The birth of conjoined or Siamese twins occurs once in every 50,000 births.1 Attachment at the skull (craniopagus malformation) is very rare and seen in only 2% to 6% of all cases of conjoined twins, which makes the incidence of craniopagus twins 1 in 2.5 million births.2 In this report, we present a case of craniopagus twins with special anatomic challenges, in whom an operative separation was carried out by a carefully planned, multistage, multidisciplinary approach to provide enhanced quality of life.
A case of 16-month-old, total vertical craniopagus twins was presented in November 2017 to our group of volunteer medical specialist doctors from Hungary in a free plastic surgery camp in Bangladesh. The patients’ parents provided informed consent for the publication of this case report. The anatomy of the twins showed a total vertical, type I conjointment according to the Stone and Goodrich classification3 (Fig 1). They shared the main venous structure that was formed from the superior sagittal sinuses, referred to as circumferential sinus, similar to that reported by Sonnenburg et al.4 The different venous structures were confirmed by computed tomography venography and reconstructed, 3-dimensional models (Fig 2, A–F). Magnetic resonance imaging (MRI) showed a flattened medial cortical region (Fig 2, H–I) and a bridge of inner cerebral white matter connecting the thalamic regions of both twins (Fig 2, I). The greatest risk to separation of these twins was determined to be the common venous pathway of the brains and the many interconnecting branches to both sides. After a detailed clinical and radiologic assessment, we decided to perform the separation by planning a multistage, endovascular and operative project with our multidisciplinary team. Ethical considerations to perform such an intervention were discussed in detail; before each phase, a medical team reviewed the planned actions with the parents who were supported by native Bangladeshi doctors present in Hungary with a translation and explanation and could read and accept a detailed consent form. We also took into account the religious and bioethical aspects of the operation. Preliminary internal medicine examinations also suggested that the twins theoretically could live separated, because they did not have cross-dependent organ functions.
Fig 1. Conjointment of the craniopagus twins. (A) Photo of the 16-month-old craniopagus twins. (B) 3-dimensional model (semi-opaque hemispheres with gray color) and T1-weighted MRI slice showing the results of the probabilistic tractography of the connection between the 2 thalamic regions. Color coding of fiber probability level: red, >50%; yellow, 26%–50%; green, 13%–25%, and blue, <13%. (C) 3-D model of the conjoined skulls at age 19 months. (D) 3-D-printed model of the frontal aspect of the attaching brains. (Color version of the figure is available online.)
Fig 2. Different phases of the embolization process and brains of the twins. 3-D models of the veins showing the state before the first endovascular intervention (A, B), 6 months after the first embolization procedure (C, D), and 5 months after the second embolization procedure (E, F). Frontal (A, C, E) and lateral (B, D, F) views. (1) Circumferential sinus. (2) Intracerebral superior sagittal sinus. (3) Occipital venous network. (G) The embolic agent (Onyx; Micro Therapeutics, Inc) in the circumferential sinus (4) on the fluoroscopic image. (H) T2-weighted MRI of the brains. (I) T1-weighted MRI of the brains, showing the connecting white matter tract (5) between the thalamic regions. (Color version of the figure is available online.)
During the entire process, the medical specialists and cooperating international participants were centrally coordinated to achieve maximal sharing of information and quick and proper logistics. The first session of the endovascular phase (stage I) of the Operation Freedom Project (OFP) was performed in Dhaka, Bangladesh, in February 2018. The intervention was preceded by a diagnostic digital subtraction angiography and balloon occlusion test. Based on the results, we decided to obliterate the cerebral venous system and 24 bridging veins originating from the cerebral venous system with ethylene-vinyl alcohol copolymer, a specific embolic agent (Onyx; Micro Therapeutics, Inc, Irvine, CA) (Fig 2, G). After the intervention, no complications or neurologic deficits were observed. Six months later, follow-up magnetic resonance angiography revealed that the diverted blood flow caused by a previous catheter occlusion resulted in an inner sinus to develop along the 2 adherent brain surfaces, which we referred to as the intracerebral superior sagittal sinus (Fig 2, C–D). Subsequently, a second session of the endovascular intervention was performed in August 2018; at that time, this intracerebral superior sagittal sinus and the shared sinus transversus system were obliterated by Onyx. The following MRI in January 2019 confirmed that the endovascular separation was successful (Fig 2, E–F). Four months later in January 2019, extensive MRI with consequent probabilistic tractographic analyses were performed under general anesthesia in Budapest, Hungary, to check whether transecting the crossing pathways would affect vital functions. Data were acquired on a 3T MRI system, Philips Achieva 3.0 T (Philips Medical Systems, Andover, MA), including diffusion-weighted imaging data sets with 64 diffusion directions.
