Compactness of Brain Matter (TMI Warning)

Factual Questions
1

I was watching a TV commercial where a women explains that after getting severe headaches her doctor discovered a brain tumor the size of a lemon in her head. Once it was removed her headaches went away (duh). I can’t remember what was being advertised, but it got me thinking.

I’ve heard of gargantuan (football sized) tumors being removed from someone’s abdomen, but I didn’t think there was that much empty space inside your cranium. Since the cranium is bone and can’t expand, a brain tumor displaces brain tissue as it grows.

In college we did some brain dissections and the brain seemed compressible, but mainly squishy like a sponge. It was almost rubbery in texture, but this was obviously post-mortem.

So how big of a tumor can someone have in their brain since the brain matter can’t compress down to nothing without killing the person. Does anyone know?

2

I would think that water or blood would be the first things getting displaced when adding something to an allready full container.

3

I’m not too sure about that. Removing blood or spinal fluid from the brain cavity often leads to unconsciousness…

4

Well, there are large fluid filled ventricles within a normal brain that are not really doing very much. They could be squished down quite a bit without that, in itself, causing much trouble. (That is not the same as removing CSF and just leaving a space.) On the other hand, people can apparently get by by perfectly well with a lot less volume of brain tissue than most of us have: Is Your Brain Really Necessary? [PDF]

Incidentally, I suspect that the stuff you got to dissect had been pickled in formaldehyde, so living brain tissue is probably a good a deal squishier than the stuff you experienced.

5

I agree with you, I think thats where the problems would come in.

6

My sisters fiancee got up one day, tried to walk and fell over. This was rather odd so he went to the doctor.

They found a tumor about the size of a fist in his skull.

Prior to the falling incident, he did not have any symptoms that anything was wrong.

Regrettably he passed away a little over a year later. They did surgery but the cancer was too advanced. It sucked, 'cause he was a good guy.

Slee

7

Many tumors in the brain are actually cancer that spread there from another part of the body. A friend died because lung cancer spread to his brain, but I don’t think he had any symptoms of lung cancer.

8

The unconsciousness in those circumstances is a result of a severe drop in pressure when blood and/or CSF are suddenly removed, with blood not getting to parts of the brain that need it. That is not the case with a tumor gradually growing in there, and squeezing out some of the CSF that is uselessly filling up the ventricles.

9

Accommodating a lemon in your brain may not be as remarkable as it seems.

Let’s say the lemon is about ten percent of the volume of your brain. So, to accommodate it inside the skull at the ‘expense’ of the brain, the latter must be compressed by only about 10 percent overall. I’m not saying that’s healthy, but it doesn’t seem all that physically implausible.

10

Brain material isn’t going to be actually compressible to any significant degree, except by fluids being squeezed out as if from a sponge.

Liquids and solids without any contained voids are pretty nearly non-compressible in practical terms - if the brain contained gas filled pockets (which I don’t believe it does) it would be compressible - otherwise, something is being wrung out.

11

You can have a brain so compact that it forms a thin layer against your skull. See this guy, the black spaces are (at least two of four) the ventricles mentioned by njtt, except much bigger. Some can survive about half of their brain and be somewhat functional. The catch is: your prognosis is much higher if it happens when young.