Microsurgical reconstruction and secondary corrections improve outcomes for infants with brachial plexus birth palsy who fail to recover function by 3 to 6 months, though normal function is rarely fully restored.
Most infants with brachial plexus birth palsy who show signs of recovery in the first 2 months of life will subsequently have normal function. However, infants who do not recover in the first 3 months of life have a considerable risk of long-term limited strength and range of motion. As the delay in recovery extends from 3 months to beyond 6 months, this risk increases pro-portionately. The presence of a total plexus lesion, a partial plexus lesion with loss at C5-C7, or Horner's syndrome carries a worse prognosis. Microsurgery is indicated for failure of return of function by 3 to 6 months. The exact timing of intervention is still open to debate. With microsurgical reconstruction, there is improvement in outcome in a high percentage of patients. However, the neural lesion is too severe and complex for present methods of reconstruction to restore normal function. Secondary correction of shoulder dysfunction with either latissimus dorsiteres major tendon transfer or humeral derotation osteotomy is clearly beneficial for patients with chronic brachial plexopathy, as is reconstruction of supination forearm contracture with biceps rerouting transfer and/or forearm osteotomy. Reconstruction of the hand is also indicated for the patient with chronic disability. All of these procedures improve, but do not completely normalize, function.
Peter M. Waters (1997) studied this question.