Assumptions Surrounding the Diagnosing of SBS
Despite how straightforward the diagnosis appears to be, there is a great deal of controversy surrounding the triad of symptoms that are considered indicative of SBS. One area of controversy revolves around the nature and course of subdural hematomas, which are believed to be caused by either a disease process or trauma. When an underlying disease has been ruled out, the diagnostician is left with trauma as the causal factor. Yet, minor brain hemorrhages have been found on the MRIs of 26% of “normal” babies, especially in those delivered vaginally (Looney et al., 2007).
Debate also exists as to whether all subdural hematomas are immediately symptomatic and resultant in morphological change. It has been shown that relatively mild structural damage can result in comparatively immediate death, while infants with major damage can survive indefinitely (Geddes, Hackshaw, Vowles, Nickols, & Whitwell, 2001; Geddes, Vowles, et al., 2001). Furthermore, shaking victims have shown no evidence of cognitive impairment for varying lengths of time before ultimately succumbing to their injuries (Denton & Mileusnic, 2003).
Another area of controversy surrounds retinal hemorrhages, which are typically considered the product of non-accidental trauma and pathognomonic of SBS, especially when seen in conjunction with perimacular retinal folds (Emerson et al., 2001; Office of Juvenile Justice and Delinquency Prevention [OJJDP], 1996). Yet, a review of the objective scientific research conducted between 1966 and 2003 does not support this conclusion (Lantz, Sinal, Stanton, & Weaver, 2004). With few exceptions, the existing research is methodologically flawed and, as a whole, conflicting. While retinal hemorrhages may eventually be proven to be diagnostic of SBS, to date, there is insufficient evidence to support unquestioning acceptance of this claim. There is no agreement as to what presentation of retinal hemorrhages (in terms of number, size, location, etc.) points unequivocally to SBS.
Bleeding in the eye is more common than thought and not always non-accidental (Lantz et al., 2004). Research conducted between 2004 and 2006 on approximately 1,500 corpses found retinal hemorrhages in approximately 1 out of every 6 bodies (BBC, 2008). For example, they have been shown to occur at childbirth, with coagulation disorders; in osteogenesis imperfecta, as a result of near or fatal suffocation, straining, repeated, and forceful sneezing; and very occasionally as a byproduct of resuscitation efforts (Goetting & Sowa, 1990). Approximately 6% of children who were abused, but not by shaking, developed ocular findings, including retinal hemorrhages (Levin, 1990, 1998). Because retinal hemorrhages are not always present in confirmed cases of SBS and because their etiology can be other than trauma, they should perhaps not be considered either necessary or sufficient for the diagnosis of SBS.
Controversy also surrounds the diagnostic significance and certainty of the presence or absence of external injury. The diagnosis of SBS is based on the premise that shaking alone is sufficient to cause subdural hematomas and retinal hemorrhages in healthy infants. In addition, it assumes that the injuries (which, again, vary widely in severity and type, etc.) are caused by violent, intentional trauma. The prevailing notion is that the injuries “characteristic” of SBS are equivalent to those seen in a 35 mph automobile accident in which the infant victim was unrestrained, or a fall from a two-story building. Yet, research (including biomechanical analysis) has shown that, although fortunately not the norm, infants and toddlers can and do die from falls as short as 1-4 feet (Omaya, Goldsmith, & Thibault, 2002; Plunkett, 2001).
It is generally accepted that bouncing an infant or toddler on one’s knees, tossing a toddler into the air (and catching them), and rough play will not cause SBS (CTF, 2004). Yet, there is not uniform consensus as to what force is minimally necessary to cause subdural and retinal bleeding from shaking. Although some believe that shaking alone is sufficient to cause the type of injuries seen in SBS, others contend that there must also be impact (BBC, 2008; Bandak, 2005; Plunkett, 2001). According to some, impact on a hard surface is necessary, while others believe a soft-surface impact is sufficient.
Biomechanical research using infant crash test dummies and corpses has cast doubt on several theories associated with SBS (BBC, 2008; Bandak, 2005; Plunkett, 2001). The levels of force and speed necessary to achieve SBS-type trauma by shaking alone would result in significant injury to the cervical spine, which is seldom seen in SBS cases. In addition, biomechanical research has demonstrated that in simulated one-and-a-half month old dummies, the damage caused by aggressive shaking is statistically similar to that caused by a 1-foot fall onto concrete covered by carpet. A fall from 3 feet on the same surface produces a force that is 40 times greater than that produced at 1 foot, and it is far greater than that produced by vigorous shaking by a human. In brief, biomechanical research suggests that basing the diagnosis of SBS only on the presence of the triad of symptoms lacks scientific certainty.
Not only does SBS describe a constellation of (varying) symptoms but, more importantly, it implies or purports to identify their etiology-that is, non-accidental, criminal behavior. The co-occurrence of subdural hematomas and retinal hemorrhages in a child under the age of 6 years is taken as indicative of child abuse, and a report of such is filed if the injuries were not sustained in an automobile accident or a substantial fall. Based on the belief that symptoms of SBS are non-accidental and have an immediate onset, the adult with the victim at the determined time of onset is considered to be the perpetrator.
Much of the literature connecting the triad of symptoms in SBS with shaking alone consists of case studies in which the alleged perpetrator “admitted” to shaking the given victim (Leestma, 2006). These comparatively limited number of confessions have been used as “proof ” that the triad is always and only caused by shaking. Aside from the body of literature surrounding the validity of confessions in the absence of eyewitnesses, a review of the body of research and scientific evidence (from 1966 to 1998) used to support the triadic theory of SBS reveals it is not as reliable as presumed (Donohoe, 2003).
The use of SBS in criminal trials has been successfully challenged, both in the United States and the United Kingdom, although none of these cases are considered binding legal precedent (Gena, 2007; Dyer, 2005). In addition to the term “shaken baby syndrome” being barred on the grounds of possibly prejudicing the jury, SBS used as a causation of death has failed to pass the “Daubert” test.[See: Greenup Circuit Court Case No. 04-CR-205, Commonwealth of Kentucky Plaintiff vs. Order and Opinion re: Daubert Hearing (Christopher A. Davis, Defendant) concerning the issue of Shaken Baby Syndrome.] In its decision, the Court concluded that SBS is a “theory” (not scientific “proof “) founded on “educated guessing” regarding the cause of injury or death. The Court disallowed either side to use SBS unless there is clear evidence of impact.
Given the serious consequences faced by alleged perpetrators in SBS cases, it is clear that more research is needed to resolve the areas of contest surrounding the diagnosis. Until then, as suggested by Minns & Busuttil (2004), the term SBS should perhaps be replaced with “non-accidental head injury,” thereby avoiding the implication of causation.
For the full article which includes the characteristics, context and diagnosis of shaken baby see:
The Forensic Examiner