BMJ  2004;328:719-720 (27 March), doi:10.1136/bmj.328.7442.719


The evidence base for shaken baby syndrome; We need to question the diagnostic criteria

The phrase "shaken baby syndrome" evokes a powerful image of abuse, in
which a carer shakes a child sufficiently hard to produce whiplash forces
that result in subdural and retinal bleeding. The theory of shaken baby
syndrome rests on core assumptions: shaking is always intentional and
violent; the injury an infant receives from shaking is invariably severe;
and subdural and retinal bleeding is the result of criminal abuse, unless
proved otherwise.1 These beliefs are reinforced by an interpretation of the
literature by medical experts, which may on occasion be instrumental in a
carer being convicted or children being removed from their parents. But
what is the evidence for the theory of shaken baby syndrome?

Retinal haemorrhage is one of the criteria used, and many doctors consider
retinal haemorrhage with specific characteristics pathognomonic of shaking.
However, in this issue Patrick Lantz et al examine that premise (p 754) and
conclude that it "cannot be supported by objective scientific evidence."2
Their study comes hard on the heels of a recently published review of the
literature on shaken baby syndrome from 1966 to 1998, in which Mark Donohoe
found the scientific evidence to support a diagnosis of shaken baby
syndrome to be much less reliable than generally thought.3

Shaken baby syndrome is usually diagnosed on the basis of subdural and
retinal haemorrhages in an infant or young child,1 although the diagnostic
criteria are not uniform, and it is not unusual for the diagnosis to be
based on subdural or retinal haemorrhages alone.w1 The website of the
American Academy of Ophthalmology states that if the retinal haemorrhages
have specific characteristics "shaking injury can be diagnosed with
confidence regardless of other circumstances."4 Having reviewed the
evidence base for the belief that perimacular folds with retinal
haemorrhages are diagnostic of shaking, Lantz et al were able to find only
two flawed case-control studies, much of the published work displaying "an
absence of... precise and reproducible case definition, and interpretations
or conclusions that overstep the data."2 Their conclusions are remarkably
similar to those of Donohoe, who found that "the evidence for shaken baby
syndrome appears analogous to an inverted pyramid, with a very small
database (most of it poor quality original research, retrospective in
nature, and without appropriate control groups) spreading to a broad body
of somewhat divergent opinions."3 His work entailed searching the
literature, using the term "shaken baby syndrome" and then assessing the
methods of the articles retrieved, using the tools of evidence based
inquiry. Reviewing the studies achieving the highest quality of evidence
rating scores, Donohoe found that "there was inadequate scientific evidence
to come to a firm conclusion on most aspects of causation, diagnosis,
treatment, or any other matters," and identified "serious data gaps, flaws
of logic, inconsistency of case definition."3

The conclusions of Lantz et al and of Donohoe make disturbing reading,
because they reveal major shortcomings in the literature relating to a
field in which the opportunity for scientific experimentation and
controlled trials does not exist, but in which much may rest on
interpretation of the medical evidence.5

If the concept of shaken baby syndrome is scientifically uncertain, we have
a duty to re-examine the validity of other beliefs in the field of infant
injury. The recent literature contains a number of publications that
disprove traditional expert opinion in the field. A study of independently
witnessed low level falls showed that such falls may prove fatal, causing
both subdural and retinal bleeding.6 w2 A biomechanical analysis validates
that serious injury or death from a low level fall is possible and casts
doubt on the idea that shaking can directly cause retinal or subdural
haemorrhages.7 w3 An important lucid interval may be present in an
ultimately fatal head injury in an infant.8 Neuropathological studies have
shown that abused infants do not generally have severe traumatic brain
injury and that the structural damage associated with death may be
morphologically mild.9 10 What is the relevance of the craniocervical
injuries to corticospinal tracts, dorsal nerve roots, and so on that have
been described?10 11 We do not know. What is the force necessary to injure
an infant's brain? Again, we do not know.

While most abused children indisputably show the signs of violence, not all
do. No one would be surprised to learn that a fall from a two storey
building or involvement in a high speed road traffic crash can cause
retinal and subdural bleeding, but what is the minimum force required? "It
is one thing clearly to state that a certain quantum of force is necessary
to produce a subdural hematoma; it is quite another to use examples of
obviously extreme force... and then suggest that they constitute the
minimum force necessary."12

Research in the area of injury to infants is difficult. Quality evidence
may need to be based on finite element modelling from data on infants'
skulls, brains, and neck structures, rather than living animals. Any
studies on immature animal models, if performed, will need to be validated
against the known mechanical properties of the human infant. Pending
completion of such studies, the reviews by Lantz and Donohoe are a valuable
contribution and provide a salutary check for anyone wishing to cite the
literature in support of an opinion. Their criticisms of lack of case
definition or proper controls can be levelled at the whole literature on
child abuse. If the issues are much less certain than we have been taught
to believe, then to admit uncertainty sometimes would be appropriate for
experts. Doing so may make prosecution more difficult, but a natural desire
to protect children should not lead anyone to proffer opinions unsupported
by good quality science. We need to reconsider the diagnostic criteria, if
not the existence, of shaken baby syndrome.

J F Geddes, retired (formerly reader in clinical neuropathology, Queen
Mary, University of London)

London (

J Plunkett, forensic pathologist

Regina Medical Center, 1175 Nininger Road, Hastings, MN 55033, USA

Editorial p 720 Clinical review p 754 Letters p 766 Personal view p 775

Additional references w1-w3 are on

Competing interests: JFG and JP have given evidence in criminal cases at
the request of both the prosecution and the defence.


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