One man knows immediately what to do.

This “insane” 24-year-old draws a picture for her doctor. When he sees it, he knows he must act immediately!

Susannah Cahalan's story may sound like the beginning of a horror film, but it actually happened. The 24-year-old was in the prime of her life, healthy, and had recently gotten a job as a journalist when she noticed that something was wrong.

At first she thought she had bedbugs, but the exterminator found nothing. Then Susannah began to feel lethargic, and stopped going to work. She became increasingly paranoid and started to experience hallucinations. Her relatives could barely recognize her. Finally she was overcome by seizures, and taken to the hospital.

In the hospital, Susannah's condition worsened. She was aggressive, violent towards the nurses, and tried to escape. She even became violent towards her relatives. The doctors suspected that the young woman was experiencing a nervous breakdown and were very close to admitting her to a psychiatric ward. Fortunately there was a doctor who drew the correct conclusions: Dr. Souhel Najjar.

In order to find out what was wrong with Susannah, Dr. Najjar decided against blood tests and X-rays. Instead, he performed a very simple test: He asked her to draw a clock. As he studied the results, he discovered that his assumption was correct: Susannah's "madness" had a physical cause.

On Susannah's clock, all of the numbers were on the right side, which indicated brain damage. After further investigation, a diagnosis of Anti-NMDA Receptor Encephalitis was made. Anti-NMDA Receptor Encephalitis is an immune disorder, in which antibodies produced by the immune system attack the brain. Without Dr. Najjar's resources, Susannah would have probably fallen into a coma and died. But a proper diagnosis and the right medication allowed her to be completely cured.

Susannah was kept in the hospital for one month. When she thinks back to this time, she realizes just how unreal it all felt:

"Because I literally don’t remember the good part of the month that I was in the hospital, I had to rely on medical records, interviews with doctors, interviews with my family, interviews with my boyfriend, you know, pretty much, I had to just recreate that time using the skills of a journalist.”

She writes of her "journey" into madness in her book "Brain on Fire," which is being made into a film this year.

In an interview, Susannah reflects on her experience: