An illustrative anecdote

I’m always going on about the inexperience of the current leadership of the medical arm of the FIA. I think it’s important, especially in view of the issue of intentional water/calorie restriction (which may well need regulatory input from the Medical Commission), that people understand that this is not (only) residual anger and bitterness because I was fired. So here’s a small example of what happens when important decisions are left to people without the background, experience or knowledge to carry them out appropriately.

At a 2012 meeting of the Medical Commission (I was still an observer), the president (Gérard Saillant) and vice president (Jean-Charles Piette, also the Formula 1 Medical Delegate) presented a draft regulation to the commission members, for what they expected to be rubber-stamp approval. In essence the regulation said the following:

In closed cockpit series, if the cockpit of the car is too small to allow either expeditious extrication of the driver or prompt removal of the helmet, drivers are REQUIRED to wear open face helmets.

Sounds simple, eh? Maybe even logical, right? They were happy that the cause of driver safety was being advanced. Interestingly, neither of the authors of this regulation have ever, in any way, managed an airway.

The intention of this regulation was laudable – to allow airway access rapidly under conditions of difficult extrication. But beneath the face of it, this proposition illustrated everything that is wrong with the current leadership.

The reading of the reg was met by silence around the table. I need to point out that the members of the medical commission are massively experienced, massively motivated, and massively frustrated. The president, until he was appointed by his friend Jean Todt, never had direct involvement in motorsport medicine. Same with the vice president, until he was named F1 Delegate, for the same reason.

Just as this proposition was about to be put to a vote, I raised four questions.

Question 1: How many drivers have suffered an adverse outcome due to failure to access/control the airway in a closed car? The answer is rather simple – ZERO. Although this is the nightmare situation of every motorsport doc, IT JUST HASN’T HAPPENED.

Question 2: How many drivers have suffered catastrophic head and/or maxilla-facial injuries due to contact with cockpit elements WHILE WEARING FULL-FACE HELMETS? The answer – well, I can name 4 or 5 off the top of my head. And I’m pretty sure had they been wearing open-face helmets, things would NOT have been better.

Question 3: How will the FIA answer the lawyers representing the family of a driver killed as a result of head injury wearing a mandatory open-face helmet?

Question 4: Why just accept that there are FIA-homogolgated cars still racing, with cockpits so small and roofs so low as to preclude satisfactory rescue operations? As the FIA body responsible for medical regulations, when the Medical Commission gets it wrong, lives are at stake. Why, I asked, has the Med Comm not gone on record with the relevant OTHER commissions to demand a say in cockpit design, before closing the technical regs for each series? This is the concept of cockpit-out design that I blogged about some months ago.

The reg was immediately withdrawn. I needn’t point out the eye-rolling among the membership at having been presented such a . . . silly proposition.

This is why I’m a bit fearful of knee-jerk, symptomatic responses to the weight control issue. This is why I’m enraged by the stagnation in medical progress in motorsport – it’s not down to nothing left to do, or to obstacles to advancement being thrown up. Rather, it’s down to a total lack of vision, perspective and knowledge of the ins and outs of this field, resulting from nepotistic, incestuous appointments. Again, Jean, you can give your mates titles, but that doesn’t mean you’ve made them competent.

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Something NOT about head injury!

No seriously, are you guys KIDDING?

I guess we shouldn’t be surprised about Jenson and Lewis’ “revelations” about drivers intentionally compromising their health and well-being to minimise their weight. This is a sport that requires total commitment, and pressure to do anything to shave a tenth or so off one’s lap time. Millions are spent on aero tweaks, on salaries for the best designers around, etc. Remember that in the 80s we had a spate of drivers passing out post-race, because they were all taking beta-blockers. These were felt to improve performance under stress. Not.

I’m shocked and very very concerned about this development. I’m almost equally apprehensive of the potential reaction of the FIA in an attempt to mitigate this insanity. Oh and I think we need to be grateful to Louis and Jenson for their forthrightness about this.

