FAQ: glioma vs glioblastoma

Been getting a couple questions about brain tumors lately. Obviously because of Ted Kennedy (so sad) but also because of a family member recently diagnosed with glioblastoma (also very sad). Here goes:
A glioma is a tumor that arises from cells in the brain called glial cells. Basically these are all the cells in the brain that aren't neurons; they are the "glue" that holds the neurons together. Any tumor that comes from glial cells is called a glioma. But each kind of glial cell (for example astrocytes or oligodendrocytes) can have its own tumor arise from it, and each tumor has its own name. A tumor arising from astrocytes is called an astrocytoma. A tumor arising from oligodendrocytes is called an oligodendroglioma. These are types of gliomas.
Astrocytomas comprise 80% of primary brain tumors in adults. (Primary simply means that the tumor doesn't originate as cancer somewhere else in the body and metastasize to the brain.) There is a spectrum of badness for astrocytomas. Grade IV astrocytomas are the most aggressive and have a special name: glioblastoma. (I didn't come up with this naming system, people.)
Contrary to popular belief (or my interpretation of popular belief, I guess), brain tumors rarely present with headaches. This is because there are NO nerve endings in the brain, so tumors don't cause pain. Crazy, right??? (If there was some way to get inside your skull pain-free, you could undergo brain surgery without anesthesia.) They usually present in one of two ways: with seizures (a la Ted Kennedy), or with something called mass effect. Mass effect means the signs and symptoms that arise from having a mass in the brain, since the brain really doesn't like to be pushed around inside the skull. Symptoms include mostly nausea and vomiting, though a classic sign is vomiting without nausea. One more time: headaches rarely mean brain tumor.
Hmmmm....any other burning questions about brain tumors?....