Wrist Drop

Wrist drop is due to weakness of extensor carpi radialis longus ( supplied by C5/6 and the radial nerve ) and the extensor carpi ulnaris ( supplied by C7/8 and the posterior interosseous branch of the radial nerve ).

Anatomy of radial nerve:
It originates from the posterior cord of the brachial plexus with roots from C5, C6, C7, C8 & T1.

Branches

• Above spiral groove - nerve to triceps
• Below the spiral groove and above the elbow - brachioradialis
• Below the elbow - nerve to extensor carpi radialis longus and posterior interosseus nerve

Posterior interosseus nerve supply the extensor carpi ulnaris and extensor digitorum.

Radial nerve has sensory supply to posterior arm, forearm and dorsum of hand.

Causes of wrist drop:

• Radial nerve lesion
• Radiculopathy ( C7,8 ), if there is involvement of the finger flexors as well.
• Cortical lesion

Management:

• Nerve Conduction Study should be done.
• Spontaneous recovery is the rule and splinting helps hand function.
• If the palsy last more than 12 weeks then surgical decompression is an another option.