Inflicted Head Trauma in Children

From Clinical Update, Summer 2003

by Thomas A. Nakagawa, MD, FAAP
Department of Anesthesiology and Pediatrics

Abstract: Shaken baby syndrome is a serious form of child maltreatment that often goes unrecognized because of the diverse presentation of symptoms. Life-threatening complications such as respiratory embarrassment and/or cardiopulmonary arrest in a previously healthy infant with no explanation for the severity of symptoms is a common presenting scenario. The injuries sustained are the result of violent acceleration/deceleration forces as the head is whiplashed back and forth during violent shaking resulting in cerebral edema, subarachnoid and/or subdural hemorrhage, and retinal hemorrhages. Permanent neurologic injury or death can occur from this form of child abuse.

Introduction

Eighty percent of deaths related to head trauma in infants and children less than 2 years of age occur because of non-accidental trauma (1), and homicide continues to be a leading cause of death in children under 1 year of age. Injuries sustained from violent shaking will result in the hospitalization of an estimated 1,500 infants annually, and many of these victims of shaken baby syndrome will have permanent neurologic injury. One-third or more of these infants will die from injuries sustained from violent shaking.

Shaken baby syndrome is a serious form of child maltreatment with recorded injuries related to violent shaking dating back at least 50 years. (2,3) It often involves children less than 2 years of age, although it may be seen in older children. Peak incidence occurs between 6 weeks to 4 months of age and males tend to be affected slightly more than females. The actual incidence of shaken baby syndrome is unknown since many cases go undiagnosed. In fact, a recent article by Jenny and colleagues reported that 31.2% of confirmed abusive head trauma cases were missed on initial presentation, and many infants sustained additional injury because of the delay in diagnosing abusive head trauma. (4) Therefore, the clinician must have a high index of suspicion that abuse may have occurred or the diagnosis of abusive head trauma may never be diagnosed. Bruising in any child who is non-ambulatory should raise suspicion of abusive trauma and be investigated.

Pathophysiology

The infant is at greater risk to sustain injury from violent shaking for several anatomic reasons. The head of the infant is the largest part of the body. The weak neck muscles allow the head to move in linear and rotational or angular directions if left unsupported. Additionally, the brain has a higher water content because of lack of mylenation and the larger subarachnoid space allows for more movement of the infant brain inside the skull. (5)

Injuries sustained from shaking are the result of violent forces. The American Academy of Pediatrics states, “The act of shaking leading to Shaken Baby Syndrome is so violent that individuals observing it would recognize it as dangerous and likely to kill the child.” (6) Playful bouncing of an infant cannot generate enough force to create the injuries seen from violent shaking. Falls from beds, sofas and changing tables are commonly reported; however, studies show that falls from < 10 feet do not result in significant injury. (7) Additionally, vaccinations and seizures do not cause the constellation of symptoms seen with violent shaking. (6) Repetition of the shake injury is common, and although it may only last a few seconds, tremendous forces are generated and substantial intracranial injury can occur during this violent act. Although some medical professionals believe that impact injury must occur to produce the traumatic brain injury seen with violent shaking, the AAP states that violent shaking with or without impact identifies child abuse. (8) Lastly, the perpetrator is always larger than the victim.(6)

The common scenario is a crying infant with a frustrated caretaker who picks the infant up and violently shakes the child in an effort to stop the baby from crying. (6) The infant is grabbed by the shoulders or under the armpits and shaken violently. This violent shaking causes the infant’s head to move back and forth rapidly, creating linear and rotational acceleration and deceleration forces. Linear forces result in retinal injury causing a hemorrhagic retinopathy. Additionally, compression of the chest may impede venous drainage from the head and neck region elevating intraretinal pressure contributing to retinal hemorrhages. (9) Rotational acceleration forces also occur and result in subarachnoid and subdural hemorrhages as the bridging veins are torn. Shearing of axons can result with longer shaking episodes resulting in diffuse axonal injury. The perpetrator may actually throw the infant back into the crib or bed causing further injury to the brain due to sudden deceleration forces. Impact of the head against a stationary surface can result in cerebral contusion or skull fractures and increases the magnitude of force generated from shaking. (10) During this violent act, the infant may actually cry more because of painful injury or lapse immediately into unconsciousness. Following this event the infant may be put to bed in hopes that recovery may occur, only to be found at a later time cyanotic, dyspneic, apneic, or in full cardiopulmonary arrest. The delay in treatment results in irreversible damage to the brain because of hypoxic and ischemic injury that is the major contributor to the poor neurologic outcome of many of these infants.

