Analysis of Missed Cases of Abusive Head Trauma FREE

Abusive head trauma (AHT) is a dangerous form of child abuse. More child abuse deaths occur from head injuries than any other type of injury.¹ Infants and toddlers who survive AHT often have serious neurologic sequelae.^2- 3

Head injury in infants and toddlers can be difficult to diagnose because symptoms are often nonspecific. Vomiting, fever, irritability, and lethargy are common symptoms of a variety of conditions seen in children, including head trauma. When caretakers do not give a history of injury and the victim is preverbal, an abusive head injury can be mistakenly diagnosed as a less-serious condition.

In March 1995, we evaluated a 14-month-old child who had sustained an abusive head injury 4 months previously. Shortly after his initial injury, he had been examined by his physician and his new-onset seizures were attributed to his history of prematurity. During the next 4 months, the child had 7 physician visits and 2 cranial imaging studies. At each visit, the diagnosis of AHT was not recognized. When we examined him 4 months later, he had multiple old and new fractures and healing brain injuries, including extensive brain atrophy and healing brain infarctions. This case encouraged us to review our experience with AHT cases to determine if the appropriate diagnosis had been previously missed. We also examined factors that may have contributed to the unrecognized diagnosis of AHT.

We studied cases of AHT in children younger than 3 years evaluated at the Children's Hospital, Denver, Colo, from January 1, 1990, through December 31, 1995. The Children's Hospital is an academic medical center affiliated with the University of Colorado School of Medicine. It is a referral center for Colorado, Wyoming, Montana, and western Nebraska.

The children in this study were evaluated by the hospital's Child Advocacy and Protection Team (CAP Team). The CAP Team is a multidisciplinary group that consults on cases of suspected child abuse and neglect. The team is led by pediatricians whose clinical focus is child abuse. Social workers, nurses, psychologists, child psychiatrists, and attorneys also participate. The team routinely interviews caretakers to document medical history and the history of the acute injury, review previous medical and social service records, review prior radiological studies, perform a careful physical examination, and order appropriate new diagnostic studies. In all cases, organic illnesses that mimic AHT are ruled out. Confirmation that head trauma was inflicted requires multidisciplinary team consensus.

Head trauma cases were identified from the log records of the CAP Team and charts were reviewed in depth. To ensure concurrence, study cases were reviewed by at least 2 of the authors (including C.J.) and radiological imaging studies were reviewed by a pediatric radiologist (T.C.H.). Permission for the anonymous chart review was granted by the hospital's human subjects committee. Information gathered included demographics, social and family data, details of the children's injuries, presenting complaints, clinical course, and details of previous medical visits related to head trauma, if applicable.

We limited the study to children with head injuries who were younger than 3 years for 2 reasons. First, children older than 3 years are not as likely to sustain severe injury when struck in the head or shaken. Second, children older than 3 years are more likely to be able to articulate their experiences. Hence, AHT is much less likely to be missed as the appropriate diagnosis.

Abusive head trauma was defined as inflicted cranial injury. Researchers debate whether shaking alone or shaking and impact cause the signs and symptoms commonly referred to as shaken baby syndrome.^4- 6 The mechanism of injury cannot always be accurately determined in child abuse cases. Because shaking, impact to the head, or both are all potentially harmful to infants and toddlers, we grouped all head injuries caused by abuse into the single category of AHT.

Factors considered by the multidisciplinary team in reaching the diagnosis of AHT (rather than nonintentional head injury) included (1) confession of intentional injury by an adult caretaker; (2) inconsistent or inadequate histories given by caretakers (the history given did not explain the nature and severity of the injuries); (3) associated unexplained injuries, such as fractures or intra-abdominal injuries; and (4) delay in seeking care.

Cases of AHT were defined as missed if review of medical records and radiological studies confirmed the following predefined criteria: (1) Prior to the diagnosis of AHT, a physician evaluated the child (on ≥1 occasions) for nonspecific clinical sign(s) compatible with head trauma (ie, recurrent vomiting, irritability, facial and/or scalp injury, altered mental status, abnormal respiratory status, and/or seizures). (2) The medical evaluation(s) for these nonspecific clinical sign(s) did not result in a diagnosis of AHT. (3) Thereafter, 1 or more of the following scenarios occurred: (a) The child improved clinically, later experienced (repeat) acute trauma confirmed as abusive, and underwent diagnostic imaging that revealed old cranial injuries and other new injuries. (b) The child remained symptomatic or experienced worsening clinical signs until head trauma was recognized, verified by cranial imaging studies, and confirmed as abusive. (c) The person who injured the child later admitted to abusing the child shortly before the onset of the child's nonspecific clinical sign(s). In all cases, the estimated age of the cranial injuries documented by imaging studies was consistent with the prior time of onset of the child's nonspecific clinical sign(s).

