Although most pediatric patients with mild head injuries can be safely discharged after some period of observation, a minority of patients will have an underlying TBI requiring neurosurgical intervention [14]. Intracranial injuries that may be amenable to surgical intervention include, but are not limited to, epidural hematomas, subdural hematomas, intraparenchymal hemorrhage, and intraventricular hemorrhage (Fig. 26.2). These lesions may result in increased intracranial pressure, mass effect, brain herniation, and ultimately death.

The use of computed tomography (CT) is integral in the early detection and diagnosis of TBIs requiring surgical management [14]. Cranial CT is currently the reference standard investigative procedure for intracranial injury. It provides rapid identification and guides management. Early diagnostic imaging has been linked to improved outcomes and reduced admission rates [12, 13, 16].

Over the past decade, the use of CT for minor head injury has become increasingly common [14]. About 50 % of children assessed in North American emergency departments for head trauma undergo CT [11].

An important question should be addressed : Due to the high-risk nature of the injury and potential for serious and life-threatening sequelae, why not image every pediatric patient with a mild head injury? The answer is twofold: The increased use of CT scans adds substantially to rising healthcare costs, and more importantly, scanning every child with a mild head injury would expose a large number of children each year to the potentially harmful effects of ionizing radiation [2–4, 13, 14]. See Chap. 20 (L. Heier) for a full review of this important topic. The estimated rate of lethal malignancies from CT is between 1 in 1000 and 1 in 5000 pediatric cranial CT scans, with risk increasing as age decreases [2, 4, 11]. The responsibility, therefore, falls on pediatricians providing primary care for the mild head injury pediatric patient to make a sound clinical decision regarding the need for further imaging. Fast, limited sequence MRI protocols for head injuries and hydrocephalus are gradually being introduced and utilized and pediatric hospitals, but routine use across the country remains more of an ideal than a reality. The vast majority of emergency departments are not equipped with 24-h MRI availability, pediatric anesthesiologists, and the expertise to institute these protocols. CT is faster and cheaper, rarely requires sedation, and is ubiquitous.

Clinical decision rules (CDRs) are algorithms, based on peer-reviewed studies, that help clinicians make well-informed, evidence-based medical decisions. They use elements of patient history, physical examination, or simple tests to provide the clinician with a decision-making tool. In an attempt to optimize the balance between identifying significant intracranial injury and minimize the risks associated with cranial CTs, several CDRs for mild pediatric head injuries have been derived [8, 11, 14]. There are three large, well-recognized, CDR studies regarding the use of CT scans in the pediatric patient with mild head injury. They include the PECARN [11], CHALICE [8], and CATCH [14] studies. All are well written and regarded highly and provide a decision-making tool regarding CT imaging in the pediatric patient with minor head injury.

We will review the results and CDRs from the Pediatric Emergency Care Applied Research Network (PECARN) study to provide an infrastructure upon which primary care providers may make their own evidence-based decisions and to gain a more complete understanding of CT decision-making rules in the pediatric patient presenting with mild head injury. Compared to the CATCH and CHALICE studies, PECARN had the largest number of enrolled patients and has been prospectively validated.

PECARN is a large-scale, prospective study whose aim was to identify children at very low risk of clinically important traumatic brain injuries (ciTBI ) for whom CT might be unnecessary. A clinically important traumatic brain injury was defined as a TBI that resulted in a hospital admission of more than one night, intubation for more than 24 h, neurosurgical intervention, or death. The authors enrolled patients younger than 18 years presenting within 24 h of head trauma with Glasgow Coma Scale scores of 14–15 in 25 North American emergency departments. Age-specific prediction rules for ciTBI were then derived.

Below, we present the recommendations from the PECARN study in order to help educate and guide the pediatrician appropriately. It is important to remember, however, that although this algorithm was developed in order to help guide the clinician, there is no replacement for sound clinical judgment and clinical experience. As such, the pediatrician should take the following recommendations in context.

A CT scan is recommended if the child has a GCS of less than 15 (i.e., anything less than a perfect GCS score ) or has any other signs of altered mental status, including agitation, somnolence, repetitive questioning, or slow response to verbal communication. Additionally, if the child has a palpable skull fracture, it is recommended to obtain a head CT. In the PECARN study , this group included 13.9 % of enrolled children under the age of two presenting with a mild head injury. Within that population, there was a 4.4 % risk that those children would have a “clinically important” traumatic brain injury (TBI) as defined above.

If the patient (younger than 2 years of age) has none of the aforementioned signs or symptoms, the clinician must then consider the following questions: Does the patient have an occipital, parietal, or temporal scalp hematoma? Notably, there was no significant increased risk of clinically important TBI , according to the PECARN study. Did the child lose consciousness for more than 5 s? Was there a severe mechanism of injury? The PECARN study included severe mechanisms of injury as motor vehicle crash with patient ejection, death of another passenger, or rollover; pedestrian or bicyclist without helmet struck by a motorized vehicle; falls of more than 3 ft (more than 5 ft in children 2 years and older); or head struck by a high-impact object. Finally, an important question that should be directed toward the parent is as follows: Is the child acting abnormally? If the answer to all of the above questions is “no,” then it is suggested to not proceed with a CT scan. In the PECARN study, a CT scan was not recommended in the majority (53.2 %) of enrolled children under the age of two that presented with a mild head injury. Within this group of children, the associated risk of ciTBI was less than 0.02 %. If “yes” was answered to any of the above questions, then the child falls into a third category.

The third category is described as “observation versus CT on the basis of other clinical factors.” In the PECARN study , 32.9 % of the enrolled participants fell within the third category. The risk of a ciTBI (0.9 %) is still low in this group of patients. In this group, the physician may make a clinical decision as to whether or not the patient should be taken for a CT based on their experience. Additionally, the parents may have a preference after weighing the pros and cons of a CT scan, as explained by the pediatrician. Although it is widely accepted that effects of harmful ionizing radiation increase with decreasing age of the patient, a CT scan should be more strongly considered in patients under 3 months of age. Notably, in patients with certain isolated findings (i.e., with no other findings suggestive of traumatic brain injury), such as isolated loss of consciousness, isolated headache, isolated vomiting, and certain types of isolated scalp hematomas in infants older than 3 months, a head CT may not be warranted. These patients have a risk of ciTBI substantially lower than 1 %. Of course, worsening signs or symptoms should prompt the clinician to obtain a head CT.