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CNN Sunday Morning

Weekend House Call

Aired October 26, 2003 - 08:30   ET

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.


DR. SANJAY GUPTA, CNN MEDICAL CORRESPONDENT: Good morning and welcome to WEEKEND HOUSE CALL. This morning we're talking about the captivating stories of conjoined twins. Well, this year has been a very busy one for these unusual siblings with three high profile operations that have been completed since last August.
(BEGIN VIDEOTAPE)

GUPTA (voice-over): The trip's almost 9,000 miles from Manila to Manhattan. 18-month-old Carl and Clarence Aguirre arrived here together. But, their parents are hoping they'll be separated. Another set of Conjoined Twins. Without an operation they would never walk or develop normally.

DR. DAVID STAFFENBERG, MONTEFIORE MEDICAL CENTER: We really expect Carl and Clarence to be up and around and exploring and interacting with their environment. And they simply can't do that the way they're conjoined. And, they've begun to suffer in developmental terms for that reason.

GUPTA: This week's operation is largely preparatory, the first of many over the next few months. It's called staging, and doctors expect the approach to improve chances for survival.

UNIDENTIFIED MALE: Underneath the scalp...

GUPTA: Doctors insert balloon-like tissue expanders into their scalps to gradually expand the boys' skin. That will be used for later to cover the separated skulls. They also performed a craniotomy cutting a window into the boys' shared skull to figure out how tightly merged the two brains really are. The biggest concern is separating a vein called the sagittal sinus, the is a major blood supply drainage funnel between their two brains.

DR. JAMES T. GOODRICH, MONTEFIORE MEDICAL CENTER: If we're not successful at, the risk is neurological damage, risk is blood loss, and of course the ultimate risk is death of the children.

GUPTA: The outlook for the Guatemalan twin, the two Marias, seemed promising. But, there have been setbacks. This is Maria de Jesus and this is her sister, Maria Theresa. Of both Marias, Maria de Jesus is recovering better.

CHRIS EMBLETON, CAREGIVER: And she'd ding really well, and with -- you know, at times she's even is starting to stand now, which is really exciting. I thinks she'll grow up to be fairly normal in a lot of ways. Yes, she will have some limitations physically. She'll probably have a few bad hair days, but other than that, she's a pretty with it kid.

GUPTA: But, Maria Theresa is lagging far behind. Before the separation, it was Maria Theresa who was more outgoing. After surgery, when she was back home in Guatemala, that's when she contracted E. coli meningitis, an infection of the brain lining. Now she's deaf, brain damaged, and vision impaired.

EMBLETON: We lost all our gains in that she's basically starting life over again. She will probably not have a normal life. But, I know that children who do not -- quote, unquote, "fit the normal profile" still have so much to give to us.

GUPTA: For the twins, it's a long road to recovery, together.

EMBLETON: This is a starting point. This is not the finish line.

(END VIDEOTAPE)

GUPTA: A kind of finish line has also been crossed in Dallas, as well. This time by the Egyptian twins, Mohamed and Ahmed Ibrahim (UNINTELLIGIBLE). These two-year-old brothers saw each other for the first time in their lives after being separated two weeks ago. Doctors have upgraded both boys from serious condition from critical, but it will still take several weeks to see if there's any brain damage from the operation.

Now, as if being conjoined isn't rare enough, just about one in 200,000 births, being joined at the skull happens in only about 4 percent those cases. Although those operations are becoming more common, they're still high risk. Overall survival rate varies between five, 25 percent. It's a fascinating topic. We know that because we hear from you and we want to hear from you this morning, again. 1- 800-807-2620, that's our phone number. E-mail us housecall@cnn.com.

We have the perfect guest, today. Someone who's a leader in this field. Dr. Ben Carson, he is the chief of Pediatric Neurosurgery at Johns Hopkins Children's Center. He's led surgical teams around the world in the separation of such Conjoined Twins and he's a personal hero of mine, as well.

Dr. Carson, thank you, welcome.

DR. BEN CARSON, JOHNS HOPKINS: Thank you. Very nice to be here.

GUPTA: As you can imagine, I'm sure you know lots of calls, lots of things coming in. Let's start right away with a phone call from Linda in North Carolina.

Good morning, Linda, welcome to House Call.

LINDA, NORTH CAROLINA: Good morning, doctors. How are you this morning?

GUPTA: Doing well, good morning.

