Chapter 1: The Theater of IllnessCHAPTER 1 The Theater of Illness THE STUDENT LOST HER vision so gradually, so insidiously, that not until days after the symptoms first began did she realize that she had been struck blind. First came the headache, a boring pain in her right temple. The pain was dull when she first woke, but later that morning, as she looked down at her folded hands during the liturgy at church, she felt as though someone had pierced her right eye with a sewing needle. At school, she realized that the pain seemed to swell and subside as her eye moved. She found herself turning her entire head as she read the pages of her textbooks, keeping her eyes as still as she could. That night, she looked at the embroidered border of her new white nightgown and wondered how it had become so worn, wondered when the color of the thread--once maroon--had faded to pink. As she closed first her right eye and then the left, the border seemed by turns bright and dim. She was fasting for Lent, and she thought her symptoms--the headache, the fogginess--had been brought on by hunger.

She went to bed early, and by the next morning, she could see only a sliver of the world through her right eye, a narrow crescent of preserved vision the shape of a fingernail clipping. By the afternoon, the vision in her left eye had begun to dim, too. At nineteen, she still lived with her mother and grandmother while she took classes at the local community college, but she did not tell them about the blindness. She had grown up attending an insular Ethiopian Orthodox church, had quietly been taught since she was a teenager never to enter the church or take the Eucharist when she was on her period, to instead pray alone outside, and she was certain that the blindness was a form of divine punishment, levied against her for a secret sin: one week earlier, she''d had her first kiss, snuck in the church parking lot. She stayed home from school that day, unsure whether the fragments of vision she had remaining would allow her to navigate the two city buses she took to the college. She had initially pleaded a headache and then a stomachache, but when she bumped into the wall walking from her bedroom into the bathroom, her grandmother brought her to the emergency room to find out what was wrong. I was a medical student barely older than she was, one week into my first neurology rotation. The student told me about her vision--the pain, the fading colors--and then, after visiting hours ended and her grandmother had reluctantly left her bedside, she told me, weeping, about the kiss.

I had never seen a person suddenly struck blind. I still understood nearly nothing about the fragility of bodies and brains, but I had already started to absorb cynicism from the doctors around me, started to learn that the appropriate response to emotion was skepticism. Watching her cry, I wondered whether the blindness was imagined, a sort of self-flagellation for the sin of the kiss. But the blindness was not imagined. Rather, it was the result of an inflammation of her optic nerves, the bundle of fibers that travel like an extension cord from the back of the eye to the visual centers of the brain. On an MRI of her brain, these nerves glowed ghostly white, tumescent with inflammation. In their quest to find the cause of the inflammation, the doctors tested her for every possible infection. Only one came back positive: a blood test for Epstein-Barr virus, which causes mononucleosis, that adolescent plague of exhaustion that spreads through saliva--"the kissing disease.

" To her, it felt like incontrovertible proof: the kiss caused the blindness, and the blindness was punishment for her sin, divinely ordained rather than the random failure of a body assembled of parts as prone to malfunction as the gaskets of a car engine. In a way I, too, thought that the kiss caused the blindness, although my explanation was both more vague and less satisfying: a dysregulated immune system, somehow inflamed by the virus. Unmoored by her loss of sight, the student began to have visions. Every night, she saw her own body rising up and hovering above her bed, suspended in her hospital purgatory with the seams of her gray cotton infirmary gown floating beneath her like angel wings. I told her that the visions, too, were something quotidian, an illusion manufactured by the misfiring of neurons in her visual cortex, robbed of actual sight. Secretly, though, I knew that my explanations, like hers, were grounded only in faith, in my own unshakable belief in things I could not see--viruses, neurons, electrical impulses. A DECADE LATER, while teaching my own students the ways someone could be struck blind and then have their sight restored, I would come across the story of a fourteenth-century Dutch saint, Lidwina of Schiedam. At sixteen, Lidwina fell while ice-skating, breaking a rib and tearing into her skin a wound that would not heal.

