Over time, the lack of control and sensation can cause the muscles in your hand to tighten, leading to a claw-like deformity. This usually only occurs in severe cases of ulnar nerve palsy.

Ulnar deviation, or ulnar drift, occurs when the joints in the wrist and hand shift so the fingers ... causing pain, joint deformities, and permanent joint damage. Lupus is an autoimmune disease ...

They diagnosed ulnar palsy, or “claw hand”, by analyzing the depiction of his right hand in two artworks. It had been suggested that Leonardo's hand impairment was caused by a stroke.