1	Nonaccidental Pediatric Head Trauma: A Neuroimaging Pictorial Review and the Pitfalls. Jessica Ozsvath, M.D. Vinh Nguyen, M.D. Debra Esernio-Jenssen, M.D.
2	OBJECTIVES Review the epidemiology, risk factors and morbidity/mortality of nonaccidental pediatric head trauma. Discuss the role of neuroimaging in child abuse. Discuss pathophysiology of inflicted head injuries and how they relate to imaging findings. Review sample cases on CT and MR, reiterating the most reliable signs of child abuse. Demonstrate and discuss various pitfalls, mimics and controversies of nonaccidental head trauma.
3	EPIDEMIOLOGY Primarily pertains to children under 3 years of age and occurs in approximately 12% of all physically abused children. (11, 17) Most cases of inflicted traumatic brain injury occur within the 1^st year of life, accounting for approximately 64% of all head trauma and 95% of severe cases. (3, 9, 13) According to a population-based study conducted in the U.S. in 2003, the incidence of inflicted traumatic brain injury among children younger than two years was 17 per 100,000 person-years and the incidence was greater in the first than in the second year of life (30 versus 4 per 100,000 person-years). (9) There is a higher incidence amongst boys then girls (21 versus 13 per 100,000 person-years). (3, 9)
4	RISK FACTORS In General: Low education level and socioeconomic status, Young a/o single parents Domestic violence Drug/alcohol abuse, Added parental stressors parental depression natural disasters. (10) Factors specifically associated with inflicted head injury: Disability a/o prematurity of the child Family disruption and Incessant crying or the so-called “colicky” baby. Perpetrators are often male and usually the father of the child. According to one retrospective study, the person responsible, in decreasing order of frequency, was as follows: father (50%), stepfather or any male partner of the mother (20%), female babysitter (17%) and mother (12%). (14,15)
5	MORBIDITY AND MORTALITY Nonaccidental head trauma is the LEADING cause of morbidity and mortality in the abused child. Estimated mortality rates for infants with inflicted brain injury range from 15 to 38%. (11,16,17) In a well known clinical series by Bruce and Zimmerman, it was found that 80% of deaths from head trauma in children <2 years old were secondary to inflicted injuries. (4) For most who do survive their futures entail a life of neurological impairment, suffering from entities including mental retardation, speech and hearing impairments, blindness, learning disabilities, behavioral problems and, at worse, institutionalized in a persistent vegetative state.
6	ROLE OF NEUROIMAGING Essential component and often crucial to the clinical diagnosis of nonaccidental head trauma. Can give extent and timing of injuries, thus, providing documentation for prosecution when surgical and pathological evidence are often unavailable or incomplete. Noncontrast CT is the primary imaging modality à quick, readily available and accurate in detecting acute intra/extra-axial hemorrhages. MRI is employed to further characterize CT findings à better picture of the timing, extent and pattern of injuries. More superior at detecting shear injuries, such as diffuse axonal injury, and hypoxic-ischemic insults. (1) May play a role in the evaluation of children at high risk for abuse, but have normal neurological exams and no evidence of external trauma. In a retrospective series involving children with suspected abuse (posterior rib fractures, facial injury, or age < 6months), screening neuroimaging detected occult injury in 37%. (2)
7	TYPES OF INFLICTED BRAIN INJURY Two main forms of injury: Primary (contact vs. noncontact) and Secondary (6) Primary injuries from “Direct” trauma to the head, brain and surrounding vasculature. Findings include: Extra-axial hemorrhages (subdural, epidural and subarchanoid) Intra-axial hemorrhages (parenchymal contusions and intra-ventricular hemorrhages) Diffuse axonal injury Skull fractures. Secondary injuries occur as a consequence of a primary insult. Findings include: Cerebral edema, herniation, hydrocephalus, infarction, CSF leak, leptomeningeal cyst and encephalomalacia.
8	MECHANISM AND IMAGING OF PRIMARY INFLICTED CONTACT INJURIES Contact injuries are generally straightforward and more often associated with accidental trauma. Generally cause damage at the site of impact (scalp laceration, skull fracture w/or w/o underlying hemorrhage). Type of contact injury linked with inflicted, more so than accidental, injury is the subgaleal hematoma (bleeding in the potential space between the skull periosteum and scalp). Often associated with hair pulling or “smooshing” of head against a hard surface. (11)
9	MECHANISM AND IMAGING OF PRIMARY INFLICTED CONTACT INJURIES Skull fractures: relatively common in both inflicted and accidental trauma. -features associated with abuse include: -multiple fracture sites -fractures that extend into sutures -suture diastases (>3mm) a/o - bilateral fractures. (12)
10	MECHANISM AND IMAGING OF PRIMARY INFLICTED NONCONTACT INJURIES In 1974 Caffey coined the term “whiplash shaken-baby syndrome” to describe a constellation of findings related to primary brain injury (subdural hemorrhages/axonal injury and retinal hemorrhages) in infants who suffered from linear and angular (rotational) acceleration/deceleration trauma, such as being violently shaken. (5) Evidence suggest that infant brains are more susceptible to injury secondary to rotational deceleration for several particular reasons including: The base of the infant skull is relatively flat, permitting the brain to move more readily in response to acceleration-deceleration forces. A relatively large and unstable head, in conjunction with weak neck musculature, permit greater movement when the head is acted upon by acceleration-deceleration force. Brains of infants and young children have higher water content due to lack of myelination and larger subarachnoid spaces making the developing brain more susceptible to injury from movement. (6) However, the minimal amount of force required to produce the pattern typically linked to inflicted injury remains unknown, with apparent ethical considerations preventing further investigation. General agreement is that normal handling and minor trauma do not cause this pattern of serious injury.