During their stay in Hungary, the children were under continuous care, having 24-hour nursing care aided by a pediatric psychologist, and conductive education5 was applied as well.
The plastic surgery phase (stage II of the OFP) aimed to implant silicone, subcutaneous tissue expanders along the axes of symmetry of the conjoined heads to be inflated to a point where the skin would reach adequate size and quality to close the defects created on the heads during the final operation. Using 3-dimensional (3-D) modeling software (Amira for Life & Biomedical Sciences 6.0; ThermoFisher Scientific, Waltham, MA; FEI Visualization Sciences Group; 3-D Slicer; and Autodesk Meshmixer), we visualized the most favorable position for the expanders, the design of the expected final arrangement, the sizes, and the planned incisions for placement (Fig 3, A, B, D). In January 2019, 3 silicone expanders (a custom-made, over expandable, 1,200-cm3 Polytech textured expander [Dieburg, Germany] to the occipital area; a rectangular, smooth surface, 250-cm3 Polytech expander to the frontal area; and a rectangular, smooth surface, 270-cm3 Sebbin expander [Paris, France] to the temporal area) were implanted by a minimally invasive, endoscopic-assisted technique to the subgaleal space to expand the hair-bearing scalp and soft tissues. The expanders were expanded regularly (1–2 times per week) (Fig 3, C) through remote fill valves, and a special supportive bandage of adhesive foam was applied to the heads to protect the expanded area. For strengthening of the scars, the twins received scar treatments with a diode laser (Intermedic Multidiode Surgical Series 4G/980/1470; Intermedic Laser & Light Solutions, Barcelona, Spain) and autologous injectable platelet-rich fibrin.6,7 A total of 47 expansion procedures were required during phase II in Budapest, Hungary, during which we were able to increase the volume of the implants to 3,595-cm3.
Fig 3. Tissue expanders and separation of the conjoined twins. (A) 3-D model of the skin in the final stage of the expansion procedure. (B) 3-D models of the subcutaneous tissue expanders and the skull (frontal view). (C) Photo of the twins with the expanded skin. (D) 3-D models of the subcutaneous tissue expanders and the skull (occipital view). (E) Surgical separation of the 2 brains. (F) The twins at 3 months after the final operative separation. (Color version of the figure is available online.)
The final separation of the 3-year-old conjoined twins (stage III of OFP) took place 22 months after initial presentation on August 1 and 2, 2019, in Dhaka, Bangladesh (Fig 3, E). During the operation, adherent brain surfaces were separated manually under a microscope, and vascular redistribution was performed; this maneuver was followed by a duraplasty and a partial cranioplasty. The separation procedure took 33 hours; 4 neurosurgery, 4 plastic surgery, and 4 anesthesia teams worked in rotation during the operation. At the end of the technically successful separation, the twins were admitted to the intensive care unit in stable cardiopulmonary conditions on controlled ventilation.
In the postoperative period after the final separation, neither wound, central nervous system infection, nor cerebrospinal fluid leakage occurred. Because of the possibility of formation of transient brain edema and defective cerebrovascular autoregulation caused by the surgical manipulations, monitoring of intracranial pressure via a ventricular catheter and maintenance of age-specific cerebral perfusion pressure were a high priority in the early postoperative period. Given the vulnerability of the brain tissue as demonstrated by the clinical picture and follow-up computed tomography images, deep analgosedation was implemented for several days. After regaining consciousness and reaching a stable general condition, 1 of the twins was weaned from the ventilator and then extubated on the sixth postoperative day. The weaning of the other child was only possible in the sixth week.
Currently, 8 months after the separation, the cranial reconstruction and rehabilitation of the twins (stage IV of OFP) are still under process. One of the twins can walk alone without assistance, is capable of sophisticated verbal communication, actively participates in age-appropriate play, and recalls events before her operation in detail. Her sister is able to sit and stand with support; has a lessening degree of spasticity in her extremities; is capable of doing purposeful arm, hand, and head movements in an inconsistently reproducible manner; and can be fed orally. Her vital functions are stable. Both of them spend most of their time with their parents and participate in a complex neurorehabilitation program in Bangladesh with the active help of Hungarian rehabilitation specialists (Fig 3, F).
