Traumatic brain injury (TBI) is a leading cause of death and disability among children and young adults.1,2 Unintentional injuries (ie, car accidents and falls) are the leading cause of death for children 1 to 14 years of age.3 Among such injuries, TBI is a leading cause of injury-related morbidity and mortality.4 Furthermore, despite modern automobile design and injury prevention campaigns, important causes of TBI have increased in recent years.5 In addition to unintentional injuries, child abuse remains a significant problem and constitutes the leading cause of serious head injury in infants.6 With nearly half a million children affected each year, TBI is a serious public health problem.7

Traditionally, TBI severity has been defined using the Glasgow Coma Scale (GCS). The GCS, shown in Table 19-1, was developed in order to standardize the neurological assessment of adult patients with traumatic brain injury.8 It was specifically designed to be easily performed based upon clinical data and to have a low rate of inter-observer variability. Despite its limitations when applied to children,9,10 the GCS is widely used for the initial assessment and for monitoring progress of pediatric TBI. A pediatric version of the GCS also seems to be a reliable tool for predicting the need for acute intervention in preverbal children with TBI.11

The GCS score is determined by adding the values for eye opening, verbal response, and motor response. Possible values range from 3 to 15. Note that this scale rates the best response only. In patients who are intubated, in whom assessment of best verbal response cannot be performed, notation of this is made in the GCS score by adding a “T” to the end of the score. In patients who are intubated, the best possible score would therefore be 11T. For patients 4 years old or younger, the Pediatric Glasgow Coma Scale is recommended (Table 19-2).

Certain numerical values of the Glasgow Coma Scale have been used to define the severity of TBI:

Both severe and mild to moderate TBI represent significant neurological diseases for children. Although mild to moderate traumatic brain injury very infrequently will result in severe disability or death, outcomes are variable and long-term sequelae have been reported.

Although our understanding of the mechanisms of damage to the immature brain after TBI remains quite limited, it is becoming clear that mechanisms of cellular injury and death in the immature brain are different from those described to date in the mature brain. Just as comprehensive evaluations of outcome describe functional differences, modern biomechanical and biochemical techniques have demonstrated that cellular and molecular responses to injury differ in the immature brain. That such differences exist seems intuitive given critical periods of vulnerability for the developing nervous system. As an example, better characterization of cerebral blood flow before and after injury is needed to enable appropriate strategies that will optimize oxygen delivery to the brain in children.

Pathologic changes that occur following trauma may be considered to occur in two stages. Damage that occurs at the time of the injury is referred to as the primary injury. This includes damage to axons, neurons, and cerebral blood vessels that occurs as a result of the force of the injury—that is, shear and strain forces that result in tearing of delicate cerebral structures. This injury may result in diffuse axonal injury, intracerebral/ subdural/epidural hematomas (from disruption of cerebral or dural blood vessels), or cortical contusions. Injury to the brain that occurs at any time after the initial impact of the traumatic event is termed the secondary injury. Events that may result in secondary injury to the brain and that have been shown to adversely affect outcome include hypoxia, hypotension, and hyperthermia. These types of injuries are preventable by caregivers, and their prevention may result in significant improvements in outcome. Figure 19-1 illustrates the concept of primary and secondary injury. Secondary injury may irreversibly damage brain tissue that was weakened by, but survived, the primary injury.

Mild and Moderate Traumatic Brain Injury

Mild head injury is a term first described by Rimel and associates and was taken to mean GCS 13 to 15 in a 1981 article.12 Although minor, head injuries not associated with a loss of consciousness constitute one of the most common public health problems. A certain number of children with minor head injuries (GCS 14-15) who have also lost consciousness are found to have significant intracranial pathology requiring neurosurgical procedures. With that in mind, a number of authors have attempted to redefine mild TBI since that original article. Because of the immense magnitude of the problem, numerous organizations, including the American Academy of Pediatrics, the American Academy of Family Physicians, and the American Academy of Neurology, have come up with practice parameters that address different aspects of mild pediatric head injury.13,14