All remaining cases of AHT evaluated during the study period were considered recognized. Children who sustained any new inflicted injuries during the period of diagnostic delay were classified as reinjured. Study patients whose medical records after their inflicted head trauma revealed abnormal head growth, recurrent seizures, psychomotor delays, chronic anemia, vomiting, weight loss, and/or sensory deficits were classified as having medical complications of AHT.

We examined data to determine what factors were associated with a missed vs recognized diagnosis. We used χ² testing to assess the independence of 10 variables on the outcome variable of a correct diagnosis of head trauma. Variables resulting in χ²P≤.25 or less were entered into an initial multivariate logistic regression model. We then used Wald and likelihood ratio testing to iteratively remove noncontributory variables from the model.⁷ Analysis was performed using Stata software, Version 5.0 (Stata Corp, College Station, Tex).

A total of 232 children with suspected head injuries were evaluated by the CAP Team from January 1990 through December 1995. Fifty-nine children did not meet study criteria. Of these, 8 were eliminated because they were aged 3 years or older. It was determined that 38 were not abused. The medical records of 13 children could not be located. The remaining study sample included 173 abused children with head injuries.

The mean age of the 173 children was 247 days (range, 10 days to 2.9 years). Ninety-five (55%) of the children were male and 78 (45%) were female. The boys' ages at the time they were first seen for symptoms of AHT were not significantly different than the girls' ages. In our study sample, minorities were overrepresented (33.5% minority) compared with the racial distribution of the Denver metropolitan area (19.7% minority).⁸

The types of injuries noted in the children are shown in Table 1. Many of the children sustained more than 1 type of injury. Eighty-nine children (51.4%) were covered by Medicaid-funded insurance programs. Twenty-seven children (15.6%) were uninsured. The remainder had private health insurance.

In the 173 children with AHT, 54 cases (31.2%) were classified as missed. For children with missed AHT, the mean number of physician visits before the trauma was recognized was 2.8 (range, 2-9 visits).

For children in whom the diagnosis of AHT was missed, the mean length of time to diagnosis of head trauma from the day of the first visit was 7 days (range, 0-189 days). In 5 cases, the children were seen twice in the same day and the diagnosis was made on the second visit; hence, the designation of 0 days until diagnosis in some cases of missed AHT.

When missed cases were compared with recognized cases, several factors were found to be significantly different.

Children with missed AHT were much younger than those in whom the diagnosis was recognized on the first physician visit. The mean age of missed AHT cases at the time of their first medical visit for head injury symptoms was 180 days (95% confidence interval [CI], 125-236). The mean age of the recognized cases was 278 days (95% CI, 228-328). The mean ages of children with missed and recognized AHT were significantly different (independent samples t test, P = .02).

Abusive head trauma was missed significantly more often in white children than children of minority races. In white children, 43 (37.4%) of 115 cases of AHT were missed and in minority children, 11 (19%) of 58 were missed (Pearson χ², P = .01).

Abusive head trauma was more likely to be missed in families in which both parents lived with the child. Thirty-seven (40.2%) of 92 cases were missed in intact families. In families in which the mother and father of the child were not living together, 14 (18.7%) of 75 cases were missed (Pearson χ², P = .003).

Not surprisingly, the more severely symptomatic children were more likely to be recognized as having head trauma at first visit to the physician. Table 2 summarizes the number and percentage of children who were missed and recognized as having AHT compared with their symptoms and signs. At the first visit, children who were comatose, whose breathing was compromised, who were having seizures, or who had facial bruising were more likely to be accurately diagnosed. Conversely, children who presented with irritability or vomiting at the first visit were less likely to be identified as having AHT.

Several factors were found not to differ between children with missed vs recognized AHT. These included whether the parents were employed, whether the parents had private insurance coverage, the sex of the child, the birth weight of the child, and whether the child had been born prematurely (<37 weeks' gestation).

