What is it?
Erb’s Palsy (also known as Brachial Plexus Paralysis) is a condition which is mainly due to birth trauma. It is a paralysis of the arm that can affect 1 or all 5 of the primary nerves that supply the movement and feeling to an arm (specifically the upper trunk C5-C6 is severed to cause the palsy, but not exclusively). These nerves form part of the brachial plexus. They come out of the spinal chord between the bones of the neck (the vertebrae), comprising the ventral rami of spinal nerves C5, C6, C7, C8 and T1. The brachial plexus are the major nerves of the arm and run from the neck, passing under the collar bone to the level of the armpit.
Each baby’s injury is individual and the paralysis can be partial or complete. The damage to each nerve can range from bruising to tearing, so prognosis depends on the extent of the damage. Some cases resolve on their own over a period of months, whilst others require specialist therapy or even surgery. In all cases, however, early intervention is crucial so that the full extent of the damage can be ascertained and treatment begun. Treatment in the first year of life can have a significant impact on recovery.
Nerves are chord like structures of tissue from a collection of nerve fibres. One nerve may contain thousands of fibres (like a telephone cable). These fibres in the arm carry electrical messages from the brain to the muscle so that the muscle can work and move the arm. When a nerve is damaged the muscle that moves the arm may be weakened as the message is not getting to the muscle. Damaged nerve fibres that are outside the spinal chord can repair themselves; however, if an entire nerve is damaged or broken it can not grow back to the muscle.
The most common cause of Erb’s Palsy is an abnormal of difficult childbirth or labour. It can happen if there is excessive pulling on the shoulders during a head first delivery. It can also be the result of the baby’s head and neck being pulled towards the side at the same time as the shoulders pass through the birth canal. The injury can also occur in a breech delivery where there is pressure on the raised arm. Similar injuries can occur at a later age following a traumatic fall onto the side of the head and shoulder, where the nerves and plexus are violently stretched.
The signs of Erb’s Palsy include loss of sensation in the arm as well as paralysis and atrophy of the deltoid, biceps, and brachialis muscles. This results in a characteristic position of the arm where it hangs by the side and is rotated medially; the forearm is extended and pronated. The child can not raise the arm from the side and the elbow can not be flexed (bent). The forearm can not be supinated (rotated and turned upwards with palm facing up). The classical physical position is called a “waiter’s tip” (turning backwards).
When all the nerves are affected and the entire arm and hand is limp, there may be an associated Horners syndrome. This is when the child’s eye lid droops and the pupil in the eye may be smaller. There may be an associated Torticollis too (the baby faces away from the affected arm and is unable to face forward for any length of time). If the injury occurs at birth it may stunt the growth of the arm from the shoulder to the fingertips.
There are many factors that affect how severe the injury is and this, in turn, depends on the number of nerves affected. The paralysis can be partial or complete and the most commonly involved nerves are the suprascapular nerve, musculcutaneous nerve, and the axillary nerve. Sometimes all the nerves may be affected causing weakness or paralysis of the entire arm or hand. The injury is so individual where by one or all of the muscles can become paralysed. Treatment will, therefore, depend on the specific patient. There are, however, four classifications of Erb’s Palsy that describe the severity of the injury:
· Avulsion (most severe type)
Stretch- The fibres have only been mildly stretched and the child can recover use of the muscle quite quickly. The more fibres that are stretched or pulled apart, the weaker the muscle will be and the longer it will take to start working properly again.
Neuroma- The nerve is severely damaged, but still remains connected. It may heal, but scar tissue may form at the site of the injury. The scar tissue may stop the electrical messages from the brain getting to the muscle.
Rupture- The nerve is completely pulled apart and can not repair itself. The muscles it controls will remain paralysed. It is sometimes possible to have surgery that will restore some nerve function; however, the child is likely to be left with some residual weakness in the arm.
Avulsion- In rare cases the nerve is torn away from the spinal column. Neonatal/paediatric neurosurgery is often required.
For the babies that do not fully recover on their own (usually evident within 3 to 4 months), specialist intervention is required. Range of movement is usually recovered within a year, but individuals that have not healed after this point will rarely gain full function in their arm, but may continue to improve. They may also be prone to developing arthritis.
Occupational Therapy and Physiotherapy (combined with Hydrotherapy) are the main forms of treatment besides surgery. Once the child has had surgery they will need OT and PT to support the surgical results.
Most of the initial Occupational Therapy treatment will involve the parents. They usually have home programmes and their therapist shows them how to carry out the exercises and activities. These have to be done several times a day with at least 10 repetitions of each motion. The programme becomes part of baby’s life and daily routine.
The programme includes gentle range of movement exercises for the baby in a prone lying position. The aim is to increase joint flexibility and muscle tone as well as sensory awareness with tactile stimulation using various textured materials. The extremity of the limb needs vibration and massage to increase its sensory awareness in the overall body scheme.
Joint compression/weight bearing throughout involved extremity will increase the proprioceptive input/muscle contraction.
The active use of the arm in purposeful activities that are developmentally appropriate will encourage range of movement and increase strength and co-ordination. These movements should be graded beginning in gravity eliminated and then advancing to against gravity.
Bilateral motor planning activities should always be included.
Sometimes splinting may be necessary e.g. to hold the arm in supination and external rotation. The Occupational Therapist will advise on suitable and necessary splinting methods.
Usually the last movements to return are:
· Full shoulder flexion/abduction using deltoid musculature
· Supination (children do not actively and spontaneously do this until 11 months of age)
· External rotation
· Full elbow extension using triceps
In eighty percent of these cases, a baby born with Erb’s palsy will recover without the need for surgical Erb’s palsy treatment. In other cases children can benefit from surgical Erb’s palsy treatment and other rehabilitative techniques. Research has shown that children between the ages of five and twelve months benefit most from surgical Erb’s palsy treatment. Surgical Erb’s palsy treatment is often less effective after one year of life. Younger children tend also to recover more quickly from surgery to repair Erb’s palsy.