Concussion is an entity that is commonly seen in pediatric patients with mild to moderate head injury. It is defined as a trauma-induced alteration in mental status that may or may not involve loss of consciousness.14 Patients with a concussion experience an immediate loss of consciousness, suppression of reflexes, transient cessation of breathing, and amnesia. The reflexes return and the patient begins to reconnect with the surrounding environment. The time to recovery is variable and may take several hours to days. The duration of the amnestic period, particularly anterograde amnesia, is probably the most reliable indicator of the presence of pathologic lesions. Postconcussive emesis in children is another worrisome problem in the acute setting. It can affect nearly one-half of patients and usually resolves within a few hours. Postconcussive emesis has not been associated with an increasing frequency of intracranial lesions.15 Concussions also occur without a defined loss of consciousness. Sports-related concussions are another common entity that primary care physicians, pediatric neurologists, and pediatric neurosurgeons have to deal with every day. Most children will recover from a sports-related concussion though recovery may take time, up to several months after the injury. The symptoms following a concussion are divided into three categories. Somatic complaints include headaches, fatigue, sleep disturbance, balance problems, and sensitivity to light and noise. Emotional and behavioral problems can manifest as irritability, lowered frustration tolerance, increased emotionality, depression, anxiety, and other personality changes. The last, and some feel the most important, category, especially in the school-age child is cognitive problems. Children may have slowed thinking, poor concentration, distractibility, trouble with learning and memory, and other problem-solving difficulties.

Severe Traumatic Brain Injury

Severe TBI in children carries a mortality of 8% to 22%.16,17 Approximately seven children between the ages of 0 to 14 years die every day, and many more suffer permanent disabilities as a result of TBI.4

Severe TBI is defined as a GCS score of 8 or less. By definition, children with severe TBI present with significant abnormalities in their neurological exam including coma, abnormal breathing (including at times apnea), focal neurological deficits, seizures, and even signs of herniation. Evolving brain edema or intracranial bleeding can result in acute deterioration of the child’s neurological exam. Consideration should always be given to extracranial injuries, since such injuries can result in secondary injury to the brain.

Mild and Moderate Traumatic Brain Injury

In the pediatric head injury population, the most common clinical situation will be the child who rapidly regains consciousness after an injury. By the time the child is examined, the child will commonly have a GCS score of 13 to 15 or a mild head injury. The child also has a defined risk for having an intracranial injury. The Glasgow Coma Scale has long been considered a reliable indicator of severity of injury.

A number of tools have been developed to aid in the assessment of concussion. One of the most commonly used tools is the Standard Assessment of Concussion. It has been extensively validated and has significant normative data. The concussion symptom index has also been used, especially in athletes with normative data in high school as well as college athletes.18 Additionally, neuropsychological testing is one of the most important tools for detecting deficits in pediatric TBI, especially in patients with mild TBI. In sports-related concussion, the baseline use of neuropsychological testing has been used to determine return-to-play parameters in the absence of postconcussive symptoms.

Skull radiographs have a limited role in the diagnosis of intracranial injury following either mild or moderate pediatric head injury. Given the low predictive value of skull radiographs, the American Academy of Pediatrics recommends that cranial computed tomography (CT) scanning is the desirable imaging modality.13 Over 5 million children present to emergency rooms across the country with this diagnosis, and CT scanning of each of these patients, while considered the gold standard, would overwhelm the facilities and expose countless children to pointless radiation. Because of the higher degree of intracranial injury associated with a GCS score of less than 15, the authors recommend that any patient with a GCS less than 15 undergo a head CT. Another potential high-risk category is the patient who presents with a focal neurological deficit. The frequency of an intracranial injury in this population has been reported to be 11%.19

While the utility of computed tomography after minor head injury has been extensively studied, and different clinical criteria for predicting intracranial injury have been identified (Table 19-3), CT scanning can be associated with increased risk for long-term cancer, the need for sedation to accomplish the scan, and a prolonged ED evaluation, and this in turn has lead to multiple studies attempting to identify clinical predictors of intracranial injury. Boran and associates studied 421 patients with a GCS of 15 and were able to determine injuries found by either CT or plain radiographs. Intracranial lesions were found in 8.8% of the patients. They were able to determine that the only clinical parameters associated with an increase in intracranial lesion were posttraumatic seizures and loss of consciousness.15 In NEXUS (National Emergency X-Radiography Utilization Study), a large study looking at 1666 pediatric blunt trauma patients, CT was found to detect significant intracranial injury in 138, or 8.3%, of the patients. These authors also attempted to utilize a modification of the University of California-Davis Pediatric Head Injury Rule to identify patients with an intracranial injury. The sensitivity of their tool was found to be only 90.4%, with 13 children being misclassified as low risk.