11	MECHANISM AND IMAGING OF PRIMARY INFLICTED NONCONTACT INJURIES Probably the most specific sign and characteristic injury of nonaccidental trauma is the interhemispheric subdural hemorrhage which layers along the tentorium cerebelli. (2,7, 11)
12	MECHANISM AND IMAGING OF PRIMARY INFLICTED NONCONTACT INJURIES Subdural hemorrhages of mixed densities (different ages) are a common and more characteristic finding of inflicted, rather than accidental injury. In one retrospective series, heterogeneous subdural hematomas were noted in 67 percent of children with inflicted head injuries, as compared with 18 percent in those whose injuries were accidental. (1,2,6,7,11,16)
13	MECHANISM AND IMAGING OF PRIMARY INFLICTED NONCONTACT INJURIES Parenchymal shearing tears (diffuse axonal injury) à well known outcome of inflicted injury most prominent at gray-white matter (corticomedullary ) junctions and large white matter tracks. MRI, particularly gradient-echo sequences, are superior in demonstrating the paramagnetic effects of petechial hemorrhages at these sites. (1,2,7,11)
14	MECHANISM AND IMAGING OF SECONDARY BRAIN INJURIES Neuropathologic and clinical studies stress the importance of secondary injuries, especially hypoxic-ischemic insults, in the pathogenesis of cerebral damages. (8,11)
15	"Let’s Review Some of the..." Let’s Review Some of the Imaging Pearls on Confirmed Case by Case Basis and Certain Pitfalls
16	11 month old boy s/p fall – Retinal hemorrhages seen on physical examination.
17	Follow-up MRI of the Patient
18	7month old girl with new onset seizures – Retinal hemorrhages on physical examination
19	Follow-up MRI
20	4 month old girl change in mental status.
21	3 month old boy with emesis and bulging anterior fontanelle
22	4 mo boy transferred from outside institution with h/o SDH
23	Axial Gradient Echo MR of Same Child w/ Loss of Signal at Corticomedullary Junction c/w DAI
24	2 month old girl with new onset seizures
25	6 month old boy transferred from outside institution for SDH.
26	10 month boy with vague symptoms, suspected nonaccidental
27	3 month old boy with increasing head circumference
28	9 week old with altered consciousness
29	PITFALLS, MIMICS and CONTROVERSIES No other condition fully replicates the imaging findings of nonaccidental abuse. Entities which may deceive us include: Variations in suture anatomy, myelination patterns. Different appearances of normal anatomy (particularly infants) Coagulapathies (such as von Willenbrand’s and hemophilia). Metabolic disorders (especially Glutaric Aciduria Type I and Hemophagocytic Lymphohistocytosis) Accidental and Birth Trauma and Other Disease States (i.e. meningitis or malignancy) There is debate over the importance of SDHs and retinal hemorrhage in abuse. Especially controversial is the association of benign external hydrocephalus and global hypoxia as a cause of SDH and retinal hemorrhages w/o trauma.
30	SUTURE VARIANTS: PITFALLS FOR CALVARIAL FRACTURES
31	SUTURE VARIANTS: PITFALLS FOR CALVARIAL FRACTURES
32	Pitfall: “Reverse Cerebellar Sign” Secondary to Varying Myelination Patterns and Prominent Tentorium Cerebelli
33	BENIGN EXTERNAL HYDROCEPHALUS (BESS) AND ASSOCIATION W/ SPONTANEOUS SDHs - CONTROVERSIAL MIMIC OF CHILD ABUSE
34	PSEUDO-SDH: NORMAL PROMINENT TENTORIUM CEREBELLI MIMICING ABUSE
35	CONCLUSION Recognition of the abused child is one of the most important and sometimes hardest job a physician has. While the clinical history and presenting symptoms are often vague, the trauma is very real. Unfortunately there is no one specific neuroimaging finding on CT or MRI that’s independently diagnostic of child abuse. Familiarity with the certain neuroimaging features that are highly suggestive of abuse and their mimics lends to establishing an increased level of comfort and certainty in the diagnosis.
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