After simple dental surgery, William lost his ability to form new memories • Hacker News Board

Re: After simple dental surgery, William lost his ability to form new memories

#91

Post by rusabd » Sun, Jul 05, 2015, 9:03 PM UTC

userbinator wrote: post #5

iopq wrote: post #3

This is the condition that was described in Memento. Really fascinating stuff. It makes me want to keep notes on everything, because most people rely on their memory for a lot of things. When we forget something we are frustrated "Oh darn, I forgot it again!". Imagine not being able to remember anything at all...

Imagine not being able to remember anything at all... ...including the fact that you can't remember anything? That would certainly be scary.

I once lost a memory for couple hours - I was fully aware that I don't remember anything

Re: After simple dental surgery, William lost his ability to form new memories

#92

Post by chx » Sun, Jul 05, 2015, 9:11 PM UTC

joezydeco wrote: post #15

csomar wrote: post #11

The doctors initially suspected that he’d reacted badly to the anaesthetic, causing a brain haemorrhage – yet they failed to find evidence of injury. So he was discharged with the mystery still hanging over him, and the family moved back to England, where he was referred to the office of Gerald Burgess, a clinical psychologist in Leicester. Scouring the medical literature, he found five similar cases of mysterious me…

Earlier this year I had a medical procedure and was given "twilight" anesthesia. I was explicitly told "you need to have your spouse or a friend here because we're going to give you instructions afterward and you probably won't remember it". And, sure enough, my memory was pretty much wiped for the hour or so after the event. Later that evening I had a conversation with my wife that went like this: "Um, did you help…

Oh yeah, conscious sedation. It's 9am, I am in the dentist chair and getting pills. Next it's 5pm and I am in my bed at home and I have zero idea how we progressed from event1 to event2 yet I am told I was talking to people. WTF.

Re: After simple dental surgery, William lost his ability to form new memories

#93

Post by RowanH » Sun, Jul 05, 2015, 9:19 PM UTC

chx wrote: post #92

joezydeco wrote: post #15

Earlier quoted context omitted.

Earlier this year I had a medical procedure and was given "twilight" anesthesia. I was explicitly told "you need to have your spouse or a friend here because we're going to give you instructions afterward and you probably won't remember it". And, sure enough, my memory was pretty much wiped for the hour or so after the event. Later that evening I had a conversation with my wife that went like this: "Um, did you help…

Oh yeah, conscious sedation. It's 9am, I am in the dentist chair and getting pills. Next it's 5pm and I am in my bed at home and I have zero idea how we progressed from event1 to event2 yet I am told I was talking to people. WTF.

Yep - had my wisdom teeth out, same deal - I remember counting backwards, waking up in the chair, magically getting to waiting room, I blinked and my flatmate was magically there, then I magically was upstairs at home. Definitely would repeat that again rather than recall the procedure!

Re: After simple dental surgery, William lost his ability to form new memories

#94

Post by tptacek » Sun, Jul 05, 2015, 9:19 PM UTC

carbocation wrote: post #87

tptacek wrote: post #69

Earlier quoted context omitted.

And that makes intuitive sense. I'm still left with the question: is the experience of surgery really that bad?

I'll say yes. For example, sometimes we have to run electrical current through someone's chest to correct an arrhythmia. Depending on the urgency, we will give a medication such as midazolam. Ideally you want the sedation to have taken effect, but you don't always have the time to wait for that before your hand is forced and you have to cardiovert. The amnestic properties will help reduce some of the traumatic memori…

Sure. That makes sense. You gave me enough keywords with that comment to look up electrical cardioversion and pain, and so now there's something new that I'm scared of (kale for dinner tonight!) (thanks!).

But that's actually something different than what I'm asking. I have no trouble understanding why I wouldn't want to remember a pain "similar to that of surgical incision". Similarly: I wouldn't want to remember an unanesthetized incision!

But before learning that surgical patients were routinely given midazolam to zap their memory, my impression was that surgical patients were completely zonked out by general anesthesia, and so there'd be no need to zap their memory, because they weren't going to consciously experience the incision in the first place.

Now I'm like, is all of general anesthesia a scam, and we're all enduring horrible pain, and we just don't remember it? J/K ONLY SERIOUS.

Re: After simple dental surgery, William lost his ability to form new memories

#95

Post by DanBC » Sun, Jul 05, 2015, 9:26 PM UTC

tptacek wrote: post #69

jandrewrogers wrote: post #68

Earlier quoted context omitted.

The use of amnesiacs like midazolam in conjunction with unpleasant surgery has become common practice because it has been shown to significantly reduce the psychological trauma associated with surgical procedures and related changes in behavior as a result. You will still experience the trauma at the time whether you remember it or not, but the experience is not persistently encoded into your brain. This is important…

And that makes intuitive sense. I'm still left with the question: is the experience of surgery really that bad?

A friend of mine had a skin graft done under a local anasthetic. Debriding the wound was worst. Harvesting the skin was unpleasant. Attaching the graft was unpleasant. Dressing it all was not fun.

Re: After simple dental surgery, William lost his ability to form new memories

#96

Post by metasean » Sun, Jul 05, 2015, 9:32 PM UTC

rusabd wrote: post #88

metasean wrote: post #65

Earlier quoted context omitted.

