Erb’s palsy

• A type of brachial plexus injury.
• Causes paralysis of the muscles causing movement of the upper arm and rotation due to an injury to the upper part of the brachial plexus specially the C5 (mainly) and C6 (partly) nerve roots.
• Commonly seen in neonates following a difficult birth, hence also termed as obstetrical palsy.
• Cause: Undue separation of head from shoulder.

IN NEONATES - Mainly due to obstetrical causes like:

• Shoulder dystocia
• Large birth weight and/or maternal diabetes
• Breech presentation
• Second stage of labour lasting more than 60 minutes
• Assisted delivery
• Intrauterine torticollis
• Fracture clavicle

Position of the limb: Arm hangs by the side; it is adducted & internally rotated; forearm is extended & pronated (`policeman`s tip hand`).

Reflexes-

• Biceps & supinator jerks are lost.
• Asymmetric Moro`s reflex Functional limitations.

Functional limitation:

• Inability to reach and grasp by affected extremity.
• Inability to perform tasks requiring bilateral manual abilities such as catching a large ball or lifting a large object.

Frequency

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.

Mortality/Morbidity

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^.

• X-rays of the chest - to rule out clavicular or humeral fracture
• MRI of the shoulder- may demonstrate shoulder dislocation; presence of pseudomeningoceles indicates avulsion injury of the affected spinal roots
• CT Scan of the shoulder- may demonstrate shoulder dislocation; presence of pseudomeningoceles indicates avulsion injury of the affected spinal roots
• EMG/Nerve conduction studies- presence of fibrillation potentials indicate denervation

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.

2.ROM exercises

3. muscle strengthening exercises.
4.  Parents must be taught to take an active role in maintaining ROM and keeping the functioning muscles fit. Exercises should include bimanual or bilateral motor planning activities.

• Careful handling is required and extremes of motion are to be avoided for the first 1 to 2 weeks to allow for the initial inflammatory response to the injury to calm.
• Avoid picking a child up by the arm. or from under the armpit. This can compress or stretch the brachial plexus and cause further injury
• Placing a child on their back or in side-lying, with affected limb up, to avoid compression of the injured limb
• Place the affected arm into sleeves before the unaffected arm. This will help avoid extreme movement at the shoulder and will help make dressing quicker and easier.

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.

• Activities and exercises to promote recovery of movement and muscle strength
• Exercises to maintain range of movement in the joints to prevent stiffness and pain
• Sensory stimulation to promote increased awareness of the arm
• Provision of splints to prevent secondary complications and maximise function
• Educating parents on appropriate handling and positioning of the child and home exercises to maximise the child’s potential for recovery
• Constraint induced movement therapy may be useful
• Electrical Stimulation may be beneficial
• Referral to Occupational Therapy for assessment of function in day to day activities

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

• Maintain movement at the joints – Ensuring that the joints of the affected limb, especially the shoulder, keep their full range of movement and avoid excessive shortening of the muscles, also called a contracture. This will include passive, assisted and active exercises.
• Increasing the strength of muscles in the affected limb.
• Increasing the child’s awareness of the arm through tactile touch and contact.
• Teaching parents, carers and the child how to handle the affected limb and how to position it for both comforts, prevention of complications and practicality.
• The use of Constraint-Induced Movement Therapy (CIMT) and bimanual/bilateral therapy are sometimes also considered by Physiotherapists.

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.