I do not know whether she expected this: a crowd of 10 curious students in this small, overlit room deep in the bowels of the hospital. She seemed so exposed and frightened in her wheelchair, like a hapless musician unwittingly pushed on stage. The neurologist, standing by her side, was hitting a tendon hammer against his palm.

“Please gather around,” he ordered, “and get as close as you can to the patient.” We encircled her. A student in the front row took a history.

Anastasia Hayes (who wishes to have her name published) was in her 60s, with golden hair and thick glasses that magnified her eyes. Her voice was soft, close to a whisper. She explained how, months ago, her left leg became weak. Then the weakness spread to her right hand. “I thought it was just one of those things,” she said. Today Anastasia cannot get changed or wash herself unassisted. …