BRAIN INJURY

 

Brain injury is a major societal problem.  The costs in the UK are estimated at many billions of pounds each year   There is often devastation to the injured individual and their family.  The patient journey is far from straightforward and often complex with a lack of resources in the UK.  When litigation is involved, these complexities are magnified but often in my experience it is the intervention of both the Claimant’s legal team and informed insurers who initiate appropriate rehabilitation and ongoing care. Many people just fall through the net within our NHS which seems to have neurological ravines rather than holes within it.

 

Definition

Traumatic brain injury (TBI) occurs when a sudden trauma from external mechanical forces damages the brain and disrupts the normal function.  Brain injury is not the same as head injury. The latter may not have underlying neurological consequences.  With a severe TBI, cognitive, memory and executive functioning difficulties will emerge as well as psychological, emotional and behavioural challenges.  Assessments within the medico-legal process require the evaluation of how these particular parameters evolve and most important the actual or likely outcome.

 

Mechanism of primary injury

Brain injury occurs because of an initial contact which tends to injure the scalp, fracture the skull and generate surface contusions.  It may lead to bleeding around  or within the brain.  There will also be rotational and so-called acceleration deceleration injury which tends to generate shearing and compressive strains on the brain.  This type of injury predisposes to bleeding within the skull and brain, more diffuse vascular injury and also a tearing of the cranial nerves and the pituitary stalk that would lead to endocrine or hormonal difficulties.  The term brain contusion is frequently seen on imaging reports.  This refers to a swollen brain often with bleeding within.  The front part of the brain, particularly the inferior surface of the frontal lobes, the brain around the so-called sylvian fissure and the infero-lateral aspects of the temporal lobes are the most vulnerable because of the way the brain sits within the skull.  Where there is bleeding, brain may be damaged directly or secondary to compression or by damage to the blood supply.

Bleeding within the skull can be extra-dural, sub-dural, intra-cerebral and subarachnoid depending on the site where the blood vessel has ruptured.  A further term frequently used is that of diffuse axonal injury.  This represents microscopic damage to the brain and often will not be seen on even the most sensitive imaging though early MRI brain scanning is more likely to detect. 

Secondary brain injury may occur from soon after the accident or hours or days later depending on how the brain reacts.  The brain may swell as a non-specific reaction to brain injury.  Cerebral blood flow decreases with increase in the intra-cranial pressure.  A whole range of metabolic responses are triggered including release of so-called excitatory amino-acids which in turn produce an inflammatory response which produces further injury.  If a blood vessel gets torn, then cerebral infarction may also occur, the extent of which will depend on the vessel.  Each of these concepts and anatomical points could be the subject of its own article.

 

Classification of brain injury

The usual classification would include blow to the head, mild TBI, moderate TBI, severe TBI, very severe TBI and catastrophic TBI.

 

How do we measure severity?

Neuroscientists use a number of observations to assist in the determination of brain injury.

 

i)       Glasgow coma scale

 

The Glasgow coma scale (GCS includes observations opening, motor responsiveness and verbal response.  The combined scores at best reach 15.  The lowest score is 3/15.  Although it is assumed that scores between 3-8 indicate severe TBI, 9-12 moderate TBI and 13-15 mild TBI, in practice more severe brain injury can occur with higher scores. 

The GCS was originally designed to help junior doctors and nurses assess injured patients in a simple way that enabled efficient hand-over to colleagues working following shifts.  It was not designed as a prognostic measure although there is some association. 

 

ii)      Loss of consciousness

 

The duration of loss of consciousness is I think a better measure of severity of brain injury but there can be difficulties in the definition of consciousness outside this brief article.

 

iii)     Post-traumatic amnesia

 

If there is controversy about the extent of loss of consciousness, the commentary about post-traumatic amnesia makes that discussion look easy. 

