Brachial plexus assessment and common injuries

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 axilla¹ .

Brachial plexus

Brachial plexus injuries in adults²

Severe brachial plexus injuries cause dramatic consequences on the motor and sensory functions of the upper limb. The increased incidence of motor vehicle accidents during the past century has been associated with a significant increase in brachial plexus injuries² .

Milder injuries of the brachial plexus can occur, with transient symptoms and with a full recovery. Milder injuries are more common in some sports, such as martial arts³ .

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 the shoulder.

• Neck and shoulder pain.

• Paraesthesiae and weakness in the arm.

• Horner's syndrome, which indicates complete lesion in the lower plexus, ie C5-C7.

Examination

See also the separate Neurological Examination of the Upper Limbs article.

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

Motor nerves
Examination can be made difficult by anomalous nerve distribution, including C4 contributing to the brachial plexus and also because many muscles are supplied by more than one motor neuron. Assessment of loss of motor function at the cervical root:

Brachial plexus injuries in neonates

Obstetric palsy is classically defined as the brachial plexus injury due to shoulder dystocia or to procedures performed during difficult childbirths. Obstetric palsy occurs in uncomplicated deliveries and in caesarean deliveries, and there are multiple factors that can cause it⁴ .

Many cases are temporary, with full function recovering within one week. However, permanent injury is not uncommon. See also the separate Birth Injuries to the Baby article.

• There are two 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.

• In the UK the incidence is 0.42 per 1,000 live births⁵ .

• They can occur when the head is pulled away from the shoulder during delivery. A small proportion is unrelated to delivery⁶ .

Risk factors

• Large birth weight and/or maternal diabetes.

• Shoulder dystocia (increases the risk for brachial plexus injury 100-fold).

• Breech presentation.

• Multiparity.

• Second stage of labour lasting more than 60 minutes.

• Assisted delivery.

• Intrauterine torticollis.

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). The infant is unable to move the arm or shoulder. See the separate Erb's Palsy article.

• Klumpke's palsy - Horner's syndrome is present, ie meiosis, ptosis, anhydrosis.

Investigations²

Myelography, CT myelography, and MRI are indicated for the evaluation of brachial plexus. Electrodiagnostic and nerve conduction studies in association with the clinical findings can provide information regarding the location of the lesion, the severity of trauma, and expected clinical outcome.

• High-resolution MRI requires no radiation exposure, is non-invasive and provides more detail than CT myelography⁷ .

• 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.

Brachial plexus treatment and management^{8 9}

Nerve damage causes a multifaceted clinical picture consisting of sensorimotor disturbances (pain, muscle atrophy, muscle weakness, secondary deformities). Brachial plexus injury may result in severe and chronic impairments for both adults and children. Therefore early treatment and extensive rehabilitation are required. Psychological problems associated with brachial plexus injury may limit rehabilitation effects and increase disability .

General measures

• Adult trauma: rehabilitation may play an important role in reducing disability.

• Neonatal: spontaneous recovery usually occurs and can start within days but can take months:
  

  • Physiotherapy can help¹⁰ .

  • Other treatments include botulinum toxin injection and electrical stimulation¹¹ .

  • 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.

• Prevention of obstetric injury is not always possible, as a significant proportion of injuries may occur in utero¹² .
  

Surgical

• Specialist surgical repair in tertiary centres: options include nerve transfers, nerve grafting, muscle transfers and neurolysis of scar around the brachial plexus¹³ .

• Phrenic nerve transfer has shown useful recovery of arm function in some patients; however, there is very little information about long-term functional and quality-of-life outcomes. There is also some evidence of consequent impairment of respiratory function. However, because patients with brachial plexus injuries are often very disabled and treatment options may be limited, the National Institute for Health and Care Excellence (NICE) recommends that phrenic nerve transfer may be considered as a treatment option¹⁴ .

• NICE guidance states the evidence on the safety of free-functioning gracilis transfer to restore upper limb function in brachial plexus injury shows well-recognised complications (pain, bleeding, infection and graft failure). However evidence on its efficacy is adequate to support the use of this procedure. This procedure should only be performed in a specialist brachial plexus unit by a multidisciplinary team including specialised physiotherapists, with input from microvascular surgeons¹⁵ .

• Arthrodesis of the shoulder may be considered but much more rarely in view of advances with nerve, tendon and free muscle transfers. Wrist arthrodesis may also be considered for wrist pain and gives stability to the hand.

• In neonates, surgery is recommended as an early intervention, as outcome is best if repair is undertaken within three months¹⁶ .

Complications

• 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.