Shaken Baby Syndrome

Clinical Presentation of SBS

SBS victims can present with a wide variety of symptoms ranging from the very mild to the most critical of states. In the less severe cases, the infant may present with the parents or caretaker relaying a history of poor feeding, vomiting, lethargy or irritability, hypothermia or chills, a generalized failure to thrive, increased sleeping, and a failure to smile or be verbal. These symptoms may persist for days to weeks and are apparent to any caretaker or parent as problematic and abnormal; however care at this stage may or may not be sought. These fairly nonspecific signs may be minimized by physicians or attributed to other causes of origin such as viral illness or colic and may resolve without the root cause being discovered.

In more severe SBS cases, the infant may exhibit more life-threatening signs and symptoms of neurologic impairment. Following a violent shaking, immediate medical attention may or may not be sought. The caretaker may put the infant to bed anticipating the child will recover. This leads to a missed opportunity for early intervention. Nevertheless, in these more severe cases, presentation to the hospital can reveal the following:

1. Respiratory difficulty including apnea
   
   

2. A decreased level of consciousness
   
   

3. Seizure activity
   
   

4. Bradycardia
   
   

5. Bulging fontanels indicative of increased intracranial pressure
   
   

6. Possible complete cardiovascular collapse requiring cardiopulmonary resuscitation (CPR)

One of the hallmark presentations of SBS is a lack of external injuries (Fulton, 2000). This may lead to a missed diagnosis even in the most severe SBS cases. The lack of obvious trauma may falsely minimize the health care provider's suspicion of possible maltreatment. In the event that external injuries are noted, however, they must be carefully documented. The use of forensic photography can aid in clear and accurate documentation of the injuries. Repeated physical examinations may also reveal further signs of trauma. Evidence of other injuries including bruises, rib fractures, long bone fractures, abdominal injuries, and retinal hemorrhage should be carefully assessed and accurately documented.

In SBS, the mechanism of injury resulting in retinal hemorrhage is not conclusively known, however several theories exist including rapid movement of the vitreous body combined with a sudden rise in intraocular pressure, increased intracranial pressure due to trauma (whether by impact or inertia), and extravasation of subarachnoid blood (Fulton, 2000; Munger, Peiffer, Boouldin, Kylstra, & Thompson, 1993). It is somewhat controversial whether retinal hemorrhage in children is a definitive sign of SBS. It has been noted, however, that large retinal hemorrhages are unusual in other forms of cerebral trauma, occurring in about 1% of children with serious head trauma (Keenan & Runyan, 2001). Furthermore, the AAP (2001) offers that retinal hemorrhage can be seen in 75-90% of all SBS cases. The number, location, size, and character of retinal hemorrhage varies with each case, however more severe hemorrhage can be associated with a more serious brain injury. In a similar fashion, a relationship can be drawn between the extent of the hemorrhage and the forcefulness of the shaking episode. This shaking can lead to permanent vision impairment and, in the more severe cases, blindness.

An accurate diagnosis of retinal hemorrhage in SBS is crucial for appropriate medical care and for legal reasons as well. The AAP (2001) suggests that where available, the child should be examined by an ophthalmologist, pediatric neurologist, pediatric neurosurgeon, or other experienced practitioner who is experienced with such hemorrhages and is equally familiar with the examination equipment and technique for this very reason. Furthermore, when the victim is examined for retinal hemorrhage by someone other than an ophthalmologist, up to 25% of the cases with injury may be missed (Santuci & Hsiao, 2003).

While no apparent injury may exist, bone fractures can be found in half of all SBS cases (Zenel & Goldstein, 2002). These fractures may occur anywhere in the body; however the most common type of injury in SBS is the metaphyseal chip fracture. These fractures occur at the bone's growth plate as a result of the child's extremities flailing uncontrollably during the shaking episode. Rib fractures may also be noted. In fatally abused infants, the ribs are the most common site for fractures. Additionally, when an infant presents with fractured ribs, it is most often the result of physical abuse. Posterior rib fractures are often caused by anteroposterior thoracic compression such as that associated with a shaking episode (Bulloch et al., 2000; Kleinman & Schlesinger, 1997).