Nine variables were found to be significantly associated with missing the diagnosis of AHT by univariate analysis. These were transformed to dichotomous variables and entered into a logistic regression model. They included age younger than 6 months, minority race, parents not living together, and 6 signs and symptoms noted at the first visit, including facial injury, seizures, decreased mental status, abnormal respiratory status, vomiting, and irritability. Of these 9 variables, 4 were retained in the multivariate logistic model. These 4 independent variables predicting the correct diagnosis of AHT at the first visit included (1) abnormal respiratory status (odds ratio [OR], 7.23; 95% CI, 2.4-21.3; P<.001); (2) seizures present (OR, 6.67; 95% CI, 2.5-17.3; P<.001); (3) facial and/or scalp injury present (OR, 4.81; 95% CI, 2.1-11.0; P<.001); and (4) parents not living together (OR, 2.49; 95% CI, 1.1-5.7; P = .03).

Applying the logistic regression model constructed from the data, we found that if none of these 4 factors were present, the probability that a physician would make the correct diagnosis of AHT was P = .20. That is, if a child had normal respirations, had no seizures, had no facial or scalp injury, and came from an intact family, the probability that AHT would be recognized was less than 1 in 5.

The 54 children with missed AHT received 98 diagnoses other than AHT during their 98 patient visits. Table 3 lists the diagnoses applied to the children with missed AHT. The most common diagnoses made were for viral gastroenteritis and accidental head injury. In some cases, the diagnoses were correct, even though coexistent head trauma was not recognized. For example, in 1 case an infant was accurately assessed to have a retropharyngeal abscess, but the accompanying subdural hematoma, retinal hemorrhages, and skull fracture were not recognized. In other cases, the symptoms of head trauma were attributed to conditions other than AHT. In 10 cases, the wrong diagnosis was applied more than once to the same child. We did not count these repeated diagnoses on our frequency table.

Twenty-five (14.5%) of the 173 children died as a result of their head injuries. Of the recognized AHT cases, 20 (16.8%) of 119 children died. In the missed AHT cases, 5 (9.3%) of 54 children died. The percentage of children in the missed AHT group who died was not statistically different than in the recognized AHT group (χ² = 1.712; P = .19). In our estimation, 4 of the 5 deaths in the missed AHT group might have been prevented by earlier recognition of abuse (Table 4).

Of the missed AHT cases, 15 (27.8%) of the 54 children were known to have been reinjured because of the delay in diagnosis. Twenty-two children (40.7%) had medical complications related to the delay in diagnosis. These conditions included seizure disorders, chronic vomiting, and increasing head size because of increasing untreated subdural hematomas.

In 7 of the children whose diagnosis of AHT was missed, radiological errors contributed to the delay. These 7 children had 8 studies in which trauma was missed, including 6 computed tomography scans of the head, 1 skeletal survey, and 1 long-bone radiograph of the arm. The 2 longest delays in diagnosis (141 days and 174 days) and 6 of 25 cases in which the diagnosis of AHT was missed for longer than 7 days involved radiological misreadings. Table 5 summarizes the nature of the errors made and the time in delay of diagnosis attributed to the radiological misreading.

It is difficult to study the cases of child abuse that clinicians do not recognize. In 1972, Jackson⁹ reviewed traumatic injuries in children at King's College Hospital in London, England, and found 18 of 100 cases to have been missed cases of child abuse. O'Neill et al¹⁰ reported a series of 110 battered children in 1973. Eighty percent of those children had signs of prior injury. Alexander et al¹¹ found physical evidence of previous head trauma in 8 of 24 children evaluated for head injury due to shaking. Ewing-Cobbs et al¹² discovered signs of preexisting brain injury in 45% of children with inflicted traumatic brain injury compared with none in children with accidental traumatic brain injury.

Incidental cases of missed child abuse have been published.¹³ In their study of abusive head injuries, Benzel and Hadden mention that 9 of 23 abused children with head injuries ". . . were known to have been seen by other physicians because of similar problems or other injuries consistent with child abuse."¹⁴ Since then, an increased awareness of child abuse has occurred, but similar studies have not been reported.

