9.20 Cheiralgia Paresthetica (Handcuff Neuropathy)
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agk's Library of Common Simple Emergencies

Presentation
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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:
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- 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:
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- 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
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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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img/cse0920.gif

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