Diffuse axonal injury

When we talk about “severe” head injury, as I mentioned Sunday, we’re talking about a classification that’s done CLINICALLY. That means the Glasgow score is assigned without taking into account exactly what the injuries are. Eyes, verbal, motor. That’s it.

We’ve spoken quite a bit about hematomas – collections of blood either outside of the membranes protecting the brain (“extradural” hematoma), within those membranes (“subdural”), under them (“subarachnoid”) or in the brain substance itself (“intracerebral”). Hematomas cause damage by compressing and displacing brain tissue, but also by increasing the intracranial pressure (see earlier posts about this).

When we take a patient to the CT scanner to see what the injuries are, we’re sometimes surprised to see that our (very) comatose patient has a shockingly “normal” looking scan. When the scan shows essentially generalised swelling with no significant focal neurosurgical lesions (i.e., bruises and hematomas), we talk about diffuse axonal injury, or DAI. We HATE when this happens. We have a scan that’s remarkably . . . pristine, with a patient who is seriously comatose.

Let’s look at the terms just a bit:

DIFFUSE: unlike hematomas, which by definition occur at a given location, using conventional imaging, DAI doesn’t show any SPECIFIC location for damage. This obviously isn’t particularly good news, because it precludes systematisation of the patient’s symptoms, makes rehabbing harder, etc.

AXONAL: the axons are the cable part of the nerve cell. They’re insulated cables, to conduct nerve impulses faster, so they’re covered in a fatty membrane, making them whitish. When you group lots of axons together you get white matter. The cell bodies of the nerve cells (neurons) are greyish . . . so when you put a bunch of nerve cell bodies together, yep, there it is, grey matter.

DAI seems to damage the white matter of the brain. The cabling. Once again, this isn’t really great, as the cabling is what allows higher-level information processing by hooking up the various brain areas (e.g., visual and auditory. I SEE you talking, HEAR your words, but actually it’s associative areas  of my brain that fuse the information and integrates it into my experience of YOU TALKING. That kind of processing is easily interrupted with DAI.

This will often be associated with brain swelling, at least initially.

I’m totally gutted, sickened, by having to ask you to go back to December and January’s posts for more about ICP if you’re interested. I don’t have the heart to go through this again. Not for another of our guys. Jeez.

DAI is usually associated with a somber prognosis. Jules is young, strong, and is being cared for by a superb team. C’mon Jules. Go for it.

139 thoughts on “Diffuse axonal injury

  1. It can be quite scary thinking that drivers with very tight budgets (like myself) aren’t even using a HANS device. I don’t think it would have helped with Jules, but I am aware everyone SHOULD really be using one…

  2. Gary as an ex F1 Dr on which side of the fence do you sit regarding trying to enclose the driver in F1 cars.

    In my view open cockpit racing will always be extremely dangerous and sometimes blind luck can seem to be the deciding factor on whether someone walks away or suffers serious injury. The death of the young Henry Surtees being struck by a stray bouncing tyre for example springs to mind. Contrasting with Nick Heidfeld who luckily walked away unscathed from his awful spectacular shunt in the formula E series.

    As a teenage f1 fan in the 90s I was left quite traumatised viewing live the accidents of the invincible Ayrton Senna in F1 and the horrific death of the young talented Greg Moore in Indycar. But at the same time it hammered home that racing at 200mph is extremely dangerous and the margins are very small.
    Unfortunately when driving at such high speeds, for all the technology in the world the human body only has a certain tolerance to such violent high speed impacts, especially when the head is exposed.

    I don’t see how an enclosed cockpit would work without genuine massive design/regulatory changes for F1 cars. Some of the theoretical mock ups I have seen on the web look cosmetic rather than being structurally viable methods of preventing head injuries. Technology both mechanical and medical will always evolve but racing at speed will always be dangerous, especially in open cockpit racing formulas. I don’t think we ever seen an enclosed cockpit in F1.

    • My initial feelings are that by closing the cockpit, something fundamental about F1 will be gone.

      More importantly, while enclosing the driver might reduce some risks to him or her, it does nothing to help the track workers who are at risk when drivers ignore the International Sporting Code and speed through double yellow zones. Let’s focus a bit more on the latter, and a bit less on the former. That’ll get the priorities right, at least to my way of thinking.

