Brachial plexus injuries are caused by damage to the nerves that control the arms. This type of injury can occur in anyone of any age after an accident or injury, but the most common cause is injury during childbirth. Infants born with a brachial plexus injury are usually able to recover within a few months and have no lasting symptoms.
Some infants born with severe injuries to the brachial plexus will have more severe symptoms and are likely to retain some degree of symptoms for the rest of their lives. Treatments are available, but with serious injuries, symptoms will probably not be totally eliminated and will persist. Even so, most people with this injury caused in birth can live a normal and full life.
How Brachial Plexus Injuries Occur
The brachial plexus is a bundle of five major nerves that originate in the spinal cord, run through the neck, and then attack to smaller nerves in the arm. The nerves are responsible for providing sensation to various parts of the arms and hands and for allowing movement and control of the movement of the muscles of the arm.
If those nerves get damaged in an injury, sensation, and movement may be interrupted. In a child or adult, this can happen because of some kind of traumatic injury that stretches the nerves. It can occur during contact sports, because of a fall, in a car accident, or as a result of a gunshot wound, just to name a few possible causes.
Infants are often born with some degree of brachial plexus injury because the head, shoulder, and neck get stretched as the child comes through the birth canal. This may happen if the person delivering the baby pulls on the arm or shoulder while the head is still in the birth canal or pulls on the lower body, stretching out the neck. It can also happen during a breech birth with the baby’s arms lifted above his/her head. Breech births, births of larger than average babies, and long and difficult labors all come with a greater risk of a brachial plexus injury.
Symptoms of Mild Injury
A mild brachial plexus injury may feel like a shock or burning feeling running down the affected arm. This is usually followed by a feeling of numbness and weakness in the arm. It can occur anywhere in the arm, from the shoulder to the fingers. In mild cases, these symptoms usually resolve on their own, in about a week (for children and adults). For infants, the injury takes about three to six months to heal and may require mild physical therapy.
Symptoms of Moderate to Severe Injuries
A more severe injury to the brachial plexus will cause significant weakness, and in the most severe cases, a complete paralysis of one or more muscles in the arm. There may even be complete paralysis of the entire arm, from fingertip to shoulder, if all the nerves of the brachial plexus have been badly damaged. There may also be severe pain in these more serious injuries or a complete loss of sensation. Pain from a brachial plexus injury usually occurs when the nerves are damaged close to the spinal cord.
Symptoms in a Newborn
Symptoms of brachial plexus injuries are similar no matter the age of the affected person, but an infant cannot tell you if they feel pain or numbness or cannot move its arm. The symptoms of this kind of injury in a newborn must be detected by a medical professional or the parents so that the injury can be assessed and treated.
Signs to look for include a weaker grip in one hand as compared to the other, movement in one arm, but none or less in the other, and an arm that is bent and held against the body. The latter is a sign that the baby is uncomfortable and is trying to find a comfortable position for that arm. Another sign is that the moro reflex is absent on one side.
The moro reflex is a reflex that infants have and that disappears by about three or four months of age. To test for the reflex, the baby is placed on its back on a flat, but cushioned surface. An adult, preferably a medical professional with experience, lifts the baby’s head just until the weight of the baby’s body is lifted slightly off the surface. The person then drops the baby’s head, catching it again gently to avoid injury. The baby should startle and move its arms sideways with the palms of the hand facing up. If that reflex is absent in one arm it may be a sign of a brachial plexus injury.
A rare but possible symptom of brachial plexus damage is called Horner’s syndrome. These symptoms affect the eye and include pupil constriction in one eye, drooping in one eyelid, and an inability to sweat on one-half of the face. These are rare symptoms, but they are caused by damage to nerves in the brachial plexus that affect nerves going to the face and eye. These symptoms may indicate a brachial plexus injury.
Location of Symptoms
Where the symptoms of a brachial plexus injury occur depends on which nerves in the bundle are damaged. Erb’s palsy refers to damage to the nerves that control the upper arm. In this case the affected person will experience numbness, tingling, weakness or paralysis in the muscles of the upper arm, from the shoulder to the elbow, but may have perfectly normal sensation and movement from the elbow down to the fingers.
Damage to the nerves that control the lower arm is called Klumpke’s paralysis or palsy. This causes symptoms anywhere between the elbow and down through the fingers. If all five nerves of the brachial plexus are damaged the symptoms will affect the entire arm. This is called a global palsy.
The outlook for a brachial plexus injury depends on the severity of the damage to the nerves. For most infants, the damage is only mild and will heal within three to six months of birth. In these cases, the child should not experience any symptoms after the nerves have healed. For more severe injuries, including those in which the nerves are torn, more treatment may be needed, including surgery to speed healing or repair damaged nerves.