Serial Radiography in the Infant Shaken Impact Syndrome

Abstract

Certain CT and/or MRI abnormalities have been used medicolegally to time intracranial injuries from the infant shaken impact syndrome (ISIS). For example, parenchymal hypodensities on CT scans are said to arise only after 6–48 h have elapsed postinjury, and the presence of chronic or mixed subdural hematomas suggests injury that occured 1–4 weeks prior. However, these statements are based largely upon inference from data obtained in other conditions such as ischemic anoxic injury and chronic subdural hemorrhage in adults. Direct evidence about the evolution of intracranial injuries in infants with ISIS is sparse, and the radiographic changes following ISIS have never been systematically studied on serial imaging studies. One hundred-seventeen serial CT and MRI scans obtained from 33 infants with ISIS were reviewed retrospectively. The exact scan dates and times were obtained directly from the scans. Acute subdural hemorrhage was the most common intracranial abnormality and was present in 27 (81%) of the 33 infants. Other intracranial abnormalities included chronic subdural collections, subarachnoid hemorrhage, epidural hematomas, parenchymal hypodensities, edema and contusions, and atrophy and encephalomalacia. In 15 of the 33 infants, the injury could be timed with reasonable certainty, and the evolution of the radiographic changes followed over time. Six of the 15 infants had evidence of prior cranial trauma such as chronic subdural collections (5 infants) or mild atrophy (1 infant). Of the remaining 9 infants, parenchymal abnormalities such as hypodensities, edema and contusion appeared in virtually all of the initial scans performed approximately 3 h following the report of injury. One ‘chronic’ subdural collection was absent on the first scan performed 2.75 h postinjury, but appeared on a second scan performed 17 h later, suggesting that some ‘chronic’ subdural fluid collections may arise much sooner than previously thought. These findings challenge some of the current dogma about the timing of radiographic changes following abuse and are important in timing the alleged abuse for legal purposes.

Serial neuroimaging in infants with abusive head trauma: timing abusive injuries

“…Homogeneously hyperdense SDH was present in fewer than one-third of our cases; mixed-density SDH, containing both hyperdense and hypodense components, was present in over half of the infants in the present study, in onethird of children in our prior study, 9 and in 91% of infants with AHT in a third study by Vinchon et al 31 Mixeddensity SDH in AHT has been interpreted as prima facie evidence of serial injuries, 6,25 but this concept has recently been challenged. 9,11,32,33,39 One child in our previous study developed a hypodense subdural collection de novo on a second CT scan performed 19 hours after an initial scan showed no SDH in that region. 9 In another study of 18 infant victims of motor vehicle crashes with SDH, 3 infants had mixed-density SDH on the initial CT scan.…”

“…Intracranial CT abnormalities conformed to the definitions used in the previous study. 9 Subdural hematomas were defined as hemorrhagic fluid collections located under the dura along the convexity, falx, or tentorium. Although a number of studies have confirmed that these hematomas technically lie within the inner dural border zone, the term "subdural" has achieved such widespread acceptance that we refer to these collections as subdural throughout the study.…”

“…published a study of 33 infants with AHT, chronicling the initial appearance and subsequent temporal evolution of intracranial abnormalities on serial CT scans. 9 The major conclusions of this study were that 1) parenchymal hypodensities first appear and are conspicuous on the initial CT scans performed an average of 3 hours after the reporting of the injury; 2) acute SDHs are present in 85% of cases and most commonly (in nearly 80% of cases) resolve without evolving to chronic SDHs; and 3) when SDHs do evolve from acute to chronic, a hypodense component (with respect to brain) first appears between 3 and 12 days after the injury. However, this study was limited by a small sample size and, in particular, by a limited number of infants (only 4) with an evolving SDH.…”

Preventing Abusive Head Trauma Among Infants and Young Children: A Hospital-Based, Parent Education Program

“…Shaken infant syndrome is the most widely used and recognized term, although shaking alone may not account for all injuries. 3 Whatever the terminology and pathogenesis, abusive head injuries among infants represent one of the most severe forms of child abuse, with 13 to 30% mortality rates 4,5,7,8 and significant neurologic impairments in at least one half of the survivors. 9 The economic costs of abusive head injuries are significant; initial inpatient hospitalization costs average $18 000 to $70 000 per child, and average ongoing medical costs can exceed $300 000 per child.…”

“…Other terms for this condition include shaken baby syndrome or shaken infant syndrome, shaken impact syndrome, 3 infant shaken impact syndrome, 4 infant whiplash-shake injury syndrome, 5 abusive head trauma, 6 and inflicted, nonaccidental, or intentional head injury. Shaken infant syndrome is the most widely used and recognized term, although shaking alone may not account for all injuries.…”