Preoperative Evaluation of Craniopagus Twins: Anatomy, Imaging Techniques, and Surgical Management.

Craniopagus twins are a rare congenital malformation in which twins are conjoined at the head. Although there is high prenatal and postnatal mortality for craniopagus twins, successful separation has become more common due to advances in neuroimaging, neuroanesthesia, and neurosurgical techniques. Joined brain tissue, shared arteries and veins, and defects in the skull and dura make surgery technically challenging, and neuroimaging plays an important role in preoperative planning. Drawing on our experience from consultation for multiple successful separations of craniopagus twins, we discuss what radiologists need to know about the anatomy, classification, imaging techniques, and surgical management of craniopagus twins.

Two is a Crowd: Two is a Crowd: On the Enigmatic Etiopathogenesis of Conjoined Twinning.

In this article, we provide a comprehensive overview of multiple facets in the puzzling genesis of symmetrical conjoined twins. The etiopathogenesis of conjoined twins remains matter for ongoing debate and is currently cited-in virtually every paper on conjoined twins-as partial fission or secondary fusion. Both theories could potentially be extrapolated from embryological adjustments exclusively seen in conjoined twins. Adoption of these, seemingly factual, theoretical proposals has (unconsciously) resulted in crystallized patterns of verbal and graphic representations concerning the enigmatic genesis of conjoined twins. Critical evaluation on their plausibility and solidity remains however largely absent. As it appears, both the fission and fusion theories cannot be applied to the full range of conjunction possibilities and thus remain matter for persistent inconclusiveness. We propose that initial duplication of axially located morphogenetic potent primordia could be the initiating factor in the genesis of ventrally, laterally, and caudally conjoined twins. The mutual position of two primordia results in neo-axial orientation and/or interaction aplasia. Both these embryological adjustments result in conjunction patterns that may seemingly appear as being caused by fission or fusion. However, as we will substantiate, neither fission nor fusion are the cause of most conjoined twinning types; rather what is interpreted as fission or fusion is actually the result of the twinning process itself. Furthermore, we will discuss the currently held views on the origin of conjoined twins and its commonly assumed etiological correlation with monozygotic twinning. Finally, considerations are presented which indicate that the dorsal conjunction group is etiologically and pathogenetically different from other symmetric conjoined twins. This leads us to propose that dorsally united twins could actually be caused by secondary fusion of two initially separate monozygotic twins. An additional reason for the ongoing etiopathogenetic debate on the genesis of conjoined twins is because different types of conjoined twins are classically placed in one overarching receptacle, which has hindered the quest for answers. Clin. Anat. 32:722-741, 2019. © 2019 Wiley Periodicals, Inc.

The surgical principles of conjoined twin separation.

The surgical management of conjoined twin separation is a complex, multidisciplinary process that requires extensive pre operative planning and organization for optimal outcomes. Identification of detailed anatomic relationships is necessary prior to the separation. The use of 3D modeling is extremely helpful for conceptualization of the operation. The principles of the separation are dependent on the type of twin, although each variant of symmetric twins has certain commonalities related to their embryology that can be considered when planning the operation. The use of tissue expansion in the pre operative planning stage is highly recommended due to known issues with closure after separation. In order to ensure a safe, successful operation, we recommend organized pre operative planning meetings with at least one simulation of the separation event with multidisciplinary involvement.

Conjoined twins: Pre-birth management, changes to NRP, and transport.

The management of conjoined twins is complex and requires careful preparation. Pre-birth management includes prenatal counseling, which is important due to the overall poor prognosis. In instances of trial of life, the delivery must be tailored to address the anticipated anatomy based on prenatal imaging and anticipated physiology. A multidisciplinary team is essential to anticipate and address the ergonomic challenges and medical issues related to organ fusion, cross-circulation and associated anomalies. There are several suggested modifications to the current Neonatal Resuscitation Program algorithm including modifications to initial assessment, airway management, administration of chest compressions, obtaining emergency access, and medication dosing. Simulation is essential to address challenges, practice Neonatal Resuscitation Program modifications, delineate clear roles during delivery and practice communication. This paper offers a discussion of unique issues associated with delivery of conjoined twins and recommendations on how to approach these challenges based on our experience and available literature.

