Nerve damage before birth or during delivery can cause problems with arm and hand function. The group of nerves affected in the neck and arm are called the brachial plexus. This study shows a second nerve problem may be causing additional muscle weakness.
Ten children with brachial plexus birth palsy between the ages of nine months and eight years were studied. All had less than 90 degrees of shoulder movement when lifting the arm out to the side. Surgery was done to take pressure off the nerves. Strength, motion, and function of the arm were all measured before and after the operation.
The authors found before surgery the children had less active motion than passive. This suggests a problem separate from the original nerve damage. After surgery all had improved arm strength and motion. Eight of the 10 children could raise their arms past 90 degrees.
The results of this study show that muscle weakness after birth brachial plexus palsy may not be due to the original nerve damage. Scarring and muscle shortening affecting the axillary nerve may be the problem. The surgeons suggest early surgical treatment to prevent this from happening.