The incidence of brachial plexus injury, a common nerve injury during delivery, is proportional to the birth weight of the child, with an incidence of 0.9% for children with a birth weight of less than 4 Kg and 2% for children with a birth weight of more than 4.5 Kg. In general, the risk factors for brachial plexus injury are large babies, difficult shoulder births, forceps deliveries, breech deliveries, and rapid maternal weight gain. Eight to 23% of babies with obstructed shoulders have brachial plexus injury, accounting for more than half of all children with brachial plexus injury.
In children with brachial plexus injury, there is a risk of brachial plexus nerve loss, axonal rupture, nerve rupture, avulsion and neuroma formation. If the nerve loss or axon dissection is simple, it may return to normal on its own. This is why obstetricians sometimes tell parents to wait and see when they encounter a child with brachial plexus injury, and the child will heal on its own.
However, some severe brachial plexus injuries do not return to normal on their own and require treatment, and 3% to 25% of brachial plexus injuries leave permanent functional impairment.
How do you determine the prognosis?
According to water PM, infants who have recovered biceps muscle strength by 2 months of age can have normal upper extremity function. In contrast, infants with recovery >3 months will have persistent neurological deficits. In addition, if the injury has not progressed at all within 2 weeks, it is unlikely that upper extremity function will return to normal.
Maintaining and improving joint motion is essential.
Delays in the onset of normal function and imbalances in the muscles of the upper extremity joints can negatively affect the growing skeleton. Therefore, we cannot simply observe, but must accurately time and intervene early and aggressively. In the early stages we can consider conservative treatment, using full range of joint motion training, muscle strength training, sensory and postural education, and apparatus training to correct upper extremity function. To improve muscle strength, plyometric training against resistance can be performed in older children, but is contraindicated in children with low muscle strength or young children to avoid weight-bearing situations that may affect the growth of the skeletal system. Joint mobility training requires more attention, for example, shoulder joint stretching must be fixed to the scapula, while forearm joint training should be done with the elbow joint fixed to the trunk. Consultation with a professional pediatric physical rehabilitation therapist is recommended for these specialized techniques.
Prompt surgical treatment can prevent skeletal deformities and reshape function.
One particular point to note is that muscle loss is irreversible at 12 to 15 months, which means that the ability to reinnervate the muscle is permanently lost, so early and effective surgical treatment is essential.
However, the timing of surgery is controversial. For complete paralysis, patients who do not show any upper extremity function at 3 months are definitely indicated for surgery. However, 12.3% of the children with flexion of the elbow can still recover on their own. It is not possible to make a surgical diagnosis at 3 months for all children, but a functional assessment of multiple muscle groups is the criterion for surgical indication. A more uniform standard is that children with upper plexus injury can be surgically explored within 6 months if surgery is indicated, and children with sudden onset of no improvement in nerve function and no recovery within 9 months can be directly treated surgically.
Overall, brachial plexus nerve injury is not as optimistic or as complicated as we think, and if treated early, the disability rate can be greatly reduced.