CARSON: Good.

LINDA: Doctors, I'm curious, there seems to be an increased phenomenon of this head-to-head conjoining. Is this something that's happened in the last 20, 30 years and is it a result of chemical, environmental -- what is causing this new phenomenon? And, god bless you gentlemen for addressing this. And, thank you so much.

GUPTA: Thank you.

CARSON: So, that's a...

GUPTA: Go ahead, Dr. Carson.

CARSON: Yeah, that's a frequently asked question, now. And I think what we're experiencing, right now, is just more communication about these things. In fact, we had asked the question, my he search associate and myself, a number of weeks ago, went back and started looking at cases. We found a number of cases that were in the literature, but we also discovered a significant number of cases that had never been reported and I believe that the communications are such that now almost all those cases are being captured. Be we also coincidentally, I think, are seeing a peek time right now. A lot of times when we're dealing with brain tumors, you know, we don't see very many. Then all of a sudden there's a whole barrage of them and it doesn't mean that the number of brain tumors is increasing. It's just that it's not level at all times.

GUPTA: And, I should point out, Dr. Carson, you've probably done more of these than anybody in the world now, is that right?

CARSON: I certainly would be one of the people amongst the most frequently done.

GUPTA: Right, well let's keep going, because there -- we're just getting flooded here, with e-mails and phone calls.

Rosemary in Utah writing: "Will the Filipino twins be able to live independently, or will they be limited in activities, be medicated and closely monitored over the course of their lives?"

And, I should point out Dr. Carson's not performing this specific operation. But, what is your sort of understanding of how they might do these Filipino twins in New York?

CARSON: Well, one of the wonderful things is that, you know, the New York team is putting a lot of time and thought and effort into this and are really going to take their time. A lot of things have been learned about these twins over the last couple of decades. The imaging capabilities have improved substantially. And so I think they have a reasonable chance. That doesn't mean that it's still not going to be extraordinarily complex and extraordinarily risky. But, obviously is goal is, in fact, to give them both a normal life and that is certainly the hope of the medical team who's putting forth a lot of time and effort and donating their time to accomplish this.

GUPTA: And, we are going to spend a fair amount of time talking about what is a normal life for Conjoined Twins later on in the show. But, one thing you'd be surprised by, Dr. Carson, lots of very specific questions from viewers. Such as this next e-mail.

Caryl from Texas writing: "How will the reconstruction of the protection skull surrounding the brain be done for the boys from the Philippines?"

I guess asking specifically about some of the reconstructive and plastic surgical techniques.

CARSON: Yeah, well, there are a number of techniques that can be employed. We can -- you know, harvest bones from other parts of the body, ribs, things of that nature. You can use bones from other sources. You can use titanium, which is a special type of metal; the same stuff that the space shuttle is made out of, it's nonmagnetic. There are computerized programs that can actually create a model of whatever defect there is and it can be simply slid in place and then secured with various types of securing devices. So, it's a technology that the plastic surgeons and reconstructive people have really developed to an art, now. And that, quite frankly is not the major part of the operation. If you get to the point where you're worried about that, you've had success.

GUPTA: A brain operation, I think, the more important, I do think people who do get that. Dr. Benjamin Carson's our guest, he's going to be joining us for the half-hour.

Lots coming up still. How common is it for these twins to be conjoined? When we come back, also: Why are we so fascinated by these children?

We want to hear from you. Call us 1-800-807-2620, e-mail us housecall@cnn.com. But first, let's check our "Daily Dose Health Quiz."

Where did the term "Siamese Twins" come from?"

That answer when we come back. Stay with us, on HOUSE CALL.

(COMMERCIAL BREAK)

GUPTA: Checking the "Daily Dose Quiz," now. Before the break we asked: Where did the term "Siamese Twins" come from?

Well the answer: The term actually originated with Eng and Chang Bunker, that's a set of twins born in Siam, now known as Thailand, of course, in 1811 the were born. The term "Conjoined Twins" is the preferred term, today.

Welcome back to WEEKEND HOUSE CALL, we're talking with Dr. Benjamin Carson. Dr. Carson is the chief of Pediatric Neurosurgery at Johns Hopkins. He's led surgical teams around the world in the separation of Conjoined Twins. Lots of e-mails, lots of phone calls coming in. They're buzzing those phone lines. Let's get right back to our questions.

