The patient may complain of pain around the thumb while
tight handcuffs were in place. The pain decreased with
handcuff removal, but there is residual paresthesia or
decreased sensation over the radial side of the thumb
metacarpal (or a more extensive distribution). The same
injury may also be produced by pulling on a ligature around
the wrist, or wearing a tight watchband.
What to do:
Carefully examine and document the motor and sensory
function of the hand. Draw the area of paresthesia or
decreased sensation as demonstrated by light touch or two-
point discrimination. Document that there is no weakness or
area of complete anesthesia.
Explain to the patient that the nerve has been bruised,
that its function should return as it regenerates, but that
the process is slow, requiring about two months.
Arrange for followup if needed. Bandages, splints, or
physical therapy are usually not necessary.
What not to do:
Do not overlook more extensive injuries, such as a complete
transection of the nerve (with complete anesthesia) or a
more proximal radial nerve palsy (see above). Do not forget
alternative causes, such as peripheral neuropathy,
DeQuervain's tenosynovitis, carpal tunnel syndrome, scaphoid
fracture, or a gamekeeper's thumb (see).
Discussion
A superficial sensory cutaneous twig of the radial nerve is
the branch most easily injured by constriction of the wrist.
Its area of innervation can vary widely (see figure). Axonal
regeneration of contused nerves proceeds at about l mm per
day (or about an inch a month); thus recovery may require
two months (measuring from site of injury in wrist to end of
area of paresthesia). Patients may want this injury
documented as evidence of "police brutality," but it can be
a product of their own struggling as much as too-tight
handcuffs
