Reporter: Tara Brown
Producer: Danny Keens
Would you risk your child's life for the hope of a better future?
Six-year-old Sasha Sabet suffers from severe epilepsy.
The seizures are unpredictable and every one of them is damaging her young brain. Her mum is offered a possible cure but it's straight out of a science fiction novel.
Doctors want to remove half of Sasha's brain.
There are no guarantees the surgery will work or that Sasha will survive the operation.
What you're about to witness is a journey inside the human brain. And it's not just a medical miracle. It's also a story of incredible courage.
TARA BROWN: This is the most delicate of medical procedures. The surgeons here are removing one side of this little girl's brain to treat her severe epilepsy. It's a rare, last resort operation on an organ we still know so little about.
TARA BROWN: It's almost impossible to fathom how difficult a decision this is - to remove half your precious child's brain, almost as difficult as it is to believe that anyone could function after such a radical operation. But this procedure is all about providing a life as close to normal as possible.
SHANNA SABET, MOTHER: It's just insane that this is her life, that she has been through so much. There is no way that I could've gone through what she's gone through and be as cheerful and joyful and, you know, active as she is.
TARA BROWN: In many ways, Sasha Sabet is like any normal 6-year-old girl - outgoing and playful. But, in reality, she's not. At just 15 months of age, her single mum, Shanna, was told her baby would require a simple and routine operation to remove water from the brain. It changed their lives forever.
SHANNA SABET: Something went wrong during that procedure and she started having seizures in the hospital shortly following that.
TARA BROWN: So, she went into this operation as a child with absolutely no sign of epilepsy...
SHANNA SABET: Correct.
TARA BROWN: ..and she came out of the operation with seizures.
SHANNA SABET: Correct.
TARA BROWN: How do you describe that sense of anger you must feel?
SHANNA SABET: I don't even think 'anger' is the right term.
TARA BROWN: It doesn't cut it?
SHANNA SABET: No, not at all. I'm so much more than angry. I mean, they completely desecrated the life of my child.
TARA BROWN: The seizures hit Sasha every month, always with an emergency dash to hospital. They last on average three hours - all the while ravaging her brain. For her mum, the episodes are heartbreaking and, because the medication doesn't work for her daughter, impossible to control.
TARA BROWN: What is it that you're most worried about?
SHANNA SABET: Ah, well, the thing I'm most worried about is that, one of these days, one of these seizures could kill her, and that's really hard.
TARA BROWN: Of course it is, you poor thing.
SHANNA SABET: But, you know, cheese.
TARA BROWN: Are you getting a happy snap of mum?
SHANNA SABET: Not so happy! DR GARY MATHERN, PAEDIATRIC NEUROSURGEON: Imagine, if you will, you feel a little funny - you can't really describe it. The next thing you know, you're kind of coming out of a fog. Visually, the room's kind of spinning around and you don't know what's going on, and then it starts to get some clarity. That's a seizure. Your brain just got hijacked. So the operation we'll do tomorrow is we'll take out a central wedge of tissue...
TARA BROWN: Doctor Gary Mathern is a paediatric neurosurgeon at the UCLA Medical Center, in Los Angeles. His scans show the damage the epilepsy has already done to Sasha's brain.
DR GARY MATHERN: The areas of red is where the brain is working normally, and the area of blue, or dark colour, is where the brain is not working normally. Most of the right hemisphere is not.
TARA BROWN: Dr Mathern believes Sasha's only chance at life, a normal life, is a hemispherectomy - a procedure that he's performed on nearly 200 children. He removes the part of the brain that causes the seizures. In Sasha's case, she will lose her entire right hemisphere.
SHANNA SABET: It's hard. It sounds like science-fiction to me.
DR GARY MATHERN: Correct, and this is the reality. It's theoretical until you're sitting in this chair and you're talking to the guy who's going to do it, and it's no longer a theory - it's a reality with a surgical date.
TARA BROWN: Sasha goes into surgery tomorrow. What makes Shanna's decision even more complicated is that, while this operation is Sasha's only chance to stop the epilepsy, there is no guarantee it will work. Dr Mathern won't even know if he's removing the correct side of the brain until after Sasha comes out of surgery.
DR GARY MATHERN: If you've taken out half the brain, and you still have seizures, where are the seizures coming from? The other side.
TARA BROWN: So, you wont know until after the operation?
DR GARY MATHERN: Correct. When we fail, we have a tendency to fail on a very spectacular fashion, so it's like a switch - You either got it, or you don't got it.
TARA BROWN: And there's no way to know if you've got it?
DR GARY MATHERN: Unless you do it. So, for families, this is incredibly scary.
TARA BROWN: He doesn't know if he's taking the right part out until he operates. How worrying is that for you?
SHANNA SABET: Are you kidding? Of course, of course that's a worry. I mean, it's been a process to make this decision and it's the hardest decision I've ever made in my life, and I think it's just the right decision. I think it's the only thing that we can do at this point. I talked to her today, actually, about it, about going into the hospital to see the doctors tomorrow and she said, "Are they going to give me a shot?" And I said, "Maybe, just a little one, and then they're going to give you something to make you not have seizures any more." And she said, "No seizures?" It was wonderful. So, I think she understands that, I think she understands that.
TARA BROWN: This will be the longest, most excruciating, day for Shanna, for she's just put her daughter's life in Dr Mathern's hands.