Sara from Connecticut asking: "What causes some twins to develop conjoined while most develop as two separate physical beings?"

CARSON: Well, that's an easy question. Of course all Conjoined Twins would be identical twins. So, they come from the same ovum. But, during the separation process, it is incomplete. And wherever the incompletion exists, that's where they're joined. And, you know, most commonly it would be at places like the hip, the abdomen, the thorax, and then the cranium.

GUPTA: We give you easy questions every now and then, Dr. Carson. Here's one that may be a little bit more challenging, though. This is more -- people are fascinated with twins, but they're also fascinated by the doctors who separate twins, people like you. What's it like preparing for an operation like this? This is really where the rubber hits the road in the world neurosurgery. How do you prepare yourself to do something like this?

CARSON: First of all, these are grueling operations that they take a lot out of you. They can last for many, many, many hours. And you know going in that your chances of success are not high. So -- you know, you have to be one of those people who's prepared and willing to take risk. I think you also have to be an individual who can integrate a lot of information, including the desires of the families or of the twins themselves, if they're old enough. So, you've got to integrate philosophical issues, as well as, scientific issues...

GUPTA: It's remarkable.

CARSON: ...and you also have to have a lot of endurance.

GUPTA: And what is the longest operation you've ever done, just out of curiosity?

CARSON: Longest operation I've personally have been involved in was 36 -- no, wait a minute, no it goes back to the Bijani twins. That was 54 hours.

GUPTA: That is incredible. I think people who hear those numbers and are just surprised. I am, too and as you know, I practice. As for 54 hours is a long time. Lots of phone calls coming in.

Dean from Florida, welcome to HOUSE CALL, good morning.

DEAN, FLORIDA: Yes, good morning, gentlemen. I have a two-part question regarding Conjoined Twins. The first part is for future research in genetics and possibly even stem cell research. Will there be any positive for Conjoined Twins? My second question is regarding -- just out of curiosity, oftentimes we see where it's either two males or two females. Has there been ever a case where it's been a male and female conjoined?

GUPTA: Good question. CARSON: Well, I'll take the last one first. Obviously, that can't be the case because they have to be identical. So, that will never happen. As far as the use of stem cells, molecular genetic research, things of that nature, I think the place where that perhaps might have a role is in restoration of function, because these operations are so challenging and because frequently there is some degree of damage done, we might have a mechanism whereby we can improve the outcome neurologically. One of the reasons that we like to try to do these early on is because of the concept of plasticity. Only in children, whose brains haven't fully developed, do you have the possibility of neurons being recruited to do new things, so that if a area of the brain is damaged, you might be able to recruit new neurons to take over that function. You can't do that in older individuals.

GUPTA: And, we are going to be talking a little bit about the difference between adults and children a little bit later on. And specifically what led to the death of the Iranian sisters who fought for independence earlier this year. Everyone remembers their story. Now, our guest was part of that team that tried separating the Bijani sisters. What went wrong or did anything go wrong? That's coming up, next on WEEKEND HOUSE CALL.

(COMMERCIAL BREAK) (NEWSBREAK) (COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

GUPTA (voice-over): Separation of twins conjoined at the head generally does not turn out favorably for one or both of them. Recently we witnessed the death of the Bijani twins in Singapore. The two Marias survived but Maria Theresa has been devastated neurologically, she's vision impaired and deaf. They are not alone. Statistically the survival rate is 50 percent for one or the twins, and close to zero for both living independent normal lives. And so, while the stories of these twins have taken on an almost mystical fascination in the media, tough ethical questions are being asked in the medial community. Is it appropriate to perform such operations that some consider elective? After all, the Bijani twins were not at risk of losing their lives. And if other conjoined twins are able to develop normally, is it really worth the risk of death or significant neuralgic complications? Also, many are concerned about the $2 million plus price tag, usually not paid for by the family. Could that money be better spent on vaccinations or preventive measures that could save more lives? Many argue the cost of science moving forward is sometimes paid in dollars and lives.

(END VIDEOTAPE)

GUPTA: We're talking about Conjoined Twins, obviously, with the perfect guest. Dr. Ben Carson, Chief of Pediatric Neurosurgery at Johns Hopkins.

These interesting questions, Dr. Carson, I'm sure things that you've thought about. What about those who say the money should be better spent on vaccines or other measures that could potentially save many lives?