Weeks after she fell, she began to have violent pains in her teeth that kept her from eating, then a paralysis of the face that left her lips hanging open. In the years that followed, she struggled to walk, first reaching for furniture to keep herself upright, then being carried like an infant from room to room. In her twenties, she, like the student, began to float over her bed among angels. Her right arm became paralyzed, then mobile, her right eye blind, then sight restored. By the end of her life, Lidwina struggled to swallow. Lidwina of Schiedam became a spectacle, physicians traveling from across Holland to see the girl who had been struck blind and then regained sight, who had been paralyzed and then limber. The disease, they said, came from God. "Even Hippocrates and Galenus would not be able to be of any help here," said one physician.

"The Lord''s hand had touched this woman." Like my patient, Lidwina was young and religious, had prayed to the Virgin Mary since her earliest childhood. She was immobilized, infantilized, haunted by excruciating pain. She would eventually believe that she had been chosen to suffer for the sins of humanity. After she died, her grave became a pilgrimage site, a chapel built upon it so that other sufferers could pray for deliverance. Centuries later, she was canonized--the patron saint of ice-skating, and of chronic pain. In 1947, Lidwina''s body was exhumed and her skeleton examined. The bones of her legs and right arm bore the stigmata of years of paralysis, of muscles in spasm.

The diagnosis was likely multiple sclerosis, the scientists speculated, which would make hers one of the first recorded cases. Her blindness and restored sight were neither curse nor miracle, but rather an affliction as ordinary as a failing nerve. MUCH ABOUT MULTIPLE sclerosis--what renders someone susceptible to it, for instance, or even what determines whether a predisposed person will begin having symptoms at fourteen or twenty-four--remains mysterious, as inscrutable to doctors now as the causes of Saint Lidwina''s suffering were in her day. What little we do know suggests that the immune system plays a key role.I Our immune system is armed for warfare, designed to neutralize and even physically devour anything it deems a threat. Most often, these threats are invaders from outside the body: viruses and bacteria, which the immune system recognizes as foreign by the telltale proteins and genetic sequences that mark their surfaces, different from the ones that make up the human body. Sometimes, these threats are from within: the dying cells filling a wound, for instance, which the immune system consumes so that they can be replaced with healthy tissue. In autoimmune diseases, including multiple sclerosis, something goes awry in the finely tuned machinery that distinguishes the body''s own healthy cells from a potential threat.

Instead of rooting out invading pathogens and cleaning up the debris of trauma, the immune system begins to devour the body it was designed to protect. At their core, these diseases represent a sort of civil war, the systems of the body in combat with one another. On the battleground of the body, the brain and spinal cord exist in a privileged space, protected from even the blood coursing through them by a microscopic barrier of tightly bound cells that rings every capillary like stones in a fortress wall. The barrier is intended to keep infections of the blood from drifting into the brain. In people with multiple sclerosis, this barrier becomes leaky, the immune cells that circulate in the blood breaching the fortress wall and invading the nervous system. In some ways, the nervous system is unfathomable; in others, it is remarkably banal. In our brains and spinal cords, the stuff of strength, sensation, and consciousness travels across vast distances--from cortex to extremities--as electricity, carried by the long, filamentous axons of each of our neurons. Each axon is encased in a fatty sheath of insulation, corralling the electrical signals it carries to keep them from leaking out before they reach their intended target.

Attacked by an overactive immune system, this insulation begins to fray, gnawed and degraded like the faulty, mouse-bitten wiring of an old house, the signal ebbing from bare patches of wire so that it grows weaker with each millimeter of the journey. Multiple sclerosis is the most common of a family of illnesses called demyelinating diseases for the way they erode the particles of protein and fat that make up this insulation-- myelin , the name derived from the Greek for "marrow," because of its abundance at the heart of the brain. On an MRI, multiple sclerosis is luminous, the gadolinium contrast injected into the blood vessels spillin.