Pain in the Brain

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Pain in the Brain

Postby vivian maxine on April 10th, 2017, 1:25 pm 

There is no pain in the brain, we are told, because the brain has no nociceptors. Surgeons can operate on the brain without causing the patient any discomfort - again, so we are told. They can sometimes even operate with the patient awake.

So far, so good. However, there are intervening places that do have pain receptors. How does the surgeon get past the meninges and the periosteum to access the brain without causing pain?
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Re: Pain in the Brain

Postby someguy1 on April 10th, 2017, 2:15 pm 

A Google search for "brain surgery anesthesia" returned many many results, of which this is one. There are a lot of others.

http://www.seanesthesiology.com/patient ... anesthesia
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Re: Pain in the Brain

Postby vivian maxine on April 10th, 2017, 2:59 pm 

But they were not using anesthesia to my understanding. No need to because the brain doesn't feel pain. I have read that there are some brain surgeries that actually require the patient to be awake and alert. Doctor needs to be able to question patient.

My question was how they pass through the Meninges, which wraps around the brain, and periosteum, which wraps around the skull bones. Both are outside the brain and do feel pain.
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Re: Pain in the Brain

Postby doogles on April 11th, 2017, 5:17 am 

vivian maxine, you’ll see from the following link that the dura mater (one of the meninges) is also anaeshetised with local anaesthetic - https://academic.oup.com/bjaed/article/ ... craniotomy - "During brain biopsy or mini-craniotomy, infiltration of local anaesthetic into the relevant area of scalp and pericranium, and later onto the dura, is all that is required. However, for a formal craniotomy, the neurosurgeon must perform field blocks of the scalp, using combinations of lidocaine and bupivacaine with epinephrine. The skin, scalp, pericranium and periosteum of the outer table of the skull are all innervated by cutaneous nerves arising from branches of the trigeminal nerve. Subcutaneous infiltration with local anaesthesia in the manner of a field block or over specific sensory nerve branches, blocks afferent input from all layers of the scalp. The skull can be drilled and opened without discomfort to the patient (no sensory innervation) but the dura is innervated by branches from all three divisions of the trigeminal nerve, the recurrent meningeal branch of the vagus, and by branches of the upper cervical roots. It must therefore be adequately anaesthetized with a local anaesthetic nerve block around the nerve trunk running with the middle meningeal artery, and also by a field block around the edges of the craniotomy. Local anaesthetic solutions deposited around the middle meningeal artery should not contain epinephrine. The early part of the craniotomy (i.e. until dural opening) may be distressing for the patient because of incomplete local anaesthesia or noise from power tools; it may be appropriate to use i.v. sedation or general anaesthesia during this phase of surgery."

I never had to do brain surgery in animals during my 25 years as a country vet, but much of my general surgery was performed using mild sedation coupled with nerve blocks and infiltration of areas with local anaesthetics which was similar in principle to that used in human brain procedures in conscious patients. This was particularly so with cattle. Eye ablations (usually for cancer), dehorning, claw amputations and abdominal operations were all performed this way. Amputation of a claw in a hind leg usually required four separate nerve blocks.

The internal organs appeared to be insensitive to surgical incisions and suturing. Caesareans were performed without anaesthesia of the uterus and could be performed with the cow in a standing position if the tranquilliser dose was not too large.
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Re: Pain in the Brain

Postby vivian maxine on April 11th, 2017, 6:59 am 

Thank you, doogles. At about 10:00 last night, it came to me. It is only the brain itself that needs no anaesthesia. I wasn't thinking straight when I answered someguy. My apologies. Like driving, good thing I don't do surgery?
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Re: Pain in the Brain

Postby doogles on April 12th, 2017, 7:30 am 

Just to add to the subject of local anaesthesia for brain surgery, the following picture shows the extent of exposure used by two neurologists over a period of 25 or more years, all under local anaesthesia.