CARSON: Well, of course, one can always make the argument about any expenditure, that it could be better used somewhere else. But, of course, if we don't try things, we don't make progress. And you know, what if we had never wanted to spend the initial money on heart transplants or kidney transplants or liver transplants or any number of other procedures, where would we be now? So, and also, must -- one must recognize that as the technology and the knowledge improves the cost comes down. That is always the case with virtually every new technology.

GUPTA: Let's explore that a little bit further now, as well, with one of the e-mails we got, one of them about the Bijani sisters. Let's start with this one from Mary in Kansas who asks: "What problems led to the deaths of the Iranian sisters? If they had been younger, would the operation have been more likely to be successful, or there -- or were there complications that had nothing to do with the greater maturity of the women?"

And, if I can add to that as well, Dr. Carson, the case of the Bijani sisters also raised part of this ethical point. Even if a patient wants the operation, understands the risks, should doctors be performing this procedure -- you know, what some consider an elective procedure, if it has a lower chance of survival?

CARSON: OK, those are good questions. If they had been younger, of course, their chances of survival would have been considerably better. And there are cases, for instance, that aren't very well publicized like the Zambian twins who were done at the Medical University of Medunsa at the end of 1997, complexly joined at the top of the head, type two vertical craniopagus. They're in kindergarten, now. Both doing quite well. But, it didn't receive a lot of worldwide attention.

But, in fact, with the Bijani twins, what went wrong there? First of all, they knew -- everybody know that the chances of success were very slim. And one would have to understand the misery that these young ladies were in. They were highly intelligent, and also they were the first case of people who could really give informed consent with this type of joining because the others have been children. They had both been to law school. There had been a very large ethics committee convened. And it had been stated that if the ethics committee did not unanimously agree that we should proceed, that the operation wouldn't be done. With all that in mind, I personally wasn't terribly enthusiastic about it. And -- but decided I would join the team since I knew it would happen whether I joined it or not, to give whatever expertise I had. Having said all that, we learned a number of things that we didn't know. First of all, because their brains had been together for such a very long period of time, the adhesions between the brains were absolutely monstrous. And that was a whole day plus worth of work just trying to go through those adhesions. The bone was incredibly thick, you couldn't simply turn them over and manipulate them like you can children. So, you know, they were liable to air embolism because they were sitting up, air getting into the venous system, affecting the heart. There were a number of huge problems and in retrospect from the things that we learned; I personally would do it in a very different way. And I think -- you know, it's a learning experience, they're not suffering. They have contributed significantly to medical advancement. And, you know, I want people to understand that if you were connected to somebody 24/7, you could never get away for any time for yourself, you might begin to understand how they felt. And why they were willing to take that risk.

GUPTA: I think you make an excellent point. I mean, I don't think anybody can truly put themselves in that situation. It's impossible to understand. Those are good thoughts, Dr. Carson. Tough issues both medically, philosophically, and economically, as well.

When we come back, we're going to get some final thoughts from Dr. Carson, plus give you a Web site. A lot of people interested. We've got a Web site that's going to give you some more information. Stay with us on WEEKEND HOUSE CALL.

(COMMERCIAL BREAK)

GUPTA: We're getting close to being out of time, which is unfortunate, because is has been a terrific show with Dr. Ben Carson chief of Pediatric Neurosurgery at Johns Hopkins. He's one of the world's leaders in pediatric neurosurgery and has done some of the first Conjoined Twin operations in the world. Lots of great points made today.

Dr. Carson, what is the point that you think you'd want people to sort of leave with, people who've really grown fond of these stories really , really curious about them?

CARSON: Well, I want people to understand that we're human beings, and as such we're imperfect. But, god gave us the ability to learn and that's what we must do with all situations that occur, learn in advance so we can improve the situation of mankind and in every arena. And, those individuals in the medical field who are taking on these challenges are going to make life considerably better for all of us in the future.

GUPTA: Well, I know you have done that, Dr. Carson. You're a personal hero to many, me included in there. So, thank you very much for joining us, today from Virginia.

CARSON: Thank you.

GUPTA: And thanks to all our viewers as well, at home, it's been a great show. That's all the time we do have for today. Thanks for all the great questions and calls that came in, as well.

Remember, this is the place for your medical news, so tune in next week as well, next Saturday and Sunday for more WEEKEND HOUSE CALL; this is the show were you're going to get all your medical answers.

CNN SATURDAY MORNING continues now.

