Friday, 24 January 2014

Neuroscience and the Nature of Brain Injury

As I reported in yesterday's post, over Christmas we heard the news that Michael Schumacher had been involved in a skiing accident, and had suffered a serious brain injury. To date, Schumacher is still in a medically induced coma - prompting some media speculation that Schumacher might be in a 'vegetative state'.

During my year on placement, I had the chance to learn a lot about disorders of consciousness, and I worked with a few patients. As neuroscience and motorsport are two of my interests, I feel I should provide more information about why Schumacher is not in a vegetative state, and why this situation is different from the common media 'knowledge' being bandied around recently. At this point I should state that I will not be speculating about Schumacher's condition - the only people who are in any position to comment are those directly involved in Schumacher's care. Any news that you hear from anywhere other than Schumacher's medical team, his manager or his family is just speculation. Unfortunately, the media does like to jump over things like this, and so I feel compelled to give a brief overview of the science behind Schumacher's condition.

First off, let's be clear, Schumacher has suffered a serious head injury. Brain injuries of any sort are bad news, and we simply don't know enough about the brain and how it recovers to say how long and how much Schumacher will recover. As I stated before, this information is only going to come from Schumacher's medical team, and may not come for some time.

Despite Schumacher wearing a helmet, the impact caused a bleed in and around his brain. To understand why this is serious, it is important to realise how the brain sits inside the skull. The brain is an incredibly soft organ, surrounded by membranes and fluid. It also sits on the brainstem and spinal cord, meaning that despite the 'packaging' around it, the brain is subject to movements. On heavy impacts, the brain can bounce forwards and backwards, hitting the inside of the skull (these are called 'cou' and 'contra-cou' movements for those of you with a technical mind). The inside of the skull is remarkably rough, causing tears and, ultimately, bleeds.

You may recall that initially, Schumacher was reported to be conscious and lucid at the scene of the accident. It was a surprise, then, when it was later reported that he was in a critical condition. The reason this was the case was due to the increase of pressure inside the skull. As the bleeding inside the brain increases, the pressure on the brain also increases. The fluid can't move fast enough, and eventually presses down on the brain, and it is this that can cause the loss of consciousness and symptoms of brain injury. Don't forget that the brain is remarkably soft, and is very sensitive to pressure and damage of this kind.

So, Schumacher underwent surgery to relieve the pressure on his brain, an operation known as a craniectomy. Once the pressure came down, some sort of stability could be approached. However, Schumacher had to be placed in a medically induced coma, and he has remained in this state for some weeks now.

This medically induced coma is perhaps the source of the speculation that I read today, that Schumacher is in a vegetative state. So, to dispel this idea, let me explain in simple terms what consciousness means (well, I shall do my best at any rate).

Alright, I'll admit at the start that neuroscientists still aren't entirely sure why we have consciousness or what it is precisely. However, there is an easy way of classifying consciousness which can be used in clinical contexts, and it is this definition to which I will stick. In these terms, consciousness is made up of two concepts: wakefulness and awareness. Wakefulness is pretty much what it says it is: the extent to which someone is alert and able to respond to stimuli. Awareness is more linked to content: the subjective experience of things around us, being aware of who we are and what is around us. While wakefulness is necessary for awareness, the levels of each may vary. Thus, we can be wakeful without awareness, unawake and unaware, or wakeful and aware. It is in these terms that different disorders of consciousness may be defined.

In normal, healthy individuals we are both wakeful and aware (well, when we're not asleep anyway). The same applies to individuals who have locked-in syndrome (a condition in which individuals are unable to respond to stimuli due to paralysis, but nonetheless awake and aware of their surroundings).

By contrast, individuals in a coma are unawake and unaware. This goes beyond normal sleep, in which individuals can be woken. No stimuli can wake someone in a coma, they may only show reflex movements and their brain activity is generally depressed (although this may vary). Comas can last any amount of time, and may have different outcomes. What we must remember though is that Schumacher is in a medically-induced coma. While the same features are present - unawake, unaware etc. - this is more linked to anaesthesia, rather than a result of problems within the brain. Individuals in a medically-induced coma are placed in this state deliberately, to slow brain functioning and allow the brain some time to recover. The healthy, waking brain requires a huge amount of energy, and by slowing its function in a medically-induced coma it is hoped that recovery may be more successful. These medically-induced comas are controlled, unlike a normal coma. Physicians are able to lighten the sedation and test the brain's functioning when they deem it necessary. However, the amount of time this takes does still vary, from a few weeks to upwards of six months. Currently, Schumacher has been in this condition for almost a month, so it's definitely not the time to start losing hope.

Now, when coming round from a 'true' coma, it is impossible to say how complete this recovery will be. Some patients are lucky enough to gradually return to a normal level of consciousness, recovering their wakefulness and awareness. Others may linger somewhere in between. These conditions are disorders of consciousness and include vegetative states (now also termed 'wakefulness without awareness' or 'unresponsive wakefulness syndrome') and minimally conscious states.

When people think of vegetative states, they think of individuals in a coma for an extended period of time. These states are not the same as comas, and patients who are in this state are not 'vegetables' (hence the shift away from this term in the scientific literature). For those in vegetative state (herewith called VS), sleep-wake cycles may be present. Thus, they possess wakefulness. However, awareness is limited. Patients may respond to some stimuli, beyond simple reflexes, but they are not completely aware of their surroundings or sense of self. After one month of being in this state, patients are said to be in a persistent VS - something which Schumacher has not yet approached. After three months, if there has still been no change in this state following a traumatic brain injury (Schumacher's injury type), patients are then deemed to be in a permanent VS (although this term is too being debated, as patients have been found to recover months or even years after this).

For those patients who regain more of their awareness, a minimally conscious state may follow. Wakefulness is intact, as with healthy individuals, however awareness is still patchy. In some cases, patients may be able to respond to questions or simple commands, however this response is inconsistent and thus individuals may not have complete awareness. Like VS, this state may continue for years, and there is no predicting how much someone may subsequently recover.

So, the upshot of all this is that Schumacher is not possibly in a VS at this point. He is still in a medically-induced coma. While it can be argued that the longer someone is in a coma, the worse the prognosis, it's also good to remember that this is still a medically-induced coma, and this is different from a disorder of consciousness per se.

What we do have to remember over the course of Schumacher's recovery is that brain injuries are difficult things. Individuals with brain damage are, unfortunately, subject to a number of conditions and changes, and this often depends on the sites and the extent of the damage. As I stated before, I am in no position to make predictions. In all likelihood, neither are the medical team in this case. Brain injuries are a waiting game, and it takes an enormous amount of time to make progress. Aside from all the cognitive conditions which may arise from a brain injury, it's not unusual for individuals to experience changes in personality and demeanour. A recent article citing Dr Richard Greenwood at UCL stated that Schumacher may not be Schumacher if and when he recovers. Life will be profoundly different for Michael, even if he makes an apparent 'full' recovery. The brain is a remarkable thing, and I don't believe it's ever impossible for individuals to recover. However, changes are normal, and this is something that Schumacher and those close to him will have to adapt to. All the F1 community and media have to do now is let the medics work in peace. Uninformed speculation about permanent vegetative states and chances of recovery are useless and unhelpful, and I hope by writing this I can dispel some of the latest nonsense. Now all we can do is wait.