After my first knee surgery, I regained consciousness midway through speaking a sentence to my mother. I was literally listening to words coming out of my mouth and had no idea where I was, who I was, or what I was talking about. My very next sentence was a panicked question to my mother trying to figure out those things. Turned out I had 'been awake and having cohesive conversation' with her for over an hour. I stil…

I read this book "The Master and His Emissary: The Divided Brain and the Making of the Western World" and based on that I would say your left hemisphere were active when right one was suppressed for some time. I can't recommend this book highly enough - it's very comprehensive and it give you an opportunity to look at the world from a different perspective

Sounds fascinating. Thanks for the recommendation!

Re: After simple dental surgery, William lost his ability to form new memories

#97

Post by carbocation » Sun, Jul 05, 2015, 9:33 PM UTC

tptacek wrote: post #94

carbocation wrote: post #87

Earlier quoted context omitted.

I'll say yes. For example, sometimes we have to run electrical current through someone's chest to correct an arrhythmia. Depending on the urgency, we will give a medication such as midazolam. Ideally you want the sedation to have taken effect, but you don't always have the time to wait for that before your hand is forced and you have to cardiovert. The amnestic properties will help reduce some of the traumatic memori…

Sure. That makes sense. You gave me enough keywords with that comment to look up electrical cardioversion and pain, and so now there's something new that I'm scared of (kale for dinner tonight!) (thanks!). But that's actually something different than what I'm asking. I have no trouble understanding why I wouldn't want to remember a pain "similar to that of surgical incision". Similarly: I wouldn't want to remember an…

Midaz can be used as premedication before induction of general anesthesia, but it's not an induction agent itself. If you're getting general (as opposed to "twilight") anesthesia, once you're induced, you should be unconscious (to the best of our ability to understand consciousness).

I'm medicine, not anesthesia, so I don't use these agents all day and therefore referred to cardioversion which is more in my domain. Cheers!

Re: After simple dental surgery, William lost his ability to form new memories

#98

Post by tptacek » Sun, Jul 05, 2015, 9:51 PM UTC

carbocation wrote: post #97

tptacek wrote: post #94

Earlier quoted context omitted.

Sure. That makes sense. You gave me enough keywords with that comment to look up electrical cardioversion and pain, and so now there's something new that I'm scared of (kale for dinner tonight!) (thanks!). But that's actually something different than what I'm asking. I have no trouble understanding why I wouldn't want to remember a pain "similar to that of surgical incision". Similarly: I wouldn't want to remember an…

Midaz can be used as premedication before induction of general anesthesia, but it's not an induction agent itself. If you're getting general (as opposed to "twilight") anesthesia, once you're induced, you should be unconscious (to the best of our ability to understand consciousness). I'm medicine, not anesthesia, so I don't use these agents all day and therefore referred to cardioversion which is more in my domain. C…

I am noting with interest and a small amount of alarm the abruptness with which you've ejected yourself from this thread after my suggestion that all of anesthesia is a huge scam. :)

Re: After simple dental surgery, William lost his ability to form new memories

#99

Post by JesperRavn » Sun, Jul 05, 2015, 9:53 PM UTC

tptacek wrote: post #69

jandrewrogers wrote: post #68

Earlier quoted context omitted.

The use of amnesiacs like midazolam in conjunction with unpleasant surgery has become common practice because it has been shown to significantly reduce the psychological trauma associated with surgical procedures and related changes in behavior as a result. You will still experience the trauma at the time whether you remember it or not, but the experience is not persistently encoded into your brain. This is important…

And that makes intuitive sense. I'm still left with the question: is the experience of surgery really that bad?

I've always been afraid of intravenous sedation (="twilight anesthetic" in other English speaking countries) for the same reason.

The only time I experienced it was for an endoscopy. Because I was a heavy drinker at the time (probably the reason for the symptoms that lead the the endoscopy, ironically) the intravenous sedation had little effect, so I was awake through the whole thing. I didn't find it traumatic, merely unpleasant, but I think other people might have. The local anesthetic at the back of my throat wore off after some time, so I was dry retching every few minutes. At one point they pumped air into my stomach so they could take a sample with a needle (which was in itself painless), and that sensation was also unpleasant.

So while I doubt people undergoing intravenous sedation during routine surgery are in extreme pain, they may be in very uncomfortable situations that most people would rather forget. Also if it had been effective, it would alter your state of mind as well, so that the immediate experience was less bad.

Re: After simple dental surgery, William lost his ability to form new memories

#100

Post by neuro_imager » Sun, Jul 05, 2015, 9:58 PM UTC

I would strongly question the idea that he has "no structural abnormality".

It would be very interesting to see exactly what type of imaging they performed on him. Bear in mind, an abnormality in the hippocampus or other memory related structures could be sub-mm in size and result in a significant impairment.

If, for example, he did not have an MRI with diffusion weighted imaging with a sufficiently high B value (gradient value) they may be missing/have missed a very small stroke (this test is also time sensitive -only positive within the first few days of insult).

If they did not perform susceptibility weighted imaging, they may have missed a tiny micro-haemorrhage. Both of these scenarios can result in memory loss if critical structures are involved.

There are also several technical issues that may have resulted in a sub-optimal scan, precluding finding a tiny abnormality. There's also the question of whether the person reading the scan got it right or whether the strength of the magnet/technical parameters of the study were sufficient to resolve a tiny abnormality.

Either of these scenarios could have been a consequence of reduced blood flow (hypoperfusion), a small clot (embolus) or a tiny blood vessel injury (dissection) that could have occurred during the procedure - possibly related to the anaesthetic but not definitively so.

I suspect there is a definitive abnormality that the clinicians that saw him were unable to pick up. This seams a lot more likely than the idea that we need to revise our entire conceptualisation of memory formation to suit a psychological theory.