SHANNA SABET: Please take care of her.
DR GARY MATHERN: I've got a whole group of people to take care of her, okay? I've got a whole group of people. They've done it before and they'll do it again.
TARA BROWN: In theatre, the focus is all on Sasha. The first step in this 8-hour operation is to expose the brain. They only get one chance to get it right, so, before they remove anything, they need to confirm with electrodes that the affected area is as bad as they thought. It is and, so, with incredible precision, they start to remove Sasha's right hemisphere. Downstairs, an anxious Shanna gets the update.
SHANNA SABET: Is everything okay?
NURSE: She's doing great. No problems, no complications at all. Everything is going really well.
TARA BROWN: It's incredible but, by taking away half her brain, doctors are giving Sasha so much more. In young children, the remaining brain takes over the function of the missing half. The right side is linked to creativity, reasoning and emotion and, so, for Sasha, the left side will step in and compensate.
TARA BROWN: And what about personality? Are there any changes if you remove -
DR GARY MATHERN: I don't know where personality is. I've taken out right hemispheres, I've taken out left hemispheres and the children come back with the same personality afterwards as they were before surgery. I don't know where behaviour is. If they were nasty little buggers before, they'll be nasty little buggers afterwards.
TARA BROWN: You've been described being able to drive as one of your greatest personal successes. Why is that?
CHRISTINA SANTHOUSE: I think, for me, once getting out of surgery when the doctors told me that I couldn't do it, it just gave me even more motivation to try.
TARA BROWN: So, you're happy when you're behind the wheel?
CHRISTINA SANTHOUSE: Oh, I'm ecstatic when I'm behind the wheel!
TARA BROWN: 23-year-old Christina Santhouse is a dynamo. Alongside her proud driving career, she's a ten pin bowling ace, recently graduated with Honours, got her Masters degree, and has just landed her first job as a speech pathologist - not bad for a girl with only half a brain.
TARA BROWN: Do you think of yourself as someone with half a brain?
CHRISTINA SANTHOUSE: I try not to, but every once in a while - this is going to sound funny, but - if I move my head too fast, I kind of feel a squishing because you figure the right hemisphere isn't there, but that space is filled with spinal fluid, so it's water. So, if I shake my head, then I'll start feeling the waves of the ocean. So, then I get a little reality check - "Oh, yeah, the whole thing's not up there!"
TARA BROWN: Christina was seven years old when her seizures started as a slight twitch in her ankle. Within months, she was having 100 seizures a day and her parents, Al and Lynne, were told she faced certain death.
AL SANTHOUSE: Watching our little girl go from soccer player to someone in a wheelchair in a matter of months was very painful.
LYNNE SANTHOUSE: I didn't know how to help her. They took over her like a demon, they just took over her whole body, you know. It started with a little shake and, before you knew it, she was on the floor, shaking uncontrollably.
TARA BROWN: Incredibly, it was Christina who told doctors she wanted to have the right half of her brain removed. And, 16 years after the surgery, like all kids who go through the procedure, she has limited use of the opposite side of her body - her left arm and leg. Her peripheral vision is also affected and, for a while, she found it hard to focus, but she believes she's gained so much more than she's lost.
CHRISTINA SANTHOUSE: I'm so happy. Life is good.
TARA BROWN: So, I guess the message is you can have half a brain and, not only function, but you can thrive?
CHRISTINA SANTHOUSE: Absolutely, who would have thought? I guess that's the magic of life - you just don't know. I was granted this awesome second life.
TARA BROWN: Does the brain still amaze you?
DR GARY MATHERN: I'm marvelled by how much we can use it and our treatments. What hurts is I will often see a person who is in their teens or 20s who's been seizing since they were, say, one or two years old. Now they're in their 20s and they don't have that plasticity, and they're not surgical candidates any more.
TARA BROWN: Why aren't they getting into your hands?
DR GARY MATHERN: There are people out there, physicians and others, who view epilepsy surgery as something of last resort. That has to end.
TARA BROWN: Back in theatre and, after eight hours, Sasha's marathon surgery is coming to an end. The prognosis should be good. Sasha is young, and there were no complications, but Dr Mathern won't know if she's seizure-free for another six months.
DR GARY MATHERN: So, the best thing that you want on a day like today is for me to come out and tell you it was another day at the office. And that's what it was - another day at the office. It's over, okay? It's over. This is the part where you get to hug the surgeon.
TARA BROWN: Just moments after surgery, Mum and little Sasha are reunited, but it doesn't take long for Sasha to do what she does best - let the world know what she thinks.
DR GARY MATHERN: We promised Mum we wouldn't take out her personality.
TARA BROWN: You haven't.
DR GARY MATHERN: Sasha?
SASHA SABET: What?!
DR GARY MATHERN: Where are you?
SASHA SABET: Asleep and tired.
SHANNA SABET: The first thing that I thought about when they told me that they wanted to do this for her was, "What if I lose her?"
DR GARY MATHERN: That's good. We'll leave you alone.
SHANNA SABET: What Sasha will I be getting back, you know? And every person that I've asked, they all tell me that you're going to be getting a better version of her back, you'll be getting a better version of her back, and you just have to believe.
TARA BROWN: Sasha has recovered well from her surgery, and we'll keep you up to date on whether it's been a success in stopping her seizures.