Occipital osteodiastasis: presentation of four cases and review of the literature

Background. Occipital osteodiastasis (OOD) is a form of birth injury characterized by a tear along the innominate (posterior occipital or supraoccipital-exoccipital) synchondrosis with separation of the occipital squama from the lateral or condylar parts of the occipital bone. The condition, frequently mentioned in the older literature as relatively common and invariably fatal, has been attributed to excessive pressure exerted over the subocciput during delivery, resulting in a forward and upward displacement of the anterior margin of the occipital squama into the posterior cranial fossa, with posterior fossa hemorrhage and other intracranial complications. Most likely as the result of improved obstetric techniques, this severe form of OOD has become quite rare or non-existent. A less severe form compatible with survival has been suggested, but so far only one case has been reported in some detail. Materials and methods. This paper reports the occurrence of this less severe form of OOD diagnosed roentgenographically in two infants who survived: a newborn and a 3-month-old child. Two additional cases of a similar lesion but of postnatal onset are also described: a 3-month-old infant with the diagnosis of child abuse who also survived and a 2-year-old girl who was involved in a fatal motor-pedestrian collision. Results. Based on cases in the literature and the present material, three forms of OOD can be considered: a classic, fatal form; a less severe variant compatible with survival; and OOD of postnatal onset. The diagnosis can be made on lateral skull or cervical spine roentgenograms showing specific changes in the area of the innominate synchondrosis.