Many, if not most, patients after brain injury will have no memory or knowledge of what happened at the time of the accident, a variable period of memory before the accident known as retro-grade amnesia and then a variable time after the injury called post-traumatic amnesia (PTA).  It is usually agreed that PTA ends when there is clear and continuous memory. This does not mean video memory.  In normal life, we only remember snapshots of past experience and do not experience a video replay.  This is obvious lay experience.  Just think of what you did yesterday.  Snapshots of memory reflect a normal memory process, not an injured memory process.  It is the extent and consistency of those snapshots that may mean that an individual remains in post-traumatic amnesia or has not fully emerged from it. For instance, if you think about a major event in your life be it pleasant or unpleasant, then if anything, memory is enhanced during that time.  If with apparent preservation of consciousness and no use of drugs, there is diminished awareness of what has happened, then that may imply that the individual is in a state of post-traumatic amnesia.

Even this rule can be challenged by what is known as sensory overload.  It is possible for instance to have no immediate awareness of a very unpleasant accident or injury with preservation of consciousness because of what is regarded as a state of sensory overload and the brain not being able to store memory for that moment or a short period of time.  That however should rapidly resolve with memories then being laid down unless there has been a significant brain injury.

It is also known that severe injury itself without brain injury, severe pain, psychological and emotional difficulty, hypoxia and hypotension, let alone the administration of analgesic and sedative drugs, will have a major impact on the laying down of memory.  If general anaesthesia is required for concurrent orthopaedic or abdominal injury, then that will also impact. 

The period of post-traumatic amnesia has become increasingly contentious in legal practice whereas clinically it is often remarkably straightforward.  How many snapshots of memory are consistent with post-traumatic amnesia?  The answer is not known! 

On the whole, the longer the period of loss of consciousness and post-traumatic amnesia, then the more severe the brain injury.  In the UK, a mild TBI reflects mental state change or loss of consciousness less than one hour (in the US less than thirty minutes).  A moderate TBI one hour to twenty-four hours (in the US thirty minutes to six hours).  Severe TBI greater than twenty-four hours (in the US greater than six hours).

 

Other important factors

The presence or absence of focal neurological signs, early seizure activity, the presence of subarachnoid blood, the development of hydrocephalus and changes on early CT brain scanning (which is often done for practical and logistical reasons) rather than MRI together with later MR scan changes will all assist in the determination of the severity of brain injury.  Late neuropsychological assessment will attest also to the outcome of that brain injury which is discussed later.

 

Subtle brain injury!

A small group of people influenced by the legal process are trying to pull the wool over Judge’s eyes and trying to introduce the concept of “subtle” brain injury.  They perceive that the concept of mild TBI is insufficient for their clients and coerce Courts into believing that neuroscientists on a worldwide basis have just got it all wrong.  Sadly, an equally small number of “experts” have rallied to this cause giving opinions that leave most of us in the world of neuroscience somewhat bemused.  These opinions are being given without any scientific basis or evidence to support the view.  If we already know that mild traumatic brain injury is a real phenomenon and well defined and the outcome of mild traumatic brain injury has been extensively investigated with 95% of patients making an excellent recovery, then what purpose can possibly be achieved by creating another category of brain injury.  This category is then supposedly meant to generate a wide range of neuro-cognitive deficits which mean that the litigating individual is able to claim very substantial sums of money even though all tests are said to be normal.

The arguments used within this sub-section of the legal profession goes something like this:  Doctors are no good at assessing brain injury.  They do not have the ability to take a proper post-traumatic amnesia history. It is in the setting of poly-trauma or other injury that the brain often gets  forgotten.  Only certain people the professional skills to diagnose subtle brain injury and for some reason these people are always Claimant instructed.

It is scientifically well established that certain symptoms such as headache, memory loss, difficulty with concentration, change in personality and mood and some emotional problems are highly prevalent in a population of people with any injury without brain injury.  These symptoms are also highly prevalent in the normal population when asked.  These symptoms do not mean that there must be a brain injury. The lawyers involved in this subterfuge tend to attack the experts rather than examine the science.  This concept is mistaken and although it is true that brain injury in the setting of poly-trauma being looked after by non-neurological colleagues is under-estimated, this is not because of anything subtle.

