Total craniopagus twins

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.

The craniopagus malformation: classification and implications for surgical separation

Craniopagus twins (CPT) are an uncommon, highly fascinating accident of nature. The clinical pathology of this complex entity is reviewed and placed in perspective. A logical classification aids understanding of the anomaly, and is essential to gauge outcome from separation attempts. 'Partial forms' lack significant shared dural venous sinuses (SDVS) and 'Total forms' with SDVS also exhibit more severe compressional brain distortion. Our classification consists of Partial Angular (PA), Partial Vertical (PV), Total Angular (TA) and Total Vertical (TV, formerly O'Connell Types I-III). Total vertical has a continuous cranium, and inter-twin axial facial rotation <40 degrees (Type I), 140-180 degrees (Type II) or intermediate (Type III). The term 'Angular' denotes an inter-twin longitudinal angle below 140 degrees , regardless of axial rotation. Our review categorized 64 well-delineated CPT, including 41 operative separation attempts in small children since initial success in 1952. Just over one-half were TV, almost one-third TA, and partial forms accounted for the remaining one-sixth. About 30% of CPT had shared or fused brain tissue, and a similar percentage of TA twins shared a posterior fossa. Partial forms had significantly higher birth weights, were separated at an earlier age (6 versus 11 months) and had lower mortality and better outcome compared with Total forms. A multi-staged surgical separation for Total CPT had a significantly better mortality than single-staged separation. Discussion emphasizes embryological, anatomical and clinical aspects of the malformation, with emphasis upon obstacles to a successful outcome.

Craniopagus twins. An unsuccessful separation and a clinical review of the entity

Craniopagus twinning is an extremely uncommon birth defect with an estimated incidence of 4-6 every 10 million births. The most complex and challenging issue is the feasibility of surgical separation, which involves not only technical but also socioethical problems and requires strict multidisciplinary cooperation between pediatricians, neuroradiologists, anesthesiologists, and plastic and neurological surgeons. The authors report a case in which separation was followed by the death of both twins and stress the importance, from the surgical and prognostic viewpoints, of the degree of vascular connections between the major dural sinuses. We propose a classification into three types according to severity.