      • The obvious thing for me to introduce would be for the F1 authorities to order every driver to flick a switch on they steering wheel which would slow them down to a predetermined speed when marshals or vehicles are track side. They already do this in the pits so the technology is already there to do something similar when on the track.

  3. I heard this item about vegetative state on BBC Radio 4 Today programme this morning (quite by chance) and thought that people who have been following Gary’s posts all year might be interested. The graphic is very beautiful showing the brain activity in various patients. Basically it shows that some people in vegetative state have brain activity similar to healthy patients.

    Quote from Sid Watkins to Richard Hammond on how little we currently know about the brain ‘oh yes – it’s tiger country out there’ – this comes from one of my all time favourite DVDs ‘Hammond meets Moss’

    http://www.bbc.co.uk/news/health-29643038

    • This is really detailed and useful and very recent – thanks KC. Did you know that Gennarelli was the one who carried out (very cruel) animal experiments recreating DAI in primates in the 80s? This was when they were trying to work out why people could be unconscious for a long time without much apparent damage to brain. There is some good work on DAI in Japan as well using computer modelling to avoid the need for animal experiments and so I think Bianchi has been injured in a country with plenty of expertise on DAI. For what it’s worth, computer modelling in Japan demonstrated how the strains were in the centre of the brain ie corpus callosum, brain stem, cingulate gyrus and inside of temporal lobe.
      Try googling ‘Head Impact analysis related to the mechanism of diffuse axonal injury’ 2008 Watanabe et al
      Thanks very much
      Jane

      • No Jane, I did not know that. I know that, for years, animals have been used in medical research. I love animals – all animals.
        Next time you hear of a project/experiment let me know. I can easily submit some political names… I am sure we all can AND most would probably none of our submissions would be missed.

        BTW, you (and Dr. Gary) are way above my pay grade. I beg the question… Are you in the medical field as well? If so, I will thank you in advance for the work that you do. If not, I still thank you for your very knowledgeable posts.

  4. So it’s like a strain of a ligament, the axon insulator having been stretched by the twisting / turning, so it has a ligament / muscle like composition? Other stuff I learned… then you get swelling around the injury to provide protection from further impact and increase blood supply for healing..??

    .. different to MS because he had an impact depression type injury hence the bruising or damage possibility, healing then benefited by the low daily impact and time of a coma…

    But then the white matter in that sense is still injured, so the body remains in a coma while the injury heals enough to reduce the prospect of further injury leading to permanent injury. So this is why you cannot develop a prognosis, because you don’t know if the injury is temporary, or what level of injury towards permanence they have, or whether it is so significant it is permanent.

    But then I heard of one guy who lost part of his brain tissue after a head injury, the tissue was actually removed, and he walks and talks completely normally as if nothing had happened.

    Interesting stuff.

      • Not much time to research stuff… because of the accident, I got the impression the white matter was between the spinal cord and brain and the condition was caused by a general strain from a whiplash injury, and didn’t imagine bleeding hence why I likened the inflammation to a ligament strain, but like shock, hence why it’s called diffuse.

        But ..? the white matter is within the brain itself and connects independent regions of the brain to create our physical functioning..?

        If this is right… he must’ve nearly severed the nerves in his spinal cord..?

  5. Gary – Did you know that Michael Schumacher had to wait in Grenoble for a neuro surgeon to be flown in to perform Michael’s first surgery to relieve the pressure on his Michael’s brain?

    See Dr. James Norman comments at motorsport.com posted: 9 October 2014. I was not aware of this ADDITIONAL DELAY. “The system failed (for Michael) that day.” Dr. Norman

      • Hi Gary, I have a theory about the delay in Michael’s early treatment before he got to the first hospital in Moutiers. I have checked times and he arrived at the first hospital at 11.53am, which is a long time after the reported accident at about 11.07am (all times reported within first 24hours by rescue staff). Flying time is much less than this and I think they may have deliberately landed the helicopter away from Michael’s entourage so that they could intubate in peace. Of course Michael was deteriorating very rapidly as well. However, I think this would be a very logical thing to do in the circumstances.

        I remember reading at the time that when Felipe Massa had his accident they were waiting for his personal doctor to arrive but had to operate before he got there. I can’t imagine that even a pampered F1 driver’s entourage can override the urgent need for an operation to save someone’s life once they are actually in a hospital.

        At least the Bianchis sound reasonable and I so much hope for a better outcome for Jules although I think current signs are very ominous.

