In this article, Dr Charles Clarke FRCP, Consultant Neurologist, reflects on the growing challenges in medico-legal neurology. Drawing on personal insights and contributions from colleagues, he examines controversial areas such as traumatic brain injury (TBI) classification, post-traumatic epilepsy and dementia risks, examining the importance of evidence-based expert opinions in court proceedings.
“Minefield” is perhaps an overstatement, given current international conflicts, but the world of medico-legal neurology has now become full of pitfalls. I am a neurologist. I work on either side of the barbed-wire legal fence.
My comments reflect not only my own views but also those of several colleagues. I am writing for lawyers, medics and all others in this multidisciplinary field.
What has changed?
First, there is more controversy now – between experts and at conferences with Counsel.
For example, long ago, that Joint Discussion between experts to produce the Joint Statement for the Court… was often over a glass of Chablis, or a pint. We might agree to differ, but on amicable terms.
Within the last two years, I have noted arguments with my “opposite number” – a current legal label for two people aiming to give unbiased opinions – of startling ferocity. One comment, fired suddenly over the phone, from a neurologist I have never met, began with something like… – “…I have never heard a Defence Expert… say anything like that…”
I am NOT a “Defence Expert.” I am an experienced and balanced neurologist, trying to give an honest opinion, ultimately to a judge, who may know something about neurology, but probably less than me.
Another aspect is my report – that used to be a final Expert Opinion. Today, my ‘draft report’ is to be discussed, edited and brought into line with Counsel’s and others’ views, delicately prefaced with: ”… in no way do we wish you to alter your views….”
This trend is not all bad, because there is now more focus upon detail. Reports in the past were sometimes vague. Opinions today are more evidence-based, rather than didactic views of a senior physician.
However, that ‘range of opinion’ insisted upon in CPR 35, seems to receive little attention these days.
Also, as a neurologist, one must also remember that the Court now relies upon the opinions of a family of experts, some allied to neurology and to the needs of the injured party.
In this family, some experts are medically qualified, others highly experienced in other fields and some hold an academic doctorate. Their views are often valuable, but each member of the “family of experts” must limit their opinion to their own specialism.
However, it is sometimes forgotten that an individual, despite having the “Dr” title, may not be medically qualified. Some have never worked in the battleground of an A&E department, or in a busy NHS outpatient clinic. I recall one opinion, given by one non-medically qualified, that diagnosed ‘…diffuse axonal injury…’ to the brain, a complex neuropathological and neuroradiological field – and a serious form of brain damage. It seemed to be inappropriate that such a non-medical opinion was voiced to a Court, and possibly accepted as a specialist view.
By contrast and in criticism of my own field, neurology has remained narrow, dwelling little on the detail of neuropsychology examination, on psychological/psychiatric opinion, or the magic of good physiotherapy, and other physical therapies – all of which are crucial to the overall outcome for the injured party.
In my training as a neurologist, I cannot recall a single lecture on these subjects. I went outside medicine, specifically, to study these fields, but I am still hardly an expert.
I shall give several examples where I have experienced difficulties:
- I. The minor head injury and the Mayo scale
- II. The interpretation of numerical data of sequelae of a traumatic brain injury (TBI) – in epilepsy and in the possibility of dementia following a TBI.
III. Non-organic complaints, including functional neurological disorders (FND), and let me be blunt – faking/feigning/malingering
I shall deal with I & II here.
I. Minor head injury: the Mayo scale et al
It is common knowledge that a minor blow on the head can be remarkably unpleasant. You clip your own head on the corner of a shelf or a beam in the garden shed. Headaches follow, as we all know and some dizziness. One “…doesn’t feel quite right….” for hours, days or exceptionally, weeks. In almost all cases, this has not been a “brain injury” at all, but a blow to the scalp – a superficial but pain-sensitive structure.
If we translate that minor blow, without any loss of awareness or loss of consciousness using the Mayo Classification for Traumatic Brain Injury Severity, the words Traumatic Brain Injury (TBI) immediately appear. The injury is categorised as a “Symptomatic (Possible) TBI”. The paper states:
“…if one or more of the following symptoms are present: blurred vision, mental state changes, dazed dizziness…headache, nausea…classify as Symptomatic (Possible) Traumatic Brain Injury.“
In other words, the vast majority of Symptomatic (Possible) TBI cases did not suffer any brain injury (TBI) at all, despite the classification firmly including those three words.
The more severe Mayo criteria, which I have summarised here, make much more sense. I am in strong support: they provide a sequence, clear for everyone:
A. Classify as Moderate-Severe (Definite) TBI if one or more of the following criteria apply:
1. Death – due to this TBI.
2. Loss of consciousness of 30 minutes or more.
3. Post-traumatic amnesia of 24 hours or more.
4. Worst Glasgow Coma Scale full score in first 24 hours.
Below 13/15 – unless … attributable to intoxication, sedation, systemic shock.
