If you look through all the lore and the equivalence to real life, Fletcher Syndrome is a systemic failure of vitals in a long lasting and painful manner.
Symptoms: Cranial Hemorrhaging, Cardiac Hemorrhaging, Spasms in disconnected tissue, Complete Muscle Collapse, Sensory Deprivation, Digestive Tract Bloating, Malnutrition, and the lowering of the immune system.
There is no cure and presumably wouldn't have any due to the lack of ability to address so many situations at once.
Multiple organ dysfunction syndrome (MODS) is the less extreme, yet real life version of Fletcher Syndrome. Though it doesn't contain all of the symptoms, it does contain the most crucial symptoms of Total Organ Failure.