Let us talk here about a relatively common brain tumor called meningioma. I shall try to keep this simple yet cover some important aspects. Meningiomas are brain tumors which do not arise from the cells of the brain (as against glioms which arise from glial cells and other tumors which arise from neural cells). As they do not arise from “brain” cells, they actually are extra-axial in location. By that I mean, they are located outside the brain but inside the skull. So meningiomas do not actually “invade” the brain, on the other hand as they grow in size they press on the brain from outside inwards.
This is how meningiomas cause their effects. Depending upon which location the tumor is, as it grows in size it exerts pressure on surrounding structures. Pressure on the surface of the brain may cause seizures (so many patients may present with seizures and when a MRI scan is done the tumor is found), if they are near the optic nerve or tracts patient may present with slowly progressive loss of vision, if near the motor tracts with weakness in the arm and leg, if near the cerebellum with gait and balance problems.
Meningiomas are slow growing tumors and as I stated earlier they usually do not invade the brain (though they may be locally invasive at times and these tumors are called atypical or malignant meningiomas). As these are slow growing, if they are small in size and discovered accidently (as in you went for a MRI for some other reason and a meningioma is found but is not the cause of your symptoms), your doctor may decide not to do anything and just wait and watch and follow you with serial MRI scans. Frequently patients outlive their tumors and die of natural causes without the tumor ever becoming symptomatic. If for some reason it starts increasing in size and becomes symptomatic then a surgical option can be explored.
So now that we know something about these tumors, we can discuss how to treat them. The treatment option pursued depends upon the size and location of the tumor. If the tumor is the right size and in a surgically accessible location, then it is easy take it out surgically if it is symptomatic. However if the tumor is symptomatic but in a surgically inaccessible location like near the optic nerves then other options like sterotactic radiotherapy may be tried. The management decisions need expert opinion and hence one should consult a specialist.
Nitin Sethi, MD