Meningiomas are tumors that form in the meninges, a membrane that surrounds the brain and
the spinal chord. The meninges, which consists of three layers the dura mater,
arachnoid, and the pia mater. On average these tumors a benign with only 10%
being malignant. Since the overwhelming majority of these tumors are benign they
do not pose an immediate threat until they begin to adhere to other structures
and put pressure on the brain. Benign meningiomas grow at a slow rate, thus a
patient can have the tumor for a substantial amount of time before symptoms
begin to surface. On the other hand, malignant menginomas can grow rapidly or
have a spontaneous spurt in growth.
Meningiomas
are the second most prevalent kind of tumor of the brain. The majority of
patients with meningiomas are middle aged and women are three times more likely
to develop this type of tumor than men. There have been some reported cases of
meningiomas in children but these are very rare as less than 2% of patients are
children.
About
90% of meningiomas occur intracranially, or inside the brain, with remaining
10% occurring in the spinal chord. Almost all menginomas that occur inside the
brain happen at one site. Although it is rare, there have been cases of
multiple menginomas that occur simultaneously among different parts of the
brain and the spinal cord. These tumors are found in various shapes such as
solitary masses, dome-shaped, oval, round, and an uncommon form called
meningioma-en-plaque is flat and conforms to the shape of the brain and inside
the skull.