Injury to Brachial Plexus Due to Birth Trauma

A brachial plexus birth injury occurs when the network of nerves connecting the neck to the arm is damaged during delivery, affecting between one and three babies out of every 1,000 births. While most infants recover fully within a few months, some require specialized treatment to regain movement in their shoulder, arm, and hand.

Table of contents

• What Is the Brachial Plexus and How Is It Injured at Birth?
• Types of Nerve Injury
• Patterns of Brachial Plexus Birth Injury
• Signs and Symptoms
• Causes and Risk Factors
• How the Injury Is Diagnosed
• Treatment Options
• Outlook and Recovery

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What Is the Brachial Plexus and How Is It Injured at Birth?

The brachial plexus is a complex network of nerves located between the neck and shoulders. These nerves carry signals from the spinal cord to control muscle function and sensation in the chest, shoulder, arms, hands, and fingers.^[1] The brachial plexus consists of five nerves that branch off from the spinal cord at the neck level and extend down into the shoulder, arm, and hand.^[2]

A brachial plexus birth injury happens when these nerves are damaged during childbirth. During a difficult delivery, the baby’s neck may be stretched to one side, or the head and neck may be forcibly pulled away from the shoulder. This can cause the nerves of the brachial plexus to stretch, compress, or even tear.^[1] In the most serious cases, the nerve roots can be pulled away from the spinal cord itself.^[2]

The injury typically occurs when the infant’s head and neck pull toward the side as the shoulders pass through the birth canal, when the infant’s shoulders stretch or the arm is pulled during a head-first delivery, or from pressure on the baby’s raised arms during a breech delivery where the feet or buttocks come first.^[7]

Types of Nerve Injury

Brachial plexus birth injuries vary greatly in severity depending on the type of nerve damage. There are different types of nerve injury that can occur, and all can happen at the same time in the same infant.^[5]

Stretch injury (neurapraxia) is the most common and mildest form. In this type, the nerve has been stretched but not torn. The injury occurs outside the spinal cord. Affected nerves may recover on their own, usually within the first three months of the baby’s life.^[1]

Rupture is a more serious injury where the nerve is torn, but not where it attaches to the spine. The injury occurs outside the spinal cord and is fairly common. This type may require surgical repair.^[1]

Avulsion is the most severe type of injury. In this case, the nerve roots are torn away from the spinal cord itself. This occurs in roughly 10 to 20 percent of cases. An avulsion cannot be surgically repaired directly, and damaged tissue must be surgically replaced through nerve transfers. This type of injury can also damage the nerve to the diaphragm, causing difficulty with breathing. A droopy eyelid on the affected side may indicate this more severe injury.^[1]

Patterns of Brachial Plexus Birth Injury

Brachial plexus birth injuries are often categorized according to which nerves are involved and the pattern of weakness that results.

Erb’s palsy is the most common type, accounting for about 45% of all brachial plexus birth injuries.^[4] It involves the upper portion of the brachial plexus, specifically the C5 and C6 nerve roots, and sometimes C7. A child with Erb’s palsy typically has weakness involving the muscles of the shoulder and biceps. The infant may not be able to move the shoulder but may still be able to move the fingers. The arm is often held in a characteristic position called the “waiter’s tip” position.^[4][5]

Total plexus involvement represents roughly 20 to 30 percent of brachial plexus injuries. All five nerves of the brachial plexus are involved (C5 through T1). Children with this pattern may not have any movement at the shoulder, arm, or hand.^[1]

Horner’s syndrome represents roughly 10 to 20 percent of injuries and is usually associated with an avulsion. The sympathetic chain of nerves has been injured, usually in the T2 to T4 region. The child may have ptosis (drooping eyelid), miosis (smaller pupil of the eye), and anhydrosis (diminished sweat production in part of the face). The presence of Horner’s syndrome usually indicates a more severe injury of the brachial plexus.^[1]

Klumpke’s palsy almost never occurs in babies or children. It involves the lower roots (C8, T1) of the brachial plexus and typically affects the muscles of the hand and forearm.^[1]

Signs and Symptoms

Signs of a brachial plexus birth injury usually include full or partial lack of movement, especially in the shoulder and elbow, a weakened grip, numbness, and an odd position where the arm may bend toward the body or hang limp.^[2]

Symptoms can be seen right away or soon after birth. A newborn with this injury may show no movement in the upper or lower arm or hand. The Moro reflex (startle response), where a baby throws back their head and extends the arms and legs, is absent on the affected side. The arm may be extended straight at the elbow and held against the body, and there may be a decreased grip on the affected side.^[7]