To the best of our knowledge, this is the third case of successful incorporation of an endovascular occlusion of the shared venous channels in craniopagus twins, and this is the first successful attempt of a full-segment, endovascular occlusion of a largely shared intracranial venous system in craniopagus twins. This endovascular approach and separation were preferred over the possibility of using pre or intraoperative clipping or bypassing the shared sagittal sinuses owing to the high risks of the latter techniques known from the literature. By using minimally invasive techniques through minimal incisions at the insertion sites, we were able to dilate the subgalear expanders to the maximum extent of 3,595-cm3 to allow adequate skin expansion to cover the estimated sizes of the operative defects after the separation.
This separation of craniopagus twins required a skilled, multidisciplinary team, a multistage approach, and incorporation of advanced imaging and 3-D-modeling techniques. Based on the stereolithography models, we also made several 3-D-printed models (in sizes of 1:1, 1:2, and 1:3, with hard and flexible 3-D prints) from the conjoined skulls, the skin before and after the expansion process, the conjoined brains, and the modification of the intracranial vascular system during phase I occlusion to more fully understand the complex relationship of the individual anatomic structures, identify the potential risk points, determine the optimal placement of tissue expanders, and to serve as dry-practice models for the operations preoperatively.
We discussed the use of the technique of distraction osteogenesis (principles used by Heuer et al in the most recently reported successful craniopagus separation8), but after considering the anatomy, the state of the conjointments, and the age (3 years old), we decided for a multistage procedure starting with the endovascular separation. We faced additional challenges in performing the operative procedures: (1) this was a case of total vertical craniopagus twins without midline inclination of the skulls, and thus the final tissue defect was expected to be quite large in surface area and difficult to cover; (2) the twins were 36 months old at the time of the final separation, compared with other craniopagi separated in an earlier stage with a smaller decreased risk of complications (eg, the patients of Heuer et al8 were separated at the age of 10 months); (3) apart from the longer circumferential sinus and the inner-opened second sagittal sinus, owing to the total vertical variant, the twins had a communicating occipital venous network; (4) the twins had a white matter connection between the thalamic regions; and (5) this was the first time, to our knowledge, that international cooperation for a multistage craniopagus separation has been realized with technology transfer between 2 countries, with the final separation organized in a developing country.
In conclusion, we believe that the application of technical novelties and planning a skillful, multistage, multidisciplinary approach are key factors in performing such a rare and complex operation successfully on craniopagus twins.
The authors have indicated that they have no funding to disclose regarding the content of this article.
Conflict of interest/Disclosure
The authors have indicated that they have no conflicts of interest to disclose regarding the content of this article.
This article is the culmination of more than 2 years of meticulous work and planning (from November 2017). There are numerous hospitals, companies, and people we wish to thank for contributing to this work. Specifically, we would like to express our gratitude to the following:
- Semmelweis University Budapest, Hungary; Military Hospital–State Health Center, Budapest, Hungary; Heim Pál Children’s Hospital, Budapest, Hungary; St. John’s Hospital; and North Buda Unified Hospitals in Budapest, Hungary, for providing medical background for the second phase of the OFP and all the essential examinations preceding the final separation.
- Dhaka Medical College for supporting anesthesia for the first and third phases of the OFP.
- The leaders and staff of the Combined Military Hospital, Dhaka, Bangladesh, and the Sheikh Hasina National Institute of Burn and Plastic Surgery, Dhaka, Bangladesh, for providing world-class conditions for the final separation.
- Peter Scott, MD and Daniel Hoffmann, MD, plastic surgeons from the Department of Plastic and Reconstructive Surgery, Baragwanath Hospital, Johannesburg, South Africa, and Arwyp Medical Center Hospital, Kempton Park, South Africa for sharing their knowledge and experience especially on the Baragwanath (1988) and Lowton (2007) craniopagus twins.
- Alexandra Valéria Sándor (Action for Defenceless People Foundation) for the general administrative support, translation, language editing, proofreading and communication.
- Zsuzsanna Császár for the support in the coordination of postoperative rehabilitation. Varinex Ltd, Hungary, for 3-D printing various high-definition models of the twins.
- Prof. H. Millat, Sharita Millat, Hasnat Mia, Ottó Albrecht, and István Joó without whom the appropriate organization of the procedures would not have been possible.
- The multi-religious international team would like to thank our common God for providing us this opportunity and the power to organize this unique international cooperation, the series of operations to give a better quality of life to these twins, and also for helping us through all the difficulties.