TO ORDER A VIDEO OF THIS TRANSCRIPT, PLEASE CALL 800-CNN-NEWS OR USE OUR SECURE ONLINE ORDER FORM LOCATED AT www.fdch.com







Aired October 26, 2003 - 08:30   ET
THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.
DR. SANJAY GUPTA, CNN MEDICAL CORRESPONDENT: Good morning and welcome to WEEKEND HOUSE CALL. This morning we're talking about the captivating stories of conjoined twins. Well, this year has been a very busy one for these unusual siblings with three high profile operations that have been completed since last August.
(BEGIN VIDEOTAPE)

GUPTA (voice-over): The trip's almost 9,000 miles from Manila to Manhattan. 18-month-old Carl and Clarence Aguirre arrived here together. But, their parents are hoping they'll be separated. Another set of Conjoined Twins. Without an operation they would never walk or develop normally.

DR. DAVID STAFFENBERG, MONTEFIORE MEDICAL CENTER: We really expect Carl and Clarence to be up and around and exploring and interacting with their environment. And they simply can't do that the way they're conjoined. And, they've begun to suffer in developmental terms for that reason.

GUPTA: This week's operation is largely preparatory, the first of many over the next few months. It's called staging, and doctors expect the approach to improve chances for survival.

UNIDENTIFIED MALE: Underneath the scalp...

GUPTA: Doctors insert balloon-like tissue expanders into their scalps to gradually expand the boys' skin. That will be used for later to cover the separated skulls. They also performed a craniotomy cutting a window into the boys' shared skull to figure out how tightly merged the two brains really are. The biggest concern is separating a vein called the sagittal sinus, the is a major blood supply drainage funnel between their two brains.

DR. JAMES T. GOODRICH, MONTEFIORE MEDICAL CENTER: If we're not successful at, the risk is neurological damage, risk is blood loss, and of course the ultimate risk is death of the children.

GUPTA: The outlook for the Guatemalan twin, the two Marias, seemed promising. But, there have been setbacks. This is Maria de Jesus and this is her sister, Maria Theresa. Of both Marias, Maria de Jesus is recovering better.

CHRIS EMBLETON, CAREGIVER: And she'd ding really well, and with -- you know, at times she's even is starting to stand now, which is really exciting. I thinks she'll grow up to be fairly normal in a lot of ways. Yes, she will have some limitations physically. She'll probably have a few bad hair days, but other than that, she's a pretty with it kid.

GUPTA: But, Maria Theresa is lagging far behind. Before the separation, it was Maria Theresa who was more outgoing. After surgery, when she was back home in Guatemala, that's when she contracted E. coli meningitis, an infection of the brain lining. Now she's deaf, brain damaged, and vision impaired.

EMBLETON: We lost all our gains in that she's basically starting life over again. She will probably not have a normal life. But, I know that children who do not -- quote, unquote, "fit the normal profile" still have so much to give to us.

GUPTA: For the twins, it's a long road to recovery, together.

EMBLETON: This is a starting point. This is not the finish line.

(END VIDEOTAPE)

GUPTA: A kind of finish line has also been crossed in Dallas, as well. This time by the Egyptian twins, Mohamed and Ahmed Ibrahim (UNINTELLIGIBLE). These two-year-old brothers saw each other for the first time in their lives after being separated two weeks ago. Doctors have upgraded both boys from serious condition from critical, but it will still take several weeks to see if there's any brain damage from the operation.

Now, as if being conjoined isn't rare enough, just about one in 200,000 births, being joined at the skull happens in only about 4 percent those cases. Although those operations are becoming more common, they're still high risk. Overall survival rate varies between five, 25 percent. It's a fascinating topic. We know that because we hear from you and we want to hear from you this morning, again. 1- 800-807-2620, that's our phone number. E-mail us housecall@cnn.com.

We have the perfect guest, today. Someone who's a leader in this field. Dr. Ben Carson, he is the chief of Pediatric Neurosurgery at Johns Hopkins Children's Center. He's led surgical teams around the world in the separation of such Conjoined Twins and he's a personal hero of mine, as well.

Dr. Carson, thank you, welcome.

DR. BEN CARSON, JOHNS HOPKINS: Thank you. Very nice to be here.

GUPTA: As you can imagine, I'm sure you know lots of calls, lots of things coming in. Let's start right away with a phone call from Linda in North Carolina.

