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.

Department of Trauma and Orthopaedics, Royal United Hospital, Combe Park, Bath, BA1 3NG, UK Correspondence to: Mr. H. Nagata, 1 Belgrave Place, Bath, BA1 5JL, UK.