Susannah is reassigned to a shared room in the epilepsy unit. The results of the biopsy confirm that Susannah's brain is inflamed. Susannah explains for the reader that the brain is immuno-different, which means that while it isn't completely separate from the rest of the body's blood system, some things (drugs, chemicals, bacteria) are allowed into the brain. The biopsy shows that Susannah's brain is allowing certain blood cells to enter the brain, and those cells are attacking it. Dr. Najjar prescribes a heavy dose of IV steroids to decrease the inflammation and then prescribes prednisone, an oral steroid.
Cahalan is careful to make sure the reader understands that this information about the brain and how it interacts with blood is new and incomplete—more information will, in the future, add to this picture. This continues to develop the idea that Susannah's story is a product of the year that she got sick and the medical information that was available at that time.
Because of this treatment plan, Susannah temporarily develops diabetes—though her parents remain oblivious and she continues to eat her Easter candy. Despite the treatment, Susannah seems to get worse and experiences more strange movements and panic attacks. She can still behave appropriately for visitors, though, and Hannah visits not long after the surgery.
Susannah's continued ability to behave well for visitors suggests that some parts of her identity—particularly her public identity, which is heavily based on personal interactions and social norms—have absolutely remained intact, despite the other ways in which the illness has ravaged her brain.
Susannah describes an EEG video. She reclines on the bed, gets up, and haltingly walks to the door. Mom, off camera, asks a nurse which button is the call button. After Susannah gets back into bed, Mom presses the button. A nurse arrives and conducts an exam. When he leaves, Susannah slowly lies back down.
This video in particular shows the limits of what can be learned from these impartial videos. It's unclear why exactly Mom called for a nurse, just as it's unclear why Susannah got out of bed in the first place. These videos offer an outside view, but little in the way of narrative explanation.