We do not know how many cases of AHT are never detected. Surely, the injuries occurring from impact or shaking represent a range of severity, from no injuries to mild concussion or small subdural hemorrhage, severe brain damage, extensive intracranial bleeding, and cerebral edema. Caffey¹⁵ speculated in 1972 that many children who are found to have mild neurologic abnormalities and learning disabilities may have been victims of AHT.

Parents who confess to shaking or hitting the heads of their children frequently report doing the same thing previously. In 1 study case, an infant was hospitalized 3 times before someone witnessed the child being shaken violently. On 1 occasion, he was evaluated and treated for possible sepsis. The other 2 hospitalizations were for apnea and reflux, respectively. The child's father admitted to multiple episodes of shaking that led to the infant's various illnesses.

In the current study, we found that 31.2% of children who were clinically symptomatic after AHT were misdiagnosed as having other conditions. Infants have few ways to demonstrate illness or injury. Nonspecific signs, such as vomiting, fever, and irritability, are seen in a myriad of conditions, including many benign, self-limited illnesses. The difficulty, then, is to be able to discern when these signs and symptoms indicate potentially serious or fatal pathology.

The possibility exists that in some of the visits we classified as missed, the child had not yet been injured. However, in another study by our group, we found that patients became symptomatic immediately after their injuries in 37 cases in which perpetrators admitted to causing head injuries in infants.¹⁶ To guard against misclassification, we examined the medical records extremely carefully to correlate clinical and radiological findings.

Not surprisingly, the infants and toddlers in our study whose head injuries were misdiagnosed were overall less ill than those whose head injuries were recognized. The fact that they were not as ill made the diagnosis of AHT difficult. Also, the children whose AHT was missed were, as a group, younger. The difficulty of diagnosing serious illness or injury in young infants is complicated by the limited range of their normal behavior. With less-sophisticated behavioral and neurologic signs to assess, the changes in young infants with head injuries are more difficult to detect.

Striking differences were seen in the race and family composition of infants with missed and recognized injuries. Infants with recognized AHT were more likely to be minority children or children whose mothers and fathers were not living together. We speculate that this may represent a subtle bias in decision making based on the physician's assessment of risk. A physician examining a white child from an intact family may be less likely to think about the possibility of child abuse. Another hypothesis is that perhaps minority and single-parent families were more likely to obtain care from public clinics or hospital emergency departments, where physicians may be more attuned to abuse issues. In the current study, the children of intact, 2-parent households were much more likely to have private insurance (Pearson χ², 23.953; P<.001). In addition, white families were much more likely to have private insurance than minority families (Pearson χ², 5.148; P = .02). However, we did not collect data on the practice setting in which missed and recognized diagnoses were made.

Are missed cases of AHT inevitable? If a child's caretakers cannot or will not give an accurate history, making the correct diagnosis is extremely difficult. Physicians cannot obtain cranial computed tomographic scans for every infant and toddler who presents with vomiting, irritability, and fever. Based on this study and on our experience with these cases, we make the following suggestions to facilitate the diagnosis of AHT.

In addition to these suggestions, other as yet unvalidated strategies to detect occult abuse could be considered. Dilated retinal examinations in infants and children with nonspecific symptoms of illness could increase the recognition of retinal hemorrhages. Retinal hemorrhages have been reported in the majority of children who are victims of AHT.²¹ Other possibilities need further research. Some markers of brain trauma are known to cross the blood-brain barrier, such as the BB fraction of creatine kinase. If rapid tests were available for such markers, a simple blood test possibly could be done to detect occult trauma. In a recent study by Hymel and colleagues,²² children with traumatic parenchymal brain injury were frequently noted to have prolonged prothrombin and partial thromboplastin times. These tests are generally available and inexpensive to run. Their sensitivity and specificity as screening tests for head trauma in infants are not known.

There are other ways for AHT to present clinically that we did not see in this group of patients. The list of signs and symptoms we examined is not universally inclusive. Another limitation of our method is that the study was done retrospectively through record review. However, this seems to be the only option we currently have for examining diagnostic errors. Finally, information concerning the training, experience, or practice setting of the physicians evaluating these patients was not obtained.

Although it is difficult to detect all serious AHT in the clinical setting, an awareness of the nonspecific nature of the signs and symptoms of AHT, particularly in less-serious cases, could increase the likelihood that more cases will be detected.