The term MTBI encompasses these people and as mentioned above, the range of symptoms thought to be specific indicators of brain injury, are not at all specific and   I would advise that anyone involved in brain injury assessment should read the volume by McCrea (2008) which deals with this in detail.  This volume also demonstrates that the prognosis of MTBI is excellent in the vast majority of people.  Telling individuals that they have had a brain injury or that they have significant residual consequences of a brain injury when in fact they do not, or at least have no structural negative outcome, is I perceive an act of medical negligence as the fragile personality will readily adopt the sick role rather than get on with the normal life that could be achieved with appropriate positive rehabilitation. 

What I would do is challenge those who perceive that there ought to be an extra category of brain injury to produce solid scientific evidence and case-controlled study material to support their notions.  I would happily discuss this evidence and consider it within the Neurosciences Peer Supervision Group to which I belong and who I know hold an identical opinion to myself.

 

Outcome

I personally think that the outcome of brain injury is the most important measure.  There is the so-called Glasgow outcome scale which is fairly basic, a five point scale ranging from dead to good recovery.  Background education seems to give a better outcome.  There is a functional independence measure (FIM).  There is also a disability rating scale.  Clinical assessment by a neurologist, a neuropsychologist who measures cognition, memory and executive functioning and a neuropsychiatrist discussing the emotional, behavioural and psychological difficulties usually allows for an accurate assessment of how the brain has been damaged and what the likely outcome would be.  The biggest difficulty lies in the assessment of so-called frontal lobe damage as the tests done by the neuropsychologist although helpful, do not mimic what happens in real life which as we all know can be complex, uninviting and sadly increasingly complicated.  I think most of us would agree that modern technology and the interaction with the living process has in fact done little to make life easier and the frustrations that we all have in daily living will be multiplied for the brain-damaged individual whose emotional, psychological and behavioural responses will often be vulnerable for many years into the future.
Having reflected in a cautious way about the symptom load with some people with mild TBI, it is important to emphasise that some people do badly with even mild TBI for reasons that are poorly understood.  In clinical practice, I find that even these people will in reality recover with the appropriate support, pharmacotherapy and multi-model rehabilitation.  For severe TBI, the situation is different.  Residual neuro-cognitive, memory and frontal executive dysfunction together with emotional, psychological and behavioural change leads to life-long functional handicap.  The identification of the extent of the disability and change in life is the responsibility and Court appointed duty of the assessing experts.  Neurologists in clinical practice will usually be both assessor and conductor of an orchestra of professionals who will report on their particular expertise.  This group includes neuro-psychologists, neuro-physiologists, neuro-radiologists, pain specialists, rehabilitation expertise, physio-therapy, occupational therapy, speech therapy and case managers (previously social workers).  Neurologists are used to handling all the data that emerges from such people in clinical practice particularly when they have been responsible for the acute and sub-acute care of those who are brain-damaged or in fact suffer from        a whole range of neurological diseases.

 

Consistency of severe TBI

Most people with severe TBI have a remarkable consistency in how they present.  Rarely do these people have “good days and bad days”.   Often severely damaged people have very few symptoms. There may be problems identified by their close family but it is uncommon in my experience to find lists of dozens of complicated symptoms. That situation is far more likely in the domain of mild TBI.  In a way, the brain needs to be working properly in order to generate such a wide range of symptoms.

It is an interesting reflection that a study looking at non-valid testing results in neuro-psychometric testing showed that under those circumstances, this was more likely to occur in the setting of mild TBI rather than severe TBI.

In severe TBI, the previous potential is often never achieved and every aspect of the victim’s life is diminished including work, leisure, social and relationship skills. This consistency within severe brain injury is akin to the consistency one sees for instance when an individual has suffered a complete transection of the spinal cord.  Those individuals will never be seen walking normally or in fact doing anything below the level of the spinal cord injury including loss of bladder, bowel and sexual feeling.  This is a different situation to those with say “whiplash” injury, chronic fatigue syndrome, fibromyalgia, chronic pain in any part of the body and mild TBI to name    a few of the controversial hot-spots of medico-legal assessment where under some circumstances, and often in the setting of video surveillance, these individuals seem to be able to function in a perfectly normal way.