Gold standard case presentation

Radial nerve palsy

This patient has a radial nerve palsy.  He displays a wrist drop and is unable to extend his hand, which is held flaccid. Wrist extension is generally achieved by muscles in the forearm which pull on tendons distally in the hand.  The radial nerve which controls these functions may become damaged if the humerus is broken due to it’s anatomical course in the radial groove on the lateral border of the humerus.  Another permanent cause of radial nerve palsy is the totally discredited practice of attempting to relocate a dislocated shoulder by placing a foot in the axilla and pulling on the arm.  Do not do this to your patients! Other permanent causes of wrist drop also relate to trauma.  Injuries to the chest wall distal to the clavicle may damage the radial nerve after it emerges from the brachial plexus, potentially with a defect in the rotator cuff also.  Always check the patient with a wrist drop for scars between the brachial plexus and the hand. Although less likely to be seen in the MRCP PACES exam, the commonest causes of radial nerve palsy are all self-limiting.  Recognised examples include:

• Crutch paralysis – prolonged usage of crutches or extended leaning on the elbows may damage the radial nerve through pressure;
• Saturday night palsy – sleeping with the back of an arm compressed by the back of a chair;
• Honeymoon palsy – individuals sleeping on the arm of another.

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