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Non Accidental Head Injury Cases (NAHI, formerly referred to as Shaken Baby Syndrome [SBS]) - Prosecution Approach

Published: 6 January 2011

Annex C: Royal College of Pathologists, Meeting 10 December 2009

Conclusion - Areas of agreement and disagreement

The following list has been agreed by the participants at the meeting

It was agreed that when the following features are all present at a paediatric post mortem:

  • widespread bilateral retinal haemorrhages and large macular folds
  • thin-film subdural haemorrhage
  • encephalopathy

(i.e. 'the triad' in characteristic form)

then, considering the case in the absence of other evidence, there should be a prima facie suspicion that the injuries are due to mechanical trauma, potentially including vigorous shaking.

It was agreed that all the individual elements of 'the triad' have a differential diagnosis, and that a thorough post-mortem examination is invariably needed to exclude, as far as possible, non-traumatic explanations of such changes.

It was agreed that in the current state of knowledge the presence of 'the triad', even in its 'characteristic' form, should not be regarded as absolute proof of traumatic head injury in the absence of any other corroborative evidence.

It was agreed that the following post-mortem findings would lend support to a suggestion of mechanical trauma to the head:

  • Bilateral optic nerve haemorrhage at the point where the optic nerve enters the globe
  • Histological changes in the brain indicating mechanical damage rather than ischaemic damage (though there was not agreement on how easy or reliable such histological assessment may be)
  • Other post-mortem evidence of cranial trauma or extra-cranial trauma

It was agreed that the following post-mortem findings would indicate a need for greater caution in suggesting that there had been significant mechanical trauma to the head:

  • One or more elements of 'the triad' being absent
  • One or more elements of 'the triad' being present in a limited or atypical form (e.g. intradural haemorrhage without subdural haemorrhage; large, space-occupying or organising subdural haemorrhage; unilateral ocular changes)
  • Young age at death (interpreted as under 3 months, with particular caution being needed in cases young enough for birth trauma or hypoxia to be a possible explanation for the post-mortem findings)

It was agreed that in some cases where death is undoubtedly due to head injury, some or all of the components of 'the triad' may be absent.

It was not agreed how the post-mortem findings should be integrated to suggest a level of probability of mechanical head injury for the benefit of a court, when considering an individual case. It is therefore anticipated that even where there is agreement on the description of the findings at post-mortem, pathologists could not be expected to agree on the precise probability of trauma being the underlying cause.

The meeting did not discuss mechanisms by which the changes of 'the triad' might develop, so areas of agreement and disagreement concerning mechanisms cannot be stated.

Suggested future steps

The meeting had not achieved complete consensus and it had only considered the pathological interpretation, excluding many other areas of relevance to these cases. Possible next steps were briefly discussed.

A further meeting?

There was agreement that it would be beneficial to follow up this closed, pathology-only meeting with a larger, open meeting that involved specialists in other relevant fields, including radiology, paediatrics, child protection, lawyers, experts in biomechanics etc. However, Professor Furness (as President of the RCPath) stressed that although the current meeting had been funded by the College any further meeting would be dependent on a different source of funding becoming available.

Research to resolve disagreements?

There was consensus that the only way in which the disagreements discussed at the meeting would be resolved was by undertaking systematic research. This would demand large studies of paediatric deaths in a variety of circumstances spanning the areas of practice of all those present at the meeting; it would therefore demand collaboration between different units, and it would demand substantial funding.

Those present, including those whose opinions currently differ considerably on the interpretation of post-mortem changes, agreed that they would all be willing to collaborate in such a project.

However, barriers to such a research project were discussed.

The main barriers were not perceived as interpersonal disagreements between pathologists, nor even the need to secure funding (though that would not be easy).

The main problem is with the regulatory environment, especially with the regulatory changes that had been put in place since the inappropriate unconsented use of paediatric post-mortem samples at Alder Hey and Bristol prior to 2000. It was reported that even for observational studies, research ethics committees and NHS R&D staff were often extremely difficult to satisfy before material could be published. Confidentiality requirements were often raised by regulators, with conventional anonymisation processes being regarded as insufficient for these unusual and high-profile cases, even (or especially) after the details of the case had been discussed in court. The difficulty of obtaining appropriate control material was discussed; while the paediatric brain would be examined at most paediatric post-mortem examinations, removal and detailed examination of the eyes would be a research-specific process for which specific consent would be necessary. It was anticipated that it would be difficult for staff to ask for, or for the bereaved parents to provide, such consent.