So let’s start with a stable of drivers who are collectively some of the fittest athletes around, whose fitness regimens, 120 km bike rides, triathlons, etc, are the stuff of tweets, newspaper articles and tv reports. Everyone understands that the price of success in Formula 1 requires total physical condition. Only that will allow one to handle the physical stress of driving the cars and to maintain concentration despite physical discomfort. Only NOW we get to watch these guys starve and dehydrate themselves in order to minimise their weight. These are the same guys who never went ANYWHERE without their drinks bottles. I’ve been next to drivers who were tooting away on their bottles WHILE THEY WERE PEEING. Presumably McLaren has issued their drivers carbon fibre “peristalsis reversal devices”. They look just like spoons, and reliably induce vomiting. Jeez. Hey guys – nicotine activates the brain somewhat reliably. Maybe you should all take up smoking?

This is insane, and most worrisome. Obviously the implications of an unwell driver at the helm of a terrestrial cruise missile are huge – for themselves, for their fellow drivers, and for others. And the message this sends to the public, and to every young driver from go karts to GP2 is obvious – train for the week after a race, then totally fuck yourselves up for a week before the next one. Yeah, that’s the message you should be sending. Brilliant.

I needn’t go into ANY detail about why this regimen of starvation and dehydration is ridiculous from a medical point of view.

This has got to stop. And it’s got to stop now. And given the competitive pressures of the sport, this will not be easy. And given the implications for the safety of the public, track workers, and other drivers, it won’t be sufficient to issue some lame statement encouraging the drivers not to act like 90s heroin-chic supermodels.

Problem is, I fear that given the lack of experience of the current medical leadership (I’ll give an example of the absurdity this can lead to in a subsequent post), the solution will be more ridiculous than the problem. Let me make it clear – it is folly to try to paternalistically control nutrition or hydration of mentally competent adults by regulation. Any solutions must be legally acceptable, enforceable, and actually serve to discourage the behaviour in question.

So what’s to be done?

I’ve spend a bit of time thinking about this and pending something better, I think:

1) a statement highlighting the FIA’s concerns about this behaviour should be released

2) it should be stated that the nature of the problem of any driver who is unwell enough at the end of the race to require medical assistance will be investigated. The points of any points-finisher requiring medical assistance after the race will be provisional to the results of this investigation. A driver found to be intentionally dehydrating or starving (go ahead, think of a better word – Jenson said some of them eat NO CARBS for a week pre race!!!!!) will have his points cancelled and will receive a grid penalty for the next race. A second violation will lead to suspension of his or her super license. Forever.

These guys want to win, and as we can see, they’re willing to do anything for that to happen. We can question their sanity, intelligence, and wisdom, but not their motivation. But this also has ethical implications for those around the drivers with a duty to care, notably team physicians and the physios. If they are allowing this to happen, and worse, encouraging this, they are violating the cardinal rule of ANY caring profession: PRIMUM NON NOCERE. First, do no harm.

I should have known . . .

It’s fairly evident that I really REALLY need to clarify what I meant, and what I didn’t mean, by my comments concerning “errors in judgment”. I see that I’m being quoted a lot, in lots of outlets. That’s not a problem of course, but it becomes problematic when what i wrote is turned into something that I most certainly did not say.

1) I am strictly referring to the period of management BEFORE Michael was admitted to Grenoble. As I said on 30 December, the people taking care of Michael in Grenoble can take care of any member of my family any day. They are professional and more than competent. This is an impressive team and they deserve to be recognised as such.

2) I am in no way criticising ANY member of the care team(s) dispatched to fetch Michael on the slope, nor of those involved in transferring him from Moutiers to Grenoble. As I made clear, prehospital medicine is difficult under the best of conditions. It’s not hard to imagine the added stress faced by the guys on the slopes, confronted with a clearly injured mega-star, and what must have been a VERY difficult entourage to manage. I don’t have sufficient facts of any kind, and it’s neither my job, my business, nor my intention to question the individual medical care provided by my colleagues.

What then exactly AM I saying, and almost as importantly, WHY am i saying it here, and why now? These are valid questions, and they deserve an answer.

