Like Garrett, most patients with the disorder recall having symptoms such as sore throats, fatigue, or diarrhea in the weeks leading up to their weakness. Our tests showed that Garrett recently had a common respiratory virus. The theory is that while battling any number of infections, the body’s immune system occasionally produces an infection-fighting antibody protein that cross-reacts with and destroys myelin.

Fortunately, most cases of Guillain-Barré syndrome subside. The immune system attacks the myelin and then retreats, allowing the body to regenerate the protein. The vast majority of patients regain almost full mobility and sensation within a few months.

That was little comfort to Garrett now. He couldn’t eat or breathe on his own, and he was experiencing terrible back pain.

I had other worries. Up to 10 percent of those with the condition die of complications. Along with the nerves controlling Garrett’s muscles, the nerves regulating his vital functions like heart rate, blood pressure, and temperature also malfunctioned. Often, his heart sped up to 150 beats per minute—twice his baseline—and his blood pressure shot through the roof, putting him at risk for a stroke or heart attack. We had to treat him with cardiac medication and keep a careful watch on his vital signs. When he ran a fever, we cooled him with a bedside fan. And while lying in the intensive care unit with artificial tubes and catheters in his body, he was to bacteria as a sponge is to water. We used antibiotics to control a blood infection.

Ironically, the infection resulted from a line that had been inserted into an artery during a treatment aimed at speeding up Garrett’s recovery. In a procedure known as plasmapheresis, the line was used to remove his plasma, where the dangerous antibodies against myelin are thought to reside. Only one other treatment has been shown to speed recovery from Guillain-Barré syndrome—injection of doses of immune proteins, or immunoglobulins, by vein. Culled from the blood serum of many donors, immunoglobulins may counter Guillain-Barré syndrome by decreasing the production of new antibodies and neutralizing the existing antibodies against myelin. We tried both treatments—twice—and neither helped.

The weeks passed. Garrett’s infections cleared. We established better control over his blood pressure. And then, slowly, he began to make small movements of his arms and legs. Every morning, we detected a little more strength. He still required a mechanical ventilator to help him breathe. And although he was awake, he couldn’t talk. Bright, young, and frequently frightened, he wanted to express himself. I ordered a consultation with a speech therapist, who provided a special board with letters that Garrett could use to spell out words just by looking at the letters. The painstaking process required patience.

As the end of my month in the pediatric intensive care unit drew to a close, a bed for Garrett opened in a nearby rehabilitation facility. To reduce his discomfort, we gave him a tracheostomy—a minor surgical procedure that creates a small hole at the front of the neck so that a breathing machine can be attached there. As soon as Garrett regained enough strength to spend some time disconnected from the ventilator, he could plug the hole and talk.

After we both left the intensive care unit, I thought often of Garrett, wondering how he was feeling. One day I showed up at his room and found his entire family there. Garrett had just returned from physical therapy, where he had taken his first steps. Now he was sitting up in a wheelchair, exhausted but visibly pleased. The family told me that he still required the ventilator most of the time, but he could now breathe on his own for short periods. The respiratory therapist came in and turned off the breathing machine so that Garrett could speak.

What he had to say came as a surprise. I had expected him to express frustration at his time in the intensive care unit. Instead, in a voice gentler than I’d imagined, he offered thanks to me and the other hospital staff who had helped him through the most severe period of his illness and into his period of recovery.