History and exam

Key diagnostic factors

common

paralysis of an arm

Lack of movement of an affected extremity defines brachial plexus birth injury. Patients with global injuries may have flaccid paralysis of the entire limb.

This is the main complaint reported by parents bringing in their child for evaluation.[5] However, if paralysis occurs following normal arm movement, an alternative diagnosis should be sought.

observed decreased motion of an arm

Quite evident in children affected by brachial plexus birth injury, including Erb's palsy.[46][47][48][49]

abnormal posture of the arm

Children affected by Erb's palsy will hold their arm differently from the other unaffected extremity, usually holding it at the side with the shoulder internally rotated, elbow extended, forearm pronated, wrist flexed, and fingers flexed, known as the 'waiter tip' position.[46][47][48][49]​ Patients with global injuries may have flaccid paralysis of the entire limb.

Other diagnostic factors

uncommon

crepitance of clavicle or humerus

Often present in children with neonatal fractures, which may or may not be associated with brachial plexus birth injuries.[50][51][83][84]

Horner's syndrome

May be present in children with severe brachial plexus birth injury related to nerve root avulsion from the spinal cord.[43]

tachypnoea, respiratory distress, feeding difficulties, failure to thrive

May indicate the presence of diaphragmatic paralysis due to phrenic nerve injury.[44][45]

lack of full range of passive movement

If present should lead to a search for evidence of dislocation (rare) or consideration of alternative diagnoses.[52]

hyper-reflexia, persistent primitive reflexes, abnormal muscle tone, or abnormal body posture

Children who have been hypoxic after delivery and required resuscitation may show signs of central nervous system dysfunction, or hypoxic ischaemic encephalopathy, such as hyper-reflexia, persistent primitive reflexes, abnormal muscle tone, or abnormal body posture.

Risk factors

strong

shoulder dystocia

Associated with a 115-fold increase in risk of BPBI.[15] Disproportion of the shoulders and birth canal allows the head to be delivered while the shoulders remain stuck. Pressure from delivery can cause traction on the brachial plexus, resulting in a BPBI.[23]​ 

Mothers with prior deliveries complicated by shoulder dystocia may be at risk of shoulder dystocia on subsequent delivery.[23][24]

large fetal size (>4000 g)

Associated with a 9.75-fold increase in risk of BPBI.[15]​ The risk of brachial plexus injury increases as fetal size increases, and is highest in babies ≥4400 g.​[25][26]​ Large width of the shoulders can lead to dystocia and increased force transmitted to the brachial plexus during delivery.

maternal diabetes (especially type 1) or gestational diabetes mellitus

Can lead to macrosomia in the fetus. A full-term delivery can result in a child over 4000 g.[19][27]

Gestational diabetes is associated with a five-fold increase in risk of BPBI.[15]

maternal obesity

Maternal obesity is associated with a fivefold increase in risk of BPBI.[28]

Estimation of fetal size and pelvic proportions may be more difficult in women with obesity.

weak

breech presentation

Associated with a 2.5-fold increase in risk of BPBI.[15] Difficulty in extracting the trailing arm during breech delivery can be a risk for BPBI.[15][29][30][31]

More severe nerve injury and injuries to the lower plexus may be seen with this type of delivery. Children affected by BPBI after breech deliveries tend to be of low birth weight.

atypical second phase of labour

Both prolonged and precipitous second stages of labour have been implicated in cases of BPBI.[20][32][33] However, many cases demonstrate an absence of abnormal labour patterns.[34]

assisted delivery

Associated with a 3.8-fold increase in risk of BPBI.[15] The use of assistive techniques such as vacuum or forceps to facilitate the delivery can cause a stretch injury or rupture.[15][19][35]

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