Good morning, Linda, welcome to House Call.

LINDA, NORTH CAROLINA: Good morning, doctors. How are you this morning?

GUPTA: Doing well, good morning.

CARSON: Good.

LINDA: Doctors, I'm curious, there seems to be an increased phenomenon of this head-to-head conjoining. Is this something that's happened in the last 20, 30 years and is it a result of chemical, environmental -- what is causing this new phenomenon? And, god bless you gentlemen for addressing this. And, thank you so much.

GUPTA: Thank you.

CARSON: So, that's a...

GUPTA: Go ahead, Dr. Carson.

CARSON: Yeah, that's a frequently asked question, now. And I think what we're experiencing, right now, is just more communication about these things. In fact, we had asked the question, my he search associate and myself, a number of weeks ago, went back and started looking at cases. We found a number of cases that were in the literature, but we also discovered a significant number of cases that had never been reported and I believe that the communications are such that now almost all those cases are being captured. Be we also coincidentally, I think, are seeing a peek time right now. A lot of times when we're dealing with brain tumors, you know, we don't see very many. Then all of a sudden there's a whole barrage of them and it doesn't mean that the number of brain tumors is increasing. It's just that it's not level at all times.

GUPTA: And, I should point out, Dr. Carson, you've probably done more of these than anybody in the world now, is that right?

CARSON: I certainly would be one of the people amongst the most frequently done.

GUPTA: Right, well let's keep going, because there -- we're just getting flooded here, with e-mails and phone calls.

Rosemary in Utah writing: "Will the Filipino twins be able to live independently, or will they be limited in activities, be medicated and closely monitored over the course of their lives?"

And, I should point out Dr. Carson's not performing this specific operation. But, what is your sort of understanding of how they might do these Filipino twins in New York?

CARSON: Well, one of the wonderful things is that, you know, the New York team is putting a lot of time and thought and effort into this and are really going to take their time. A lot of things have been learned about these twins over the last couple of decades. The imaging capabilities have improved substantially. And so I think they have a reasonable chance. That doesn't mean that it's still not going to be extraordinarily complex and extraordinarily risky. But, obviously is goal is, in fact, to give them both a normal life and that is certainly the hope of the medical team who's putting forth a lot of time and effort and donating their time to accomplish this.

GUPTA: And, we are going to spend a fair amount of time talking about what is a normal life for Conjoined Twins later on in the show. But, one thing you'd be surprised by, Dr. Carson, lots of very specific questions from viewers. Such as this next e-mail.

Caryl from Texas writing: "How will the reconstruction of the protection skull surrounding the brain be done for the boys from the Philippines?"

I guess asking specifically about some of the reconstructive and plastic surgical techniques.

CARSON: Yeah, well, there are a number of techniques that can be employed. We can -- you know, harvest bones from other parts of the body, ribs, things of that nature. You can use bones from other sources. You can use titanium, which is a special type of metal; the same stuff that the space shuttle is made out of, it's nonmagnetic. There are computerized programs that can actually create a model of whatever defect there is and it can be simply slid in place and then secured with various types of securing devices. So, it's a technology that the plastic surgeons and reconstructive people have really developed to an art, now. And that, quite frankly is not the major part of the operation. If you get to the point where you're worried about that, you've had success.

GUPTA: A brain operation, I think, the more important, I do think people who do get that. Dr. Benjamin Carson's our guest, he's going to be joining us for the half-hour.

Lots coming up still. How common is it for these twins to be conjoined? When we come back, also: Why are we so fascinated by these children?

We want to hear from you. Call us 1-800-807-2620, e-mail us housecall@cnn.com. But first, let's check our "Daily Dose Health Quiz."

Where did the term "Siamese Twins" come from?"

That answer when we come back. Stay with us, on HOUSE CALL.

(COMMERCIAL BREAK)

GUPTA: Checking the "Daily Dose Quiz," now. Before the break we asked: Where did the term "Siamese Twins" come from?

Well the answer: The term actually originated with Eng and Chang Bunker, that's a set of twins born in Siam, now known as Thailand, of course, in 1811 the were born. The term "Conjoined Twins" is the preferred term, today.

Welcome back to WEEKEND HOUSE CALL, we're talking with Dr. Benjamin Carson. Dr. Carson is the chief of Pediatric Neurosurgery at Johns Hopkins. He's led surgical teams around the world in the separation of Conjoined Twins. Lots of e-mails, lots of phone calls coming in. They're buzzing those phone lines. Let's get right back to our questions.

