Brachial Plexus Injuries

The brachial plexus is a complex collection of interconnected nerves which is placed on both sides of the neck and runs down towards the armpit where it splits into a series of nerves which run down the arm. Like all nerves this plexus is vulnerable to trauma such as knife injuries, gunshot wounds, direct blows and sudden stretching which is referred to as traction. Brachial plexus injuries can be very severe and long lasting with significant disability, in some cases leading to an intractable chronic pain problem in a useless arm.

Motorcycle injuries are the most common mechanism of brachial plexus injury, with severe traction occurring as the shoulder and head hit the ground, forcing the two structures apart and stretching the nerves severely. Wrenching the arm violently away from the body is a typical injury, with high speed car injury also providing many victims. Penetrating injuries from attacks with knives or guns or direct trauma from falls from a height or blunt objects can also give a brachial plexus injury.

The number of brachial plexus lesions is difficult to estimate as they are very variable and not common, being most common in fifteen to twenty-five year old males who make up a great preponderance of trauma victims. Narakas, who treated many of these injuries, indicated his rule of seven seventies:

Motor vehicle accidents caused 70% of the injuries and 70% of these were on motorbikes, 70% of which had multiple injuries.

70% of these had supraclavicular injuries, damaging the area above the collar bone where the brachial plexus lies

One nerve root was torn in 70% of the supraclavicular injuries, and 70% of nerve roots were the lower cervical ones, 70% of which were responsible for a chronic pain problem.

The brachial plexus nerves can be badly damaged by the wrenching injury which occurs when the arm and the neck are violently moved apart. The damage varies from a minor stretch injury to the complete rupture of the nerves away from the spinal cord. Ruptures which occur close to the spinal cord are more serious and have limited scope for reconstruction or recovery. They differ from ruptures which are located further from the spinal cord which can have a better recovery potential. If the arm is at the side at injury then the higher nerve roots (C5 and C6) are more likely to be injured, whilst if the arm is wrenched overhead in the injury the lower nerves (C8 and T1) are more likely injured.

In multiple injuries it is important to consider a detailed examination of the upper limb to exclude a brachial plexus injury. Patients complain typically of pain in the neck and shoulder, weakness and heaviness in the arm and abnormal feelings such as pins and needles and abnormal pain sensations. There may be significant shoulder swelling and if the pulses are reduced or absent then consideration should be given to vascular injury from the traction. The doctor performs a careful sensory, motor and reflex examination to indicate which nerves have been damaged and whether they are completely ruptured or still in continuity. This can be difficult as the anatomy of the plexus varies so experience is needed to interpret the results.

Conservative management of lesions of the brachial plexus was common in the past, with waiting for any recovery the main strategy, recording the changes which occurred. By twelve to eighteen months after injury the recovery was considered to be complete, accepting that some further improvement could occur with time. The aim was to make the arm more stable, predictable and useful or amputate it if it could not be made so. Modern management emphasises recovery by early surgical treatment of open sharp object injuries to repair the nerves directly, with delayed intervention in blunt injuries.

During the long period waiting for any improvement, often up to 18 months, it is difficult to manage the problems such as development of chronic pain, arm swelling and maintenance of the normal ranges of the joints. Physiotherapists are closely involved in the maintaining of healthy joints and the strengthening of recovering muscles. The restoration of functional muscle strength by surgical intervention is more predictable in younger people.