3) I am very clearly criticising a system that allows head injured patients to be brought to non-neurosurgical centers, in the absence of other clear reasons to do so.

4) The failure to adequately control an agitated patient prior to flight, as well as the delays in adequate control of the airway likely indicate insufficient training, insufficiently robust protocols, and perhaps insufficient experience under difficult circumstances (again, a mega-star patient with a difficult, demanding and perhaps even frankly hostile entourage). I am very clearly criticising a system that allows this to happen.

5) It is impossible to quantify the impact of the above on outcome in Michael’s case. Obviously. It is also obvious that someone whose neurosurgeon, the day after the trauma, describes his condition as “hematomas left, right and centre” is likely not to do particularly well. This should be obvious, at least to the “journalists” who disingenuously (at best!) implied that I said that Michael’s current situation is because of these aspects of his initial care. The delay in admission to a neurosurgeon, as well as deferred airway control, cannot have been good for a severely injured brain. Especially in a situation where the intracranial pressure has risen so high that parts of the brain are literally being squeezed out of the cranial vault. That said, in terms of prognosis, this likely pales in significance compared to the 2000-and-some-odd joules of impact energy against that goddamned rock.

The world of medicine, including the practice of prehospital medicine, has become more and more evidence- and protocol-based. This requires constant attention to new developments, and elaboration of consensuses that are often universal (for example, the algorithms of basic and advanced life support). Intense and rigorous adherence to these protocols, with the training that this implies, has been shown to very favourably impact on the outcome after trauma. I will simply say that the French have been remarkably, and unexplainably, recalcitrant to this notion of protocol-based medicine.

Why have I said this now?

I want to make it clear that the furthest thing from my mind was causing Michael’s family added pain. Malpractice? Hey, I work in Europe, which is far from having gone as nuts as the USA with this. In any event, I don’t give a shit about MAL practice. What I’m concerned with is GOOD practice. I want people who’ve not thought about it previously to now think, before heading down the hill on their skis or boards, “am I going to be well looked after, by people with sufficient knowledge, skills and maturity, if I have an accident”? And I want the answer to be yes. Wherever, whenever.

Those of you who know me a little know that if I’ve contributed anything to motorsport medicine, it’s been mainly down to education and training. The book, the systematic simulation exercises at every Grand Prix, etc. Doctors are nothing if not people who never stop, and never want to stop, learning. I think we need once again to make sure that people who do prehospital medicine, who routinely face life-threatening situations, are sufficiently trained, equipped, and mature, to carry out their duties impeccably.

With that in mind, I need to send a quick and heartfelt shout out to General Zin and the medical team at the Grand Prix of Malaysia. These guys have created a society for motorsport and traffic medicine, with a goal to fostering best practice in the community of caregivers doing this type of medicine. BRAVO!!! These guys are tops, and have been for some time. To illustrate how “on it” they are, they have the only circuit medical centre to be ISO certified. And they’re my friends!

It’s just a pity that the national federations are left alone to carry out initiatives like this (needn’t remind you of my attempts at organising an international society!), without leadership from Paris. Again Mr. Todt, it’s not because you gave your mates fancy titles that they have, by magic, acquired competency in this field. Motorsport medicine is stagnating, and will continue to do so as long as there is a total lack of leadership from the top.

Odds and ends

Well it’s been a long time, hasn’t it? As always, I follow your comments closely, both here and on Twitter, and I think it’s time to address some of the points that have been raised recently, and perhaps clarify a few definitions (nothing new here, pretty sure this stuff was covered in earlier posts) – simply because I’ve got a feeling that we’ll be hearing some of them at some point in the not-distant future. More on this later.

WEIGHT LOSS

I’ve been asked about the report that Michael has lost 25% of his pre-accident weight.

