This helmet cam stuff

Those of you who follow me on Twitter might have seen, in between the (well-deserved) rants about Putin, a long series of tweets about helmet issues. These were in answer to @jameyprice, who I’d like to thank for “inspiring” this. It’s something I meant to get to anyway, and I think the time is right.

But before we get to that (oh I should be in advertising) I also wanted to say that I read every comment any of you post. In detail. There are tons that I’d love to answer, and that deserve an answer for any of a number of reasons. I just don’t have the time! I’ll probably make notes and then blog answers in one fell swoop.

Don’t even think about asking about fell swoops. I have no idea what they are.

So. The question is whether having a helmet cam made the impact more severe.

I believe it was concluded that the camera had no influence on the severity of the injury. I will admit to not having read the report. But I’ll tell you what I know about this aspect of helmets. It also helps to understand a bit more about the mechanisms of head injury.

If we confine our analysis to linear forces, I think it’s reasonable to conclude (if the attachment was via suction cups, double-stick tape, etc i.e. a NON-invasive attachment) that the camera probably didn’t significantly weaken the helmet. The camera no doubt broke away on initial impact.

That said, I think it’s important to understand some of the more subtle problems with helmet appendages . . . of any kind.

Almost any interaction with its environment will make a helmet, and the head it contains, turn. Now this may only be a very few degrees, but the point is that the turning movement is an acceleration. Imagine an open wheel car having an angled frontal impact. The driver’s head pitches forward and to the side. As it contacts the cockpit side rest, an ANGULAR ACCELERATION , measured in (I think) radians per second per second, is produced. Since the head turns in a very short timespan, it all means very high acceleration. It’s intuitively obvious that any part of a helmet which increases interaction with the environment also increases angular acceleration (frictionally as in the example above, mechanically as with a helmet cam hitting a rock, or aerodynamically with the various aero appendages on modern racing headgear).

Why is this important?

Let’s take two nested tupperware bowls, put some foam between them. Oh yeah – the inside bowl contains jello, covered with some cling film. Let’s turn them over, and jam it all onto a piece of broomstick. Outer bowl =  helmet, inner bowl = skull. Jello = brain, and, yep, the broomstick is the brainstem.

Now we’ll grab the outer bowl, and twist it about 10° REALLY fast.

The “helmet’s” motion is coupled to the “skull”. The coupling is neither instantaneous nor perfect. The weight of the helmet’s contents cause some delays, as would any degree of slippage of the helmet. No matter.

Once the skull bowl has begun turning, the jello does too, but with another lag, And then, the jello brain transmits rotational energy to the broomstick brainstem. And again, there’s a lag. If you imagine some orange slices INSIDE the jello (thanks mom!) you can even imagine this kind of differential rotation occurring within the brain itself.

Each time contiguous structures are rotating at different speeds a SHEAR force is created. Shear forces are exactly what they sound like – forces acting parallel to each other but in opposite directions.

What’s shear doing at the skull-brain interface? Well among other things, it causes hematomas by tearing delicate veins running right there between the skull and the brain. That’s bad of course, for all the reasons we’ve spoken about in previous posts. Unfortunately, this can also happen WITHIN the brain itself, at areas of differing structural properties. And again, tearing of nerve tracts and blood vessels can occur in these areas. Damage and intracerebral hematomas result.

Worse still is what happens at the interface of the brain with the brainstem. Remember that the brainstem, in addition to maintaining and regulating the vital functions (breathing, blood pressure, etc), also sets up awakening and arousal of the brain. When rotational acceleration causes damage here, it is often devastating. Basically, these patients don’t wake up.

Because of how dramatically they contribute to the severity of head injury, helmet interactions with the environment, and the rotational acceleration they induce, need to be considered when designing a helmet for a specific purpose.

I cannot possibly know to what extent any of this contributed to Michael’s injuries. I, like most of you, am very preoccupied by the silence from Grenoble.

You guys are pretty amazing

Wow – if I was amazed before at your comments, I’m totally staggered by all the feedback from the previous post. I’m staggered by the depth of your thought and reflection, by your eloquence, and by your willingness to sit down and join the conversation.

You’ve made me realise I was certainly too strong in my criticism of the current comms policy. You’ve probably noticed this is a bit of a character trait! I’m exquisitely sensitive to the unimaginable situation Michael’s family and friends are in, and if I could think of how giving us SOME information would make their lives in any way worse, I would reverse position immediately.