5. One or more of the following: brain blood clot/bruising, subdural/extradural hematoma, penetrating brain injury, subarachnoid haemorrhage, brain stem Injury.
B. If none of Criteria A apply, classify as Mild (Probable) TBI, if one or more apply:
1. Loss of consciousness – momentary to less than 30 minutes.
2. Post-traumatic anterograde amnesia of momentary to less than 24 hours.
3. Skull fracture – depressed, basilar or linear.
The authors of the Mayo 2007 paper from the world-famous US institute did not, perhaps, realise that this scale would be used extensively in legal cases throughout the anglophone world.
Unusually, they were direct about the paucity of some data: in just over 1500 cases studied from 1985 to 1999. “…single measures of TBI severity were not available in a large percentage of these events … Glasgow Coma Scale (GCS) was absent in 1242 (74.0%); loss of consciousness, absent in 1178 (70.2%), post-traumatic amnesia (PTA), absent in 974 (58.1%), head CT, not done in 827 (49.3%)…”
Outcome – what we all need to know – was not assessed at all, other than in A1 ‘Death due to TBI.’
In reality, what is required for a Court is an overall assessment of the outcome of a head injury. This needs to be comprehensive, initially from a neurologist, coupled with an assessment of the imaging (by a neuroradiologist), a detailed neuropsychological assessment and an assessment of the patient’s needs, current and future. This does not lend itself to any classification scale.
II. Numerical data
The distant sequelae of a TBI, usually Mayo ‘moderate-severe’, also provides areas for discussion, argument and sometimes profound disagreement.
Epilepsy: post-traumatic epilepsy
The damaged brain becomes more irritable, electrically, than a healthy brain. Epilepsy follows in slightly more than 15% of moderate to severe (Mayo) TBIs. To begin with, some slight confusion, the seminal Annegers1998 epilepsy paper, to which most refer, used a different scale of severity – it preceded Mayo by nearly a decade. The differences are not important here but are sometimes used in an argument.
Annegers ‘severe’ equals, more or less, Mayo ‘moderate-severe.’
The Annegers paper measures outcome, in terms of epilepsy alone, rather than any more detailed assessment.
I find the Annegers paper easy to understand. At around 20 years post-injury, some 17 in 100 severe TBI cases suffered a seizure. 83 in 100 did not suffer a seizure.
In other words, in basic statistical terms, the Cumulative Probability at 20 years post-injury, that is of a seizure following any substantive injury to the brain, is around 17%. You can see this in Annegers Figure 1.
Most seizures will be treatable with modern drugs.
Arguments follow when experts quote the data above in terms of their perception of ‘percentage risk’. Risk is an emotive term. For example, a surgeon may tell a patient that an operation is ‘low risk’ when the complication rate is 0.5%. Taking that figure in other situations, one in 200 (0.5%) appears to me to be ‘high risk’– for example, being attacked in the street.
I tend to quote statistical data in the terms stated in a research paper, rather than my interpretation of them.
Dementia following a TBI
Dementia is common in the normal population in later life; some 10% have some degree of cognitive impairment at the age of 80.
It would seem obvious that if the brain has been damaged, following any substantive TBI and cognition remains affected, then in later life one would expect a higher incidence of dementia, than in the normal population.
In other words, when the ‘cognitive reserve’ of the brain has been diminished, an additional degenerative process (e.g. Alzheimer’s) will become more prominent. It is like arthritis developing in later life following a poorly-healed injury to a joint – it’s obvious, not science.
Several studies have demonstrated this expected increased incidence of dementia following a TBI. The issue and the legal argument is about the percentage incidence, and sometimes the degree of dementia.
Here, there are wide variations in opinion, ranging from “…it doesn’t really matter…it’s so small…” to a “…60% increase in dementia following a head injury…” I disagree with both. Many hours and thus great expense are still devoted to this.
My position is in the middle ground and agreed by some but not all neurologists. I vary my text, but indicate that:
“…my view, shared by many neurologists, but not all, is that there is not enough evidence from the literature to confirm that there is a significantly increased incidence with numerical data that can be applied confidently, during a period later in life, to an individual case, such as this one…
“Dementia is a common condition of old age, as is well-known. Multiple contributing factors are well-recognised, one being a previous TBI…”
There have also been Court judgements. One appears, to my mind, at least in part, not to accept some of the published data… “but that is outside my field of expertise.”
III. Non-organic complaints, including functional neurological disorders (FND) – faking/feigning/malingering
This IS a minefield, or at least a pond with muddy water – a topic for a later date, perhaps.