There are very few known cases of conjoined twins from the Middle Ages. What did medieval people think of these strange cases and how did they treat the twins? We can take a look at what happened with two conjoined men from 10th century Byzantium, which also happens to be the earliest known attempt to surgically separate two individuals.
Leo the Deacon, writing in his History, provides his firsthand observation of seeing the conjoined twins, sometime during the mid-940s:
At this time male twins, who came from the region of Cappadocia, were wandering through many parts of the Roman Empire; I myself, who am writing these lines, have often seen them in Asia, a monstrous and novel wonder. For the various parts of their bodies were whole and complete, but their sides were attached from the armpit to the hip, uniting their bodies and combining them into one. And with the adjacent arms they embraced each other’s necks, and in the others carried staffs, on which they supported themselves as they walked. They were thirty years old and well developed physically, appearing youthful and vigorous. On long journeys they used to ride on a mule, sitting sideways on the saddle in the female fashion, and they had indescribably sweet and good dispositions. But enough about this.
Other chronicles from the tenth and eleventh centuries add more details. The boys were born in Armenia, but soon came to Constantinople during the reign of Romanus I Lecapenus (919-944), where in the words of Theophanes Continuatus “they resided for a long time in the City and were admired by everybody as a curiosity but later were exiled because it was believed that they were a bad omen.”
Judging by the remarks of Leo the Deacon, the twins moved around the Byzantine Empire, perhaps their in the same way as the traveling ‘human freak shows’ of the 19th and early 20th centuries. The pair likely got the similar reactions that the chroniclers had – many would see them as a wonder or as a monster. However, the report by Leo also suggests that the two brothers were also physically and mentally well.
During the reign of Constantine VII (944-59) the twins returned to Constantinople. Theophanes Continuatus explains what happens next:
When one of the twins died skilled doctors separated them cleverly at the line of connection with the hope of saving the surviving one but after living three days he died also.
This is the earliest known attempt to surgically separate conjoined twins, and the fact that the second person survived for a even a few days showed that it was at least partly successful. There would not be another case of conjoined twins being separated until the year 1689.
The Synopsis of Histories by John Scylitzes, written in the 11th century also includes a similar account as well as a page of illustrations showing the twins and the surgery:
For more information, see ‘A Surgical Operation performed on Siamese Twins during the Tenth Century in Byzantium,’ by G.E. Pentogalos and John G. Lascaratos, Bulletin of the History of Medicine, Vol.58:1 (1984)