki et al (2023) indicated that it may be linked to unnecessary traction on the shoulders during birth or difficulties delivering an entrapped head.
In practice, healthcare professionals are confronted with the aforementioned difficulties, which are often interrelated (Figure 4). There is a clear association between obstetric brachial plexus palsy and macrosomia in diabetic mothers, where children have a total brachial plexus palsy and therefore a significant disability (Narendran et al, 2022).
Impact on individuals
As a child matures, other complications often develop as a result of obstetric brachial plexus palsy. A study of children with obstetric brachial plexus palsy from the Netherlands reported that more than 45% had pain in the affected arm (Spaagaren et al, 2011). According to Annika et al (2019), children often need help with everyday activities, such as washing, dressing and cutting up food, and many have pain in the affected arm. Occupational therapy input is particularly helpful with these difficulties as the child develops. In a Swedish follow-up study of children with obstetric brachial plexus palsy, Pondaag and Malessey (2020) highlighted that grip strength in the affected hand was almost unchanged over time, in contrast to the range of movement of the elbow, which increased. Many children with obstetric brachial plexus palsy develop an elbow flexion contracture. Muscular imbalance in the shoulder may increase with age and may result in glenohumeral joint deformity. Pondaag and Malessey (2020) stressed the importance of long-term follow up because of the proportion of children who will suffer from functional impairment, secondary deformities and pain.
Treatment options for children with obstetric brachial plexus palsy are intensive physiotherapy, occupational therapy, nerve reconstruction and orthopaedic surgery (Annika et al, 2019). Children with upper and total plexus palsy displaying nerve root avulsions and/or ruptures are treated by early primary nerve reconstruction in the first few months of life followed by secondary corrections (Pondaag and Malessey, 2020) (Figure 3b).
Those born in countries such as Africa often face a deficit in healthcare and have poorer outcomes than in high-income countries. Hamzat et al (2015) reported that in African countries only 52% of obstetric brachial plexus palsy cases were referred for physiotherapy within 1 month of diagnosis, the treatment disposition for the majority (88.1%) of children was not documented and only 4.8% were formally discharged from physiotherapy. The clinical, economic and social implications of the condition were discussed by the authors, highlighting the need for an early referral to physiotherapy. Children who need surgery often go without as a result of financial concerns, leaving the child with residual functional deficits.
Professional role
Healthcare professionals should consider the overall impact of obstetric brachial plexus palsy and use a multidisciplinary approach with specialist obstetric brachial plexus palsy centres, physiotherapists, occupational therapies and mental health services. Early access to intervention has been proven to support favourable outcomes in terms of recovery. Coroneos et al (2017) identified four existing gaps for the primary management of obstetric brachial plexus palsy, including historic poor use of evidence, timing of referral to multidisciplinary team, indications and timings of nerve repair and distribution of expertise.
The main aim should be to identify babies whose injury will not spontaneously recover (NHS, 2023), which is usually done by a specialist brachial plexus team in the UK, most commonly in Leeds, the Royal National Orthopaedic Hospital and Glasgow, although there are units at Alder Hay and Birmingham. Identification is done using the Toronto Scale, which was developed in 1994 to predict a child's prognosis prior to surgical intervention. On a scale of 0 (no motion or contraction) to 7 (full motion), if a 3-month old baby scores <3.5, this result is an indicator for nerve surgery (Gupta et al, 2022). A referral to a specialist within the first 6 weeks if the arms remain unequal is paramount as, if required, primary nerve surgery is a time sensitive operation (Bleasdale 2022). This should be completed earlier, at the 2-week review, if there has been no improvement, Horner's Syndrome is identified of if the baby was breech. Horner's Syndrome is a rare condition classically presenting with dropping of the eyelid (partial ptosis), a constricted pupil (myosis) and facial anhidrosis, which is characterised as an absence of sweating as a result of disruption in the sympathetic nerve supply (Khan and Bollu, 2023). A referral to physiotherapy as an urgent outpatient upon leaving hospital is also important to prevent contractures in the limb and optimise motor and sensory development (Frade et al, 2019). Figure 5 shows full guidelines on the management of a brachial plexus injury.
Those assessing the child should comment on posture, passive and active movement (Gupta et al, 2022) and reflexes. They shouls also assess the eyes for Horner's Syndrome, which is often an indication of a more severe injury, the child's breathing for phrenic nerve palsy and the clavicle and humerus for signs of fracture (Duff and DeMatteo, 2015).
There is a tendency among practitioners to be overly reassuring about the long-term prognosis of the injury, which can often lead to further upset and animosity if their child does not fully recover (DeMatteo et al, 2014). According to Evans-Jones et al (2003), around 52% of children fully recover, with 46% showing a partial recovery and 2% having no recovery at all (Figure 6). Shah and Coroneos (2021) highlighted that 80% of children with a global c5–T1 injury will continue to have persistent deficits at 18 months, with long-term consequences including development of skeletal malformations and cosmetic deformities. According to the guidelines for neonatal brachial plexus injury in Bleasdale (2022), parents should be directed to the Erb's Palsy Group Charity for further support at this difficult time. It is important to recognise that parents may go through the grief cycle and the loss of an ‘anticipated baby’, with the situation being perpetuated by the continued presence of the injury (Bellew and Kay, 2003).
Conclusions
This article reiterates the importance of early referral into brachial plexus specialist units in the UK. A multidisciplinary approach is paramount in facilitating the correct care and treatment for babies diagnosed with obstetric brachial plexus palsy. While there are many obstetric risk factors that increase the likelihood of a shoulder dystocia delivery, when it does arise, there should be clear avoidance of any downward traction. This is the best way to avoid permanent brachial plexus injuries. Do not pull hard, do not pull quickly and do not pull down.
Key points
- This article reiterates the importance of early referral to brachial plexus specialist units in the UK for obstetric brachial plexus palsy.
- Nearly half of children with this injury will not make a full recovery.
- As a child develops, complications often arise, such as pain, problems with the shoulder and elbow requiring secondary surgery and difficulty adapting to everyday activities.
- The main risk factors for a brachial plexus injury include shoulder dystocia, macrosomia, maternal diabetes, instrumental birth and breech birth.
- Best practice indicates any traction should be applied carefully, slowly and in an axial direction: do not pull hard, do not pull quickly and do not pull down.