Diagnostic Imaging in Child Abuse

Non Accidental Trauma

Simon Robben

Radiology Departement of the Maastricht University Hospital in the Netherlands

Publicationdate

Child abuse is a relatively common problem in our society.
In the U.S it is estimated that 4 million children a year are abused in some manner.
At least two thousand children die as a result of this abuse.
This overview focusses on the role of diagnostic imaging in depicting the findings that are specific for child abuse.
Awareness of the radiologist is essential in finding these skeletal and CNS injuries in order to document child abuse, to stop further abuse and to protect siblings.

by Simon Robben

Introduction

  • Shaken infant syndrome

Battered child syndrome, shaken infant syndrome, stress-related infant abuse and non accidental trauma are all terms to describe the complex of non-accidental injuries in infants and young children as a result of abuse.
The term shaken infant syndrome probably best describes the classic pattern of injuries.
The child is held around the chest and violently shaken back and forth.
This causes the extremities and the head to flail back and forth in a whiplash movement.
Intracranial injury occurs as a result of severe angular acceleration, deceleration and direct impact as the head strikes a solid object.
The chest is compressed resulting in rib fractures.
Arms and legs move about in a whiplash movement resulting in the typical 'corner' or 'bucket-handle'-fractures in the metaphyseal region.

Role of the Radiologist

The ability to identify child abuse constitutes an important concern to those involved in the medical care of children.
Studies show that at least 10% of children under 5 years old who are brought to the emergency room with alleged accidents have actually suffered nonaccidental trauma.
Since as many as 65% of all abuse cases are initially seen in the emergency room, the first step in correctly identifying abuse is to train hospital staff members to recognize abuse indicators.
The wide range of findings, which can mimic other disease processes, results in misdiagnosis of many cases of inflicted head trauma.
Jenny and colleagues reported that 31% of confirmed abusive head trauma cases were missed on initial presentation and many infants sustained additional injury because of the delay in diagnosis.

  • Role of the Radiologist

The radiologist can be the first to suggest the diagnosis on the basis of CT studies performed to evaluate for seizures or other neurologic symptoms or on X-rays performed for other reasons.
A high degree of suspicion, inability to explain the degree of injury or a reported mechanism of injury, that is inconsistent with the physical findings should alert the radiologist to possible inflicted injury.
A protocol for imaging in suspected abuse should be present to provide high quality radiographs.
The future safety of a child with the shaking infant syndrome rests on the radiologist's ability to recognize these characteristic features.

Skeletal Injury

  • Specific Fractures in Child Abuse

When we look at X-rays at the emergency department, we have to realize, that the forces needed to break a bone in an infant or young child are enormous.
Any fracture in this age group indicates a major traumatic event, not just a fall from a low height.
Fractures with a high specificity for child abuse are listed in the table on the left.
The classical metaphyseal corner or bucket handle fracture is virtually pathognomonic for abuse.
Rib fractures are very common and highly specific for abuse in young children less than 2 year.
Fractures of the acromion, sternum and spinous processes are so rare in other conditions, that this affords them a high specificity for abuse.
Occipital impression and other skull fractures occur when the head strikes a solid object.

  • Metaphyseal Corner fracture2
Typical corner fracture very specific for non accidental trauma

Corner fracture

The corner fracture was first described by Caffey who noted these peculiar fractures in children with subdural hematomas.
When a small piece of bone is avulsed due to shearing forces on the fragile growth plate it is seen as the typical corner fracture.
These fractures are often subtle, and the likelihood of detection is directly related to the quality of the radiologic studies.
It is for this reason that skeletal surveys in cases of suspected infant abuse must be performed with utmost attention to the quality of the radiographs.

  • Metaphyseal Corner fracture
Bucket handle fracture in proximal tibia. The metaphyseal fracture fragment is seen as a disk or bucket handle.

Bucket handle fractures
These fractures are essentially the same as corner fractures.
The avulsed bone fragment is larger and seen 'en face' as a disc or bucket handle.
These corner and bucket handle fractures are most common in the tibia, distal femora and proximal humeri.
They are frequently bilateral.

  • Ribfractures
LEFT: Child evaluated for soft tissue mass in costchondral region. Soft tissue swelling (yellow arrows), chondral part of rib (red arrow) disrupted from bony part (orange arrow) of rib.RIGHT:Initial chest film was negative. Chest film 2 weeks later showed fractures.

Rib fractures

In violent shaking the child is held very tightly around the chest and squeezed while being shaken.
This compresses the ribs front to back and tends to break them next to their attachment to vertebrae and laterally where they are being literally almost folded in half.
Therefore, lateral and posterior rib fractures are highly specific for abuse.
CPR is rarely, if ever, a cause of such fractures.
These rib fractures in abused children may be found incidentally on chest X-rays performed for other reasons, such as evaluation for pneumonia.