This is entirely possible, and in fact, probable. A few factors explain this. First, the initial injury, operations, and those few harrowing weeks when Michael’s life itself hung in the balance, minute-to-minute. This kind of situation subjects the body to a tremendous level of stress. Not psychological stress, mind you, but physical stress, accompanied by liberation of massive quantities of stress hormones. These hormones evolved for the “fight or flight” response, and were designed by evolution to promptly mobilise fuel for action. They do this by causing (among other things) breakdown of muscle to form amino acids, which the body can use as fuel. The problem is that when these stress hormones remain present for too long, it becomes very difficult if not impossible to replace the lost muscle mass, at least in the short term.

So Michael’s muscle mass was already fairly significantly depleted by the time sedation was stopped. At this point, what is usually called disuse atrophy starts eating away at the muscles. Since a patient in coma has very little, if any, movement, the muscles lose the mechanical stimulus that is a major factor in maintaining them during normal day-to-day activity. And although coma patients get intensive physical therapy, this is aimed at preventing the joints from stiffening, not at maintaining (or building) muscle mass.

There may well be a more subtle contributing factor as well. You see, the normal brain kicks out growth hormone at night, during our sleep. This hormone helps the body to build and maintain itself, notably by helping the muscles take up protein. It is entirely possible, even probable, that this pulsed pattern of secretion is lost (any neurosurgeons reading this, or neurologists, anyone in the know, just jump in!) in patients who no longer have sleep-wake cycles. It’s even possible that secretion of the hormone falls to very low levels chronically. This would also have the effect of taking away an important “trophic” stimulus.

Happily, the consequences are not particularly dramatic, at least immediately. To be blunt, a patient in coma doesn’t really NEED his or her muscles . . . with the exception of the diaphragm. The diaphragm, which like the heart is pretty much always active, resists atrophy rather better than other muscles, but it does atrophy. And having a machine doing the breathing for you is one of the best ways to see how disuse atrophy affects the diaphragm too. Unfortunately, and assuming (as I have until now) that Michael is being ventilated by a respirator, there is probably some degree of diaphragmatic atrophy at this point.

Now remember where Michael is coming from – one of the fittest, toned, and conditioned 45 year-old men on the planet. This means that if and when he can be weaned from mechanical ventilation, re-training his diaphragm shouldn’t be problematic. As for the rest of his muscle mass, should he awaken, the same ferocious appetite for pushing himself will no doubt lead him back to most of his former superb condition.

TRANSFER

I’ve also been asked why Michael hasn’t been transferred to a unit closer to his home.

Obviously I have no idea of the answer to this question, but several factors need to be considered.

First, from a medical point of view, once we’re out of the phase with dramatic and life-threatening elevated intracranial pressure, and barring other significant problems causing physiologic instability, the patient can be transferred arbitrarily far. The transfer needs to be prepared carefully, of course, but even hours-long flights are possible with intubated, ventilated patients such as Michael. So why is he still in Grenoble? I’m basing myself on the notion that Michael is still in the Intensive Care Unit, and is still being ventilated.

First of all, it clearly shows that his entourage is totally confident with the quality of care Michael is receiving.

It’s important to remember that Intensive Care Unit (ICU) beds are a very limited resource. Every day intensivists are asked to admit critically ill patients to units whose beds are all filled. This requires TRIAGE – deciding who has the best chance of being improved by being admitted to the unit. The “chronically critically ill”, patients like Michael who depend on technology (a ventilator) to stay alive, are a tremendous conundrum for ICU personnel. As time goes on (more detail below), it becomes less and less likely that Michael will emerge to any significant extent. Therefore, I think it is inevitable that should the status quo continue, the ICU staff may well, at some point in the not-distant future, decide that the patient they’ve just been asked to admit has a higher need for that bed than Michael, given his clinical situation and prognosis. This then could be a reason to organise a transfer – to a private clinic, or to an ICU-like environment that his entourage could build at his home.

Lastly, as I’ve mentioned furtively here and there, I think that serious lapses in judgement were evident during Michael’s initial management (I have this from usually impeccable sources who have access to this information). Because these lapses could (and almost certainly did) worsen the outcome in Michael’s case, it is possible that the staff at Grenoble feel duty-bound to NOT place any pressure on the family to transfer out, despite the terribly dismal prognosis . . . because of the clear (but unquantifiable) contribution of medical misjudgement to that prognosis.