Sara from Connecticut asking: "What causes some twins to develop conjoined while most develop as two separate physical beings?"

CARSON: Well, that's an easy question. Of course all Conjoined Twins would be identical twins. So, they come from the same ovum. But, during the separation process, it is incomplete. And wherever the incompletion exists, that's where they're joined. And, you know, most commonly it would be at places like the hip, the abdomen, the thorax, and then the cranium.

GUPTA: We give you easy questions every now and then, Dr. Carson. Here's one that may be a little bit more challenging, though. This is more -- people are fascinated with twins, but they're also fascinated by the doctors who separate twins, people like you. What's it like preparing for an operation like this? This is really where the rubber hits the road in the world neurosurgery. How do you prepare yourself to do something like this?

CARSON: First of all, these are grueling operations that they take a lot out of you. They can last for many, many, many hours. And you know going in that your chances of success are not high. So -- you know, you have to be one of those people who's prepared and willing to take risk. I think you also have to be an individual who can integrate a lot of information, including the desires of the families or of the twins themselves, if they're old enough. So, you've got to integrate philosophical issues, as well as, scientific issues...

GUPTA: It's remarkable.

CARSON: ...and you also have to have a lot of endurance.

GUPTA: And what is the longest operation you've ever done, just out of curiosity?

CARSON: Longest operation I've personally have been involved in was 36 -- no, wait a minute, no it goes back to the Bijani twins. That was 54 hours.

GUPTA: That is incredible. I think people who hear those numbers and are just surprised. I am, too and as you know, I practice. As for 54 hours is a long time. Lots of phone calls coming in.

Dean from Florida, welcome to HOUSE CALL, good morning.

DEAN, FLORIDA: Yes, good morning, gentlemen. I have a two-part question regarding Conjoined Twins. The first part is for future research in genetics and possibly even stem cell research. Will there be any positive for Conjoined Twins? My second question is regarding -- just out of curiosity, oftentimes we see where it's either two males or two females. Has there been ever a case where it's been a male and female conjoined?

GUPTA: Good question. CARSON: Well, I'll take the last one first. Obviously, that can't be the case because they have to be identical. So, that will never happen. As far as the use of stem cells, molecular genetic research, things of that nature, I think the place where that perhaps might have a role is in restoration of function, because these operations are so challenging and because frequently there is some degree of damage done, we might have a mechanism whereby we can improve the outcome neurologically. One of the reasons that we like to try to do these early on is because of the concept of plasticity. Only in children, whose brains haven't fully developed, do you have the possibility of neurons being recruited to do new things, so that if a area of the brain is damaged, you might be able to recruit new neurons to take over that function. You can't do that in older individuals.

GUPTA: And, we are going to be talking a little bit about the difference between adults and children a little bit later on. And specifically what led to the death of the Iranian sisters who fought for independence earlier this year. Everyone remembers their story. Now, our guest was part of that team that tried separating the Bijani sisters. What went wrong or did anything go wrong? That's coming up, next on WEEKEND HOUSE CALL.

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GUPTA (voice-over): Separation of twins conjoined at the head generally does not turn out favorably for one or both of them. Recently we witnessed the death of the Bijani twins in Singapore. The two Marias survived but Maria Theresa has been devastated neurologically, she's vision impaired and deaf. They are not alone. Statistically the survival rate is 50 percent for one or the twins, and close to zero for both living independent normal lives. And so, while the stories of these twins have taken on an almost mystical fascination in the media, tough ethical questions are being asked in the medial community. Is it appropriate to perform such operations that some consider elective? After all, the Bijani twins were not at risk of losing their lives. And if other conjoined twins are able to develop normally, is it really worth the risk of death or significant neuralgic complications? Also, many are concerned about the $2 million plus price tag, usually not paid for by the family. Could that money be better spent on vaccinations or preventive measures that could save more lives? Many argue the cost of science moving forward is sometimes paid in dollars and lives.

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GUPTA: We're talking about Conjoined Twins, obviously, with the perfect guest. Dr. Ben Carson, Chief of Pediatric Neurosurgery at Johns Hopkins.

These interesting questions, Dr. Carson, I'm sure things that you've thought about. What about those who say the money should be better spent on vaccines or other measures that could potentially save many lives?