Conjoined twins: From conception to separation, a review.

Conjoined twins are suggested to result from aberrant embryogenesis. The two main theories proposed to explain the phenomena are fission and fusion. The incidence rate is 1 in 50,000 births; however, since about 60% of the cases are stillborn, the true incidence is approximated at 1 in 200,000. There is a higher predisposition towards female than male gender with a ratio of 3:1. Conjoined twins are classified based upon the site of attachment. The extent of organ sharing, especially the heart, determines the possibility and prognosis of a separation procedure. Meticulous preoperative evaluation, planning, and preparedness of the team are crucial for a successful separation. Separation of conjoined twins poses several technical, legal, and ethical issues. Clin. Anat. 30:385-396, 2017. © 2017 Wiley Periodicals, Inc.

Separation of Craniopagus Twins.

Separation of craniopagus twins is fraught by ethical issues. The surgery is high risk and may involve the sacrifice of one twin. We review surgical successes in separation of craniopagus twins and consider ethical and legal concepts affecting the decision to undertake such procedures. Our discussion considers how Gillett's potentiality principle and the concept of moral permissibility may be used to arrive at fair and realistic decisions.

Classification and clinical evaluation.

Conjoined twins represent a great challenge for most pediatric specialists including pediatric surgeons, anesthetists, neonatologists, urologists, neurosurgeons, and orthopedic surgeons. This anomaly can be classified according to the type of twins׳ fusion. Various organs can be fused making the separation difficult. Conjoined twins are usually diagnosed antenatally by ultrasound. Detailed fetal echocardiography is necessary to counsel the parents during pregnancy. Postnatally, the majority of the conjoined twins can be thoroughly investigated using various imaging techniques. This allows careful planning of the operation. However, in approximately one-third of the patients an urgent operation is required at birth without a complete assessment of the joining. This is associated with a poorer outcome.

Prenatal diagnosis and obstetric management.

Conjoined twins are rare, representing 1 in 50,000 to 1 in 200,000 live births, and the prognosis is generally poor. Accurate prenatal diagnosis by an experienced multidisciplinary team using a combination of imaging modalities allows parents to make fully informed choices. This may include termination of pregnancy, which is easier and safer at the earlier gestations at which diagnosis is now being made; continuing with the pregnancy but accepting that only palliative care is appropriate after birth; or planned intensive care and separation of the twins after birth. Delivery will invariably be by cesarean section in order to minimize the risk of peripartum harm to both mother and babies.

The separation procedure.

The various stages of the separation are carefully planned but despite this, variations which will change the schedule of the procedure may exist. In general the operation commences on the opposite side from the main procedure and then the twins are turned for the remainder of the operation. Each type of conjoined twin is different but basically thoracopagus involves the hearts, omphalopagus involves the liver and small intestine and ischiopagus involves the large intestine and genito-urinary system. Our results are presented together with interesting cases from which lessons have been learned.

Imperfect twinning: a clinical and ethical dilemma.

UNLABELLED: OBJECTIVE To review the history, epidemiology, etiology, gestational aspects, diagnosis and prognosis of imperfect twinning. DATA SOURCES Scientific articles were searched in PubMed, SciELO and Lilacs databases, using the descriptors "conjoined twins", "multiple pregnancy", "ultrasound", "magnetic resonance imaging" and "prognosis". The research was not delimited to a specific period of time and was supplemented with bibliographic data from books. DATA SYNTHESIS: The description of conjoined twins is legendary. The estimated frequency is 1/45,000-200,000 births. These twins are monozygotic, monochorionic and usually monoamniotic. They can be classified by the most prominent fusion site, by the symmetry between the conjoined twins or by the sharing structure. The diagnosis can be performed in the prenatal period or after birth by different techniques, such as ultrasound, magnetic resonance imaging and echocardiography. These tests are of paramount importance for understanding the anatomy of both fetuses/children, as well as for prognosis and surgical plan determination. CONCLUSIONS Although imperfect twinning is a rare condition, the prenatal diagnosis is very important in order to evaluate the fusion site and its complexity. Hence, the evaluation of these children should be multidisciplinary, involving mainly obstetricians, pediatricians and pediatric surgeons. However, some decisions may constitute real ethical dilemmas, in which different points should be discussed and analyzed with the health team and the family.

