Abusive head trauma

Head trauma is the leading cause of traumatic death in children. Abusive head trauma is implicated in 80% of fatal head injuries in children younger than 2 years of age.[1] “Shaken baby syndrome” is a term used in the medical literature to describe children who have suffered an extremely serious form of child maltreatment that results in a specific constellation of clinical findings and injuries. The mechanism of shaking and the resultant injuries were originally described by Caffey in 1972 and later termed the “whiplash shaken baby syndrome.”[2] The injuries included subdural and/or subarachnoid hemorrhage, retinal hemorrhages, and metaphysial chip fractures. Caffey also made note of the absence of external physical findings in children who had sustained these injuries.

Since that time, much debate has arisen over the suspected mechanism of injury in abusive head trauma, as well as the types of injuries that affected children exhibit. Many injured children will present with evidence of blunt trauma to the head (e.g., skull fracture), while other injured children will not, even though the rapid rotational acceleration/deceleration forces caused by severe shaking alone can result in significant intracranial injury or death.[3-5]

Shaken baby syndrome occurs primarily in children younger than 3 years of age, with most cases presenting from birth to 1 year. It should be noted, however, that all that is needed to produce this constellation of symptoms is a brain subjected to severe enough rotational force—something that has been documented in the adult population as well.[6]

A recent Canadian study suggests that a minimum of 40 cases of shaken baby syndrome occur in Canada annually, with a mortality rate of almost 20%.[7] Unfortunately, many cases of abusive head trauma often go unrecognized, resulting in further maltreatment and, in some cases, death.[8] Several aspects of medical assessment can help physicians recognize and manage affected children.

History-taking

As might be expected, when infants and children present with abusive head trauma, the initial history provided by the caregiver is often inaccurate. The details offered may be vague or may change with repeated questioning. At times, the caregiver may suggest a mechanism of injury that would not be possible based on the child’s developmental ability.

Symptoms may seem quite mild or nonspecific in nature, including poor feeding, lethargy, or irritability. Such symptoms are seen frequently with a number of other more common and less severe pediatric illnesses, which may be partly why more than 30% of cases of abusive head trauma are initially misdiagnosed and the patient is discharged.[8]

Historical risk factors for abusive injury include an unstable family situation, young parents, prematurity, and physical or mental disability. Caregivers often cite crying as a provoking factor for anger and aggression toward the child.[9] The physician should routinely enquire about the child’s demeanor before the onset of the presenting symptoms.

Physical examination

Children who present with evidence of respiratory compromise, seizures, or coma are more likely to be accurately diagnosed with shaken baby syndrome. Careful attention should be given to the emergency management of airway, breathing, circulation, and neurological disability. Early communication with pediatric intensive care specialists, neurosurgeons, and radiologists is advised for more severely injured children in order to expedite transfer to tertiary medical care. Although surgical intervention is not always necessary, making predictions about future needs is not easy in the early stages of presentation.

In children who present with less severe symptoms, careful attention must be given to completing a full head-to-toe examination. The head circumference should be measured and the fontanel palpated. Neurological examination should include careful handling of the child, observation for visual following, response to pain, grasp, and suck. Attempts to view the fundi are often facilitated by the fact that the child’s level of consciousness may be suppressed. The child should be completely undressed to permit full skin examination. Any bruises to the head and face should be noted and considered highly suspicious in children younger than 6 months of age.[8] Gentle handling of the child and careful range of motion movements in all limbs may assist in detecting more subtle musculoskeletal injury. If abusive head trauma is suspected, consideration should also be given to the possibility of occult abdominal trauma.

Although the primary care physician might carry out the initial fundoscopic examination, further assessment should be conducted by an ophthalmologist familiar with the ocular complications that result from shaking. Retinal hemorrhages are present in up to 80% of patients with abusive head trauma.[10,11] These hemorrhages are usually extensive, bilateral, and extend out to the periphery of the retina (Figure 1). There may also be evidence of retinal detachment or retinoschisis, the latter considered pathognomonic for shaking injury.

Differential diagnosis

Following the initial assessment, the differential diagnosis for abusive head trauma will vary greatly depending on the severity of the clinical presentation. Children who require immediate intervention and stabilization may be thought to be suffering from meningitis/encephalitis, sepsis, acute life-threatening event (ALTE), accidental toxic ingestion, metabolic abnormality (i.e., glutaric aciduria type 1), or intracranial hemorrhage from a congenital arteriovascular malformation or other source.

Because up to 30% of young children with abusive head trauma may present with a history of minor head trauma, accidental head injury is one of the more common misdiagnoses.[8,12] In children with no history of trauma and more subtle signs and symptoms, the most frequent misdiagnoses are viral infection and gastroenteritis.[8]

Abusive head trauma must be included in the differential diagnosis for young children presenting with nonspecific complaints.

Investigations

The critically ill child is more likely to have the detailed complex of serological, biochemical, and radiological investigations that assist in the diagnosis of abusive head trauma. The child who is less severely ill at presentation may not immediately undergo all of the necessary investigative procedures; however, if after careful physical examination, abusive head trauma is included on the differential diagnosis, further workup is more likely to be initiated.

