Devil in the Detail

During the Renaissance, drawings were rarely considered finished works of art. They were, instead, a means to an end: a preliminary sketch, a place to work out compositions and ideas, or to set down a motif that might later be incorporated into a painting. In the world of portraits, an artist might record his sitter’s features first on paper, then later use the drawing as a guide for the final painted version. As they were not highly valued, drawings are rarely mentioned in inventories, contracts, and other accounts that provide insight into the history of a work of art. For these reasons, it is frequently very difficult to identify the subject of a drawing, whether it be a specific portrait, a simple figure study, or a smaller portion of a larger composition.

Here we have a drawing by the great Italian Renaissance artist Leonardo da Vinci (1452-1519), who, among his many skills, was a prolific draughtsman. In the drawing we see the head of a man from three different angles. This could simply be a generic study, the face of an anonymous man, yet the level of detail and specificity—including the drooping left eye—suggests perhaps it is a portrait sketch of a certain individual. Leonardo worked for several patrons in Italy, and spent the last years of his life at the court of King François I. In 1502, he entered the service of Cesare Borgia as Architecto e Ingegnero Generale, and a number of art historians have suggested that this sketch may show the face of the fearsome Borgia. The (illegitimate) son of Pope Alexander VI, Cesare Borgia lived from 1475 to 1507, spending much of his career as a condottiero, a professional military man. There are no known conclusive painted portraits of Borgia to which the drawing could be compared, however it does bear a similarity to portrait medals of Borgia. Additionally, the drawing seems to have been made during the time Leonardo was under Borgia’s employ. The most arresting of the three faces is the head at the right, notable for its drooping left eye.

Normally, the upper eyelid covers about one millimeter of the iris (the colored part of the eye around the central pupil). The lower lid comes up to the very edge of the iris. The “palpebral fissure” is the space between the upper eye lid and the lower one. When the palpebral fissure is narrowed because of a droopy upper lid, that is “ptosis.” It comes from the Greek for “a falling.” The “p” is silent—like pterodactyl. There is a small band of fibrous tissue that forms the edge of each lid. Attached to that tissue are tiny ligaments and then muscles. When the muscles contract, they pull on the ligaments which lifts the upper lid. Anything that affects the ligament, the muscles, or the nerves to the muscles can make the lid droop down.

Some people are born with a poorly formed eyelid-lifting muscle, usually just on one side (congenital ptosis). Sometimes, in older adults, the ligaments and other structures connected to the edge of the lid become disconnected (aponeurotic ptosis). If there is an infection or tumor on the upper lid then it can become too heavy for the muscles to lift normally (mechanical ptosis). But neurological ptosis is the most concerning and can be a sign of a more widespread problem.

Neurological ptosis occurs if there is a problem in the brainstem, in the nerves from the brainstem to the eye, in the muscles of the eye, or in the tiny gap between the nerves and the muscles. Normal muscle contraction throughout the body occurs when the nerve to that muscle sends an impulse. At the end of the nerve, a tiny packet of chemicals is released that crosses the gap between the nerve ending and the muscle. The muscle fiber has receptors on its surface for that chemical (acetylcholine) that when detected, signals the muscle to contract. It turns out that there is a disease that affects that tiny acetylcholine receptor that covers the surface of all muscles. Myasthenia gravis (MG) is an autoimmune disease in which patients generate an abnormal antibody that attacks just the acetylcholine receptors on muscle. The nerves are fine. They release their normal packet of acetylcholine when the brain sends the signal but the splash of the chemical creates only a muted muscle contraction because many of the receptors have been destroyed. About half of all patients with MG initially complain of a droopy eyelid, sometimes also with double vision. If that is the only part of the body that is affected, then it is referred to as “ocular myasthenia.” However, there are acetylcholine receptors on muscles all around the body. Most patients with MG, about 85 percent, end up with generalized myasthenia where the muscles of speaking, swallowing, the limbs, or even breathing can be weakened. A characteristic of MG is that patients can feel well in the morning but become weaker as the day goes on. The increased weakness that comes with increased use was noticed by Sir Thomas Willis in a female patient of his in 1672. He wrote:

Nevertheless, those labouring with a want of Spirits, who will exercise local motions, as well as they can, in the morning are able to walk firmly, to fling about their arms hither and thither, or to take up any heavy thing; before noon the stock of the spirits being spent, which had flowed into the muscles, they are scarce able to move hand or foot. At this time I have under my charge a prudent and an honest woman, who for many years hath been obnoxious to this sport of spurious Palsie, not only in her Members, but also in her tongue; she for some time can speak freely and readily enough, but after she has spoke long, or hastily, or eagerly, she is not able to speak a word, but becomes as mute as a Fish, nor can she recover the use of her voice under an hour or two…

Treatment is aimed at removing the antibody, often with medicines that suppress the immune system, like prednisone. The spectrum of the disease is wide. Some require large doses of medicines and other treatments and still suffer with troublesome weakness that comes and goes. Others are like Brandon Cox: he was diagnosed with MG in tenth grade but played on his high school football team. He eventually became the starting quarterback for Auburn University, throwing 42 college career touchdowns and ending up with a 29-9 win-loss record.