(RE) DEFINITIONS

I think it’s useful to look at a few definitions again, briefly, for when this all starts to get talked about in the press, as I’m sure it will be fairly soon.

Brain Death: A brain-dead patient is dead. There is objective, demonstrable, and irreversible cessation of ALL brain function. When you use arteriography (special x-rays that show the arteries and the flow in them) to look at the blood flow to the brain, you see that there is NO BLOOD FLOW AT ALL inside the cranial vault. There is no reaction to any stimuli except for simple reflexes (which originate at the spinal level), and the patient will not breathe spontaneously, even when carbon dioxide levels are elevated. There are no living brain cells in the skull. None. At all. Families do not have to approve disconnecting these patients, as they actually are no longer patients, they are . . . dead. These are the patients who become, under certain well-defined circumstances, organ donors. Because the brain, all of it, is needed for the body to survive satisfactorily, the hearts of brain dead patients will not continue to beat more than a few days or weeks (a few cases of longer circulatory persistence have been described but this is vanishingly rare), despite the most aggressive treatment possible.

Coma: coma is defined as a state where the patient shows neither wakefulness nor awareness. So the patient in a coma has closed eyes, shows no evidence of a “sleep/wake” cycle, and shows absolutely no sign of any awareness of (or interaction with) either the environment or him/herself. Even painful stimuli fail to cause meaningful interaction. Depending on the areas that are damaged, these patients may or may not breathe on their own. That said, they will essentially always be intubated, and then tracheotomised, to prevent episodes of airway obstruction caused by the brain being unable to coordinate the muscles of the tongue, pharynx and voice box. They are initially fed by a tube passed through the nose to the stomach, and later (as is no doubt the case with Michael) by a tube placed directly into the stomach or small intestine through the abdominal wall. Usually a coma is defined as persistent when it has lasted more than two months after the precipitating event. For info, I assume this is Michael’s current status.

Whereas brain death is inevitably followed by circulatory death within days to weeks, patients in a persistent coma have somewhat brain function, especially in areas associated with maintenance of physiological stability (body temperature, blood pressure, water volume, etc). This means that the life expectancy for a comatose patient who does not improve neurologically is measured in months to a relatively few years. Once again, the brain is necessary to integrate those of the body’s activities which contribute to a normal lifespan.

Persistent vegetative state: here we must distinguish two things that almost always go together: wakefulness and awareness. Patients in a persistent vegetative state show signs of “wakefulness”, in that they have periods of spontaneous eye opening, and can even show cycles that resemble sleep-wake cycles. They are, however, unaware. There is a total, rigorous lack of any sign of self awareness (including pain, other than reflex responses, thirst, etc) or of the environment. These patients often breathe for themselves.

A vegetative state is defined as persistent when it lasts two months after the precipitating event. As we’ve mentioned previously, the longer one remains in a vegetative state, the less the likelihood of emerging, and the higher the chances of severe sequelae if the patient does in fact emerge. Most definitions consider the vegetative state to be permanent one year after the injury.

Patients who are in a persistent/permanent vegetative state have lifespans that are measured in months to a few years. This depends on baseline function (extraordinary in the case of Michael, of course), the quality of nursing care, and other imponderables. They usually die of respiratory or urinary infections. Longer survivals have been described, but are exceptional.

Minimally conscious state: here, as with the vegetative state, there is wakefulness. But here, there are signs, inconsistent, variable, but clear, objective, and reproducible signs of awareness: interaction with the environment and/or of self. Like what? Eye tracking, motor responses, smiling, turning the head consistently to voices, etc. Or appropriate reactions to stimuli. This state can also be persistent; it is significant because it represents the first stage out of the vegetative state on the continuum towards normal consciousness . . . and the first interactions the entourage sees from their loved one.

Minimally conscious patients also have a severely shortened life expectancy, but not quite as dismal as for “deeper” levels of disordered consciousness.