Radiologic examinations, including skeletal surveys, allow the health care practitioner to pinpoint sites of orthopedic injury (Zenel & Goldstein, 2002). A skeletal survey should include radiographs of the hands, feet, long bones, skull, spine, and ribs. This should be performed as soon as the child's medical condition permits. These films can be very useful in detecting both skull and rib fractures. A 2-week follow-up skeletal survey can greatly increase the diagnostic yield. Additionally, scintigraphy, a nuclear medicine test which detects areas of increased or decreased bone metabolism, has been demonstrated an increased sensitivity for detecting rib fractures. This technique may be of particular use if the child is to be discharged to a potentially unsafe environment prior to the 2-week skeletal survey follow up (Zenel & Goldstein, 2002).

Traumatic brain injuries (TBI) occur when a sudden trauma, such as violent shaking, causes trauma to the brain. TBI symptoms can range from mild to severe depending on the extent of injury to the brain. Mild signs and symptoms include headache, lethargy, confusion, dizziness, blurred vision, and mood and memory changes. A child with a more severe TBI may exhibit these signs in addition to nausea and vomiting, seizures, inability to arouse from sleep, dilation of one or both pupils, loss of coordination, persistent crying, and a refusal to nurse or eat (Becker et al., 2002).

The key diagnostic feature of SBS is the presence of intracranial injury in an infant (Keenan & Runyan, 2001). The most common injury is a subdural hematoma; however epidural hematoma, subarachnoid bleeding and shearing injuries of the brain parenchyma can all occur. During the shaking episode, rotational forces and differential movement of the brain in relation to the surrounding tissues can tear the bridging vessels resulting in a subdural hematoma. Additionally, the rotational forces lead to strains on the nerve axons throughout the brain resulting in diffuse axonal injury (Keenan & Runyan, 2001). Inflicted head trauma seems to trigger a chain of events that result in cerebral hypoxia, cerebral edema, increased intracranial pressure (ICP), and vaso-occlusion (Zenel & Goldstein, 2002). The displacing effect of the subdural hematoma may lead to further ischemic compromise. Furthermore, cervical spine epidural hematoma may occur in a significant proportion of abused infants, in addition to focal axonal injury of the lower brainstem, superior spinal cord, and spinal nerve roots. It is also thought that the effect of stretching at the craniocervical junction during violent shaking may lead to apnea, which results in a diffuse hypoxic injury. In general, intracranial injury in the absence of significant accidental trauma is a significant indicator of inflicted injury (Blumenthal, 2002).

The onset of symptoms is useful both in understanding prognosis as well as determining a cause (Keenan & Runyan, 2001). Timing can best be established by synthesizing the history, clinical course, and results of diagnostic imaging studies. When accurate, the clinical history is the most precise means for establishing a timeline. Elapsed time from the onset of injury can be estimated through the breakdown of intracranial hemoglobin as seen on diagnostic radiological studies. Additionally, if a spinal tap is performed yielding bloody cerebrospinal fluid (CSF), a fluid which is xanthochromic should arouse suspicion that the cerebral trauma may be several hours old and the blood in the CSF is not from a traumatic spinal tap (Keenan & Runyan, 2001).

Radiologic imaging, including computed tomography (CT) scans and magnetic resonance imaging (MRI) is used to detect the presence of a traumatic brain injury. CT has the primary role in the imaging evaluation of a child with a TBI. The CT can detect injuries requiring immediate attention. Initial CT imaging should be performed without contrast and is the method of choice for demonstrating acute hemorrhage, including that involving the subarachoid space. The CT should be repeated after a period of time or if there is a rapid change in neurologic status. The use of the MRI optimizes detection and assessment of intracranial injury including intraparenchymal hemorrhage, contusions, shearing injuries, and edema. The MRI is also sensitive for detecting significant spinal injury and previous parenchymal hemorrhage. A posterior, intrahemispheric subdural hematoma as noted on either CT or MRI, in the absence of significant accidental trauma, is indicative of inflicted injury.

J Foren Nurs. 2005;1(3):111-117. © 2005 International Association of Forensic Nurses

Cite this: Shaken Baby Syndrome - Medscape - Sep 01, 2005.