IN NEONATES - Mainly due to obstetrical causes like:
Position of the limb: Arm hangs by the side; it is adducted & internally rotated; forearm is extended & pronated (`policeman`s tip hand`).
An incidence of 0.8-1 per 1,000 births has been reported for brachial plexus birth palsy (BPBP) in the US. Erb's palsy accounts for about 45% of BPBP. Additional injury to C7 is commonly discovered in 20% of cases of BPBP.
Incidence of permanent impairment is 3-25%. The rate of recovery in the first few weeks is a good indicator of final outcome. Complete recovery is unlikely if no improvement has occurred in the first two weeks of life.
Mechanism of injury
The most common cause of Erb's palsy is excessive lateral traction or stretching of the baby's head and neck in opposite directions during delivery usually associated with shoulder dystocia. This may happen during delivery of the head, the head may be deviated away from the axial plane. There can also be compression of the brachial plexus causing it to stretch and tear. Sometimes, pulling on the infant's shoulder during delivery or excessive pressure on the baby's raised arm during a breech delivery can cause brachial plexus injury. Two potential forces act on the brachial plexus during labor- natural expulsive force of the uterus, traction force applied by the obstetrician.
The classical signs of Erb’s palsy is water’s tip deformity.
This is due to loss of the lateral rotators of the shoulder, arm flexors, and hand extensor muscles.
The position of the limb, under such conditions, is characterized by : the arm hanging by the side and is rotated medially, the forearm extended and pronated and the wrist flexed. Also, there is loss of sensation in the lateral aspect of the forearm.
The arm cannot be raised from the side; all power of flexion of the elbow is lost, as is also supination of the forearm. Muscles most often paralyzed are supraspinatus and infraspinatus because the suprascapular nerve is fixed at the suprascapular notch (Erb's point).
In more severely affected patients deltoid, biceps, brachialis, and subscapular is affected (C5 and C6). Elbow flexion is weakened because of weakness in biceps & brachialis. If roots are damaged above their junction, paralysis of rhomboids and serratus anterior is added, producing weakness in retraction and protraction of scapula.
A thorough history and physical examination with focus on neurologic examination are used to confirm diagnosis.
History- aims to gather information about pregnancy complicated either by gestational diabetes or maternal obesity, fetal macrosomia, prolonged second stage labour, shoulder dystocia, use of assitive techniques-forceps to aid delivery.
Physical examination- most often shows decreased or absent movement of the affected arm.
Neurologic examination- assesses muscle power, sensation, reflexes- moro reflex is absent on the affected arm.
It might also be important to look for presence of cervical rib. In the report by Becker J, et al (2002), the authors noted that in a series of 42 infants found to have a cervical rib, 28 newborns had an Erb's palsy. They concluded that a cervical rib was a risk factor for an Erb's palsy.
Some brachial plexus injuries may heal without treatment. Many children who are injured during birth improve or recover by 3 to 4 months of age, although it may take up to two years to recover. Fortunately, between 80% to 90% of children with such injuries will attain normal or near normal function.Treatment for brachial plexus injuries includes physiotherapy and, in some cases, surgery.
1.During the first 6 months treatment is directed specifically at prevention of fixed deformities.
A systematic review suggests physiotherapy interventions like constraint-induced movement therapy, kinesiotape, electrotherapy, virtual reality and use of splints or orthotics have positive outcomes for the affected upper limb functionality in obstetric brachial palsy from 0 to 10 years.
Encourage parents to carry out specific exercises with their child 2-3 a day in the comfort of their own home - although the exercises can be carried out anywhere appropriate and comfortable. The Home Exercise Programme may focus on the following
Surgical Managmant: Surgical intervention is a possible treatment option and will be considered by the medical team after appropriate assessment. Surgery is only considered when conservative treatment (such as physiotherapy) is deemed unsuitable This may be just after birth, as the severity of the BPBP injury requires surgical intervention, or it may be later in a child’s development. Surgery for BPBP can involve nerve transplants or tendon transfer of functioning muscles. Many children show a complete recovery, but for those unfortunate not to recover fully, it is important to focus on helping a child to adapt to tasks and work on different strategies to complete activities in their daily life.
Indications for surgery is no clinical or EMG evidence of biceps function by 6 months. This represents 10% to 20% of children with obstetric palsies.
The three most common treatments for Erb's Palsy are: Nerve transplants (usually from the opposite leg), Sub Scapularis releases and Latissimus Dorsi Tendon Transfers.
Nerve transplants are usually performed on babies under the age of 9 months since the fast development of younger babies increases the effectiveness of the procedure. They are not usually carried out on patients older than this because when the procedure is done on older infants, more harm than good is done and can result in nerve damage in the area where the nerves were taken from. Scarring can vary from faint scars along the lines of the neck to full "T" shapes across the whole shoulder depending on the training of the surgeon and the nature of the transplant.
Subscapularis releases, however, are not time limited. Since it is merely cutting a "Z" shape into the subscapularis muscle to provide stretch within the arm, it can be carried out at almost any age and can be carried out repeatedly on the same arm; however, this will compromise the integrity of the muscle.
Latissimus Dorsi Tendon Transfers involve cutting the Latissimus Dorsi in half horizontally in order to 'pull' part of the muscle around and attach it to the outside of the biceps. This procedure provides external rotation with varying degrees of success. A side effect may be increased sensitivity of the part of the biceps where the muscle will now lie, since the Latissimus Dorsi has roughly twice the number of nerve endings per square inch of other muscles.
The prognosis is dependent on the severity of injury, timing of treatment- the earlier, the better the results and associated injuries (fractures of shoulder/arm). Mild cases of erb's palsy may resolve in three to six months with physical therapy. Erb's palsy resolves completely in the first year of life in approximately 70%- 80% of patients and nearly 100% if treatment begins in the first four weeks of birth.Also, effective hand grasp during treatment is associated with good prognosis.