The brachial plexus is a network of nerves connecting the spine at the base of the neck to the shoulders and upper extremities. Brachial plexus birth palsy (BPBP) is upper-limb paralysis in a newborn owing to injury to one or more nerve roots of the brachial plexus. The most prevalent form is Erb’s palsy, whereby movements around the shoulder and flexion at the elbow are impaired due to injury to C5-C6 nerve roots. Total BPBP occurs when nerve roots from C5-T1 are injured, thereby impairing all movement and sensation in shoulders, arms, elbow, wrist, and fingers. In most cases, injuries are transient and recover spontaneously within 1 month to 2 years; however, ~27-35% of BPBP cases may develop permanent upper-extremity paralysis. Prognosis depends on the severity and location of the injury.
Pathophysiology
- Maternal
- Gestational diabetes
- Excessive weight gain
- Uterine anomalies such as fibroma and bicornuate uterus
- History of BPBP during a previous birth
- Macrosomia (birth weight >4 kg)
- Decreased fetal arm movements
- First cervical rib and clavicular fracture
- Shoulder dyscotia (increases risk by 100 times)
- Birth injury to humerus
- Instrumented delivery
- Tachysystole (> 6 contractions in 10 min or 1 large contraction lasting >2 min)
- Use of oxytocin
- Short second stage of labor
- Ventral nerve roots C5-C8 and T1, originating from C5, C6, C7, and T1 vertebrae
- Depending on the nerve roots injured, ≥1 of the following muscles can become paralyzed:
- Deltoid
- Supraspinatus
- Infraspinatus
- Serratus anterior
- Rhomboids
- Clavicular head of pectoralis major
- Teres minor
- Biceps
- Brachialis
- Extensor carpi radialis longus and brevis
- Flexors of wrist
- Flexors of fingers
- Intrinsic muscles of hand
- Fetal
- Labor related
Related Anatomy
- Neuropraxia: mildest injury involving damage only to the peripheral nerve and myelin sheaths; resolves spontaneously within a couple of months
- Axonotmesis: damage to axons and myelin sheath with peripheral nerve sheath intact; recovers spontaneously
- Neurotmesis: complete peripheral nerve rupture with complete or partial transection; requires nerve repair or reconstruction
- Pre-ganglionic avulsion: most severe injury of spinal cord roots; cannot be repaired by surgery and has the worst prognosis
Exam Findings, Signs and Positive Tests
Physical exam findings:
- Erb’s Palsy
- The affected arm is adducted and internally rotated with extended elbow pronated forearm and extended wrist
- Absence of Moro reflex
- Absence of response on stimulation of the deltoid
- Absence of active flexion at the elbow
- Presence of grasping reflex and finger function
- The hand may appear flaccid in the first few hours after birth
- Intermediate palsy or extended Erb’s palsy
- The affected arm is adducted and internally rotated with elbow in extension, forearm in pronation, wrist in flexion and ulnar inclination
- Absence of Moro reflex
- Absence of response on stimulation of the deltoid
- Absence of active flexion at the elbow
- Presence of grasping reflex and finger function
- The hand may appear flaccid in the first few hours after birth
- Klempke’s Palsy
- The wrist and the hand are paralyzed; the elbow and shoulder retain normal function
- The affected shoulder is abducted, arm in supination with bent elbow and extended wrist
- "Claw hand" presentation
- Signs of Horner’s syndrome may be present in case of avulsion injury of the nerve roots
- Total BPBP
- Affected arm is inert and hanging loosely
- Absence of deep tendon reflexes
- Absence of sensory functions
- Signs of Horner’s syndrome may be present in case of avulsion injury of the nerve roots
Work-Up Options
- Initial phase after birth
- Clinical exam
- Evaluate respiratory status to assess the status of phrenic nerve
- Assess response to provocative stimulation
- Moro reflex
- Grasping reflex of the fingers
- Stretch (myotatic) reflex
- Cutaneous zone opposite to the muscle concerned
- Assess motor recovery score
- Assess sensory nerve function
- Assess sensory functions corresponding to dermatomes closely
- X-rays
- Scapular girdle and the humerus to search for clavicular or humerus fracture
- Chest if phrenic nerve involvement is suspected
- If spontaneous recovery is not seen in 3 months
- Magnetic resonance imaging (MRI) to visualize spinal cord and certain areas of brachial plexus
- Information from MRI is useful in deciding the nerve repair strategy
- MRI of the shoulder in toddlers and older children to assess glenohumeral dysplasia and to identify candidates for shoulder tendon transfer
Incidence and Related Conditions
- Incidence of BPBP is estimated to be 0.4–2/1000 live births
- BPBP is most often unilateral; it rarely affects both arms
- Erb’s palsy is the most prevalent form, occurring in 46% of cases
- Extended Erb’s palsy/intermediate palsy occurs in 27% of cases
- Total BPBP occurs in 20% of cases
- Klemke’s palsy occurs in <2% of BPBP cases
- Glenohumeral dysplasia, or posterior shoulder dislocation, may occur in association with BPBP as early as 3 months of age in ~60–80% of BPBP cases
- Horner’s syndrome (characterized by constricted pupil, droopy eyelid and decreased sweating) may be present in cases of nerve root avulsion
Differential Diagnosis
- Pseudoparesis
- Amyoplasia congenita
- Congenita varicella syndrome
- Neurological lesions at other neuroanatomical levels
- Radial nerve palsy
- Physeal injury of the proximal humerus
- Septic osteoarthritis of the shoulder