CARSON: Well, of course, one can always make the argument about any expenditure, that it could be better used somewhere else. But, of course, if we don't try things, we don't make progress. And you know, what if we had never wanted to spend the initial money on heart transplants or kidney transplants or liver transplants or any number of other procedures, where would we be now? So, and also, must -- one must recognize that as the technology and the knowledge improves the cost comes down. That is always the case with virtually every new technology.

GUPTA: Let's explore that a little bit further now, as well, with one of the e-mails we got, one of them about the Bijani sisters. Let's start with this one from Mary in Kansas who asks: "What problems led to the deaths of the Iranian sisters? If they had been younger, would the operation have been more likely to be successful, or there -- or were there complications that had nothing to do with the greater maturity of the women?"

And, if I can add to that as well, Dr. Carson, the case of the Bijani sisters also raised part of this ethical point. Even if a patient wants the operation, understands the risks, should doctors be performing this procedure -- you know, what some consider an elective procedure, if it has a lower chance of survival?

CARSON: OK, those are good questions. If they had been younger, of course, their chances of survival would have been considerably better. And there are cases, for instance, that aren't very well publicized like the Zambian twins who were done at the Medical University of Medunsa at the end of 1997, complexly joined at the top of the head, type two vertical craniopagus. They're in kindergarten, now. Both doing quite well. But, it didn't receive a lot of worldwide attention.

But, in fact, with the Bijani twins, what went wrong there? First of all, they knew -- everybody know that the chances of success were very slim. And one would have to understand the misery that these young ladies were in. They were highly intelligent, and also they were the first case of people who could really give informed consent with this type of joining because the others have been children. They had both been to law school. There had been a very large ethics committee convened. And it had been stated that if the ethics committee did not unanimously agree that we should proceed, that the operation wouldn't be done. With all that in mind, I personally wasn't terribly enthusiastic about it. And -- but decided I would join the team since I knew it would happen whether I joined it or not, to give whatever expertise I had. Having said all that, we learned a number of things that we didn't know. First of all, because their brains had been together for such a very long period of time, the adhesions between the brains were absolutely monstrous. And that was a whole day plus worth of work just trying to go through those adhesions. The bone was incredibly thick, you couldn't simply turn them over and manipulate them like you can children. So, you know, they were liable to air embolism because they were sitting up, air getting into the venous system, affecting the heart. There were a number of huge problems and in retrospect from the things that we learned; I personally would do it in a very different way. And I think -- you know, it's a learning experience, they're not suffering. They have contributed significantly to medical advancement. And, you know, I want people to understand that if you were connected to somebody 24/7, you could never get away for any time for yourself, you might begin to understand how they felt. And why they were willing to take that risk.

GUPTA: I think you make an excellent point. I mean, I don't think anybody can truly put themselves in that situation. It's impossible to understand. Those are good thoughts, Dr. Carson. Tough issues both medically, philosophically, and economically, as well.

When we come back, we're going to get some final thoughts from Dr. Carson, plus give you a Web site. A lot of people interested. We've got a Web site that's going to give you some more information. Stay with us on WEEKEND HOUSE CALL.

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GUPTA: We're getting close to being out of time, which is unfortunate, because is has been a terrific show with Dr. Ben Carson chief of Pediatric Neurosurgery at Johns Hopkins. He's one of the world's leaders in pediatric neurosurgery and has done some of the first Conjoined Twin operations in the world. Lots of great points made today.

Dr. Carson, what is the point that you think you'd want people to sort of leave with, people who've really grown fond of these stories really , really curious about them?

CARSON: Well, I want people to understand that we're human beings, and as such we're imperfect. But, god gave us the ability to learn and that's what we must do with all situations that occur, learn in advance so we can improve the situation of mankind and in every arena. And, those individuals in the medical field who are taking on these challenges are going to make life considerably better for all of us in the future.

GUPTA: Well, I know you have done that, Dr. Carson. You're a personal hero to many, me included in there. So, thank you very much for joining us, today from Virginia.

CARSON: Thank you.

GUPTA: And thanks to all our viewers as well, at home, it's been a great show. That's all the time we do have for today. Thanks for all the great questions and calls that came in, as well.

Remember, this is the place for your medical news, so tune in next week as well, next Saturday and Sunday for more WEEKEND HOUSE CALL; this is the show were you're going to get all your medical answers.

CNN SATURDAY MORNING continues now.

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