Injuries from shaking are due to tremendous forces. The forces involved with violent shaking have been estimated to be greater than 9 gravitational forces (G forces). This force is magnified if the head suddenly decelerates against a stationary object with G forces estimated to be 50 times greater. (10) The clinical presentation of infants who have been shaken can range from subtle findings including irritability, vomiting and poor feeding. In severe or lethal cases, infants may present with seizures, respiratory distress, cardiovascular collapse, coma and manifestations of cerebral edema with intracranial hypertension including vital sign changes and respiratory depression. The clinical symptoms correlate with the severity of the traumatic brain injury that occurs when the infant is violently shaken. Many times there is no history or sign of external trauma to explain why a child’s condition rapidly deteriorated resulting in a critically ill state. When serious head injury is unexplained, the chances of inflicted injury are high and must be investigated. There is no evidence to support the claim that a child who has been severely shaken will be fine for hours then suddenly develop progressively worsening cerebral edema and deteriorating mental status. (11) When traumatic brain injury occurs, the infant will show signs of central nervous system insult almost immediately.

Clinical Findings

The findings of retinal hemorrhages, subarachnoid or subdural bleeding, and cerebral edema are characteristic of shaken baby syndrome. Each one of these findings alone or in combination helps the clinician diagnose shaken baby syndrome. Imaging studies of the head may show subarachnoid, subdural bleeding, cerebral edema, or older injury such as subdural effusions. Unilateral or bilateral retinal hemorrhages will be found in 75-90% of infants who are shaken. The hemorrhages tend to involve multiple layers of the retina and are the result of linear forces and/or chest compression resulting in venous stasis that disrupts the integrity of the retinal vessels causing hemorrhage. (5,12) Evaluation by a pediatric ophthalmologist and neurologist should be obtained to further document injuries to the infant.

The child should also be evaluated for other injuries such as skeletal trauma and chest and abdominal injury. A full skeletal survey should be performed looking for skeletal trauma. Rib fractures, although not present in all cases, can occur as the infant is grabbed and shaken by the perpetrator. Forces from the hands and fingers are applied to the chest, resulting in posterior and lateral rib fractures which are diagnostic of child abuse.

Many critically ill infants may have received CPR during their resuscitation. Although CPR can rarely cause retinal hemorrhages and rib fractures, the retinal hemorrhages seen with shaken baby syndrome are clearly different from those associated with CPR (13), and posterior rib fractures are not produced by closed chest compressions. Furthermore, rib fractures in any child suggest strong evidence of abuse until proven otherwise. Anemia may be present because of intracranial bleeding, and fresh blood in the cerebral spinal fluid may be noted if a lumbar puncture is performed. A coagulopathy may be present that results from the traumatic brain injury as tissue thromboplastin is released. (14) This coagulopathy will typically correct if there is no underlying bleeding disorder.

Outcome

The poor outcome associated with shaken baby syndrome is the result of hypoxic ischemic injury that occurs secondary to cerebral edema and intracranial hemorrhaging. The delay in immediate treatment following the injury further compromises the infant’s chance for a meaningful neurologic recovery. Mortality rates range from 15-38%. (6) Many infants who survive will be left neurologically impaired and will suffer from cortical blindness, seizures, hydrocephalus, learning disabilities, or be institutionalized in a persistent vegetative state. (2)

Child abuse has no socioeconomic boundaries, and there is no specific profile of perpetrators who shake infants and children. However, studies indicate that male caretakers, especially males in their early 20s who are left with the infant for short periods of time, are at greater risk to abuse infants. (15,16) Additionally, a high incidence of abuse exists in military families. (17)

Investigation of Events

Investigation of these cases can be emotionally challenging. A high index of suspicion for an unexplained injury should prompt a thorough investigation for non-accidental trauma, and the history needs to be consistent with the injuries. It is the medical professional’s responsibility to report suspected child abuse. The case must be identified as suspicious and not the family. The health care team must be sensitive to the needs of the parents and remember our job is to treat the child and the family, not to determine who injured the child. Management includes the involvement of social services, law enforcement agencies and child protective services. Documentation of injuries and discussions with parents or guardians are essential.