Posttraumatic sequelae, especially in those patients with mild head injury, are significant, with upward of 15% of patients experiencing disabling symptoms up to 1 year after injury. Many of these patients do not have abnormalities on CT imaging. Limitations of CT scanning in detecting injury has lead to the use of magnetic resonance imaging (MRI) to detect diffuse axonal injury (DAI) and deliver prognostic information in cases of mild to moderate TBI. DAI is a type of injury characterized by significant axonal damage or shearing in brain regions such as the corpus collosum, parasagittal white matter, and gray-white matter junctions. Diffusion tensor imaging measures the microscopic random translational motion of water molecules within tissue. Wilde and others studied children with DTI and uninjured controls, and their data suggested that DTI may serve as an indicator for predicting outcome in pediatric patients with TBI.25 Magnetic resonance spectroscopy (MRS) is another imaging modality that is currently being used at some centers in the evaluation of patients with TBI. MRS has been shown to detect biochemical alterations, yet its value in providing truly valuable prognostic information in patients with mild to moderate TBI remains to be determined.

Severe Traumatic Brain Injury

Motor vehicle accidents and falls constitute the most common causes of severe TBI. In infants, the most common cause of severe TBI is child abuse, and a higher index of suspicion for intracranial injury may be required owing to an inconsistent clinical history.

The diagnosis of severe TBI is usually made based on the history and initial clinical findings. Once the diagnosis is made, children with severe TBI require close and continuous neurological monitoring, as their condition may rapidly deteriorate. In addition to abnormal neurological findings, including a GCS score of 8 or less, children with severe TBI can have signs of skull fractures, such as raccoon eyes, retro-orbital hematomas, and palpable abnormalities of the skull. The initial clinical diagnosis is usually confirmed by a CT scan in the acute phase, although children with severe brain injury can present with an initially normal brain CT. The initial scan is important because it may identify injuries that are amenable to surgical treatment, such as intracranial hematomas. Patients with a history of severe TBI and an abnormal CT scan are at increased risk of developing increased intracranial pressure.

While CT continues to be the primary diagnostic imaging modality in severe TBI, advanced MRI techniques, including diffusion tensor imaging and MR spectroscopy, are promising techniques with increased sensitivity, better prognostic capabilities, and also insights into the pathophysiology of brain injury after trauma.

Shaken Baby Syndrome

Shaken baby syndrome (SBS) is an important category of TBI in children, and children victims of SBS can present with signs and symptoms of severe TBI. In fact, SBS is the most common cause of traumatic brain injury in infants. As an entity, SBS provokes significant medical legal issues and requires careful attention to the etiology of the injury. Patients with SBS are difficult to evaluate because they often present with symptoms only, and if trauma is reported, it is usually minor. A patient’s clinical presentation can vary significantly depending on the severity of the injury. Symptoms can range from mild lethargy and seizures to coma and even death.

Computed tomography is usually the initial diagnostic study. CT findings include subdural as well as subarachnoid hemorrhage. These are often thin, exerting no mass effect, but cover the entire hemisphere. In cases where the injury is severe, patients can present with diffuse loss of gray-white differentiation on CT scan, reflecting widespread cortical loss.26 Once the child has been stabilized and is not felt to be in a life-threatening situation, most major children’s hospitals have a child protection service responsible for the complete medical workup of this patient. Workup includes a skeletal survey to assess for the presence of new or old fractures. Ophthalmology also must assess the child for the presence of retinal hemorrhages. Disorders such as coagulopathies and metabolic disorders need to be ruled out.