Imperfect twinning: a clinical and ethical dilemma / Gemelizacionimperfecta: un dilema clinico y etico / Gemelaridade imperfeita: um dilema clinico e etico

OBJECTIVE To review the history, epidemiology, etiology, gestational aspects, diagnosis and prognosis of imperfect twinning. DATA SOURCES Scientific articles were searched in PubMed, SciELO and Lilacs databases, using the descriptors "conjoined twins", "multiple pregnancy", "ultrasound", "magnetic resonance imaging" and "prognosis". The research was not delimited to a specific period of time and was supplemented with bibliographic data from books. DATA SYNTHESIS: The description of conjoined twins is legendary. The estimated frequency is 1/45,000-200,000 births. These twins are monozygotic, monochorionic and usually monoamniotic. They can be classified by the most prominent fusion site, by the symmetry between the conjoined twins or by the sharing structure. The diagnosis can be performed in the prenatal period or after birth by different techniques, such as ultrasound, magnetic resonance imaging and echocardiography. These tests are of paramount importance for understanding the anatomy of both fetuses/children, as well as for prognosis and surgical plan determination. CONCLUSIONS Although imperfect twinning is a rare condition, the prenatal diagnosis is very important in order to evaluate the fusion site and its complexity. Hence, the evaluation of these children should be multidisciplinary, involving mainly obstetricians, pediatricians and pediatric surgeons. However, some decisions may constitute real ethical dilemmas, in which different points should be discussed and analyzed with the health team and the family. .

OBJETIVO Revisar los aspectos históricos, epidemiológicos, etiológicos, gestacionales, diagnósticos y pronósticos de la gemelización imperfecta. FUENTES DE DATOS Se buscaron artículos científicos en los portales PubMed, SciELO y Lilacs, utilizando los descriptores "conjoinedtwins", "multiplepregnancy", "ultrasound", "magneticresonanceimaging" y "prognosis". La investigación no se limitó a un periodo determinado y específico de tiempo. Se complementó la revisión con material bibliográfico presente en libros. SÍNTESIS DE LOS DATOS La descripción de gemelos fusionados es legendaria. Se estima que la frecuencia sea alrededor de 1/45.000-200.000 nacidos vivos. Son gemelos monocigóticos, monocoriónicos y usualmente monoaminióticos, que pueden clasificarse conforme al local de fusión más prominente, con la simetría entre los gemelos fusionados o con la estructura de compartimiento. Se puede realizar el diagnóstico todavía en el periodo prenatal o después del nacimiento mediante diferentes técnicas, como ultrasonografía, resonancia magnética y ecocardiografía. Esos exámenes son de suma importancia para el entendimiento de la anatomía del feto/bebé, así como para la determinación del pronóstico y del plan quirúrgico. CONCLUSIONES Aunque la gemelización imperfecta sea una condición rara, el diagnóstico prenatal es muy importante para evaluar el local de fusión y su complexidad. Así, la evaluación de esos bebés debe ser multidisciplinaria, implicando principalmente a obstetras, pediatras y cirujanos pediátricos. Sin embargo, algunas decisiones pueden constituirse en verdaderos dilemas éticos, en los que distintos aspectos deben discutirse y analizarse juntamente con el equipo de salud y la familia del niño. .