Conclusion

Sadly, this preventable medical condition that plagues our society continues to exist. An estimated one-third of the American public still does not know that it is dangerous to shake a baby and that permanent neurological injury or death can occur after only 1-2 seconds of violent shaking. (18) Only through education of anyone who cares for infants and children can we hope to decrease the risk of injury from violent shaking. We must teach parents and caretakers to never, ever shake a baby. Caregivers need to understand that crying is a normal response for infants and when the caregiver becomes frustrated because of crying, the safest place for the infant is in the crib. Today’s children are tomorrow’s future. We must love them, protect them, and never, ever shake them.

References

  1. Bruce D, Zimmerman R. Shaken impact syndrome. Pediatric Annals.1984;13:482-494. 
  2. Caffey J. On the theory and practice of shaking infants. Its potential residual effects on permanent brain damage and mental retardation. Am J Dis Child. 1972;124:161-169. 
  3. Guthkelth AN. Infantile subdural haematoma and its relationship to whiplash injuries. Br Med J. 1971;2:430-431. 
  4. Jenny C, Hymel KP, Ritzen A, Reinert SE, Hays TC. Analysis of missed cases of abusive head trauma. JAMA. 1999;281:621-626. 
  5. Conway EE Jr. Nonaccidental head injury in infants: “the shaken baby syndrome revisited.” Pediatr Ann. 1998;10:677-690. 
  6. American Academy of Pediatrics Committee on Child Abuse and Neglect. Shaken Baby Syndrome: Rotational Cranial Injuries-Technical Report. Pediatrics. 2001;108:206-210. 
  7. Chadwick DL, Chin S, Salerno C, Landsverk J, Kitchen L. Deaths from falls in children: how far is fatal? J Trauma. 1991;31:1353-1355. 
  8. American Academy of Pediatrics Committee on Child Abuse and Neglect. Shaken baby syndrome: Inflicted cerebral trauma. Pediatrics. 1993;92:872-875. 
  9. Levin AV. Retinal hemorrhages: a review. In: David TJ, ed. Recent advances in Pediatrics. London, United Kingdom: Churchill-Livingstone; 1999:151-219. 
  10. Duhaime A, Gennarelli T, Thibault L, Bruce D, Margulies S, Wiser R. The Shaken Baby Syndrome. A clinical, pathological and biomechanical study. Journal of Neurosurgery. 1987;66:409-415. 
  11. Duhaime AC, Christian CW, Rorke LB, Zimmerman RA. Nonaccidental head injury in infants-The “Shaken-Baby Syndrome.” New England Journal of Medicine. 1998;1822-1829. 
  12. Nakagawa TA, Skrinska R. Improved bedside documentation of retinal hemorrhages in victims of abusive head trauma using a wide-field digital ophthalmic camera. Archives of Pediatrics and adolescent medicine. 2000;155:1149-1152. 
  13. Odom A, Christ E, Kerr N, Byrd K, Cochran J, Barr F, et al. Prevalence of retinal hemorrhages in pediatric patients after in-hospital cardiopulmonary resuscitation: A prospective study. Pediatrics. 1997;99:1-5. 
  14. Hymal KP, Abshire TC, Luckey EW, Jenny C. Coagulopathy in pediatric abusive head trauma. Pediatrics. 1997;99:371-375. 
  15. Starling S, Holden J, Jenny C. Abusive head trauma: The relationship of perpetrators to their victims. Pediatrics. 1995;95:259-262. 
  16. Starling S, Holden J. Perpetrators of abusive head trauma: A comparison of two geographic populations. Southern Medical Journal. 2000;93:463-465. 
  17. Gessner R, Runyan D. The shaken infant: A military connection? Archives Pediatric Adolescent Medicine. 1995;149:467-469. 
  18. Executive summary of the National Conference on Shaken Baby Syndrome 1996.

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