Leonardo da Vinci died 500 years ago, but doctors are still trying to diagnose the condition that disabled the artist and inventor’s right hand in the final years of his life. In a new study, a team of doctors uses 16th century drawings and texts to pin the blame on a nerve injury sustained when da Vinci fainted.
We’re pretty sure da Vinci was mostly left-handed, based on samples of his handwriting and the direction of the lines of shading and cross-hatching in his drawings. But biographies, diary entries, and letters written by people who saw da Vinci at work say that although he wrote and drew with his left hand, he painted with his right. In the final years of his life, with his right arm paralyzed, da Vinci kept drawing, designing, and teaching — but his paralyzed right hand forced him to leave several paintings, including the Mona Lisa, unfinished.
“One cannot indeed expect any more good work from him, as a certain paralysis has crippled his right hand,” wrote Antonio de Beatis, the personal assistant to Cardinal Luigi d’Aragona, when he and his employer visited da Vinci in 1517. The artist had less than two years to live, as it would turn out, but de Beatis noted that, “although Messer Leonardo can no longer paint with the sweetness which was peculiar to him, he can still design and instruct others.”
To diagnose de Vinci’s condition, plastic and reconstructive surgeon Davide Lazzeri and neurologist Carlo Rossi looked for evidence in two 16th-century drawings of an aging da Vinci, along with documents like de Beatis’ diary entry. Although a widely-accepted diagnosis blames the artist’s affliction on a stroke in an isolated area of da Vinci’s brain, which left his right arm paralyzed, the pair of doctors were skeptical. The type of stroke that usually causes such specific damage happens when a blood clot blocks blood flow to part of the brain, and that’s actually a symptom of poor cardiovascular health. Without modern treatments, the problem typically only gets worse, leading to more strokes that leave the victim with more paralysis and possibly even cognitive problems. But nobody who met da Vinci in his final years describes any paralysis other than his right hand, and his creative mind seemed as brilliant and sharp as ever.
Instead, Lazzeri and Rossi suggest nerve damage in da Vinci’s arm, not stroke-related damage to his brain. A chalk drawing of da Vinci, by artist Giovan Ambrogio Figino, offers some clues: in the drawing, da Vinci’s arm is held across his chest in folds of his clothing, like a makeshift sling. If da Vinci were recovering from a stroke, you’d expect to see his arm bend inward, palm-down, with the fingers clenched as if he were grasping something. But Figino drew him with his hand held in a more claw-like pose, and Lazzeri and Rossi say that may suggest a type of nerve damage called ulnar palsy, not a stroke.
The ulnar nerve runs from the shoulder to the little finger, and it controls most of the muscles responsible for making fine motor movements with the hand — things like drawing, writing, or painting, for instance. And it’s vulnerable to damage, either from sudden injury or longer-term pressure from bone deformities, tumors, and other chronic conditions. Injuries are actually pretty rare compared to long-term damage, but Lazzeri and Rossi say the description fits what we know about da Vinci.
In fact, the best evidence supporting the stroke theory is actually the sudden drama of da Vinci’s death. He suffered a “paroxysm, the messenger of death” and died in the arms of the king of France, who happened to be visiting at the time. It’s likely that da Vinci’s final paroxysm was actually an acute stroke, and it’s easy to see how that suggests a medical history. Lazzeri and Rossi, however, say that a sudden, fatal stroke suggests a history of cardiovascular trouble, but not necessarily earlier strokes. Instead, they say that a few years before his death, da Vinci may have fainted thanks to circulatory problems, injuring his right arm — and his ulnar nerve — as he fell.