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

Abstract

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. ABBREVIATIONS: CPT ¼ craniopagus twins; CVS ¼ circumferential venous sinus; SDVS ¼ shared dural venous sinuses; TA ¼ total angular; TV ¼ total vertical C raniopagus twins (CPT) are a rare congenital malformation in which twins are conjoined at the head. It accounts for only 2%-6% of conjoined twins, with an incidence of approximately 1 in 2.5 million lives births. 1,2 The skulls are most often joined at homologous regions on each twin in both vertical and angular orientations, with the face and foramen magnum not primarily involved. 3 CPT can manifest as total, the twins share dural venous sinuses (SDVS), and partial forms, with separate venous anatomy. 4 Although there is high prenatal and postnatal mortality for CPT, successful separation has become more common due to advances in neuroimaging, neuroanesthesia, and neurosurgical techniques. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Joined brain tissue, shared arteries and veins, and defects in the skull and dura make surgery technically challenging. 21 Separation can take place in single or multistage procedures and has evolved as the understanding of the physiology, surgical techniques, and technology of CPT have improved. 16 Neuroimaging, including CT, MR imaging, and conventional angiography, plays an important role in mapping the shared arterial and venous structures, brain parenchyma, calvaria, and dura. [22][23][24] Understanding the shared vascular anatomy is important for surgical planning because separating common vessels is associated with complications such as thrombosis, air embolism, infarction, and hemorrhage. 25 Digital and physical 3D models generated from CT and MR imaging data are important tools for operative planning and as a guide in the operating room. 21 We will review the preoperative radiologic evaluation of CPT, including the anatomy, classification systems, and surgical management, that is important for the radiologist to understand. We draw on our experience in consultation for multiple successful CPT separations with an experienced neurosurgical specialist in CPT.

Conjoined Twins: Unicephalus Non-Janiceps Tetrapus Tetrabrachius

“…A multimodal integrated imaging could provide comprehensive assessment of extracranial and intracranial anatomy before surgery [14]. Shared brain tissue, arteries and veins, and defects in the skull and dura cause surgery technically arduous [15].…”

Antenatal Diagnosis of Parapagus Conjoined Twins: 3D Virtual and 3D Physical Models

“…Recently, many technological advances are being applied and customized to improve the comprehension of the singular anatomy of CTs, including 3D imaging, virtual reality, and 3DPM printing. 8 The formation of a 3D image is the first step after imaging acquisition. The presence of multiple contrasts allows the proper segmentation of the anatomy to be studied.…”

Postnatal imaging of conjoined twins: a customized multimodality approach

“…In older children, hemispheric language dominance can be assessed before surgery using functional MRI. Diffusion tensor tractography can demonstrate the continuity of white matter tracts [ 14 , 17 ]. However, the distorted anatomy may render the interpretation of tractography challenging due to the altered color hue of the fiber tracts.…”