I do feel strongly that there’s an implicit contract, whose terms are negotiated in real time, between celebrities and their public. Paparazzi can take and publish pictures of celebrities during “private” moments that they can’t take of any of us. That’s been established as a legal principle. The line they and others either respect or step over is also defined in real time, by judges, juries, and by societal mores. But it seems a bit one-sided to want the benefits of celebrity yet retain all the perquisites of a full private citizen outside of, say, the circuit. Once again, I don’t mean this to say that all discretion, all privacy, are sacrificed to the altar of the public’s obsession to “know”, but simply that there’s a line, a very squiggly changing line, that needs to be plotted.

Once again, thanks so much for taking the time to write. I’ve learned so much, and been forced to think so much, from your input. That’s exciting and sobering, and is an immense privilege.

Frank – you’re gone coz no matter how strongly you feel about anything, this isn’t the place for vitriol. Tone it down, and read these comments before writing – smart, well thought out, passionate. You can call ME whatever you want; I’ve heard it before and will certainly hear it again. But don’t even THINK about insulting my readers.

Perplexity

I’ll admit to being perplexed.

First, about the silence from Grenoble.

If you’re not in the habit of reading the comments section after each post (I do, of course – it’s wonderful to see what those of you who read me think, and a source of wonder that you’d actually take the time to write), it’s worth a look (in chronological order) at the comments to my last entry.

It’s pretty clear that Michael’s fans are beginning to feel like their devotion, commitment, and passion for someone they’ve elevated to hero status over many years means nothing. I see strains of anger, disappointment, frustration. Others, with considerable self-abnegation, are hewing to “respect for Michael’s privacy” and accepting the lack of information with equanimity . . . but even here there is an undertone of frustration at being asked to do so.

I’m not a journalist, and I’m not a PR/communications professional. But I totally fail to see how the current comms policy helps either Michael or his family. I fail to see how talking to us about the significant ups and downs of this long hard process damages Michael’s privacy or makes Corinna and the kids’ journey more difficult. I cannot possibly understand the reasons for any of this. I’ve said it before, and I’ll repeat it. This is totally unfair to the people who made Michael the celebrity he is. The people who vibrated to his victories, and were saddened by his defeats. They deserve to be told something. I didn’t say it’s their right to know (although jurisprudence places looser limits on celebrities’ “privacy” than on that of “normal” citizens); rather I said they DESERVE to know. Why on earth is their pain not being considered? How is keeping the millions of fans in the dark helping ANYTHING?

I’m also a bit perplexed about this latest thing in FOCUS.DE about re-starting the sedation. First of all, the article is rather remarkably poorly written. That, plus a singular lack of content make it useless, and surely not even worth wasting one’s time reading.

With no knowledge of Michael’s current clinical condition, it’s impossible to say why he would be re-sedated at this stage. Generically, any situation requiring a still, tranquil patient might raise consideration of reinstating sedation. This could be, for example, respiratory deterioration that requires a new period of mechanical ventilation. It could mean that there has been a change in his neurological status, with perhaps some signs of agitation, or a systemic infection originating in one of the several catheters still present. Again, we have absolutely no idea.

Right now I’ve really only one question (that predates the re-sedation issue). Has Michael been weaned from the ventilator?

As I’ve mentioned, once the sedation was stopped, the next big step physiologically speaking was respiratory weaning. This appears to me to be a piece of news that is unequivocally good, and therefore I cannot imagine it being held from the public. Imagine having heard Sabine say “I’m happy to say Michael is now breathing on his own”. Once again, if he HAS been weaned and we’ve not been told, then this is a shameful and arrogant neglect of his fan base and the public.

If on the other hand Michael is still dependent on the ventilator, it’s important to look at why. In this case, that of a young and (remarkably) healthy man with a high probability of brainstem lesions, damage to the respiratory centres would be high on the list of reasons.

Damage to the brainstem can be associated with numerous clinical presentations. It is where breathing is controlled. As important, the brainstem contains structures that play a vital role in waking the brain and maintaining wakefulness and attention. It’s also where the nerves to and from the face (for hearing, sight, taste, feeling and movement) enter the brain.

With sufficiently widespread damage to the brainstem, the patient shows no sign of awakening, and remains ventilator dependent. This is obviously a devastating situation. Brainstem injury is suspected based on the clinical status of the patient, and is then sought using imaging, especially MRI scanning. The actual function of the brainstem can be interrogated using several techniques, including what are called “brainstem auditory evoked potentials”. This involves placing headphones on the patient and playing a series of several thousand clicks through them. Then, sophisticated software is used to detect, embedded within the electroencephalogram, the passage of the sound information through the brainstem (where it enters and undergoes initial processing).

Let’s cut to the chase.

If Michael is not breathing on his own, and is (as we suspect) not showing signs of purposeful interaction with his environment (I am ignoring the mouth movements of which Felipe Massa spoke), AND if there is imaging and functional evidence of extensive and irreversible brainstem damage, Michael’s doctors will discuss withdrawing treatment with the family, as under these circumstances there is essentially no chance of recovery. It is possible that this discussion has already happened.

