The network of nerves that conducts signals from the spine to the shoulder, arm and hand is called the brachial plexus. The nerves to the arm, hand and fingers exit the spinal cord between the vertebrae of the neck and travel into the arm below the clavicle. While the nerves to the arm exit high in the neck, those leading to the hand and fingers exit lower in the neck just above the chest.
When these nerves are damaged, the hand may feel limp or paralyzed as a result of the loss in muscle control. Damage can result from a number of different types of injuries. When the nerves exiting high in the neck are affected, the condition is called Erb’s palsy and affects arm movement. And if both the lower and upper nerves are damaged, the condition is called Global palsy.
There are four primary types of brachial plexus injuries including: an avulsion, which is the most severe – as the nerve is completely torn from the spine; a rupture, which results in a torn nerve though no detachment; a neuroma, which is a damaged nerve that has tried to heal itself but scar tissue has grown around the injury – applying pressure to the injured nerve and disrupting signals to the muscles; and neuropraxia (stretch injury), which is among the most common type and results in a damaged nerve that is not torn.
Those at Risk
While a number of different types of injuries can result in a Brachial Plexus Injury, it is often seen in newborns experiencing a prolonged delivery and compression on the shoulders while passing through the birth canal or strong pulling on the neck during an assisted exit.
The loss of movement or paralysis in the hand is a strong indicator of nerve damage. Following a patient history and description of how the injury occurred, an electromyogram (EMG) or nerve conduction studies (NCS) may be used to determine if nerve signals are present in the upper arm muscle.
If the affected nerves show no signs of healing, or the condition is severe, nerve surgery followed by a period of splinting may be necessary for young children. These surgeries are most successful on children under the age of one.
A tendon transfer is often performed on older children and adults – followed by a period of casting and then splinting. Physical therapy is important in the recovery of any injury, but particularly when there is a period of casting as muscles quickly deteriorate they are not exercised. A patient-specific program is developed to restore strength and resume normal hand movement.