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W.Q.HUANG，J.Y.FANG，L.C.XIAO，X.P.JIANG，J.H.XIA，X.FENG and N.JIANG

Department of Anesthesiology，First Affiliated Hospital，Sun Yat－sen University，Guangzhou，China

　　CRANIOPAGUS refers to twins joined only at the head. Craniopagus is the least common type of conjoined twins，only 6.2％of the total（1）.O’Connell’s classification is based on relative facial orientation（2）.K. R. Winston’s classification is according to the deepest structure that is shared（3）.

　　Case report

　　The conjoined craniopagus twins（A and B）were delivered by caesarean section. Twin B had developed anuria at 2months of age. Informed consent for publication was given by the parents.

　　Magnetic resonance imaging showed that the two heads of the twins shared dura and brain （Fig.1）.Cerebral angiography revealed that the superior sagittal sinus of Twin B was anastomosed with the superior sagittal sinus of Twin A. The flow direction in the anastomosed sinuses was from Twin B to Twin A. The craniopagus were classified as type D（3）.

　　At the time of separation，the twins were 17months old with a combined weight of 25 kg（Fig.2）. They were symmetrical and normally developed except for the conjoined heads. The angle of their face’s sagital axis was 130°.Their behavior and personalities were independent. Intravenous ketamine and midazolam had been used for insertion of tissue expanders and radiologic studies without respiratory or circulatory complications.

　　Separation of the craniopagus was carried out in 2001. The total duration of surgery was 52h.

　　The twins were premedicated with atropine 0.15mg each to reduce respiratory tract secretion. Fiftymg of ketamine was intramuscularly given to each twin before establishing intravenous lines. After vecuronium 1.5mg and fentanyl 0.05mg，Twin B was held 15° left laterally and intubated.Twin A was assisted by mask ventilation during intubation of Twin B.Twin A was intubated after the same doses of vecuronium and fentanyl. Intubation was accomplished in one attempt.Similar cases reported involved inhalational induction without muscle relaxant（4－6）.

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　　Anesthesia was maintained with 1.2－2.0％ isoflurane and propofol 0.5－3mg kg^－1 h^－1 to Twin A，0.5－1.5％ isoflurane and propofol 0.3mgkg^－1 h^－1 to Twin B，and vecuronium 1 mgkg^－1 h^－1 to both twins.The total dose given to Twin A was higher than that given to Twin B. Separate anesthetic machines were used.

　　Before the operation，Twin A’s blood pressure was 122/55mmHg and heart rate 125 beats min^－1，and Twin B’s blood pressure was 70/45mmHg and heart rate 133 beats min^－1. The difference in blood pressure persisted until completed division. During surgery，the recorded heart rate for Twin A was 105－140beats min^－1 with a blood pressure of 110－135/50－60mmHg.Corresponding values for Twin B were 110－155 beats min^－1 and a blood pressure of 60－80/35－50mmHg. Blood pressure increased and decreased simultaneously，and vasoactive drugs given to one twin affected the other twin.

　　Perioperative blood loss was extensive. When the brain tissue had almost been separated，profuse bleeding suddenly occurred and consequently both twins developed severe hypovolemic shock and bradycardia.The separation was completed and both twins were resuscitated. Twin A was chest compressed and given blood，norepinephrine，epinephrine and sodium bicarbonate.

　　Twin B was sent to the adjacent operation room with manual ventilation and underwent similar resuscitation.Norepinephrine was continuously infused as required. After surgical hemostasis，the hemodynamics of both twins stabilized.

　　The total perioperative fluid input was 20 570 ml.Blood，platelets，cryoprecipitate and fresh－frozen plasma was used during the operation（Table 1）.

　　Twin B received continuous hemodialysis which was complicated by clotting in the circuit and she died of renal failure，hyperkalemia and shock 22 h after the end of surgery. To manage renal failure in conjoined twins，emergent separation （7）and renal transplantation （8）but also spontaneous improvement after separation has been reported.Twin B had been planned for hemodialysis after separation.Twin A survived. She was conscious 1.5 h after surgery （Fig.3）.To date she has developed no problems during follow up.

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　　Acknowledgements

　　The authors acknowledge the team effort of surgeons，all faculty members，and others who made it possible for us to present this report.We thank Dr Anthony M.H.Ho，Associate Professor，for his advice.

References

1. Edmonds LD，Layde PM. Conjoined twins in the United States，1970－77. Teratology 1982；25：301－8.

2. O’Connell JE. Craniopagus twins. Surgical anatomy and embryology and their implications. J Neurol Neurosurg Psychiatry 1976；39：1－22.

3. Winston KR. Craniopagi：Anatomical characteristics and classification. Neurosurgery 1987；21：769－81.

4. Wong KC，Ohmura A，Roberts TH，Webster LR，Cook GL. Anesthetic management for separation of craniopagus twins.Anesth Analg 1980；59：883－6.

5. Khan ZH，Tabatabai SA，Saberi H. Anesthetic and surgical experience in a case of total vertical craniopagus. Surgi Neuro 1999；52：62－7.

6. Georges LS，Smith KW，Wong KC. Anesthetic challenges in separation of craniopagus twins. Anaesth Analg 1987；66：783－7.

7. Lai HS，Chu SH，Lee PH，Chen WJ. Unbalanced cross circulation in conjoined twins. Surgery 1997；121：591－2.

8. Klein DJ，Filler RM，Azarow KS，Geary DF. Extrauterine twin－twin transfusion affects renal function and management of conjoined twins. J Pediatr Surg 1998；33：354－6.