[Thoracopagus symmetricus. On the separation of Siamese twins in the 10th century A. D. by Byzantine physicians].

The byzantine author, Leon Diakonos, mentions in 974/975 A.D. a pair of "siamese twins", e.g., a thoracopagus symmetricus. He had seen them personally several times in Asia Minor when they were about 30 years old. This pair is possibly the same that was "successfully" surgically separated after the death of one of the twins in the second half of the 10th century in Constantinople. This operation is mentioned by two historiographs, Leon Grammatikos and Theodoros Daphnopates. Although the second twin survived the operation, he died three days later. In spite of its lethal outcome, the operation left a long-lasting impression on the historians of that time and was even mentioned 150 years later by Johannes Skylitzes. Furthermore, the manuscript of Skylitzes, now in the library of Madrid, contains a miniature illuminating this operation. This is likely to be the earliest written report of a separation of siamese twins illustrating the high standard of byzantine medicine of that time.