Neuropathy in the hands and/or arms in patients with rheumatoid arthritis may in rare cases cause wrist drop. "When a joint swells, it can pinch the nerves of sensation that pass next to it. If the swelling irritates the nerve, either because of the inflammation or simply because of pressure, the nerve can send sensations of pain, numbness, and/or tingling to the brain. This is called nerve entrapment. Nerve entrapment most frequently occurs at the wrist (carpal tunnel syndrome) and elbow (ulnar nerve entrapment). A rare form of nerve disease in patients with rheumatoid arthritis that causes numbness and/or tingling is neuropathy. Neuropathy is nerve damage that in people with rheumatoid arthritis can result from inflammation of blood vessels (vasculitis)." Types
Types of wrist drop are distinguished by the nerves affected:

Weakness of brachioradialis, wrist extension and finger flexion = radial nerve lesion
Weakness of finger extension and radial deviation of the wrist on extension = posterior interosseous nerve lesion
Weakness of triceps, finger extensors and flexors = c7,8 lesion
General weakness of upper limb marked in deltoid, triceps, wrist extension and finger extension = corticospinal lesion

Diagnosis
The workup for wrist drop frequently includes nerve conduction velocity studies to isolate and confirm the radial nerve as the source of the problem. Other screening tests include the inability to extend the thumb into a "hitchhikers sign". Plain films can help identify bone spurs and fractures that may have injured the nerve. Sometimes MRI imaging is required to differentiate subtle causes.
Pruritus scroti is itchiness of the scrotum that may be secondary to an infectious cause. : 55

See also
Pruritus vulvae
Pruritus ani
Pruritus

References


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