Ischiopagus and pygopagus conjoined twins: neurosurgical considerations.

BACKGROUND: Neurosurgeons are familiar with the challenges presented by craniopagus twins, but other types of conjoined twins may also have neurosurgical implications. We report our experience in the management of ischiopagus and pygopagus conjoined twins.
METHODS: This is a retrospective review of the management of conjoined twins at Red Cross Children's Hospital in Cape Town, South Africa.
RESULTS: Twenty-three pairs of symmetrical conjoined twins were managed over a 40-year period (1964-2003), of which 16 (70%) were separated. Of these cases, 6 are the focus of this study, namely 4 pairs of ischiopagus twins and 2 pairs of pygopagus twins seen between 1993 and 2003. In 2 cases, there was direct involvement of the nervous system at the site of union, with 1 pair of ischiopagi manifesting end-to-end union of their spinal cords, while a pair of pygopagi had back-to-back fusion of the conus. Another pair of ischiopagi had a fused dural sac without joined neural elements, but one of these children developed syringomyelia 2 years after separation. Neuroimaging was invaluable in detecting these abnormalities. The one pair of ischiopagi who died before separation were HIV positive and had severe brain atrophy and cystic encephalmalacia at autopsy. Nine of the 12 children (75%) had bony abnormalities of the spine remote from the area of conjunction. The most common finding was the presence of hemivertebrae, usually in the thoracic spine. Six children manifested scoliosis, which has already progressed in the oldest two. Technical aspects such as timing and sequence of separation, the division of neural tissues and reconstruction are discussed, as are the long-term complications of their spinal abnormalities.
CONCLUSIONS: Ischiopagus and pygopagus conjoined twins manifest an interesting array of spinal abnormalities, which present challenges, not only at the time of separation, but also in their long-term management.