OBJETIVO Revisar os aspectos históricos, epidemiológicos, etiológicos, gestacionais, diagnósticos e prognósticos da gemelaridade imperfeita. FONTES DE DADOS: Pesquisaram-se artigos científicos nos portais PubMed, SciELo e Lilacs, utilizando-se os descritores "conjoined twins", "multiple pregnancy", "ultrasound", "magnetic resonance imaging" e "prognosis". A pesquisa não se delimitou a um período específico de tempo. Complementou-se a revisão com material bibliográfico presente em livros. SÍNTESE DOS DADOS A descrição de gêmeos fusionados é lendária. Estima-se que a frequência seja em torno de 1/45.000-200.000 nascidos vivos. São gêmeos monozigóticos, monocoriônicos e usualmente monoamnióticos, que podem ser classificados de acordo com o local de fusão mais proeminente, com a simetria entre os gêmeos fusionados ou com a estrutura de compartilhamento. Pode-se realizar o diagnóstico ainda no período pré-natal ou depois do nascimento por meio de diferentes técnicas, como ultrassonografia, ressonância magnética e ecocardiografia. Tais exames são de suma importância para o entendimento da anatomia do feto/criança, bem como para a determinação do prognóstico e do plano cirúrgico. CONCLUSÕES Embora a gemelaridade imperfeita seja uma condição rara, o diagnóstico pré-natal é muito importante para avaliar o local de fusão e sua complexidade. Logo, a avaliação dessas crianças deve ser multidisciplinar, envolvendo principalmente obstetras, pediatras e cirurgiões pediátricos. Contudo, algumas decisões podem se constituir em verdadeiros dilemas éticos, nos quais diferentes aspectos devem ser discutidos e analisados juntamente com a equipe de saúde e a família da criança. .

Separation of craniopagus conjoined twins with a staged approach.

The separation of craniopagus conjoined twins is a very rare and complex challenge. As with many rare challenges, it presents initially as a deceptively simple problem requiring only the most basic clinical techniques. As in many reconstructive problems, this paradigm mandates that the neurosurgical team performs the separation with the plastic surgeons providing closure at the end of the separation. Historically, these approaches have included, as with the separation of many other types of conjoined twins, the use of tissue expansion before separation followed by separation surgery. In the best hands, at the most capable medical centers, the mortality reported in the literature for the past 50 years is greater than 50%. Craniofacial surgery frequently demands a coordinated effort between plastic surgery and neurosurgery and many other specializations; separating craniopagus twins takes this coordination to a stratospheric level. It is, however, this coordination that is of paramount importance. Success clearly requires an understanding of the complex interrelationship between the "separation" and the "reconstruction" and that decisions made for 1 aspect of the surgery will have a profound impact on another aspect of the surgery. The impact can be disastrous or, if planned well, can be advantageous.We were contacted to evaluate craniopagus conjoined male infant twins for separation. Radiographic studies suggested that the brains were separate, and their medical team suggested that they were "fit for separation." We reviewed the literature and reviewed our colleagues' experiences with similar cases around the world. It became clear that whether separation had been unsuccessful or successful, a variety of issues accompanied surgery as follows: (1) massive intraoperative hemorrhage, (2) cerebral edema, (3) venous infarcts, (4) swelling of flaps, and (5) dehiscence of repairs with cerebrospinal fluid (CSF) leak, meningitis, or brain exposure. Although the initial plan was to separate the twins in the same fashion as in previous cases (ie, single-stage separation surgery preceded by tissue expansion of the scalp), it was clear that this approach increases cerebral venous pressure during the separation component of surgery and therefore set up a cascade of events favoring failure rather than success. Wishing to favor success, we elected to design an open-ended multistaged separation to improve venous collateral circulation. We believe that this would improve venous drainage, prevent increased venous pressure, diminish cerebral edema, and favor the integrity of the dura and flap repair that would in turn lessen the risk of CSF leak. The stages would also allow the twins to recover from each stage before progressing to the next stage while continuing to receive nutritional support and physical therapy. Four major stages for 9 ½ months led to their successful separation. There has been no CSF leak or meningitis. To our knowledge, this technique has since been applied to 2 other sets of craniopagus with similar outcomes.A review of the pertinent literature, our rationale, and methodology are discussed in this article.

Conjoined twin separation: lessons learned.

BACKGROUND: The separation of conjoined twins presents a unique challenge to many pediatric surgical specialties. A multidisciplinary approach is essential for successful twin separation, and plastic surgeons are critical members of this surgical team when soft-tissue requirements preclude simple closure. METHODS: In this article, the authors review multiple techniques available to plastic surgeons for providing adequate soft-tissue coverage in this unique clinical situation and present lessons learned from their experience at The Children's Hospital of Philadelphia with seven conjoined twin separations performed between the years 1980 and 2007. RESULTS: Successful separation was accomplished in six of the seven conjoined twin pairs, expander complications requiring reoperation occurred in three twin pairs, and skin grafting was required because of insufficient expansion in two twin pairs. The techniques found to be critical to successful separation include maximal extracavitary tissue expansion with smooth-wall remote port tissue expanders, protection of expanded skin through pressure-reducing strategies, fluorescein vascular territory mapping, the use of frozen banked autogenous skin for salvage, and the use of supplemental nutritional support. CONCLUSIONS: The overall success of conjoined twin separation depends on the experience and preparedness of the treating team and the resources available at the pediatric specialty center. Multiple techniques are available to plastic surgeons to optimize success in this challenging clinical situation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, V.