    • I’m not convinced that Dr James Norman is correct about this. Doctors at the original press conference were both based at Grenoble which is the local centre for Alps medicine and has full neurosurgical facilities. The doctor who carried out the operation was Stephan Chabardes neurosurgeon at Centre Hospitalier Universitaire hospital in Grenoble. The other doctor present was Prof Jean-Francois Payen, chief anaesthetist at the hospital in Grenoble.

      There were reports that they were waiting for Professor Gerard Saillant to fly in from Paris, but this was not so that he could carry out the operation. He was just coming to advise, just as he has in the Jules Bianchi case.

      There may well have been delay before Michael reached Grenoble but his treatment after that point has been widely praised in the UK as the best possible.

      I was always taught to go back to original sources and I think this is needed more than ever with the current standard of sloppy journalism.

      • Jane A
        Thank you for your commentary regarding Dr. Norman’s statement. Clearly we have seen that when one speaks and another writes there can be significant differences in interpretations, and then writing about that -new- understanding(?) of what was said to possibly gain a higher level of readership… Maybe FURTHER inquiry would have given clarification.

        The tragedy that has befallen Jules Bianchi has once again brought PAIN back to the surface for so many.

        Again, thanks

        KC

  6. I just heard a couple “news” on both our injured drivers – obviously to be taken with a grain of salt. A Japanese neurosurgeon said that Bianchi is to remain paralyzed, if he ever were to regain consciousness. And a French journalist who talked with little Mick reported how Michael is “very slowly awakening (or maybe progressing, who knows)”, but actually still progressing/awakening.

    • Although it’s a bit sad that they are pumping a 15-year old boy for information this does fit in with previously posted statistics of recovery from minimally conscious state (thanks Gary and Jussi)

      Roughly one third of minimally conscious patients emerge after one year although they nearly all remain very severely disabled – ie unable to walk or talk but conscious and able to communicate in some way. They might be able to operate electric wheelchair by using mouth or other available small movement. We are really, really not talking about being seen in public, giving interviews etc now but it doesn’t necessary mean that Michael will not make any progress at all and I’m sure it would give the family great comfort if they could communicate with him in some way. I don’t think Michael is likely to die for a long time with his own protected environment and very little risk of infection now he is at home.

      In a retrospective cohort study, Lauate et al compared the long-term functional outcome, improvement or deterioration, of patients considered to be in a VS or a MCS 1 year after coma onset, then yearly for up to 5 years using the five categories of the Glasgow Outcome Scale.

      They followed 12 patients in VS and 39 in MCS:
      • None of the patients in VS improved during the follow-up period: 1 was lost to follow-up, 9 died,
      and 2 remained in VS.
      • Among the 39 patients in MCS, 3 were lost to follow-up.
      • Five years after coma onset, the outcomes of the other 36 patients were as follows:
      – 13 severe disabilities (33.3%)
      – 9 MCS (23.1%)
      – 14 deaths (35.9%).
      • Of those who emerged from MCS, 8 (61%) had emerged by 2 years, and a further 4 by 4 years. Only
      1 more had emerged by the fifth year of follow-up

    • “A Japanese neurosurgeon said that Bianchi is to remain paralyzed, if he ever were to regain consciousness. ”

      Is that even something we could say at this stage, unless there’s actually a spinal cord issue?

  7. Hi Gary

    Earlier I stumbled upon a post (link : http://torquef1.wordpress.com/2014/10/08/the-story-of-roberto-guerrero-and-why-to-keep-every-faith-in-bianchis-recovery/ ) quoting former CART doctor Steve Olvey’s autobiography about Roberto Guerrero’s crash in autumn 1987 which also resulted in severe DAI.

    Roberto recovered at a seemingly astonishing rate, getting back behind the wheel the following April and even finishing second in his first race back. Whilst I realise that every individual and every injury are unique it does show that miraculous recoveries can be possible.

    In terms of Jules’ case, are barbiturates still used as a form of treatment in DAI? Were the results in Roberto’s case a one in a million shot that paid off or is that form of therapy in general use nearly 30 years later?

    • Hi Dan, and thanks for writing!

      Barbiturates are still used quite a bit in neurointensive care. Simply because I’m massively busy right now with clinical stuff, I’d refer you to some of my posts of January. I talk about how sedation and anaesthesia are used for head-injured patients. If you don’t find your answers there, hurry back and I’ll give you what you need.

