9.19 Radial Neuropathy (Saturday Night Palsy)
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agk's Library of Common Simple Emergencies

Presentation
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The patient has injured his upper arm, usually 
by sleeping with his arm over the back of a 
chair, and now presents holding the affected 
hand and wrist with his good hand, complaining 
of decreased or absent sensation on the radial 
and dorsal side of his hand and wrist, and of 
inability to extend his wrist, thumb and finger 
joints. With the hand supinated (palm up) and 
the extensors aided by gravity, hand function 
may appear normal, but when the hand is pro- 
nated (palm down) the wrist and hand will drop.

What to do:
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- Look for associated injuries. This sort of 
    nerve injury may be associated with 
    cervical spine fracture, injury to the 
    brachial plexus in the axilla, or fracture 
    of the humerus.
- Document in detail all motor and sensory 
    impairment. Draw a diagram of the area of 
    decreased sensation, and grade muscle 
    strength of various groups (flexors, 
    extensors, etc.) on a scale of 1-5.
- If there is complete paralysis or complete 
    anesthesia, arrange for additional 
    neurological evaluation and treatment right 
    away. Incomplete lesions may be 
    satisfactorily referred for followup 
    evaluation and physical therapy.
- Construct a splint, extending from proximal 
    forearm to just beyond the metacarpo- 
    phalyngeal joint (leaving the thumb free) 
    which holds the wrist in 90 degree 
    extension. This and a sling will help 
    protect the hand, also preventing edema and 
    distortion of tendons, ligaments, and joint 
    capsules which can result in loss of hand 
    function after strength returns.
- Explain to the patient the nature of his 
    nerve injury, the slow, rate of regener- 
    ation, the importance of splinting and 
    physical therapy for preservation of 
    eventual function, and arrange for 
    followup.

What not to do:
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Do not be misled by the patient's ability to 
extend the interphalangeal joints of the 
fingers, which may be accomplished by the 
ulnar-innervated interosseus muscles.

Discussion
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This neuropathy is produced by compression of 
the radial nerve as it spirals around the 
humerus. Most commonly it occurs when a person 
falls asleep, intoxicated, held up by his arm 
thrown over the back of a chair. Less severe 
forms may befall the swain who keeps his arm on 
his date's chair back for an entire double 
feature, ignoring the growing pain and paresis. 
If the injury to the radial nerve is at the 
elbow or just below, there may be sparing of 
the wrist radial extensors as well as the 
radial nerve autonomous sensation. The 
deficient groups will be the wrist ulnar 
extensors as well as the metacarpophalyngeal 
extensors. A high radial palsy in the axilla 
(e.g., from leaning on crutches) will involve 
all of the radial nerve innervations, including 
the triceps.

Illustration
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img/cse0919.gif

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