The nerves that supply the skin
and muscles of the shoulder, arm, and hand emerge
from the spine and form the brachial plexus. This
complex collection of nerves is arrayed between the
spine and the shoulder joint. Along the way, it is
subject to various types of injuries and entrapments.
Among the milder injuries causing
pain and weakness is a group of conditions collectively
called Thoracic Outlet Syndrome (TOS) — these
involve entrapment or irritation of the nerves. More
severe trauma can injure the nerves, stretch them
severely, or even break or tear them. The most common
causes of severe injuries to the brachial plexus are
motor vehicle injuries - particularly motorcycle injuries
- and sever blows to the shoulder. An entirely different
cause affects infants at the moment of their birth
as the shoulder becomes caught in the birth canal
in a difficult delivery.
When the brachial plexus is injured
so severely as to cause a paralysis of the arm, it
is important for the physician to try to determine
whether the problem will resolve on its own or whether
in will require surgery to repair or reconstuct the
nerves. Often, MR Neurography can provide definitive
information about the precise location and severity
of the injuty. In general, in the case of complete
paralysis requiring surgical nerve repair, the surgery
should be undertaken within six months of the date
of the injury.
