ABSTRACT
This is usually an acute phenomenon following compression of the radial nerve in the spiral groove of the humerus after falling asleep in a chair (‘Saturday night palsy’). The nerve may also suffer infarction due to occlusion of the vasa nervorum in diabetes mellitus. Wrist extension is also weak in corticospinal lesions. Wrist drop is due to weakness of extensor carpi radialis longus and extensor carpi ulnaris. It most commonly results from compression of the radial nerve in the spiral groove. Tone in the upper limbs will be normal in a lesion of the peripheral nerve or roots and usually increased in a corticospinal lesion. Test shoulder abduction, elbow flexion, elbow extension, brachioradialis, wrist extension, finger extension, finger flexion, finger abduction and thumb abduction. Test finger abduction with the hand and wrist firmly supported such as resting on a hard surface.
