Cause of Brachial Plexus Injury

The most recent edition of the textbook Child Neurology has just been published. Child Neurology is arguably the most authoritative textbook of pediatric neurology. The just published 7th edition debunks the myth, asserted repeatedly in the obstetrical literature, that most brachial plexus injuries occur in utero.

The textbook states that “whatever scant evidence exists for a classical brachial plexus injury resuloting from intrauterine maladaption is principally based on faulty interpretation of EMG.”

In other words, obstetricians have often relied on the fact that most brachial plexus injuries are apparent immediately upon birth. Consequently, they argue that if the insult occured immediately before birth, it would take several days before the injury would be readily apparent. This hypothesis is based upon EMG studies conducted in adults who have suffered a nerve injury. Those studies, in adults, revealed that it took several days for the injury to be readily apparent particularly via EMG. However, the textbook of Child Neurology points out that the hypothesis is based upon the faulty assumption that infant and adult nerves act similarly. They do not. An infant’s nerve fibers are shorter. Consequently, it takes dramatically less time for an injury to become apparent.