If Michael is breathing on his own but still not showing purposeful interaction with his environment, then patience is still very much in order. Remember that at one month post-sedation, persistence of this state means roughly a 50% chance of awakening, with the quality of that awakening an open question. This falls to 20% at six weeks (three weeks from now), with a larger portion of these patients having severe functional handicaps. And at one year, essentially no one still comatose wakes up.

Lastly, if Michael is breathing on his own AND showing signs of meaningful interaction with his environment (I very much hope, but very much doubt that this is the situation), then a certain number of people should be ashamed of themselves for denying this good news to his fans. If there is indeed progress and good news ready to be told, then the current comms strategy will go down in the annals as among the most ill-guided, unprofessional, and hurtful in the history of Formula 1 PR.

What should we be thinking now?

It’s just about two weeks since the team caring for Michael Schumacher stopped administering sedatives in order to allow him to emerge from the pharmacologic part of his depressed consciousness. Where are we now?

As usual, a few caveats. I am not receiving medical information from Grenoble. I am basing most of what I say on experience-related conjecture, as well as cautious interpretation of whatever is leaking from the hospital. This obviously means that it all needs to be taken with a rather large grain of salt!

I’m assuming, taking as axiomatic, that if there was significant good news we would be told. Despite the totally understandable need of Michael’s family for privacy and “space”, Michael is a public figure, admired and revered throughout the world. It’s the public who largely made Michael the hero he is to so many. If my assumption is wrong, if there has been a decision to effectively embargo all news, then I think this is somewhat unjust, unfair, and maybe even a strategic error in terms of communications. What’s more, it automatically means the only “information” we get is from leaks.

I’ve heard that the hospital staff is warned every day about protecting confidentiality. This is normal – but so is a passing comment made by a staff member to a friend or family member (prefaced of course by “you mustn’t tell anyone” and relayed in turn to another, trusted person, but still preceded by “you mustn’t tell anyone”) that then gets relayed to a journalist, hungry for anything to write. This is usually a tabloid, as only they would publish such unconfirmed stuff. So in the current state of affairs, I’m somewhat inclined to accord Bild’s latest output “there’s rarely smoke without fire” status. For what it’s worth.

First, as to the “gradual” reduction in the sedation.

In terms of the pharmacology of ICU sedation, we tend to use drugs that are eliminated quickly. This is to allow rapid adjustments in the level of sedation. Several drugs fit the bill; the actual choice depends on local practice, patient characteristics, and the objective of the sedation. 

I’ve seen one article that implies that Michael was sedated using anaesthetic gases. It correctly points out that after prolonged administration these agents take considerable time to be eliminated. It is almost certain that these were NOT used. While some ICUs (as opposed of course to operating rooms) use anaesthetic gases, it is rare, requires special equipment, and has numerous drawbacks. And IF anaesthetic gases were turned off two weeks ago, well there’s none left ANYWHERE in Michael’s body, for over a week now. So much for “coaxing the last molecules” from his body, as I saw written somewhere!

As I’ve mentioned, it’s quite possible (in fact highly likely) that a long-acting agent (a barbiturate) was used as a sedative during the period with what appears to have been dangerously high and resistant intracranial pressure. These agents would almost certainly NOT have been administered for more than 5-10 days at the beginning of Michael’s care. They would simply have been stopped, not weaned, and another agent (or agents) with much shorter actions would be started. In a young fit patient with normal liver and kidney function (certainly the case with Michael), the barbiturates would have been cleared within three to five days – but remember, shorter acting agents were started when the barbiturate phase stopped. These agents have such a fast on/off that they have to be administered continuously (by carefully calibrated pumps). This phase of sedation would be based around either propofol or a cousin of valium (a benzodiazpine), usually with a low-dose infusion of a morphine relative.

When the time has come to stop the sedation, it is usually just . . . stopped. I mentioned this in my previous blog post. Any problems along the way are usually cause to re-start the sedation, and make another attempt at stopping later. It is very rare that the first attempt succeeds. That said, it is two weeks since we were told that the sedation was being stopped. I think it’s a very fair assumption at this point that sedation has been stopped sufficiently long for there to be no residual pharmacologic effects.

Still with me? I never fail to amaze myself with just how wordy i am . . .

