KELLY MCEVERS, HOST:
Here's a medical mystery. It starts with a kindergarten teacher who we'll call by her first initial, M. We're not using her full name to protect her privacy. M. taught reading to 4- and 5-year-olds. But a few years ago, something happened that changed her life. She lost the ability to read. NPR's Rebecca Hersher reports.
REBECCA HERSHER, BYLINE: M. always knew she wanted to be a teacher.
M.: A teacher is all I ever knew how to do. It's all I ever wanted to do. I wanted to work with the younger children.
HERSHER: M. taught reading at a kindergarten outside Chicago. She had walked the 4- and 5-year-olds in her class through their first sight words, the dog is brown. She had her own condo and taught Sunday school on weekends.
M.: I'm a single person. I was living independently, lots of friends. I thought I had a pretty good life. I don't know, I loved teaching. I loved what I did, and it just made life very fulfilling.
HERSHER: But in the fall of 2011, a week before Halloween, weird things started to happen.
M.: There was a Halloween party at the park district, and I was taking money. And I remember, oh, there's three people here, that will be $9. And the woman looked at me and said, there are six of us. I didn't realize I had lost vision. I just knew that there was something weird.
HERSHER: And other strange things were happening. M. got lost driving in her own neighborhood. She was confused about dates and times. And about a week after it began, she was trying to take attendance at school when she realized she couldn't type the numbers and letters of her computer password. Something was wrong.
Dr. Murray Flaster is one of the doctors who's treated M.
DR. MURRAY FLASTER: We believe that she had an inflammation of blood vessels in the brain. And that inflammation led to the cutoff of blood flow to a few areas in the brain.
HERSHER: When blood doesn't get to the brain, that's a stroke. M. had had many, maybe even dozens of little strokes. And as she recovered, her most striking symptom was this: M. could write but she couldn't read.
FLASTER: So if you give her a book and you ask her to read it, she knows it's a book. She knows there must be letters on the page. She knows there's words there, but she cannot recognize letters and put letters into words because of the exquisite nature of the brain damage.
HERSHER: The strokes damaged the connection between the part of M.'s brain that takes visual information from the eyes and delivers it to the part of the brain that deciphers words. In a healthy brain, when you open a book, one part of your brain says, hey, those are words you're seeing. And it sends the words to be decoded in another part of the brain. In M., that connection, which she built when she first learned to sound out words as a little kid, it's gone, which means she can't read anymore.
M.: I miss the normalcy of it. There's so many things in the world that you take for granted. I never thought that I would say that reading was something that I took for granted.
HERSHER: But here's where M.'s story goes from pretty dismal to kind of beautiful. Remember, M still knows how to write. In fact, she can understand language using other senses, just not sight. So she can listen to audio books, write stories and even transcribe words as they're said to her, which gave M. an idea. Instead of relying on her eyes, she would use touch and hearing to read. It works like this.
When M. sees a jumble of shapes that look like a word, she begins by tracing each letter with her finger.
M.: Let's say pit is the word that I'm looking at. So I would start M, N, O, OK, P. And I would keep tracing the P. Then I would go to the next letter, and I would trace A, B, C, D, E, F, G, H, I. OK. The first letter was a - and I would forget the first letter by this time.
HERSHER: It's a maddeningly slow way to do it, but it's reading. Dr. Flaster says without knowing it, M. came up with a genius way to work around the damaged parts of her brain.
FLASTER: She discovered that all by herself. And we speculate that the fact that she was an expert in teaching children how to read perhaps made her more likely to discover that than someone else who might otherwise be stricken similarly. Of course, I can't prove that, but it seems to make sense.
HERSHER: M. isn't the first person to come up with the tracing method. It's actually worked for other patients too. But it's a long road. Two years after her strokes, M.'s reading is still laborious. On a good day, she can decipher about one word every two seconds. But she's not letting it slow her down too much.
She has a new job, working at the community gym. And she wants to tell her story. In her free time, M. is writing a book, typing it word by word and getting friends to help her read it.
Rebecca Hersher, NPR News.