Three weeks later when she went back to see her doctor, the patient still hadn’t gotten the test. And now she had a new problem: Her mouth felt weak. Talking was hard; her voice was different. By the end of even a short conversation, her words were reduced to whispers. She couldn’t smile, and she couldn’t swallow. Sometimes when she was drinking water, it would come out of her nose rather than go down her throat. It was strange. And scary.
Chen wasn’t there, so she saw a colleague, Dr. Abhirami Janani Raveendran, who was also a trainee. Raveendran had never seen M.G. either but knew that it could affect the muscles of the mouth and throat. She urged the patient to get the blood test, and she sent Keung a note updating him about the patient’s disturbing new symptoms and the possible diagnosis.
When Keung saw the message, he was alarmed. He agreed that these symptoms made myasthenia gravis a likely diagnosis. And a dangerous one: Patients with M.G. can lose strength in the muscles of the throat and the diaphragm and become too fatigued to take a breath. He called the patient. Her voice, he noticed, was nasal and thin — signs of muscle weakness. She said she wasn’t having any trouble breathing, but Keung knew that could change. That’s why he told her to go to the hospital right away. He scared her. He meant to.
A Series of Small Shocks
After the patient got Keung’s urgent call, her daughter drove her to the emergency department at Yale New Haven Hospital, and she was admitted to the step-down unit. This is the section for patients who are not quite sick enough to need the I.C.U. but might get to that point before long. Every few hours a technician came in to measure the strength of her breathing. If it got too low, she would have to go to the I.C.U. and maybe end up on a breathing machine.
Keung wasn’t certain that the patient had myasthenia. Her eyelid was always droopy, her vision always double. With M.G., he would expect those symptoms to worsen after using the muscle and improve after resting. And M.G. usually affected the muscles closest to the body. He would expect her shoulders to be weak, not her hands. Despite his uncertainty, he decided to start the treatment for M.G. He didn’t want to risk having her become even weaker. She was given high-dose steroids and intravenous immunoglobulins to suppress the parts of the immune system attacking the connection between her nerves and her muscles.
The next day Keung performed a test that would show whether the patient had M.G. In the repetitive-nerve-stimulation test, a tiny electrode is placed over the muscle, in this case the abductor digiti minimi, the muscle that moves the pinkie finger. A series of small (and uncomfortable) shocks is delivered in rapid sequence, each causing the muscle to contract. In someone with normal nerves and muscles, each identical shock will produce an identical muscle contraction. In this patient, though, the first shocks produced weak contractions and then they became even weaker. That drop-off is characteristic of M.G. The blood test that Chen had been urging her to get was done in the hospital. It was positive. She had myasthenia gravis.