If my assumption is correct as to sedation, the next question I’d ask would be about ventilatory support. I hope Michael is breathing unassisted at this point, through the tracheostomy that has no doubt been placed two or so weeks ago. This qualifies as some of the good news I spoke about above. If Michael is indeed autonomous from a respiratory point of view, it’s a milestone. And one about which I think you deserve to be told. Again, I assume that this has been accomplished. If on the other hand Michael cannot be weaned from the respirator, especially if this is because of lack of ventilatory drive, this is more than ominous. At this phase post injury and post sedation, this kind of strong evidence of severe brainstem dysfunction (especially if corroborated by other testing) would likely prompt discussion with the family about withdrawing support. I do not think that this is the situation. At least I truly hope not.

If ventilatory weaning has been successful, the next question one asks is what is Michael’s level of reactivity with the environment. It’s here that we need to think about the Bild report. 

The motor response of a head injured patient is one of the most important prognostic indicators. People involved in caring for head injured patients use a standardised scoring system (called the Glasgow Coma Score, or GCS) in order to do this. The motor component of the GCS has six steps. These range from obeying simple commands (stick out your tongue, put your thumb up, etc) down to no reaction at all. In between, on the way “down” from obeying, one sees progressively less organisation in the response. Makes sense.

So IF what Bild says is true (and I looked on their site summarily, but didn’t see where this was said), we need to figure out what they meant by “no reaction to external stimulus”. If there is no response at all to painful stimulation, not even archaic stereotypical responses organised deep within ancient parts of the brain, then this is very bad news indeed. This would likely imply extensive damage to the brainstem, and at this stage post injury would, I think, be associated with a patient who was also dependent on the ventilator, as mentioned above. I would simply note, as one of those things I wish I had never heard, that when the neurosurgeon spoke about hematomas “left, right and centre”, this is what I feared. The brainstem is one of those things in the centre… 

If the motor response to external stimulation is one of the primitive stereotypical responses, this is bad news but leaves hope of some level of recovery. Numbers? Well, this level of response would indicate the persistence of a vegetative state, but roughly 50% of these patients emerge, usually with some level of residual dysfunction.

To be honest, based on Bild I don’t think any other reactions (all of which are MORE organised than what I mentioned) would lead someone familiar with the care of these patients to say he’s not reacting.

Upshot: not good. Starting to be really not good.

Lastly, I spent three days last week teaching on a trauma course with a bunch of motorsport medicine mates. One of them is a professional neurointensivist. He works in one of England’s regional neurointensive care centres. They get 600 PATIENTS LIKE MICHAEL A YEAR. One regional centre. That means that we’re all just 2 or so degrees of separation from someone affected by this. So I really hope that more than just provide “information” about Michael’s condition, I hope my “head injury” blog entries sensitise us to this devastating society-wide plague.

Stopping the sedation!

Let’s be unambiguous about this – the announcement that Michael’s care team is discontinuing his sedation is the news we’ve been waiting for. It’s the first big transition – from acute, life-threatening head injury to subacute recovery. Followed no doubt, let’s not forget, by a chronic rehabilitation phase. But this is wonderful news.

In terms of how this is done, well it’s actually pretty simple. The electronic pumps driving the continuous infusions of the sedative drugs are turned off. That’s it. But doing that means that the people taking care of Michael have a reasonable expectation that he will not exhibit untoward reactions to the “stress” of these medicines being turned off. The most undesirable of these would be elevations in . . . you guessed it . . . intracranial pressure, but to be honest, we’re now more than four weeks post-injury, and I’d rather think that we’re past that.

So what will happen now that this stuff is turned off?

1) It may or may not be true that, in general, French neurointensivists maintain sedation longer than their Anglo-Saxon colleagues. It doesn’t matter. The people taking care of Michael know what they’re doing.

2) while it’s possible that a long-acting drug may well have been used in the early, “suppressive” phase of Michael’s care, it’s quite likely that if so, it’s been replaced with one or more short-acting substances. These usually allow signs of emergence to appear within several hours of stopping the infusions.

3) What actually happens? Well in general, the first attempt to stop sedation usually gets interrupted by something. The patient gets agitated, the blood pressure goes up, the oxygen saturation goes down . . . something. So you turn the sedation back on, let the situation settle down, and then either try again or wait until tomorrow. It often takes a few tries before everything goes the way it should.

How should it go? Well ideally Michael will start to want to breathe, and allow weaning from ventilatory support. And just as important of course he will hopefully start to show meaningful interaction with his environment. Following simple commands, visual tracking, etc.

Now I’ve heard (from unconfirmed sources), unconfirmed reports (double “unconfirmed” should ring alarm bells of course) that Michael has indeed already done this.

I’d love any neurosurgeons to jump in and comment, but if this indeed is true, it is fairly astonishingly good (but indeed totally conceivable) news. So we need to cross our fingers and hope something like this DOES get confirmed in the future.

