the radiologist saw this and sort of went wild over this. look at the size of this, they re three to four times bigger. reporter: they ve probably never seen anything like this. right. because there s no way to make those muscles big by moving your eyes a lot. it s not like lifting weights. so why would they be that big? reporter: it s a clue. it suggests something inside the muscle itself. so the udp team took a sample. you took some muscle from her arm. right. and really, this was one of those sort of judgment decisions. because she had had a muscle biopsy one year before that was read as normal. so we weren t like 99% sure we should do this. we were like 70%, 80% sure. reporter: in five days the tests are complete. sally is sent home to north carolina, but no diagnosis. not yet. in fact, gahl and his team treat their patients like a crime scene. they collect all the evidence they can find and then try to make sense of it. in medicine, it s striking that
everything was increasingly difficult. was it worse during the day or night? trying to sleep? you know, i wasn t able to function normally at any time. how about pain? were you having pain how did you control it? it was very painful. i don t know the condition itself was so painful but i think mechanically what it did to my body, being so heavy, the muscles were so heavy and they were so very tight and they would just cinch up tighter and tighter that there would be a lot of pain, and the muscles were so weak they would fatigue very, very quickly. that s a misconception. people thought you were actually stronger but you were in fact weaker and less mobile. the muscles would fatigue very quickly. when dr. gahl told you when you came in the chances were remote that they were going to figure this out, 85% to 90% chance they wouldn t figure it out, what did you think when you
whole lot of time in the gym. reporter: but sally didn t lift weights. in fact, whatever was causing her body to bulk up uncontrollably was also taking away her ability to live her life. it was very frustrating. i was losing the ability to do the things i loved to do. it became increasingly difficult just to walk. at some point i knew if it continued it would kill me. reporter: she d seen countless medical specialists. no one had an explanation. that s why dr. william gahl and his team of specialists at the undiagnosed diseases program was trying to solve the mystery. this is super impressive. look at these things.
medical version of csi. patients are literally scoured for clues during a week of intensive tests and exams. no test result is left unturned. if you ve got to crack a case that has stumped every doctor before you, you need to think outside the box. you need to work together. that s the premise of udp. would it all work for kylie and sally? no one, no doctors, no specialists, no researchers could explain what was happening to sally massagee. her muscles had grown grotesquely large and hard, like rocks underneath her skin. it became increasingly difficult just to walk. at some point i knew if it continued it would kill me. reporter: for one week, dr. gahl s team of world class medical experts probed and collect exhaustive scans, blood work, and a tissue sample from sally s bicep. we do liken it to detective work, but remember, a lot of the detective work takes place after the patients have gone. reporter: after five days,
very symmetrical. reporter: they could point to epilepsy partiala continuea. we don t have an understanding of the underlying mechanism that s brought it on. yeah. this will help it not hurt. reporter: by friday, the tests are complete. dr. gahl and his team are planning what they re going to tell kylie s parents. waiting in another room, kylie s mom and dad are anxious. hopeful. they might have some things back from that. so it s exciting and i m nervous. so we want to document that for her. reporter: but the doctors have no diagnosis. working all sorts of things that have yet to come back for us to consider. reporter: instead they explain how the results will guide their investigation. we continue to work together on this. reporter: for kylie s mom and dad, gina and steven, the