Ischiopagus and pygopagus conjoined twins: neurosurgical considerations

Parasitic pygopagus conjoined twins' incidental findings in the obstructed labor of an intrapartum dead baby that had undergone emergency C-section: rare case report in South Papua

BACKGROUND

Conjoined twins (CT), which used to be historically defined as "monstrous human" and previously so-called Siamese twins in the early eighteenth century, are one of the very rare congenital malformations with an uncertain etiology and complex yet remain inconclusively debatable regarding its pathophysiological mechanisms of fusion and fission theories. Among all types of CT, parasitic CT, especially the pygopagus sub-type, is exceedingly rarer. To the best of the authors' knowledge, no parasitic CT had been reported in Papua, and this is the first finding in South Papua.

CASE REPORT

Herein, a 30-year-old multigravida female with 37th-week gestation, previous twice spontaneous miscarriage, and non-adequate antenatal care history is presented with a chief complaint of painful construction and greenish fluid leakage from the vagina, with an examination that showed a cephalic presentation with a "peculiar" big mass at the upper uterus and complete cervical dilation toward second-stage inpartu. Vaginal delivery was performed with a complication of obstructed labor due to uncommon dystocia with a suspected "big mass" below the fetal buttocks and intrapartum dead. Intrapartum transabdominal ultrasound demonstrates a gross anatomically like an organ inside a fluid-filled mass with unidentified parts, leading to a suspected type of congenital malformation at the baby's sacral region. Emergency C-section was done with findings of parasitic pygopagus CT, showing an attachment of a large irregular fluid-filled mass-like incomplete twin (parasite) with palpable soft tissue and bony structure inside to the buttocks of a male autosite twin, and an additional third leg which happened to be an under-developed lower extremity with a sacrum-like structure.

CONCLUSIONS

An obstetrician's routine ANC and critical radiological evaluation will increase the odds of identifying CT or other congenital malformations to provide better delivery planning or further management. Increasing maternal health knowledge in society, improving medical skills and knowledge levels for health providers, and advancing supporting facilities and specialists are future strategies for managing and preventing such cases in low-middle-income countries.

Gastrulation and Body Axes Formation: A Molecular Concept and Its Clinical Correlates

During the third week of human pregnancy, an embryo transforms from two germinal disc layers of hypoblast and epiblast to three germinal layers of endoderm, mesoderm and ectoderm. Gastrulation is a complex process that includes cellular mobility, morphogenesis and cell signalling, as well as chemical morphogenic gradients, transcription factors and differential gene expression. During gastrulation, many signalling channels coordinate individual cell actions in precise time and location. These channels control cell proliferation, shape, fate and migration to the correct sites. Subsequently, the anteroposterior (AP), dorsoventral (DV) and left-right (LR) body axes are formed before and during gastrulation via these signalling regulation signals. Hence, the anomalies in gastrulation caused by insults to certain molecular pathways manifest as a wide range of body axes-related disorders. This article outlines the formation of body axes during gastrulation and the anomalies as well as the clinical implications.

Successful separation of male pygopagus with anal canal and urethral reconstruction: a case report

Background

Pygopagus is a type of conjoined twin binding at the buttocks. Some cases of pygopagus involve the fusion of the gastrointestinal tract, urinary tract, and spinal cord. Few cases of male pygopagus have been reported; however, the prognosis after separation is unclear. Herein, we report a case of male pygopagus in which successful separation was performed with the reconstruction of the anal canal.

Case presentation

Twins with male pygopagus were born at 35 weeks by cesarean section. They shared a common anus, penis, and scrotum with four testes. The infants had normal defecation and urination after birth. The separation surgery was scheduled when they were 5 months. Two distinct anesthesia teams and four surgical teams (neurosurgery, pediatric urology, plastic surgery, and pediatric surgery) were involved in the multidisciplinary approach. After separating the spinal cord, we found that the anal canal and sphincter muscle complex were fused near the anal aperture, and we separated them. The fused penis and testis were separated and reconstructed using the same incisional line as the other separation, and the reconstructions of the anal canals with the sphincter muscle complex were completed. Both patients had an uneventful postoperative course. At 2 years of age, they could walk and defecate independently. In addition, they voided spontaneously without urinary incontinence at the time of 3 years and 11 months.