There was agreement that poor drafting of the Human Tissue Act 2004 had made the difficulty of conducting this research considerably more severe. It was pointed out that to study tissue samples for research in these cases, appropriate consent was invariably needed. But consent had to be provided by a parent, so in many cases consent had to be requested from a person who stood accused or convicted of murder. Putting aside the practical difficulty of obtaining access to such a person to request consent, the circumstances would effectively guarantee that, from a scientific perspective, any group of cases where consent was obtained would have to be regarded as a biased sample.

Several representations had been made to the Government to the effect that this was not an intended outcome of the Human Tissue Act 2004 and that the law therefore needed to be changed. These representations notably included the Joint Parliamentary Select Committee on the Human Tissue and Embryos (Draft) Bill in 2009 and amendments to the Coroners and Justice Bill 2009, proposed by Baroness Finlay in the House of Lords. Others, including the Coroners' Society, have also recommended that the 2004 Act be changed. All such approaches had been rebutted by the Government, apparently without giving any justification beyond the observation that Parliament had already debated the Human Tissue Act prior to its passage in 2004.

The Human Tissue Authority had acknowledged the problem in undertaking research in this context but had refused to recommend any change to the legislation, again without giving reason. Those present deplored this attitude of the Government and the Human Tissue Authority.

Personal comment by Professor Peter Furness, President of the Royal College of Pathologists

I convened and Chaired this meeting despite having no specialist expertise in the area, because I was aware that Fellows of the College of which I am President were expressing different opinions, in and out of the context of Court hearings. I was informed that this was producing problems for the courts as well as generating a regrettable level of discord amongst Fellows of the RCPath.

I did not expect the meeting to produce complete agreement and it did not. However, it was held in a considerably more cordial atmosphere than I had been led to expect. This led me to suspect that some of the antagonism that had developed between participants had been exacerbated by their previous experiences in the adversarial context of court hearings.

Another factor that I believe contributed to the level of disagreement is the very different types of practice of the pathologists who were present. Some see only forensic cases, the majority being deaths at more than 3 months of age; others see a caseload predominantly of deaths in hospital, predominantly less than 3 months of age. This results in practitioners having radically different personal experiences, and it is natural that over many years of such experience they form firm but different opinions on the appropriate interpretation of the post-mortem findings.

I attempted to listen to the debate with an open mind. If I had any preconceived suspicions, it was that a cohort of very experienced forensic practitioners were being challenged in their interpretation by new evidence and they were reluctant to admit that the opinions they had expressed in court over many years might be incorrect. After the meeting I was convinced that this is not an accurate representation of the true position.

I left the meeting convinced that where 'the triad' is present in typical form in an infant of 3 months or older it represents strong evidence of mechanical injury, consistent with 'shaken baby syndrome'. However, I was reassured that no-one present regarded such a finding as absolute proof. It seemed to me that in all such cases a court should seek some further corroborative evidence.

I was also convinced that there are circumstances where all the individual elements of 'the triad' can be produced by insults other than mechanical trauma. For example, it seems to me probable that the natural events around a 'difficult' birth may induce these lesions. It follows from this that all three might be present in a case where intentional mechanical trauma is not the underlying cause.

Consequently, in cases where the dead child is very young, or where one or more elements of 'the triad' are absent or are present in some atypical form, the need for other corroborative evidence is proportionately greater before a court should decide that the evidence justifies a decision 'beyond reasonable doubt'. Pathologists cannot be expected to agree on precise probabilities in this situation. This problem can only be alleviated by research, not by further discussion. Unfortunately the barriers to undertaking such research are considerable, and have become much greater in recent years.

The meeting did not consider mechanisms by which shaking might generate the post-mortem changes that were discussed. This is an area of considerable debate, and some of those present at the meeting regarded this omission as a serious defect in our meeting. I was less concerned by this omission, observing that the absence of a known mechanism does not prove that a mechanism does not exist. At risk of trivialising the matter I drew the attention of those present to reports some years ago that an aerodynamic study of bumble bees 'proved' beyond scientific doubt that they cannot fly.

Personal observation is, of course, to the contrary. A more accurate statement would have been that current aerodynamic theory was unable to explain how they fly. Subsequently, more refined scientific theories took account of the fact that, for structures as small as a bee, air has a significant viscosity, and the flight of the bumble bee now has a scientific explanation.

When the science improved, the explanation became apparent. Until that happened, the observation that bees can fly showed the scientific theory to be inadequate. The same might be true of the problems in explaining precisely how vigorous shaking can generate the lesions we have been discussing.

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