PERSONAL NOTE

I always knew Michael was adored. I spent years at circuits drenched in red by the ferrari caps, flags, and shirts, and all of that for Michael. I’m still staggered by the depth and persistence of his fans’ love for him. And whereas I worried more than a bit about what was going to happen when and if really bad news got announced, I’ve realised that perhaps the lack of status updates has given us all a chance to move on a bit, to process what’s happening, and to start to . . . detach. And I think this is probably one of the unexpected “benefits” to the media strategy chosen by Michael’s family. Somehow, I get the feeling that people are going to be ok, no matter what happens, because they’ve now had the time to process this all. I just regret that to get here, you’ve all had to work through feeling abandoned. That will go away too. I hope.

Only a miracle

So now the Telegraph is reporting that the doctors caring for Michael have told his family that “only a miracle can save him”.

1) doctors, no matter their spiritual bent, do NOT talk to patient’s families about miracles saving anyone. Ever. From a practical viewpoint, this gives a patient’s family absolutely NO useful information on which to act. It provides hope, yes, but not for anything with any medical reality. And this hope will then cloud all subsequent decision-making.

A statement like this is more than ambiguous – it lets each recipient interpret it in his or her own context, the opposite of clear precise information. What would the care team mean with a statement like this? Are they saying “let’s wait a bit more for the miracle”? Or are they saying “miracles don’t happen in reality so we’re pretty much out of hope”?

I can only guess that what this report means by “save” is “recover sufficiently to have meaningful interactions with his loved ones”. So you see why this is kinda a dumb thing to say. And why it is impossible for me to imagine doctors EVER communicating like this with a grievously injured patient’s family.

If something like this WAS said, I can only try to “reverse engineer” it, and from there consider what they were saying and how it’d be said.

1) If there is now clinical, radiologic, physiologic and other data that leads to the conclusion that a resumption of any meaningful consciousness at all is impossible (see? no mention of miracles), they would be VERY unambiguous with this. In a situation like this, there must be no guesswork – NONE on the part of the medical team, who need to put the data together and reach an unquestioned and unquestionable conclusion. In this situation, ANY ambiguity in communication with the family is disastrous. They will often cling to any hope left, and this conversation is going to be, tragically, THE conversation that finally (and gently and compassionately) needs to remove all hope. This is crucial. If the message is misunderstood, it will almost inevitably lead to major problems, conflicts and tension subsequently.

Let me just say here that medical ethics allow, and virtually require, doctors to refuse to provide treatments they reasonably consider to be futile. My neighbour cannot show up at the hospital and demand that a surgeon remove her appendix. And in the above situation, where there is incontrovertible evidence of damage so severe as to make resumption of consciousness impossible,  doctors can certainly undertake the process of “therapeutic de-escalation”. Even if the patient’s family insists that “everything be done”, if there is NOTHING left to be done, there is no requirement to do anything more. At that point the patient’s family can make other care arrangements. It’s obviously critical to avoid this kind of situation, so once again you see the need for perfectly clear, concise information, with no ambiguity. Families need time to accept this, whether it’s in intensive care, or oncology, or genetic anomalies, and so on. But with open honest and clear communication, this will happen.

Please note that this is NOT the situation for a patient in a persistent vegetative state, at least not necessarily. This is the situation for a patient whose condition is even WORSE. The essential point is that the impossibility of recovery has to be as certain as current medical science can be AND that this certainty be transmitted to the family.

2) if the clinical situation is desperate, but not without all hope, the family would be told this, with as close to numerical precision as possible. In a situation where there is hope, it mustn’t EVER be taken away. On the other hand, families need to know, at the most basic level, that most patients like this get better, or that a few get better, or that really VERY few do. That 60%, or 20%, or 1% get better. No talk of miracles.

As I mentioned a few posts ago, if this conversation has happened, if Michael’s family has been told that it is extremely unlikely that he recover “satisfactorily”, then it is quite possible that the “several steps of separation effect” between hospital personnel and the press could have led to this kind of language appearing in these articles.

And again, despite a day during which we’ve been told Michael is breathing on his own AND that it would take a miracle to save him, we know nothing more than we knew yesterday or the day before.

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.