Obstetrical Brachial Plexus injury
The brachial plexus is a network of nerves that originates at the spinal cord near the neck and passes down your upper arm from under your collar bone. This network can be injured during the birthing process and is referred to as Obstetrical brachial plexus injury.
The brachial plexus consists of 5 nerve roots. These include nerve roots from the lower cervical segment of the spinal cord known as C5, C6, C7 and C8, and a nerve root from the first thoracic spinal cord segment known as T1. These nerves join to form the upper, middle and lower trunks of the brachial plexus which split into nerves that supply your upper limbs, controlling your shoulder, elbow, wrist and hand. An injury to any part of these nerves can stop signals to and from the brain and may partially or completely paralyze your arms.
Types of brachial plexus injuries that may occur in infants include:
Neurapraxia: the nerves are stretched, but their internal architecture is maintained. With time they are likely to recover more or less completely.
Axonotemesis: the nerves are stretched and their internal structure is partially damaged with the outer sheath still intact. Such nerves are likely to recover over time, to a greater or lesser extent, depending on the magnitude of damage
Neurotmesis/Rupture: nerves stretch to a point where they tear at a region some distance from their origination from the spinal cord.
Avulsion: the nerve roots are torn completely out from the spinal cord.
There are three main categories of OBPI.
a. Involving C5 and C6
b. Involving C5, C6 and C7
c. Involving all the roots(Global)
The first two categories are usually referred to as Erb’s Palsy which disrupts functions of the shoulder and elbow muscles. Erb’s palsy is the most common pattern of brachial plexus injury in infants.
The third category involves injury to both the upper and lower nerves. It is a severe condition called global or total brachial birth palsy.
Another type, called Klumpke’s Palsy (Involving only C8 and T1), is extremely rare and affects the functions of the forearm and hand.
Injury to the brachial plexus can occur during the birthing process when the baby’s shoulder gets lodged in the birth canal requiring external force for the baby to be delivered. This force may stretch or tear the nerves of the brachial plexus. This type of injury is commonly seen in larger than average babies born to diabetic mothers.
Other causes for brachial plexus injury in babies include:
Extended period of labor.
Breech presentation- baby positioned with feet or buttocks near the vaginal opening.
Mothers with a small birth canal.
Signs and Symptoms.
You may be able to observe the symptoms of injury in your child immediately after birth. Common symptoms include:
Limp arm and loss of flexion in elbows.
The baby does not actively move or rotate the arm from the shoulder.
The baby is unable to actively move fingers, or has a decreased grip strength on the affected side.
As mentioned above, the injury to nerves is incomplete in a majority of cases. Thus, in about three-fourths of cases, there is complete or near-complete recovery of function over a period of months.
During the process of recovery or nerve regeneration, some nerves may get misdirected or cross-innervate. This causes opposing groups of muscles to contract and is called co-contractions. Uncoordinated muscle recovery may cause muscle imbalance. Co-contractions and muscle imbalance together can lead to contracture (rigidity) of muscles and joints, ultimately causing shoulder and elbow deformities.
When your child presents with symptoms of brachial plexus injury, the paediatrician will first take your child’s medical history, conduct a physical examination and order tests to diagnose Erb’s or birth palsy. Physical examination will help the doctor identify the limited movement and range of motion of the upper extremity.
Imaging tests such as X-rays, computed tomography (CT) and Magnetic resonance imaging (MRI) may be used to detect damage to the bones, joints or nerves. The purpose of the physical examination and X-ray’s is to rule out other conditions which may mimic Obstetrical brachial plexus injury, such as fracture of the humerus.
Most obstetric brachial plexus injuries heal or recover on their own by the age of 3-12 months. During this time, your doctor will regularly monitor your child.
Physical therapy may be recommended to maximise the use of your child’s affected arm. Your child’s physical therapist will educate you on range of motion exercises to be performed on your baby to improve the functioning of the shoulder, elbow, wrist and hand, and avoid joint stiffness.
In infants with mild obstetrical brachial plexus injury of the C5 or C6 nerves, 80percent generally recover spontaneously and do not require surgery. Recovery depends on the type and severity of nerve injury.
Doctors usually follow Gilbert’s criteria to indicate a requirement for surgery. This criteria states that when the injury fails to recover, surgery should be indicated at 3 months in infants with Erb’s palsy and before 3 months for global birth palsy cases.
Surgery performed within the first six months of life yields the best results following an obstetrical brachial plexus injury. Injuries involving rupture or avulsion may require microsurgical intervention that includes a nerve graft or nerve transfer. Several surgical options are available depending on the patient’s condition:
Nerve graft surgery involves replacing the damaged section of the nerve with a nerve section removed from another part of the body.
Neurotization or nerve transfer surgery is performed to connect the lower end of the damaged nerve to a less important upper end of an intact nerve from the spinal cord.
Older children (above 2 years) who have had partial recovery from the nerve injury often require other surgical procedures to improve their function.
Contracture release: Some of these children develop tightness of the shoulder joint because of decreased mobility. This tightness can be corrected surgically.
Muscle or tendon transfer surgery may be necessary if the arm muscles have deteriorated. This involves transfer of a muscle or tendon from another part of your body to the damaged part of your arm.
Capsulorraphy surgery can be performed to place the head of the humerus, the bone of the upper arm, back into the shoulder joint in order to treat shoulder dislocation or joint instability caused by muscle weakness.
Osteotomy involves cutting the bones of the upper arm or forearm and reorienting them in a better position.
Risks and Complications.
As with any surgery, there can be certain risks and complications involved. Associated risks of nerve reconstruction surgery may include:
Failure to improve.
Prognosis of the brachial plexus injury is directly related to the extent of the nerve damage. Mild injury to the brachial plexus may resolve within 3 to 6 months, whereas severe injuries may require treatment for over a year and regular follow-ups. While mild injuries can recover spontaneously, it needs to be emphasized that severe injuries are unlikely to recover without surgery. All infants with OBPI need to be seen by an expert and started on appropriate treatment as early as possible. For children requiring nerve surgery, best results will be achieved if the surgery is performed before they are 3-4 months old.
Infants with stretch or neuropraxia injuries and upper brachial plexus injuries generally have a good prognosis.
Obstetric brachial plexus injury may cause permanent disability in infants. Minor injuries may heal spontaneously or benefit from physical therapy, but more severe injuries may require surgical intervention. The critical factor that needs to be considered for treatment is the stage of intervention. Appropriate early diagnosis and treatment can make the difference between a good recovery and severe and lifelong disability.