  • Fracture localisation
Localisation of fractures in 31 children who died as a result of child abuse

Rib fractures are very common and highly specific for abuse.
In 31 children who died as a result of child abuse, there was an extremely high incidence of ribfractures and metaphyseal fractures.

  • Ribfractures
Old posterior rib fractures very indicative of non accidental trauma.

Rib fractures pose difficulties similar to those of metaphyseal injuries in that they are easily overlooked on radiographs.
These fractures usually are not evident on radiographs in the acute stage, as little displacement occurs.
They are identified in the healing stage as a result of associated callus.

  • Skull fractures
LEFT: eggshell fractures in a child who died of cerebral injury after being thrown of a heightRIGHT: skull fracture crossing suture in abused child

Skull fractures

Skull fractures are common child abuse injuries, but they are also common in accidental trauma.
Patterns of skull fracture that suggest child abuse are:
- Multiple 'eggshell' fractures
- Occipital impression fractures
- Fractures crossing sutures

The infant's skull is very resistent to trauma, so any fracture that is inconsistent with the history should raise the question of non-accidental injury.

  • Diaphyseal fractures
Two infants with a femur fracture. Child abuse was suspected because of the age of the child and an inconsistent history given by the parents.

Diaphyseal fractures

Diaphyseal fractures are non-specific as they do occur in both accidental and non-accidental injury.
However in these cases the age of the child and the history become very important.
A fall out of a bed will usually not produce a diaphyseal fracture.
In order to break a femur you have to fold it with enormous power.
Spiral fractures are a result of twisting forces which are uncommon in accidents in young children, but more common in adults. So a simple fall does not produce a spiral fracture in a child.

  • Fracture healing
Diafyseal femur fracture with a lot of callus is at least 2 weeks old.

Fracture healing

Callus in diaphyseal fractures generally forms no earlier than 5 days after a fracture, but will usually form by 14 days.
Thus, fractures without visible callus may be up to 14 days old, and fractures which demonstrate a little bit of callus are at least 5 days old. Large amounts of callus indicate at least 2 weeks old.
These signs can be used to correlate with the history. For instance a child that fell out of bed the day before cannot have a fracture with callus formation.
Metaphyseal fractures do not typically heal with callus as there is no periosteal disruption, so dating of metaphyseal fractures is difficult.

CNS injury

  • Head trauma related to nonaccidental injury

CNS injury related to nonaccidental injury is a leading cause of morbidity and mortality in infants and children.
Some state that eighty percent of deaths of children under 2 years of age result from nonaccidental head trauma.
A baby's neck muscles are very weak and its head is large and heavy in proportion to the rest of its body.
The infant brain is poorly myelinated and is surrounded by larger subarachnoid spaces than the brain in older children and adults.
When a baby is shaken, the neck snaps back and forth, much like in a whiplash injury, causing the brain to hit the front and back of the skull. This can damage the brain and cause it to bruise, bleed and swell.

  • Old and new subdural hematoma
Hypoechoic subdural fluid collection indicating an old subdural hematoma (yellow arrow) and hyperechoic subdural mass (red arrow) as a result of a fresh subdural hematoma.

Subdural hematoma

Imaging studies of the head may show subdural or subarachnoid bleeding, diffuse axonal injury and associated cerebral edema or older injuries such as subdural effusions.
The case on the left shows an ultrasound examination that demonstrates an old and a new subdural hematoma in an abused child.

  • Subdural hematomas
Child died of CNS injurie. Further examination also revealed ribfractures. CT: hematoma in the interhemispheric region.

Subdural hematomas arise from disruption of delicate bridging veins extending from the cortex to the dural sinuses.
Although bleeding can occur at any site, the tendency is for blood to extend into the posterior interhemispheric fissure.

  • MR subdural hematoma
T1WI shows bilateral fluid collections as a result of chronic bilateral subdural hematomas and new subdural hematomas in the right frontal and posterior interhemispheric region.

MR examination is even more sensitive in detecting subdural hematomas.
The case on the left shows chronic bilateral subdural hematomas and new subdural hematomas in the right frontal and posterior interhemispheric region.
The bright signal is a result of methemoglobin indicating subacute hematoma ( about one week old).

Other injuries

  • Visceral injury
Common abdominal injuries in abused children are liver laceration, duodenal hematoma and pancreatic laceration.

Visceral injury
Visceral injury is seen at autopsy of young infants, but it is rarely documented radiologically in living victims less than 1 year of age.
It is estimated that 2-10% of all abdominal injury results from child abuse.
The mean age of these children is about 2 years, which is older than the cases we have discussed before. It is more common in boys than girls.
The mortality rate is 50% due to 'patients and doctors delay'.
These children are brought to the hospital days after the injury, when a perforation already has resulted in peritonitis and sepsis.
The history given by the abusers usually does not correlate with the symptoms, which makes these cases very difficult to evaluate for the clinician.