Conclusions

Separation of the spinal cord with anal canal and urethral reconstruction is important for male pygopagus patients as it allows them to preserve their independent function.

Gastrulation : Current Concepts and Implications for Spinal Malformations

It has been recognised for over a century that the events of gastrulation are fundamental in determining, not only the development of the neuraxis but the organisation of the entire primitive embryo. Until recently our understanding of gastrulation was based on detailed histological analysis in animal models and relatively rare human tissue preparations from aborted fetuses. Such studies resulted in a model of gastrulation that neurosurgeons have subsequently used as a means of trying to explain some of the congenital anomalies of caudal spinal cord and vertebral development that present in paediatric neurosurgical practice. Recent advances in developmental biology, in particular cellular biology and molecular genetics have offered new insights into very early development. Understanding the processes that underlie cellular interactions, gene expression and activation/inhibition of signalling pathways has changed the way embryologists view gastrulation and this has led to a shift in emphasis from the ‘descriptive and morphological’ to the ‘mechanistic and functional’. Unfortunately, thus far it has proved difficult to translate this improved knowledge of normal development, typically derived from non-human models, into an understanding of the mechanisms underlying human malformations such as the spinal dysraphisms and anomalies of caudal development. A paediatric neurosurgeons perspective of current concepts in gastrulation is presented along with a critical review of the current hypotheses of human malformations that have been attributed to disorders of this stage of embryogenesis.

The growth of pediatric neurosurgery in southern Vietnam and the first separation of pygopagus twins: case report

Conjoined twins are a rare congenital abnormality with an estimated incidence of 1:50,000 pregnancies and 1:200,000 live births. Pygopagus twins are characterized by sacrococcygeal fusion that is commonly associated with perineal and spinal abnormalities. Management of this complex disease requires a well-developed surgical system with multidisciplinary capacity and expertise.A decade ago there were no dedicated pediatric neurosurgeons in southern Vietnam. This has changed within a few short years; there are now 10 dedicated pediatric neurosurgeons with continually expanding technical capacity. In August 2017 a multidisciplinary surgical and anesthetic team successfully separated female pygopagus twins with fused sacrum and spinal cord with associated myelomeningocele defect.The authors present here the first successful separation of pygopagus twins in Vietnam as a representative case of gradual and sustainable pediatric neurosurgical scale-up.

Long-term urological outcomes in six sets of conjoined twins

AIM

To review the long-term urological outcomes of six sets of ischiopagus and pygopagus conjoined twins. Emphasis is placed on the particular genitourinary challenges of separation, reconstruction and monitoring of these patients.

PATIENTS AND METHODS

We performed a longitudinal, retrospective analysis of six sets of conjoined twins who presented to a single center and describe their long-term urological outcomes.

RESULTS

Six sets of ischiopagus (4) and pygopagus (2) conjoined twins presented from 1993 to 2003 and have been followed up for a mean of 12 years (range 7-17 years). Separation was achieved in 5/6 cases; the remaining one died of intestinal perforation and resultant sepsis. One further child died of malaria after separation. Patterns of genitourinary anatomy found in these conjoined twins are described. Urinary continence was achieved in 2/6 ischiopagus and 3/4 pygopagus twins. Renal failure has developed in one child. Urinary tract infections have been common. Secondary urological surgery has been required in 3/6 ischiopagus twins, usually to perform an incontinent urinary diversion.

CONCLUSION

Complex urological problems occur in ischiopagus and pygopagus conjoined twins. Beyond the challenge of surgical separation, they continue to provide management challenges requiring secondary reconstructive surgery and close urological monitoring.

Successful separation of the conjoined thecal sac with an epidermal cyst in pygopagus twins

Pygopagus conjoined twins are very rare, and half of all pygopagus twins have other anomalies. This report describes the successful surgical separation of pygopagus twins who had a conjoined thecal sac and an epidermal cyst. Meticulous preoperative planning, development of a model simulator, multispecialty teamwork, and a staged surgery contributed to a successful outcome.