Tell you what – let’s not talk about any other alternatives right now, ok, so we keep it positive.

One last thing.

I’ve seen some very heartfelt comments here and there about articles, tv pieces, and blog speculation “hurting” Michael’s family. I wanted to just weigh in for a second.

I’ve been pretty harsh with the tabloid press, and deservedly so. But not because the Daily Mail’s moronity hurts Corinna, Gina Maria and Mick. ARE YOU KIDDING? Could they possibly hurt more? And if so, is it likely to be because of the suffering induced by a British rag? Of course not. I think it’s detestable coz it’s shit “journalism”. I kinda don’t think it’s on Corinna’s reading list, I don’t think their “journalism” could possibly add to their pain, and lastly, Michael’s care team have no doubt been TOTALLY up front with the family. Meaning they have a better idea than any of us of just what the . . . hell . . . is up.

If I thought for a second that anything I’ve written might hurt Michael or his family, I’d not have written it. To be honest, I’ve spoken to you as I’d speak to Michael’s family. I assume you know that, because I think it’s to THAT that you’ve reacted (to my infinite astonishment), more than to the information that I’ve transmitted.

Catching up with questions and comments

I wanted to just reply to a few comments and questions that have appeared here and on Twitter. I’m very gratified that so many people have clearly been thinking about this stuff.

I think we can and should generalise what I said about ski helmets to just about any realm of activity where they are “counted on” to provide protection. Construction hard-hats, bicycle helmets, hockey, Formula 1 pit crews, etc. The injury patterns almost certainly are different in each endeavour, and each therefore probably needs a different helmet. In general, we can’t expect the end user to do anything except have confidence in the equipment he (or she, that’s assumed in all my blog posts) chooses to use, or is obliged to use. That means that those who supply those helmets need to have a good idea of exactly what sort of injuries they need to mitigate. Clearly access to an appropriate level of protection has to be monetarily feasible. I chuckle to hear national-level rally drivers complain about a €2000 helmet (before going out and spending more than that on a set of tires! Helmets don’t make you fast!). I assume that a top of the line ski suit costs at least €800-1200. So that’s a constraint within which the manufacterers will have to work. They’re smart people. They’ll figure it out if the data gets generated.

Measuring g’s at the helmet with accelerometers is interesting, but there are severe enough problems with coupling to the head to make this data almost unusable in terms of BRAIN g’s. The DoD, and the FIA Institute, have been working on earpiece accelerometers for some time. These incorporate tiny 1 x 1 x 1 mm triaxial accelerometers into the part deepest into the ear canal. While this should theoretically give robust values for BRAIN g’s, that’s not happened yet. IRL has used earpiece accels for a while now, but I’m not sure they’re generating clinically useful data . . . yet.

Several people have sent me clippings concerning the effects of fish oil. Apparently someone “woke up” a comatose child using mega doses of fish oil. The explanations given were something like, well the brain is made up of fats, and so we give this good fat and it’s anti inflammatory too. The problem is that the person who administered this treatment published his results . . . on CNN. He should have published them in a peer-reviewed journal. Call me old-fashioned, but in terms of TREATING (not experimenting on) human beings, good quality evidence is the way to be guided, not what you saw last night on Dr. Sanjay Gupta’s show. That said, were I to be the close relative of a comatose head trauma patient, and were i to be  convinced that the risk profile of this kind of use of fish oil was acceptable, it is entirely possible that I’d be willing to have a go. But at the moment, let’s be clear, this is closer to ritual incantation than to medical science.

Lastly, something that’s been bothering me. A lot. As a doctor who practices pre-hospital medicine regularly.

Here goes: why was Michael brought to the hospital at Moutiers initially, and not to a neurosurgical centre? I am not trying to second guess (ok, just a bit) my colleagues who landed there on the 29th of December . . . BUT

  • reliable witnesses report to you that the victim hit his head
  • the victim’s helmet has been damaged in the impact
  • there’s blood on the snow
  • there is obvious signs of an open head injury
  • the victim is agitated (in any event his behaviour is not ENTIRELY normal)

Now I’m sorry, but it doesn’t take a doctor to put this together and figure out, “hey this person may have a head injury”.

Thing is, it is a general principle of pre-hospital medicine to take a patient to the closest APPROPRIATE facility. In a given Emergency Medical System’s territory, if this is applied “conservatively” it pretty much ALWAYS includes, for example paediatric cases and potential head injury. Thing is, there’s no neurosurgery at Moutiers. Why then was Michael brought there?

This question needs to be answered. As devastating as the injuries produced directly by the fall are, any delay in proper airway control and neurosurgical intervention cause further damage and must be minimised.

