tricephaly

Tricephaly is a rare congenital anomaly in which a single individual has three heads. It is a form of polycephaly, a broader category of multiple cranial structures arising from abnormal embryonic development. In tricephaly, the three heads may be anatomically distinct or partially fused, and the degree of shared torso, skull, and brain tissue varies among cases.

The condition is believed to result from abnormal embryogenesis during the early stages of development. It can reflect incomplete division (fission) of a single fertilized egg or the fusion of developing twins or triplets. Depending on how the cranial primordia separate or merge, three faces and skulls may sit on one body, with varying degrees of shared brain tissue and cranial nerves. This leads to substantial anatomical and neurologic complexity.

Clinical presentation ranges from stillbirth to live birth with severe congenital anomalies. Common features may include multiple facial structures, abnormal facial symmetry, and extensive neural tissue anomalies. Imaging and examination after birth help define the extent of brain involvement and shared structures. The prognosis is generally poor, with many infants dying shortly after birth. Survivors often suffer profound neurological impairment and limited functional capacity.

Management is typically supportive and focused on comfort, with decisions guided by the extent of organ involvement and overall prognosis. There is no standard or curative surgical separation for tricephaly, given the complexity and the usually extensive cerebral malformations.