Academic question regarding pain & loss of limb

[Alex Franke]

NOTE: If you're very squeamish, you may not want to read this post. This time it's not gravity that has me thinking too far over my head, it's how my nerves work...

I hope this isn't too gruesome, and I hope I (or anyone I know) never have to find out for myself, but I got to thinking about this the other night when my arms "fell asleep" as they sometimes do when I cross them under my pillow... I hate that feeling (or rather the lack of feeling) when you just can't move a part that you know you're supposed to be able to move.

I've accidentally cut myself a few times with very sharp blades and it never really hurt that bad -- not like dropping a plate on the toe anyway -- just a strange throbbing sensation. But the nerves must have been sending "pain messages" to the brain... maybe cloaked by adrenaline at first, though. I don't know.

So what happens when you lose a finger, toe or limb? Do you feel a "phantom" pain from all the nerve endings that were cut off? Or do you just feel it where the injury occurred? I mean, what do the nerves communicate to the brain? Is it the nerve ending that says "I'm hurt" or is it a kind of open circuit sensor in the brain that says "there's pain out there"?

And when does the pain stop? When the brain learns to ignore the messages, when the nerves heal, etc? I've read that people who lose a limb can often still "feel" it after it's gone -- is there a medical reason for that, or is it psychological?

[crokett]

My brother lost his foot about halfway up his calf when he was 10. I remember for several years after he would feel hot/cold/pain in the foot that was no longer there. I think it was an open circuit that eventually closed and the brain was used to getting messages from that foot.

[LinuxRandal]

I have several friends who are missing limbs, as well as those who aren't but are incapacitated. I will not speak to the pain issue, because I have seen some variance, that I don't know enough about their medical history (were they still on pain killers, recent surgeries, etc).

But I will say some of the "sensations" are sensory memory.

You ever have a dream where you could smell something cooking? Taste it? Feel something, or one? Those are examples of Sensory memory.
Different things can and do trigger it/them.

[HarmsWay]

Coming from an electronics background it would seem to me that sensation would go away - like a sensor on a piece of wire getting cut off, but apparently that's not what happens. Pain or other sensations can arise spontaneously without the 'sensor' due to chronic overactivity of the neurons. That's what my Principles Of Neural Science text says anyway. Sort of like noise on a disconnected line I guess. Definitely not psychological though.

Bob

[Tom Slick]

A friend of mine is missing his ring finger and he says it still itches sometimes.

[bigdaddyjohn]

I'm a paramedic by trade. Never had anyone smiling when they've lost a body part. I give lots of narcotics for that. My guess, Hurts like ****.

[billwmeyer]

I read a story on the net a few weeks ago about how they are treating loss of limbs with mirrors. Somehow using a mirror to make it look like a person had two legs helped ease the phantom pain, and sped recovery time. It didn't make sense to me, but since it is phantom pain, I guess it tricks the brain somehow.

Like you I hope I or no one I know has to deal with this, however I am diabetic, so my chances are much larger than many.

Bill

[430752]

yes and no

Does one feel a phantom pain? ys and No, depending on person I think. Maybe it is depending on where the amputation was and how it occurred. No one really knows. But it is real and some people do have it. it seems to usually strike loss of limb victims, not loss of digit or other body parts. As another poster here mentioned, they're treating it with mirrors.

Like I said, it is real but does not always occur. Also, the cuase is not known although the treatment suggests a cause. The answer is that when a limb is severed, the nerve endings still exist. They send nothing to the brain (so we think), but they are there. Or, they send a white noise signal to the brain. Not sure anyone is certain whether nerves operate on the "always-on" position to send an all clear signal unless events dictate otherwise, or whether nerves operate on an always off pattern where they don't send anything at all unless circumstances dictate a signal. In any event, the theory explaining phantom limb syndrome goes, the brain sees the limb missing and checks its nerve receptors and fails to "see" a nerve alert and thus overrides the nerve center for the missing limb and issues its own "panic" alert which trigger pain receptors, etc. Its like a false positive. Again, no one is quite sure, but this explanation seems accurate to the mirror study people who have demonstrated from numerous veterans of the Iraq conflict that by using a mirror to trick the brain into seeing two limbs instead of one subsides the pain pretty quickly. I think at first the brain is reset only for 10-30 minutes, but the more often it is used (as in longer history of use over weeks or months), the more the brain stops trying to override the lack of nerve signals. Of course, the phantom limb pain is not a constant to begin with and comes and goes. The mirror thing works so well I believe it has been recently adopt as SOP for army hispitals and the army doctor who "discovered" it (he admits he read about it in ancient greek or midevil literature, from whence it was forgetten by doctors for centuries) has began a doctors without borders type effort to educate doctors in war torn areas such as parts of africa and southeast asia to instruct their doctors how to help their civilians who often suffer amputations due to long forgotten land-mine, etc.

I have no idea what they do if you lose both legs or arms. And I have no idea if a realistic looking prostethic achieves the same results.

The whole thing, however, is part of a fascinating and recent push into the mind by neuroscientists, philosophers and psychiatrists. Yes, philosophers. Anyway, people are trying to figure out the human cognitive abilities and how the mind works. Not entirely on a physical level, but what does consciousness mean and why do some types of pain seem more important to the brain than others, and how can the brain override certain signals but others, including issues dealing with sight (why does the moon on the horizon appear bigger than when high in the sky, after all the moon is always the same distance from the earth, and the answer ain't because of perspective - there ain't no answer to that one yet). Unfortunately, wars are very good to this area of inquiry as the first tow World Wars gave quite a bit of insight since often (and this is a really odd thing to say) those wars had enough explosives to hurt, but not enough to always kill, whereas modern warfare has often more accurate and powerful weapons resulting in less surviving casulaties of the brain. anyway, there are studies of vets who had parts of brains blown-out or removed that had really odd behaviorial results and odd physical adaptations to overcome the lost parts. They all provide a window into how the brain works, but no one has figured it out since, as you might imagine, it ain't anywhere near half as simple as people originally thought (that is, the theory that we're all just a set of carbon atoms arranged in a certain way resulting in neural tubes which can be identified just doesn't explain it all yet. Maybe it one day will, but it seems the whole is greater than the parts).

