The brachial plexus is a collection of nerves that exits the spinal cord on each side of the neck and travels through the armpit into each arm. These two nerve collections are responsible for nearly all muscle control and skin sensations in the arms. In adults, injuries to these nerve centers can occur at any time, and are generally associated with shoulder trauma in auto or bike accidents. A common injury to the brachial plexus occurs during football games, when a player is tackled by an opponent whose helmet strikes at the joint of the neck and shoulder. On rare occasions, other medical conditions, such as lung or breast cancer, can result in brachial plexus injuries.
Unfortunately, the most common type of brachial plexus injury results from birth trauma. The injury occurs during vaginal delivery when the baby’s head is delivered, but one of the baby’s shoulders gets stuck behind the mother’s pelvis. This birth complication is known as shoulder dystocia. Obstetricians are trained to recognize shoulder dystocia, and should perform a maneuver that frees the shoulder, resulting in a safe delivery. Unfortunately, if a physician does not perform the maneuver correctly, and instead attempts to push the baby’s head toward either shoulder, this can result in damage to the infant’s brachial plexus. This incorrect pressure applied to the baby’s head can result in the baby developing a condition called Erb’s Palsy. In Erb’s palsy, the brachial plexus injury occurs at a specific level of the spinal column, and can result in a range of disability in the child. The injury generally affects only one arm.
There are known risk factors for shoulder dystocia occurring during childbirth. These include a large maternal weight gain, maternal diabetes, high birth weights, breech births or multiple births (twins). Obstetricians should monitor the predicted birth weight of the baby to determine if an early or Caesarian delivery is not more prudent. Babies over 8lb13oz are five times more likely to develop shoulder dystocia, and thus are at increased risk for a brachial plexus birth injury.
If a brachial plexus birth injury does occur, the exact location of the damage, and the extent of the damage to the nerve will determine the amount of the disability. If the nerve is only stretched (neuropraxia), the injury is generally mild and can heal without treatment by the time the baby reaches about four months of age. The symptoms of neuropraxia can include burning, numbness and poor coordination. Rapid identification of the condition and physical therapy can help with more severe cases of neuropraxia.
If the injury is severe and the nerve is completely torn, or avulsed, it is rare that the nerve can be reconnected. In some cases, a nerve graft or nerve transfer may be performed. A nerve avulsion can result in total paralysis of the affected arm.
Erb’s Palsy birth injuries occur with a frequency of approximately 1 in every 2000 births. Most commonly, the injury is mild and resolves with little or no treatment. Only about 20% of these injuries are severe enough to require further treatment. The vast majority of cases can be prevented by proper training of obstetricians and other medical personnel and appropriate prenatal care, such as monitoring the baby’s weight, and the mother’s general health during pregnancy. All obstetric personnel should be trained on proper procedures for delivery, if shoulder dystocia should occur. With proper training and appropriate prenatal care, nearly all brachial plexus birth injuries such as Erb’s Palsy should be prevented.