I raise this point simply because local protocols should be reviewed, and adjusted appropriately, in order to optimise the time it takes to get head-injured skiers cared for appropriately.

What may be going on now, and where this might be going (long, speculative and detailed)

The Daily Mail has done it again. With today’s headline they’ve “forced” me to take to my blog to help clarify some of what’s being said.

As with everything that I’ve said, tweeted or written since Michael’s accident, I need to make clear that I have not seen Michael, not seen his scans, and not had any contact with the medical team caring for him. I’m going to base the following on what has been said by his care team, on the things that have not been said (by anyone), and on my clinical experience (and that of colleagues) with similarly injured patients.

What is likely happening now? Michael is almost certainly still in the Intensive Care Unit (ICU). I say this primarily because it is rather likely that he still requires this level of care given his injuries, but also because had he been moved from the ICU to a normal room, this would have been sufficiently newsworthy to have almost certainly been announced. If Michael’s breathing is still handled by a respirator, he will almost certainly have had a tracheostomy done. This is more comfortable for the patient, spares the patient from potential damage to the vocal cords, and can make weaning from the respirator easier. It can also be easily closed later, when appropriate.

More importantly is the question of the “artificial coma”. Now those of you who’ve been reading me since the beginning have no doubt noticed that I HATE the term “artificial coma”. It’s confusing and doesn’t transmit any useful information. Initially Michael was no doubt maintained at a VERY deep level of sedation, deep enough to virtually suppress most electric activity in the cerebral cortex (the outer layer of the brain, responsible for higher intellectual functioning). This was done to help manage what were extremely high and dangerous levels of intracranial pressure (ICP, see previous blog entries).

Now that the acute phase of the injury has largely passed, it is almost certain that ICP is no longer problematic. The swelling and bruising are being resorbed. This means that the sedation will certainly have been lightened. Remember that having a tube in the windpipe is a pretty significant and painful stimulus. So sedation is almost always needed to help the patient tolerate the tube, to allow mechanical ventilation, and permit all the other “aggressions” that are part of day-to-day ICU routine. If this is the case, then the care team will be repeatedly, and considerably, lightening the sedation, in order to start weaning Michael from the ventilator, and to allow neurologic evaluation.

This would be good – if the sedation is light, and if respiratory weaning (getting Michael to breathe by himself) is progressing, with a neurological status that allows this, then we can relax for a few weeks, and see how the situation evolves. This situation would mean progress has been made, and renders further prognostication impossible. Progress will continue at an unknown and unknowable speed, and will stop at an unknown and unknowable level of function.

It is also conceivable, at the other end of the “goodness” spectrum, that the sedation has been turned off, that Michael is tolerating the tube, but is neither breathing adequately on his own nor showing significant signs of emerging. You understand that tolerating a tube with no sedation implies rather severe problems with deep levels of the brain, as does the lack of adequate breathing despite stopping the sedatives. At three weeks post injury, this is the worst outcome we could hope for, as it would indicate a rather high probability that normal consciousness will not be regained.

A brief word about the terms “critical” and “stable”. First of all, as used with respect to the condition of hospitalised patients, neither is precisely defined. So it’s important to see them rather more like an impressionistic image than as an accurate statement of  physiology. Critical means imminent life threat or threat to a vital system. Stable means that something is not changing, and is usually being maintained within normal limits. So Michael is no longer CRITICAL (the ICP has normalised), and STABLE, as his physiological parameters are now acceptably “constant”.

Ok let’s get down to the hard stuff here. What are the possible outcomes? I’ll look at some of them, mostly with an eye to defining terms we’re likely to see thrown about in the near future, so that we can be precise ourselves, and be critical when faced with imprecise, ambiguous, or misleading information from others (are you listening Daily Mail?).

Now remember, all we know with certainty about Michael’s injuries comes from the press conferences given by his care team. After explaining the how and why of evacuating the right-side extradural hematoma (on the Sunday) and then the left-sided intracerebral hematoma (on the Monday), the neurosurgeon let slip a VERY telling statement.

I’m almost quoting him here, translating from the French. He said “don’t think that we evacuated two hematomas and that’s it”. “Michael has lots of hematomas in his brain, on the left, on the right, and in the middle”.

Damn. See, the “middle” is where all the important stuff happens – awareness, arousal, control of blood pressure, respiration, swallowing etc. And the left – well that’s usually language. Etc etc. The neurosurgeon, intentionally or not, painted a rather catastrophic neurologic picture.

First off let me say that it is EXTREMELY unlikely (I’d honestly say virtually impossible) that the Michael we knew prior to this fall will ever be back.

