9.20 Cheiralgia Paresthetica (Handcuff Neuropathy)

agk’s Library of Common Simple Emergencies

Presentation

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.

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.

Illustration

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