Photo credit: Gemini Untwined
By Face2Face Africa
Mercy and Goodness, twin sisters conjoined at the head, have undergone a groundbreaking separation using advanced artificial intelligence techniques. Born in June 2023 in Nigeria’s Ekiti State, they had fused skulls, shared brain tissue, and blood vessels.
At six months old, they were referred to the U.K. charity Gemini Untwined, which specializes in the care of craniopagus twins.
Just 5% of conjoined twins are joined at the top of the head, making craniopagus twins extremely uncommon. They happen once every 2.5 million births, according to London’s Great Ormond Street Hospital. About 40% are stillborn or die during labor, while a further third pass away within the first 24 hours after birth.
According to Gemini Untwined, Mercy and Goodness visited Abu Dhabi, United Arab Emirates, in 2025 and spent four months undergoing multiple procedures at SEHA Sheikh Khalifa Medical City.
The highly complex separation involved an international collaboration of over 60 medical specialists from the United Arab Emirates, the United Kingdom, Nigeria, and Brazil. Marking only the ninth documented case of its kind, the complex surgical endeavor spanned more than 40 hours, with the final procedure lasting 12 hours.
According to Gemini Untwined, Mercy and Goodness have achieved a complete recovery following their separation at 19 months of age. The young sisters have now returned to their home in Nigeria.
Medical practitioners employed the “Open Book” method, which minimizes pressure and lowers the risk of trauma by using gravity to support the brain instead of the more conventional steel retractors.
For the first time, implants were designed using mixed reality technology, according to Gemini Untwined. Surgeons were able to plan the reconstruction with greater clarity before entering the operating theater by overlaying CT scan data into detailed 3D models.
The team mapped the anatomy of the twins in detail, using a combination of 3D imaging, virtual reality simulation, augmented overlays and ultrasound-guided expansion, in the months leading up to the final procedure, working together in a shared virtual environment across multiple countries.
According to The Times, doctors also used AI to implant silicone skin expanders into their heads earlier than in past surgeries, allowing their skin to grow large enough to cover their new skulls and avoiding the need for skin grafts after surgery.
The lead pediatric neurosurgeon for the procedure, Professor Noor ul Owase Jeelani, co-founder of Gravity Untwined, stated, “The techniques we develop in these cases continue to evolve, helping to make surgeries safer and more effective.”
He continued, “Over time, this work is contributing not only to better outcomes for craniopagus twins, but also to wider advances in paediatric surgery.”
He called the separation a “landmark” case in an interview with The Times, saying it was “planned and executed with a precision not encountered before.”
“Building on the experience of our previous eight cases, using novel techniques and strategies, we are able to give these girls and their families a new future, where they can enjoy their childhood as intact but separated twins,” he went on.