I think that it will have to be considered to be a triumph of human physical resiliency, and of modern neurointensive care, if Michael is able to walk, feed himself, dress himself, and if he retains significant elements of his previous personality. If recovery proceeds to this point (which is totally POSSIBLE, if perhaps rather improbable), it is an open question as to how well the “higher functions” (memory, concentration, reading, planning, etc) will recover. Please note, I would love to be proven wrong about this! 

At the other end of the spectrum would be continued coma. Coma is defined as a state where there is neither wakefulness nor awareness (the patient cannot be woken by stimuli), no meaningful interaction with the environment, and no voluntary actions. This is obviously catastrophic. This outcome is entirely possible based on what we know about the brain’s primary injuries (the fall, the hematomas, bruises, etc) as well as the relatively long period with high ICP.

It happens that patients in coma emerge sufficiently to show spontaneous eye-opening, and even sleep-wake cycles (demonstrating wakefulness or arousal), but show no interaction with the environment, and no signs of any higher function (thought, speech, etc). This is called a vegetative state. Definitions vary somewhat, but usually after four weeks it is termed a persistent vegetative state, and after one year it is called a permanent vegetative state. Very roughly speaking, about 50% of head trauma patients who are in a vegetative state one month after injury become conscious, often with significant neurologic impairment. If the vegetative state persists for six months, this falls to roughly 20%, usually with severe impairment. After one year, resumption of normal consciousness is very rare, and, when it happens, function is usually gravely altered.

Whereas a patient in a vegetative state shows no signs of awareness, a patient in a minimally conscious state will show definite signs of awareness of either self and/or of the environment. This may include obeying simple orders, some intelligible language use, or other behaviors that seem “goal directed”. Examples would be appropriate emotional responses, appropriate eye tracking, consistent and appropriate movement or vocalisation in response to language (not just sounds). These signs usually fluctuate through the day, and over time. Importantly, the chances of meaningful recovery from a minimally conscious state are higher than from a vegetative state. They are however, still disappointingly low.

There is certainly reason for worry – lot’s of worry. But no reason to lose hope. Everyone who works with head-injured patients has seen VERY severely injured patients (who were not expected to do well) recover acceptably. All we can do is wait, pray, and be behind Michael and his loved ones.

 

 

These recent reports

It seems an article in The Daily Mail has everyone concerned. I’m being asked what I think. Here goes.

I hope we’ve all been VERY worried since the first reports of Michael’s accident. That surely is the appropriate attitude.

The guys quoted in the online article I saw have taken care of patients like Michael. They have not, however, examined Michael, reviewed his scans, etc. Because their titles imply that these men are consummate professionals, I’ve no doubt that they made clear (much clearer than the Mail does) that they were speculating as to possible outcomes.

Because that is what they are doing.

Look, I think that we need to look at this speculation rather like the arrival time estimates of your satnav. Their initial estimate is based on some assumptions and statistics. Obviously, as you get closer and closer to the destination the estimate gets better and better. Duh.

It is highly unlikely that when Michael and his family are finished with hospitals, finished with rehab centres, he will be the same Michael we had known until that Sunday.

Having said that, which is admittedly saying very little that isn’t, unfortunately, painfully obvious, the range of impairment we may see spans the spectrum from mild sensory/motor/behavioral problems to more dramatic sequelae.

Once again, patience, long painstaking work by all concerned, and just maybe our thoughts, best wishes and prayers will be needed. Long periods with no news are perfectly normal, and will remain so. We will likely enter a chronic phase, punctuated by (hopefully) several steps forward and (hopefully) many fewer backward.

Evaluating depth of coma

While we are all being remarkably patient (we don’t really have a choice, do we?) as Michael’s injuries heal and his state stabilises, I thought it would be useful for what’s to come to explain a bit of how doctors evaluate coma patients. This includes assessing how “deep” the coma is, as well as tracking the patient’s progress as the clinical situation evolves.

Now I’m sure that Michael’s care team will NOT be releasing any of this stuff when they begin lightening his sedation, but I still think it’s useful that we have an idea of what’s going on, how it’s done, and that we can interpret any details that do manage to filter out.

Because by definition a coma is defined as a prolonged state of diminished consciousness making meaningful contact between the patient and his environment impossible, we can’t just ask the patient a series of questions and go from there. What’s needed is a tool to evaluate more basic levels of brain function, in a reproducible, standardised and validated way. This tool is called the Glasgow Coma Score (GCS).

The GCS was described in 1974 by a duo of neurosurgeons working in Glasgow. For those of you interested in the original article, a landmark in neurointensive care, here is the reference:

Assessment of coma and impaired consciousness. A practical scale. Teasdale G, Jennett B; Lancet, 1974, July 13; 2(7872):81-4

The GCS involves observing the patient spontaneously, and if necessary determining his or her response to graded levels of stimulation. The initial stimulus is speaking to the patient. If needed, a painful (but harmless) stimulus is applied. There are several ways of doing this – steady heavy pressure on the forehead, deeply pinching the trapezius muscle, or deep pressure on a fingernail bed.

