[Shaken baby syndrome and osteogenesis imperfecta]

Shaken baby syndrome (SBS) is a form of physical abuse that includes the presence of a subdural or subarachnoid haematoma or diffuse cerebral oedema, retinal haemorrhages and, in general, absence of other physical signs of traumatic injury. Osteogenesis imperfecta (OI) is a genetic disorder affecting the synthesis of type I collagen that leads to brittle bones with frequently occurring fractures, with presenting clinical symptoms taking a variety of forms. A differential diagnosis allowing it to be distinguished from physical abuse is known, due to the existence of bone fractures with no known traumatic injuries, but we do not understand the link between OI and SBS.

We describe the case of an infant who, at the age of 3 months, suffered symptoms of acute encephalopathy with convulsions, subdural haematoma and retinal haemorrhages compatible with SBS, as well as bilateral rib fractures. The skeletal series of X-rays revealed alterations in bone structure and texture, which led to a diagnosis of OI that was confirmed by a study of the collagen in skin fibroblasts.

The suspected existence of SBS is unpleasant both for the health care professional and for the patient's relatives. The existence of rib fractures in an obvious case of shaken baby syndrome suggested malicious abuse; however, the parents' attitude and the existence of OI made us think that no harm was intended. Shaking could have been secondary to bouts of crying due to microfissures related to the OI. The differential diagnosis of processes that can be mistaken for shaken baby or from favourable or predisposing medical factors must be taken into consideration.