Computed tomography (CT) of the head is the mainstay of the diagnosis of abusive head trauma. Interpretation of these scans should be carried out by a radiologist familiar with pediatric imaging techniques. CT findings may include subdural hemorrhage (both acute and chronic), interhemispheric falx hemorrhage, diffuse axonal injury, and cerebral edema (Figure 2). Magnetic resonance imaging (MRI) may be helpful in interpreting equivocal CT findings or in differentiating between subarachnoid and subdural hemorrhage. Recent data indicate that MRI may also play an important role in the dating of intracranial hemorrhage.[13]

All children suspected of sustaining an injury caused by abusive shaking or impact should undergo a full skeletal survey. Radiology technicians should be versed in the appropriate technique for this study, and radiologists should be familiar with the interpretation of pediatric trauma indicating abuse. Fractures associated with abuse include rib, long bone, and skull fractures. More than 80% of abusive rib fractures are posterior rather than anterior or lateral.[14] While these injuries may not be apparent on initial chest radiographs, repeat studies performed 2 weeks postinjury may show the fractures more clearly. Long bone fractures are characterized by metaphysial chip fractures.[2] Skull fractures are often seen more clearly on plain films than on CT scans.

Serological investigation should include complete blood count and coagulation profile. Anemia or coagulopathy may arise from intracranial hemorrhage or parenchymal brain injury itself. If the possibility of associated occult abdominal trauma exists, consideration should be given to performing liver function tests and serum amylase.

Lumbar puncture may be included in the initial evaluation of a child thought to be septic or suffering from meningitis. A bloody tap must not be interpreted as physician error, as it may be the first clue to the possibility of intracranial hemorrhage.

Metabolic studies should include a quantitative analysis of organic acids in the urine to identify those patients with glutaric aciduria type 1. Children with this rare but life-threatening condition share many of the same neurological complications as children who have sustained shaking injuries.

Current research is focusing on establishing serological markers for head trauma in children. These may soon serve as screening tools to identify children who should undergo further diagnostic tests such as CT scan and ophthalmological examination.

Management

Initial management must focus on treating the devastating complications of abusive head trauma, which can include seizures, increased intracranial pressure, and cardiorespiratory arrest.

All potential victims of shaking/impact injury should be hospitalized in order to closely monitor their neurological status, to ensure a complete diagnostic workup is performed, and to allow for initiation of the investigative process by both police and social workers. In cases of abusive head trauma, hospital social workers and physicians need to work closely with the community services responsible for both the criminal and child protection investigations, as well as the occupational services that may be necessary upon the child’s discharge from hospital.

Reporting

By law, any suspicion of abusive trauma must be reported to the Ministry of Children and Family Development (MCFD). The safety of the patient and of any other child in the home must be determined.

A clear, concise medical report should be completed with the understanding that it will likely be subpoenaed for legal purposes at some time in the future. The report should detail the initial history provided to the physician and state clearly who provided the history. The full physical examination should be documented and the results of all investigations should be included. If the physician is relying on assistance from other specialists to interpret the investigative findings, direct communication with these specialists is strongly recommended. The report should clearly state whether the injuries the child has sustained are consistent with the history provided and whether abusive head trauma is suspected.

Outcome

The outcome for children sustaining abusive head trauma may range from no apparent effects to permanent disability, developmental delay, seizures, paralysis, blindness, and death.[12] A recent Canadian study that looked at 364 children diagnosed with shaken baby syndrome revealed that 19% died, 59% had neurological deficits or other health problems, and only 22% appeared well at discharge.[7] Other data indicate that some children may have a symptom-free interval of 12 to 18 months before manifesting signs of neurological or developmental abnormality.[16] These numbers likely do not accurately reflect the true outcome, as clearly there are a number of children who are misdiagnosed and possibly some who never receive medical attention. Caffey speculated that a significant number of older children with learning disabilities or neuropsychological problems may have sustained shaking injuries as young infants or toddlers.[2]

Many children will need long-term assistance from health care and social service personnel. Ongoing support may involve infant development specialists, speech and language therapists, occupational therapists, special education teachers, psychologists, neurologists, neurosurgeons, pediatricians, family doctors, respite caregivers, and adapted or residential housing programs. Although the burden placed on the health care system and society is significant, it is far less than the frequently devastating impact upon these children and their families.

Summary

Current areas of research into pediatric abusive head trauma include the biomechanics of shaking and impact-type injuries, the utility of diagnostic serological markers, the long-term consequences for survivors, and the development of effective prevention strategies. Health Canada recently published a statement on shaken baby syndrome, which many hope will serve as a framework for developing multidisciplinary guidelines.[17] In the meantime, health care providers must educate themselves about making an accurate diagnosis of abusive head trauma. Everyone involved must maintain a healthy index of suspicion, learn to recognize the more subtle signs and symptoms, seek adequate diagnostic services, and communicate clearly with other health care professionals and investigative personnel. The future safety of a child subjected to abusive head trauma may ultimately hinge on the vigilance and actions of our community health care providers.

Competing interests
None declared.

Margaret Colbourne, MD, FRCPC

Dr Colbourne is a clinical assistant professor in the UBC Department of Pediatrics, a pediatric emergency medicine physician at BC’s Children’s Hospital, Vancouver, BC, and a pediatrician with the Child and Family Clinic (Child Protection Service Unit) at BC’s Children’s Hospital.