Siameses: reporte de un caso / Conjoined twins: a case report

El embarazo gemelar siempre ha sido visto con mucho interés y, como es conocido, existen dos tipos; los dicigóticos o fraternos, que representan el 70 por ciento, y los monocigóticos, que son alrededor del 30 por ciento. En ocasiones los gemelos monocigóticos no se separan por completo y se producen los llamados gemelos unidos o conectados, y se clasifican según la región anatómica que los une, desde dos individuos bien desarrollados, independientes y simétricos, unidos tan sólo por una pequeña conexión superficial, hasta los que están representados sólo por porciones de cuerpo mutuamente adheridos o incluidos en un huésped más desarrollado. El objetivo de este trabajo es presentar un caso infrecuente de gemelas unidas o siameses toraco-onfalópago. Se comenta la literatura revisada.

Twin pregnancy has been seen with great interest and, as it is well-known, two types exist; the fraternal or dizygotic twins, that represent 70 percent, and the monozygotic ones, which are around 30 percent. Sometimes the monozygotic twins do not separate completely and the so-called joined or connected twin take place, and they are classified according to the anatomical region that joins them, from two well-developed, independent and symmetrical individuals, joined by a small superficial connection, to those which are just represented by mutually adhered parts of the body or included in a more-developed guest. The objective of this work is to present an infrequent case of thoraco- omphalopagus conjoined twins. It is commented on the reviewed bibliography.

Siameses: reporte de un caso / Conjoined twins: a case report

El embarazo gemelar siempre ha sido visto con mucho interés y, como es conocido, existen dos tipos; los dicigóticos o fraternos, que representan el 70 por ciento, y los monocigóticos, que son alrededor del 30 por ciento. En ocasiones los gemelos monocigóticos no se separan por completo y se producen los llamados gemelos unidos o conectados, y se clasifican según la región anatómica que los une, desde dos individuos bien desarrollados, independientes y simétricos, unidos tan sólo por una pequeña conexión superficial, hasta los que están representados sólo por porciones de cuerpo mutuamente adheridos o incluidos en un huésped más desarrollado. El objetivo de este trabajo es presentar un caso infrecuente de gemelas unidas o siameses toraco-onfalópago. Se comenta la literatura revisada(AU)

Twin pregnancy has been seen with great interest and, as it is well-known, two types exist; the fraternal or dizygotic twins, that represent 70 percent, and the monozygotic ones, which are around 30 percent. Sometimes the monozygotic twins do not separate completely and the so-called joined or connected twin take place, and they are classified according to the anatomical region that joins them, from two well-developed, independent and symmetrical individuals, joined by a small superficial connection, to those which are just represented by mutually adhered parts of the body or included in a more-developed guest. The objective of this work is to present an infrequent case of thoraco- omphalopagus conjoined twins. It is commented on the reviewed bibliography(AU)

Di-symmetric cephalopagus conjoined twins described by Hovorakova et al.: some additions and corrections.

This article provides some additions and corrections on a recently published case report concerning a pair of di-symmetrical cephalopagus conjoined twins. Eight different types of conjoined twins can be distinguished; one is cephalopagus, which is fourth in rarity of occurrence. Between 17 and 24% of cephalopagus is of the male sex. More than 30 case reports of di-symmetrical cephalopagus can be traced in Western literature, the oldest one described and illustrated in 1569.

[Conjoined twins--rare biological phenomenon. Case report].

Authors are discussing a rear case of multiple pregnancy--conjoined twins. The case is personal by exact antenatal diagnosis and delivering is made by the author. It is proposed a classification of conjoined twins and theoretical interpretation of pathological mechanism of fusion.