|ECR 2019 / C-3147|
|Neuroimaging findings in children with abusive head trauma|
AHT is the leading cause of fatal head injuries in children younger than 2 years and is responsible for 53% of serious or fatal traumatic brain injury cases. AHT fatality rates are more than 20%. These patients often develop severely impairing sequelae that include developmental delays, seizures, para- or tetraplegia, ventilation dependence, deafness, blindness, or behavioral abnormalities. Outcomes are shown to be worse in patients with AHT than in those with accidental trauma. Although these numbers likely underrepresent the true incidence, however, because of the high probability of underdiagnosis and misdiagnosis.
The etiology of this injury is multifactorial, mechanisms that include shaking, shaking and impact and impact so the current best and most inclusive term is AHT.
The diagnosis of AHT should be concluded by a multidisciplinary team of caregivers that should include paediatricians and paediatric neurologists, socialworkers, among others. Regularly these children present incomplete or inconsistent history that doesn’t match with the clinical findings. Often these infants and children present to the emergency department, where they may demonstrate a wide range of symptoms, from nonspecific to severe, making accurate and prompt recognition a substantial challenge for providers. Most of the presenting symptoms are associated with CNS injury. Vomiting, altered mental status, seizure, and apnea are among the most common. Therefore the radiologist should be able to access complete clinical information to be able to assess whether the story is a plausible explanation for the abnormalities.
Usually impulsive injuries are secondary to nonimpact forces generated by acceleration/deceleration of the parenchyma. Impact loading is secondary to a direct force to the head. Both mechanisms produce different patterns but it has seen that they can overlap.
Acceleration/deceleration force produce a shearing injury to the parenchyma and the meninges. This type of shaking mechanism was classically associated with the triad of subdural haematoma (SDH), retinal haemorrhage (RH), and focal or diffuse parenchymal injury often in the absence of external signs of injury.
The other type of injury, in which a direct force is applied to the vault results mainly in skull fracture and parenchymal contusions with associated focal extraaxial and subperiosteal haemorrhage. Impact injuries are less common in infants with AHT and are more frequent in older children. In reality the causal mechanism is rarely confirmed and may well include elements of both impact and acceleration-deceleration injury.
The incidence of retinal haemorrhage in AHT is approximately 85%. Although RHs are of only moderate specificity for AHT, RHs are more predictive of AHT when they are bilateral, multilayered, and peripherally extend to the ora serrata.
Skeletal injury, particularly posterior rib fractures and long bone fractures, has repeatedly been found to be associated with AHT in infants. Posterior rib fractures are thought to occur as a result of squeezing around the infant’s chest during shaking or slamming and have been described repeatedly as being highly associated with physical abuse. The two most commonly metaphyseal fractures in AHT are of the humerus and femur.
A full skeletal survey according to international guidelines should always be performed to obtain information on possible underlying bone diseases or injuries suspicious for child abuse, especially in the context of AHT. Also lab examinations should be performed to exclude bleeding and bone diseases.