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.
The commonest mechanism of injury is a traction injury where the arm is wrenched suddenly away from the body, with the neck in some cases travelling the opposite way, adding to the stretch. The commonest reasons for this kind of injury are motorcycle injuries where the shoulder and the head are stretched apart as the person hits the ground with speed, with high speed car injuries also contributing. Penetrating injuries from knives, bullets or other objects in a fall, falls from a height and a direct blow from a hard object can all cause this 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:
70% were from traffic accidents of which 70% were motorcycle accidents and 70% of these had multiple injuries
70% of those with multiple injuries had injuries above the clavicle area, so-called supraclavicular injuries.
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.
A detailed examination of the arm may be necessary in a case of multiple injuries to ensure a brachial plexus lesion is not present. Typical symptoms are pain in the shoulder and neck, heaviness and weakness in the arm and abnormal sensations such as abnormal pain feelings or pins and needles. The shoulder can be very swollen and vascular injury from blood vessel traction should be suspected if pulses are absent or reduced. Medical examination of the reflexes, motor power and sensibility is performed to establish the nerves which have been injured and the degree of their injury. Testing for this can be difficult as nerve anatomy is variable and experience is necessary for interpretation.
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.
As useful recovery may take more than eighteen months the maintenance of joint ranges, the control of swelling and the management of the chronic pain problem can be difficult. Surgery is much more effective for younger patients in terms of restoring functional strength.
Jonathan Blood Smyth, editor of the Physiotherapy Site, writes articles about
Physiotherapy, back pain, orthopaedic conditions, neck pain, injury management and
physiotherapists in Glasgow. Jonathan is a superintendant physiotherapist at an NHS hospital in the South-West of the UK.
