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

Background. Occipital osteodiastasis (OOD) is a form of birth injury charac terized by a tear along the innominate (posterior occipital or supraoccipit al-exoccipital) synchondrosis with separation of the occipital squama from the lateral or condylar parts of the occipital bone. The condition, frequen tly mentioned in the older literature as relatively common and invariably f atal, has been attributed to excessive pressure exerted over the subocciput during delivery, resulting in a forward and upward displacement of the ant erior margin of the occipital squama into the posterior cranial fossa, with posterior fossa hemorrhage and other intracranial complications. Most like ly 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 s urvival has been suggested, but so far only one case has been reported in s ome detail. Materials and methods. This paper reports the occurrence of this less sever e 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 di agnosis of child abuse who also survived and a 2-year-old girl who was invo lved 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 cervi cal spine roentgenograms showing specific changes in the area of the innomi nate synchondrosis.