Shoulder dystocia is a well documented complication of childbirth. It occurs when a baby’s anterior shoulder becomes stuck behind the mother’s pubic bone following delivery of the head. If the treating obstetrician or midwife is unable to free the baby’s shoulder within a few minutes the infant will suffer irreversible brain damage or death. Prompt and effective action through the use of various manoeuvres and procedures is therefore essential.
Brachial Plexus Injury
The brachial plexus is a network of nerves, arising from the spinal cord that supplies the hand, arm, and part of the shoulder with movement and feeling. It consists of the nerve roots of spinal cord segments C5, C6, C7, C8 and T1.
Brachial plexus injury is one of the fetal complications which can arise in cases of shoulder dystocia. Injury can occur when the baby’s brachial plexus, is temporarily, or permanently damaged.
One cause of brachial plexus injury is believed to be the stretching of the nerves in the baby’s neck during the manoeuvres used to release the baby’s shoulder. Some schools of thought argue that brachial plexus injury results solely or primarily from excessive traction by the healthcare professional whilst others suggest that maternal propulsive force can contribute to the injury.
Fortunately fewer than 10% of incidents of brachial plexus injury result in a permanent neurological dysfunction.
Brachial plexus injuries are not always associated with injuries to the spinal cord, however, in particularly severe cases, such as avulsion, when the nerve is pulled out from the spinal cord, people can suffer from paralysis of the muscles in the shoulder and upper limb.
The two main types of brachial plexus injury are: Erbs Palsy and Klumpke palsy.
Erbs palsy is the more commonly occurring injury and involves the upper trunk of the brachial plexus, nerve roots C5 through to C7. Injuries in cases of Erbs Palsy are variable but generally affect the shoulder, upper arm and chest wall as well as the thumb, index and middle fingers of the hand.
Klumpke palsy is less common and involves injuries to the lower nerve roots, C7, C8 and T1, which tend to affect elbow, forearm, wrist and hand function.
In some injuries, nerve fibres transversing T1 may be damaged leading to Horner’s syndrome, a condition with symptoms which include drooping of the mouth and eyelid.
These conditions can cause complex, life altering injuries, often involving impaired arm and hand function, which in many ways are comparable to the injuries sustained by people with incomplete spinal injuries.
Mismanagement of Shoulder Dystocia
The management of shoulder dystocia is an area fraught with difficulty and characterised by a need for quick thinking and appropriate action. Healthcare professionals are faced with unenviable time pressures to release the baby, whilst at the same time, they will be conscious of the importance of trying to preserve the integrity of the brachial plexus. In some circumstances, negligent mismanagement of this stressful situation will be responsible for a brachial plexus injury.