DEGREE OF BRAIN EXPOSURE - Copy.jpg


The picture on the left shows the outline of the skin incision flap and as you can see, the amount of the temporal lobe exposed is quite extensive. After incising the skin they obviously sawed out the underlying scalp bone plus the dura mater and folded them downwards to expose the amount of temporal lobe in the picture.

While the patient was quite conscious, the surgeons applied electrodes to various areas of the temporal lobes, hoping to trigger the areas causing epilepsy. The primary aim was to identify the troublesome areas and to excise them surgically and thus remove the cause of the epilepsy. As you can see, this is not keyhole surgery.

Quite incidentally, the triggered area sometimes resulted in the conscious patient recalling auditory or visual images from the past, as well as experiencing a variety of feelings associated with those images.
I have a full hard copy of this article by Wlbur Penfield and Phanor Perot. I find it extremely interesting for many reasons.

1. It is a journal article, published in Science in 1963, vol 86, and is 100 pages long (pp 596-695). This must be unique. The title of the article if you wish to acquire it is The Brain’s Record of Audiory and Visual Experience: A Final Summary and Discussion.
2. The patients were not only conscious but also able to correct the surgeon’s interpretation of what they were reporting eg on p601 “The surgeon and the patient are able to discuss the effect of each application of the electrode to cortex, and the conclusion is then dictated by the surgeon to a secretary who sits behind the glass of a viewing stand. Since the patient is hidden under surgical drapes, and since he cannot feel it when the brain is touched, the surgeon can check the reliability of the responses with certainty. The patient, on his part, occasionally interrupts and corrects the surgeon’s dictation.”
3. Of the 1132 cases reported, 7% of temporal lobe stimulations resulted in experiential responses and 10% in spontaneous experiential hallucinations.(p 602).
In their discussion and conclusion, the authors state that “ … the evoked experiential response is a random reproduction of whatever composed the stream of consciousness during some interval of the patient’s past waking life. It may have been a time listening to music, a time of looking in at the door of a dance hall, a time of imagining the action of robbers from a comic strip, a time of waking from a vivid dream, a time of laughing conversation with friends, a time of listening to a little son to make sure he was safe, a time of watching illuminated signs, a time of lying in the delivery room at childbirth, a time of being frightened by a menacing man, a time of watching people enter the room with snow on their clothes.
It may have been a time of hearing someone call your husband’s name, a time of listening to your mother scold your brother, a time of watching a guy crawl through a fence at a baseball game, a time of standing on the corner of ‘Jacob and Washington , South Bend, Indiana’, a time of telling the doctor the sensation you had when you got ‘the disease from water’, a time of grabbing a stick out of a dog’s mouth, a time of listening to (and watching) your mother speed the parting guests, a time of listening to a broadcast from Philadelphia, a time of seeing the nurses from the hospital as you lay in bed and hearing what they say, a time of hearing your mother and father singing Christmas carols.” Etc.

These responses were elicited in only a minor percentage of patient’s, and I wonder of course whether more responses could have been achieved with maybe more modern refinements of the techniques.
4. The authors do not personally interpret these findings the way I do, but I would postulate that all of the events recalled by the patients would have to have been present as some, as yet unknown, form of residue in the brain. And that these residues were stored in the form of images. None of the responses came out as lines in a book being read. Words per se in written form were not part of the recalls. The responses all appear to have been recalled in the manner in which they must have been perceived by the patients at the time they were stored.

This is a bit off topic, but I just regard this paper as containing a smattering of some evidence that we store information as residues of images in the way we perceive them at the time they are stored. I would love to see some more refined studies of this nature, particularly when they can be conducted at the time of other surgical procedures without any apparent risk to the patient.
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Re: Pain in the Brain

Postby Eclogite on April 12th, 2017, 8:44 am 

You have to take your hat off to brain surgeons.
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Re: Pain in the Brain

Postby vivian maxine on April 12th, 2017, 11:58 am 

The story is fascinating but I think, if I ever have a brain pain, I'll just keep it. :-(

Seriously, thank you for the education.
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