David Dunaway's voice briefly shook with emotion yesterday as he explained how it was his team's hope that Rital and Ritag Gaboura would go on to lead normal lives.
"I can't say what a joy it has been. It is hard to say what it feels like to have been involved in the team that managed to do this. It has been a wonderful experience. A few weeks later and they are smiling and developing properly. It has been wonderful for us," said the cranio-facial surgeon.
It is a fleeting indication that, far from being a miracle, the separation of the conjoined twins was the culmination of months of work by a team of more than two dozen experts who pushed themselves to their surgical and medical limits. "We feel very lucky that our girls have been able to have the surgery that they needed, but we also know other children who need complete sponsorship and families who are searching for someone to help them," says the girls' father Abdelmajeed.
Rital and Ritag weighed just 6kg together when they were born by caesarean section in Khartoum, Sudan, in September 2010, joined at the top of their heads. Their parents Abdelmajeed, 31, and Enas, 27, both doctors, knew the odds against them were terrible. Only a fifth of conjoined craniopagus twins make it to their first birthdays, while 90 per cent of them die by the time they reach 10 years old. Even fewer get a chance to lead a normal life.
The two little girls would be confined to lying down but, worse still, Ritag was supplying half of Rital's blood, keeping her twin alive, but slowly her heart was failing in the task.
For the girls' parents, it was the beginning of a fight to find the funding and the expertise to separate them safely. They approached one organisation after another in vain.
Eventually, they were put in touch with Facing the World, a charity that was set up by some of the UK's leading craniofacial surgeons almost a decade ago to provide hope for youngsters with terrible disfigurements. Over those years it has helped children from nearly 20 countries.
The charity managed to raise almost £300,000 to cover costs, while experts donated their time for free. They handled all the logistics, including the problem of finding the transport that would fly the girls in from Sudan.
Sarah Driver-Jowitt, Facing the World's executive coordinator, who travelled to Sudan to make arrangements when the girls were two months old, says: "Even bathing them was difficult. Mum was really struggling to carry them both while supporting their necks. But they got around it in the most graceful way. They had large pillows to put them on. One twin would sleep while the other was crying. Just watching their mum cuddle one while the other sister was asleep, you forgot they were conjoined."
Armed with new toys and clothes, the family arrived in London in April to begin a mammoth round of medical treatment. The team immediately fell head over heels for the pair. Rital, the stronger one, was "the boss", while Ritag was chattier.
"They have always been little laughing girls. They just giggle. They would beam and start laughing even before I would talk to them," says Driver-Jowitt.
The two little girls' brains were separate but touched and shared a single dural layer (a thick fibrous membrane enveloping the brain). Parts of Rital's brain were also supplied by her sister's blood.
The surgeons were faced with a dilemma, says team leader Dunaway, as they wanted to complete the surgery in "slow, steady" stages. The initial plan had been to wait until the twins were around a year old, but the doctors knew that Ritag's high blood pressure and failing heart were putting her in mortal danger and they simply could not afford much more time.
"One thing was encouraging us to go slower but Ritag's heart failure was demanding that we go quickly. Her heart was having to pump for both twins and she was underweight, almost unable to take in enough nutrition to cope. Meanwhile, however, Rital was having a fairly easy time."
Medication, he explained, was also causing a major problem as one twin had high blood pressure while the other's was low, a tremendous challenge for the anaesthetists.
The team included craniofacial and plastic surgeons, neurosurgeons, anaesthetists, neuro-radiologists, paediatricians, cardiologists and a host of specialist nurses.
On 9 May, the first operation began. Over 10 hours they separated one third of the brains through limited cuts to the skulls. A silastic sheet was placed partially between them to replace the joint dura. The surgery went well, but it seemed that Ritag's heart problems were getting worse.
Seven days later the twins went through another 10-hour operation when the surgeons separated the common vein in their brains, giving it to Rital, and extended the silastic sheet across the rest of the heads.
"This was a small 3cm blood vessel in a whole set of vessels so the chance of making an error was high," explains leading neurosurgeon Owase Jeelani. But the surgery was successful and both twins were functioning well. The strain on Ritag's heart was also beginning to lift.
Then on 4 July, when the girls had recovered enough and put on some weight, they went back into surgery yet again. This time, over six hours, tissue expanders were inserted under the scalp. These were inflatable silicone balloons which over the coming weeks would be gradually inflated with injections of saline. As they expanded, they stretched the scalp so that both girls would have enough to cover their heads when the separation came.
Then on 15 August, they went through the final major operation. Over 13 hours the surgeons worked to separate the girls. A new skull was made by splitting the inner and outer layer of their bone to cover both heads.
Doctors had worked for months on three-dimensional models to try to ensure that any scarring or disfigurement would be kept to a minimum. The skin was replaced so the direction of hair growth was normal.
The girls appeared to be doing well. Ritag, who had always had to fight harder to survive, had blossomed, while Rital was progressing a little bit more slowly, the surgeons explain.
"It is a delight to see how well the girls are doing. Rital was up and holding her own milk bottle again within days of surgery. Ritag took a day or two longer but she too is back to her laughing self," says craniofacial surgeon Simon Eccles.
"After 11 months of spending most of their time lying on their backs it is amazing how quickly they have adapted. The girls are already doing all the things that they were able to do pre-surgery – playing with toys, clapping, holding their milk bottles and so on."
They will both need further reconstructive surgery to ensure normal shaped heads, says Dunaway, and they will need physiotherapy to make their neck muscles stronger, but the prognosis is good for both girls: "It is for the family now to be able to settle down and lead a normal life.
"This was a real surgical challenge, a very rare and complex operation, drawing together many different disciplines. But also these were two little girls with a loving family, and we had to get both children through the procedures safely."
Driver-Jowitt says: "The most moving thing for me was watching their parents the first time they had to deal with them separately. They were desperately running from one cot to the other, not sure where to be. They had never had to do that before."
Deeply religious, the parents believe that their faith, as well as the extensive medical team, had helped their little girls survive, says Driver-Jowitt. "Their mum says the moment she woke and they were no longer conjoined it was all like it had been a dream. When we put the girls together in a cot, they just linked arms and started playing with their teddy bears."
On Thursday, the twins will celebrate their first birthdays but Driver-Jowitt says: "Their mum and dad have already said that they will have two birthdays, one to mark their birth and one to mark their separation.
"The parents always said that all they ever dreamt about was to have two healthy girls to go home with and that is now about to happen."
Facing the World, www.facingtheworld.net
A modern miracle
It was not until three decades ago that conjoined twins had much hope of surviving separation. Until then, parents faced the agony that one child would die, and sometimes neither would survive due to blood loss and surgical complications.
In 1987, neurosurgeon Benjamin Carson, from John Hopkins Hospital in Baltimore, gained worldwide recognition as the first man to successfully separate craniopagus twins. A 50-member surgical team worked 22 hours to separate Patrick and Benjamin Binder, who both survived.
Seven years ago James T Goodrich and David Staffenberg led the first multi-disciplinary medical team in a stage twin separation in New York. Though Carl and Clarence Aguirre still require close monitoring, it was the first double separation with no immediate signs of neurological impairment.
Two members of yesterday's team, David Dunaway and Richard Hayward, led the first UK separation of craniopagus twins five years ago.