  • pancreatic laceration
Pancreatic laceration in child abuse

The most common non-accidental abdominal injuries are:
- visceral perforation or hematoma
- liver- and pancreatic laceration
- adrenal bleeding
Suprisingly the most common abdominal accidental injuries, which are laceration or subcapsular bleeding of the spleen and the kidney, are unusual in these children.
The figure on the left shows a case of pancreatic laceration in child abuse.

  • liver laceration
Liver laceration in child abuse

The figure on the left shows a case of liver laceration in child abuse.
These abdominal injuries are non specific and could also be attributed to accidental injury.
However in most of these cases of child abuse, there is a history that does not correlate well with the injuries, that are found.
So you have to look for other more specific skeletal injuries in these children.

Retinal hemorrhage
Retinal hemorrhage is seen in nearly all cases of infant abuse in which shaking is documented.

Cervical spine compression
Cervical spine compression results as shaking or impact injury damages the spinal cord.
Infants are vulnerable to spinal cord injury because of their large head and weak underdeveloped paraspinous and neck musculature. Spinal cord injury may be difficult to document. These infants may exhibit apnea or vasomotor collapse similar to spinal shock.

Imaging survey in suspected abuse

  • Imaging survey in suspected abuse

Radiographic skeletal survey is necessary in all children less than 2 years old suspected of abuse.
It consists of individual AP X-rays of chest, skull (also lateral) and extremities.
In children 12 months or younger, also perform a lateral thoracolumbar spine film.
Head CT scan shoud be performed on all suspected abuse victims 1 year of age or younger and in all children with neurological symptoms.
Expert attention to technique and detail is necessary to get quality radiographs that show some of the very subtle injuries of abuse.
Do not perform a 'babygram'.
Remember that these are the radiographs that will go to court.
Repeated skeletal imaging in 7-10 days may provide evidence of a healing injury, that was inapparent on the initial study.

Nuclear bone scan is usually not necessary. Perform this if there are equivocal findings on the skeletal survey or if there is a high clinical suspicion of skeletal injury but the skeletal survey is normal.
Plain X-rays of the skeleton in the areas of abnormality identified at bone scan, are still needed to evaluate for the exact nature of the abnormality.

Differential diagnosis

  • Accidental injury
1 day old child with multiple fractures after a problematic delivery. Birth weight was 5500 grams.

Accidental injury
Accidental subdural hemorrhages have been reported in infants after motor vehicle collisions or falls involving substantial angular deceleration.
In cases of accidental head injury, the history is clear and consistent, the infant's symptoms reflect the forces described, and no unexplained skeletal injuries are identified.
Birth trauma resulting from high birth weight and traumatic delivery has been postulated as a cause of rib fractures in infants, but this is extremely rare (figure).
Rib fractures associated with accidental trauma are rare and require significant force to produce such as direct chest wall trauma from motor vehicle crashes, because the elastic and more flexible chest wall of infants allows for greater compression without injury.
Cardiopulmonary resuscitation also has been implicated as a cause for rib fractures. Many critically ill children receive CPR and have no evidence of rib fractures, however, including children with osteogenesis imperfecta.
More important, CPR does not cause posterior rib fractures.

Coagulopathies
A variety of coagulopathies is associated with intracranial hemorrhage in infants, including hemophilia and hypoprothrombinemia caused by vitamin K deficiency.
These disorders are suggested by the clinical history, physical findings, and laboratory tests.

  • Osteogenesis imperfecta
Osteopenia and fracture in a child with osteogenesis imperfecta.

Osteogenesis imperfecta
Osteogenesis imperfecta is a rare inherited disorder of connective tissue. Other skeletal findings in these patients are generalized osteoporosis, wormian bones, bowing and angulation of healed fractures and progressive scoliosis.
In addition to fractures, suggestive findings include blue sclerae, hearing impairment, dentinogenesis imperfecta, hypermobility of the joints, bruising and short stature.
Subdural hemorrhage is a rare complication of the disease.

  • Menke's disease
Small metaphyseal hooks seen in a patient with Menke's disease.

Menke's disease
Menke's disease is a very uncommon inborm error of metabolism. In these patient's small metaphyseal hooks can be seen that resemble corner fractures.

  • Metaphyseal dysplasia

Metaphyseal dysplasia
A case of metaphyseal dysplasia is shown on the left.
In these children the form of the metaphysis is irregular resembling an old corner fracture.

Abundant periosteal bone formation in a case of Caffey's disease

Caffey's disease
This is a rare disease of unknown etiology.
These children have extreme periosteal reactions.