The affected arm may flop when the infant is rolled from side to side. Because only one arm is affected in most cases, the difference between the two arms becomes quite noticeable.^[7]

Causes and Risk Factors

Brachial plexus birth injuries typically happen during long or difficult deliveries. This is especially true if the baby is large and in a breech position, meaning the feet or buttocks come first.^[3]

Several factors increase the risk of this injury. These include breech delivery, maternal obesity, a larger-than-average newborn (such as an infant of a mother with diabetes), and difficulty delivering the baby’s shoulder after the head has already come out, a complication called shoulder dystocia.^[7] The injury is more likely when the birth is complicated by a very long labor, when the baby weighs 8 pounds or more, or when the baby’s shoulders are too wide to fit through the birth canal.^[2]

While cesarean delivery is used more often when there are concerns about a difficult delivery and can reduce the risk of injury, it does not prevent it entirely.^[7]

How the Injury Is Diagnosed

Identifying brachial plexus injuries in newborns can be challenging. A physical examination most often shows that the infant is not moving the upper or lower arm or hand. Doctors will check the affected arm for paralysis, numbness, position, and grip strength. They will also check the baby’s Moro reflex.^[2]

The healthcare provider will examine the collarbone to look for a fracture, as brachial plexus injury can be confused with a condition called pseudoparalysis, where the infant has a fracture of the collarbone and is not moving the arm because of pain, but there is no nerve damage.^[7]

A specialist who treats infants with these injuries usually oversees the tests and treatments. The specialist might order X-rays to check for bone fractures, a nerve conduction study and electromyogram to test nerve and muscle function, or magnetic resonance imaging (MRI) to visualize the nerves and surrounding structures.^[2]

Treatment Options

Treatment for brachial plexus birth injury depends on the severity of the injury. Around 70% to 80% of children recover fully.^[4] Most babies with a brachial plexus injury regain both movement and feeling in the affected arm. In mild cases, this might happen without treatment.^[2]

Physical therapy and occupational therapy are recommended for all children with brachial plexus birth injuries in order to maintain motion and prevent contracture (permanent tightening of muscles, tendons, or other tissue) while the nerves heal and reconnect to the affected muscles.^[4] Home physical therapy often begins when a baby is 3 weeks old to prevent stiffness, muscle wasting, and shoulder dislocation.^[1] A physical therapist will show parents gentle massage techniques, stretching exercises, and range-of-motion exercises to do at home to help their baby get better.^[2]

Botulinum toxin injections may be used if muscle imbalance is present at either the shoulder or the elbow. The toxin is injected into the stronger muscle that may be overpowering the weaker muscles. This temporarily weakens the stronger muscles, allowing the weaker muscles the opportunity to be strengthened through therapy. The effect wears off in three to four months.^[8]

Surgery may be needed for more severe injuries. Children without full recovery by 3 months are likely to have some residual impairment, and early referral to a brachial plexus birth injury clinic is important for oversight of care and timely surgical intervention if recovery is inadequate.^[4] Surgery may be considered if strength does not improve by 3 to 9 months of age.^[7]

Common surgical procedures include nerve grafting, where damaged sections of nerve are replaced with healthy nerve tissue from another part of the body, and nerve transfers, where a less important nerve is connected to a more important one to restore function. Muscle and tendon transfers may be performed to correct muscle imbalances that limit function.^[8] The time frame for surgical repair is an important factor for recovery, as muscles that have not been reconnected to nerves within 18 months of injury weaken to the point where reconnection may no longer be possible.^[8]

For more severe injuries, a child will be cared for by a team of specialists that may include experts in neurosurgery, neurology, orthopedic surgery, and physical medicine.^[2]

Outlook and Recovery

Most babies will fully recover within 3 to 4 months.^[7] Most newborns recover from brachial plexus birth injury within the first 3 months of life.^[8] Those who do not recover during this time have a poorer outlook for full recovery. In these cases, there may have been a separation of the nerve root from the spinal cord.^[7]

The potential for recovery differs depending on the severity of the injury. Stretch injuries, the most common type, have the best prognosis. More severe injuries such as ruptures and avulsions may result in permanent weakness or loss of function despite treatment.^[5]

Possible complications include abnormal muscle contractions or permanent tightening of the muscles, and permanent partial or total loss of function of the affected nerves, causing paralysis of the arm or arm weakness.^[7] Children without full recovery by 3 months are likely to have some residual impairment, most commonly affecting the shoulder, elbow, or forearm.^[4]

Parents should contact their healthcare provider if their newborn is not moving an arm, as early evaluation and treatment can maximize outcomes.^[7]