Brachial Plexus Assessment and Common Injuries

The nerve supply to the arm is from nerve roots C5-T1 via the brachial plexus. The nerves pass under the clavicle and end in the axilla.¹

Signs and symptoms

Traumatic injury mostly occurs in severe road traffic accidents (especially on a motorcycle) and falls from heights. Young men are most commonly affected. The position of the arm (as the injury occurs) will determine the levels involved.

If the arm was held at the side, a C8-T1 injury is usual. However if the arm is abducted, C7 is commonly involved.
Symptoms are often associated with:

• Broken clavicle
• Swelling around shoulder
• Neck and shoulder pain
• Paraesthesiae and weakness in arm
• Horner's syndrome indicates complete lesion in lower plexus, i.e. C5-C7

Examination

Sensory nerves:

Pinch nail base, pull finger outwards and ask about feeling anything. A burning feeling indicates continuity in the following nerves; absence does not necessarily mean nerve is divided but may be due to neurapraxia instead.

Many cases are temporary, with full function recovering within 1 week. Permanent injury is found in up to 25%.²

• There are 2 types of brachial plexus paralysis in neonates; the upper plexus injury is called Erb's palsy. The lower plexus injury is called Klumpke's palsy.
• They occur in approx.1 per 1,000 term deliveries and are particularly associated with a heavy birth weight and shoulder dystocia.²
• They can occur when the head is pulled away from the shoulder during delivery. A small proportion is unrelated to delivery.³

Risk factors

• Large birth weight and/or maternal diabetes
• Breech presentation
• Multiparity
• Second stage of labour lasting more than 60 minutes
• Assisted delivery
• Intrauterine torticollis
• Shoulder dystocia

Examination

Examine 48 hours after delivery for a more reliable assessment.

• Erb's palsy (C5-C6 injury) - the arm is characteristically held adducted and internally rotated with the forearm pronated, hand and wrist flexed ("waiter's tip" position). Infant is unable to move the arm or shoulder.
• Klumpke's palsy - Horner's syndrome is present, i.e. meiosis, ptosis, anhydrosis.

Investigations

• High-resolution MRI requires no radiation exposure, is non-invasive, and provides more detail than CT myelography.
• Plain X-rays can be useful to diagnose hemidiaphragm paralysis from phrenic nerve involvement, or fractures of the clavicle or humerus.
• Electromyography.
• Nerve conduction studies.

General measures

• Adult trauma; physiotherapy with possible bracing to prevent contractures.
• Neonatal; spontaneous recovery usually occurs and can start within days but can take months. Physiotherapy can help.⁴ Other treatments include botulinum toxin injection and electrical stimulation.^5,6 Neuromuscular electrical stimulation (NMES) is a treatment used in an older child, where muscles are stimulated by pulsating alternating currents. It should be titrated with guidance from the child to allow muscle contraction without pain.

Surgical

• Specialist surgical repair in tertiary centres; options include nerve transfers, nerve grafting, muscle transfers and neurolysis of scar around the brachial plexus.
• In neonates, surgery is recommended if function has not returned after 3-4 months.

• Progressive contractures.
• Deafferentation pain; this occurs when the nerve roots are avulsed in preganglionic lesions. The cells in the dorsal column are robbed of their nerve supply. After the injury (days to weeks), spontaneous signals are generated by these cells, which result in intractable pain for the patient.
• Bony deformities.
• Scoliosis.
• Posterior shoulder dislocation.
• Agnosia of the affected limb.