Three criteria are scored: the patient’s eye opening, motor response, and verbal output. As you can see if you look at the scoring criteria, the points for each parameter go from higher (representing a “higher” level of function) to lower scores, representing “worse” function.

In terms of eye opening, 4 points are assigned if the patients opens his or her eyes spontaneously, 3 points if they open to vocal stimulation, 2 if they only open to pain, and 1 if there is no eye opening at all.

Attention then turns to the patient’s verbal responses. Appropriate, oriented responses to simple questions get 5 points. Confusion or disorientation is scored 4; inappropriate, unrelated words “earn” 3 points. If the patient only makes incomprehensible sounds in response to stimulation, 2 points are given, and as with the eyes, if there is no verbal response only 1 point is given. Obviously this criteria cannot be assessed accurately when the patient is intubated, and this fact is noted, often by assigning a “value” of “T” to this criteria.

Motor responses are extremely important. If the patient follows simple commands (wiggle your toes, move your index finger, etc) he or she gets 6 points. When the response to the painful stimulus is an oriented attempt to remove the stimulus, 5 points are assigned. Next comes a withdrawal response (4 points), an unorganised series of movements representing a primitive response to escape from the stimulus. If the coma is still deeper, the patient will respond to painful stimulation with an abnormal flexion of the arms and/or legs (3 points), a response that originates in mid-levels of the brainstem. Still deeper is abnormal extension, because this is integrated at even lower levels of the brainstem. This is assigned 2 points. And as above, no motor response at all gets 1 point. If there is a difference in the response of the right and left sides, the BEST response is used in scoring (but the “score” of the other side is noted also).

As you can see, scores range from a high of 15 to a low of 3. The GCS score is evaluated quite often (several times a day), and provides a reliable and reproducible way of assessing whether the patient is “emerging”, “plunging”, or staying the same. It is also used to roughly stratify the severity of injury.  Scores from 13-15 are considered to be “mild” (and often correspond to what’s seen in concussion patients). Moderate head injury is present if the score is 9 to 13, while a score from 3-8 is defined as severe head injury. A patient with a score of 8 or less is considered to be in a coma.

The Glasgow Coma Score cannot be reliably evaluated until sedation is off, temperature is normalised, and other factors that could confound the scoring are taken into consideration.

Other elements are also evaluated of course including the size, symmetry and reactivity of the pupils, imaging, sometimes electroencephalography, in order to get a picture of how the patient is progressing and where the problem areas of the brain are.

Hope this helps.

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Tuesday press conference – take 1

I really need to get out and get stuff done, so I’ll post a more (this sounds SOOOOO ridiculous) ummmm . . . detailed analysis (ahem) of the presser when I’m back. Meanwhile, a synthesis. 4 main conclusions for me, for now:

  1. Michael is in VERY good hands. It doesn’t matter a hoot that this or that famous neurosurgeon and/or neurointensivist would or wouldn’t do this or that element of Michael’s treatment, the point is that these guys are smart, they’re talking to each other and to the family, and they seem technically up to the job. Oh and by the way, the decision to evacuate the second, intracerebral, hematoma seems to me, a non neurointensivist, to make sense. But more on this later.
  2. It sounds retrospectively that MichaeL’s ICP was worrisomely and persistently high yesterday, despite the right sided bone flap not having been closed. This was a standard and totally normal decision Sunday in the OR. The ICP problem was so worrisome that they considered a dip to be a “respite” allowing them to scoot to the scan. Now remember, I’m piecing this together from the words used, so everything I say is therefore subject to interpretation. But we’ve all had patients like this and agonised over going to the scan, coz until just before (the respite they’re talking about) every time we TOUCHED them their ICP shot up. So the decision was made to gain some room, and drain what sounds like superficial left-sided hematoma. These are usually left alone, and it had previously (and reasonably) been decided NOT to touch this one. But given the ICP problem, and that overall the brain was less “angry”, it was decided to evacuate it, especially as this meant leaving the left sided bone flap off.
  3. This leads me to insist on just how sick Michael was yesterday. These guys were sweating bullets, doing everything known to man to help, and they deserve a lot of credit. But this was SERIOUSLY life threatening minute to minute yesterday.
  4. Lastly, I think we can A) reset all the countdown clocks we started yesterday (time to reduce sedation, time to wean from vent, etc). And B) insist on just how severely Michael is injured. Be patient. This is gonna take a long time.