  8. 9 years ago on this very day (8th October 2005) I suffered a ‘freak’ motorway accident on the M6 toll road in the UK, I aquaplaned and hit a rescue vehicle that had stopped to assist another car who had aquaplaned. I was driving a Honda S200, alas the fabric roof offered the right side of my skull very little protection as it impacted with a rescue vehicle at speed.

    My story is here https://www.midlandsairambulance.com/your-stories.php?story=13

    I suffered a suspected DAI and spent 2 weeks in a medically induced coma, my hospital records indicate at one point during my admission I had a GCS of 3.

    I was very lucky, thanks to an amazing paramedic James Dean, a charity Air Ambulance and an incredible Trauma team at Selly Oak Hospital in the West Midlands led by Dr Ali, I am 99.9999% fine. (I can’t sing in tune anymore and my hand writing is terrible.)

    I know every head injury is different and Jules is fighting his hardest ever battle.

    I want to give Jules’ family some hope, don’t give up, keep fighting. Jules needs time, love and positivity. Every little bit of love and the positive thoughts of everybody may help him even more. I am proof that positive outcomes are possible. I am thinking of you all.

    Please FIA keep the drivers even safer.

    I was lucky enough to work in the pit lane of the British Grand Prix at Brands Hatch in 1984 as a runner. F1 is a stunning sport competed by people with astounding and incredible talent. Having seen them up close over 30 years ago I have always be in awe of their courage and skill.

    #forzajules you can beat this.

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  10. Hi Doc.
    I’ve been thinking about this a lot over the last few days.
    Putting aside the circumstances that led up to and caused the crash, I’ve come to wondering if this sort of injury was all but inevetible sooner or later?
    Previous serious injuries and deaths have often been caused by the body/head of the driver striking an object or part of the car, or the neck and basal skull structure suffering trauma due to sudden deceleration. With the introduction of HANS devices, in-cockpit padding, cockpit surround foam structures, and Zylon anti-penetration body panels covering the safety cell, a lot of the danger of these types of injuries have been reduced or mitigated.
    With the body and head and neck safely restrained and cocconed from external blows as much as possible, its seems only natural then, that injuries will come from internal organs impacting their surrounding structures (Skull, ribcage, abdomen) during the deceleration of an impact? Or potentially Traumatic Aortic ruptures?

    • Hi Phil! Sorry for that – this somehow got lost and I was pretty sure I’d put it up.

      I think you’re right – we’re protecting against more and more of the “foreseeable” injury mechanisms, meaning that we’re leaving the esoteric and bizarre mechanisms to be managed.

      It’s all about energy management – slowing the loss of energy to keep it below the thresholds of injury.

      • Except, of course, for the thorny issue of foreign objects (walls, springs, undersides of JCBs, tyres) breaching the roll-cage perimeter.

        As an F1 fan, I really don’t want to see closed cockpits – it is an open-cockpit formula, and that’s a key part of its magic. I’d be curious to know what you think as a doctor, particularly vis a vis extrication from a closed-canopy vehicle.

      • I agree that F1 is open cockpit open wheel racing. Period.

        I think inverted canopied “F1” cars might be a nightmare to extricate from.

        I think this has as much chance of ever being adopted as a solution (to anything) as there is of a Grand Prix in Azerbaijan. What’s that? Oh. OK maybe a bit less . . .

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  15. To all of you blaming the helmet he wore… DAI is similar to shaken baby syndrome…. it is damage from the brain being shaken around within the skull. The helmet did it’s job as best it could, but there is no helmet available that can hold the brain steady within the skull.

    • Sorry, my previous post may not have been worded correctly.

      I don’t believe there is any blame to be placed on the helmet at all. The fact that it appears relatively intact from the images after the incident, (without seeing the left side of the helmet) is remarkable. Without the helmet as currently designed, and the HANS system, Jules would not have made it this far. I have no doubt that the current equipment worn by all of the drivers is the best in the world, and built from the best technology currently available.

      The question is could a helmet be developed which could both withstand the force of an impact of this kind, which is also able to limit the effects of deceleration/rotation on the brain, thus limiting the likelihood of this sort of injury in the future?

    • Maybe, after this horrific injury, someone a lot smarter, more inventive than I, can come up with a solution. Imagine, if you will, a race car that upon any type of impact, places the driver in some type of suspension whereby only the vehicle would take the violence holding the driver completely safe.

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