Once in a while NOVA has episodes on this, especially one doctor out in California that discovered very odd brain happenings in patients with rare brain diseases. Highly recommended to watch if you come across it.

[dlminehart]

I was once told by a doctor (can't vouch for its truth) that phantom pain is more likely when the missing limb had been sending pain signals to the brain for some time before its removal, versus a situation in which a limb was cleanly removed under anesthesia before a pain signal had been sent for a while. E.g., a crushed limb, amputated hours later, is more likely to result in phantom pain than a limb removed because of some non-painful condition.

[MilDoc]

Phantom limb pain can occur in people that are born without limbs, or in paralyzed people too. The absence of a part of the body does not have to be due to amputation or trauma, and may have little to do with sensation from cut nerves etc since a missing part at birth never had such sensation.

Up to 80% of amputees experience it, sometimes as a burning, sometimes very painful, sometimes as if the missing part is twisted and distorted. Or anything else (cold, itching, warmth, tingling).

It apparently originates in the brain itself. The area of the brain originally "feeling" for the severed limb no longer receives any signals. Adjoining areas "remap" those "empty" areas and stimulation of the adjoining area body part results in sensation that "feels" like it coming from the "phantom limb." For example, a missing hand may feel phantom sensations if parts of the face are stroked.

There is some evidence that pain in the amputated limb prior to amputation leads to pain afterward also, but again not related to the severed nerves.

And local factors in the amputation area can lead to pain being perceived in the missing area, such as formation of a neuroma at a severed nerve, or, of course, an ill fitting prosthesis. But thta is locally induced pain, not quite the same thing.

[iceman61]

A friend of mine is missing his ring finger and he says it still itches sometimes.

I have a friend like that also. He says his missing finger still itches from time to time. To scratch the missing finger, he scratches just behind his elbow on the same side.

[LinuxRandal]

Sometimes googling for stuff, doesn't find it..........ARGH...........



There WAS a video on Youtube, that dealt with this a little bit. A speaker at the TED tv event, had a patient who had suffered an electrical burn and lost at least one arm (from memory). He was able to control a fake arm, via nerves which were in chest. The Dr. could touch an area, and he could feel it, in the no longer there limb.

There is also a newer TED tv about a prosthetic limb that can be controlled to a MUCH finer extent then current ones.

There was also the story about a woman, who received a bionic arm and regained her sense of touch.

There is also things like Acupressure and Acupuncture where one can affect one end of a nerve by affecting either the other end, or an adjoining nerve.

There is more to this then we currently know.

[germdoc]

What is very interesting to me is how many persons have a dysfunctional extremity that they physically "neglect"--that is they really don't pay attention to the way you would if you had a normal extremity--but they have an extreme psychological attachment to.

I've seen this many times with persons with neuropathy who often develop infection in their feet to the point they can't use the foot. They feel no pain and unintentionally injure the foot again and again. Yet, when a doctor recommends amputation, they are adamantly against it, even though they could actually rehabilitate and walk sooner with a prosthesis.

I guess we all love our hands and feet, but if they're totally useless, deformed and in fact gross, what's the point?

Maybe I'd feel differently if it were my foot, but I don't think so...

[dlminehart]

LinuxRandal, the scientist/physician responsible for the "bionic" arms on the electrician who lost both arms in a high voltage accident and on the woman who lost an arm in a motorcycle accident happens to be my brother-in-law, Dr. Todd Kuiken. He's an MD/PhD in biomedical engineering, and has been working for twenty years to develop this technology. Just received a grant from the DoD to work on bionic legs. He's also a woodworker (and carpenter and cabinetmaker and . . . ) who built his own bedroom set, has remodeled a few houses and kitchens, etc. I don't know how he finds the time! A remarkable guy, in every way.

[1index only]

It looks like I might be the only one that can speak on this from experience

Yes to all, Phantom pain and feelings, although they have subsided in intensity over time. Nov 05 when it happened. 10,000 piece of firewood

I occasionally have sensations of tapping my finger at the desk as if I'm tapping to music. I also have a ball of nerves at the base of my middle finger, leftovers per say from the lost Index finger that if I tap on it, the feeling is like a someone pounding on my index finger with their fist.

The painwell actually the initial cause hurt like h#*# for about 5 -10 minutes then I think shock took over. My wife was definetly more upset than I was. From then the throbbing was strong but bearable until the length of wait time at the E-room started to get excessive. The nurse finally saw me and said as she was pointing to the little smiley face pain scale "what level of pain to you think your at?" I looked and #10 was crying so I commented " well #10 is crying and I'm not but it sure hurts like h***" we all laughed and soon after they were shooting ladacaine into the cut and giving me some morphine

My hand around the thumb and index start to hurt and ache after using a hammer for a bit, as does alot of handwriting. I still write, shoot rifles, paint cars and what not with my right hand.

I have lots of fun telling co-workers I'll be back in 4 minutes as I hold my hand in the air, that or "give me a high 4"

Lots of rambling here, hope I made sense of everything