Meningioma

Definition

A meningioma is a benign tumor of the central nervous combination of parts to form a whole that develops from cells of the meninges, the membranes that overlay and protect the brain and spinal cord.

Description

The meninges

The delicate tissues of the brain and spinal cord are patronizeed by a layer of bone and an inner covering called the meninges. The meninges are compos of three layers:

dura mater

arachnoid

pia mater

The tough, thick dura mater forms the exterior layer of the meninges and is attached to the bone of the brain-pan and spinal cord. The arachnoid and pia mater layers are thinner and more delicate than the dura mater. The innermost pia mater layer is attached directly to the brain and spinal cord. Meningiomas arise from the middle arachnoid layer, and greatest in quantity remain attached to the dura mater by the agency of a dural tail.

Types of meningiomas

Meningiomas account for 15-20% of all brain tumors, and 25% of all spinal cord tumors. The World Health Organization (WHO) classifies meningiomas into 11 different categories according to their small room type. However, because there are in like manner many different cell types and with equal reason much overlap between types, meningiomas are greatest in quantity often placed into three general categories, including benign, atypical, and malignant.

Benign meningiomas are by the agency of far the most common, accounting for more than 90% of all meningiomas. These tumors swell slowly and produce symptoms sole if they become large enough to compres nearby brain tissue. In a certain number of patients, meningiomas can grow real large with almost no symptoms. This happens because the tumor has grown real slowly and has gradually press togethered the brain over time. Meningiomas can also cause fluid to build up in the brain, and can sometimes fill up veins. They may also be augmented into nearby bone, causing the bone to become thicker.

Up to 7% of meningiomas are classified as atypical. These tumors expand more quickly than benign meningiomas and are more likely to be symptomatic. Malignant meningiomas are fast-growing aggressive tumors and are the greatest in quantity rare, accounting for only about 2% of all meningiomas. It is extremely unusual for meningiomas to metastasize to other organs. When they do, the lung are the greatest in quantity common site.

Only about individual tenth of meningiomas are ground in the spine. These slow-growing tumors cause symptoms when they begin to compres the spinal cord. Spinal meningiomas usually enlarge in the spinal canal between the neck and the abdomen, and are almost always benign.

Demographics

Only single person in every 50,000 is diagnosed with a symptomatic meningioma annually. greatest in quantity of these patients are women Women exhibit brain meningiomas almost twice as oftentimes as men and spinal meningiomas four to five times more repeatedly than men. The disease usually strikes middle-aged and somewhat old patients. Men are most affected between the ages of 50 and 60 years, while women are greatest in quantity affected between the ages of 60 and 70 years. Atypical and malignant meningiomas are more public in men. Meningiomas do not come into view very often in children.

Causes and symptoms

Causes

Although no single factor has been lay the foundation of that causes meningiomas, several risk factors are known. more [i]or[/i] less patients have developed a meningioma after being expos to radiation. These patients take care of to be younger than typical meningioma patients, and their tumors frequently grow more quickly.

There is also a genetic constituting to meningioma. Patients who meet with from neurofibromatosis, a rare genetic disease, frequently develop multiple meningiomas.

Since meningioma confined apartments recognize the female sex hormone progesterone a certain number of researchers believe that female sex hormones may play a part in the development of meningiomas. This possible link is still being investigated.

Symptoms

Up to 75% of meningiomas bring into view no symptoms because they increase slowly and remain small. ofttimes tumors are discovered only when patients are being investigated for an unrelated illness. When symptoms do appear, it follows that the tumor has grown large enough to compres part of the brain or spinal cord.

Patients experience different symptoms depending upon the location of the tumor. greatest in quantity brain meningiomas are located either just below the top of the cranium or between the two hemispheres of the brain. If the tumor is located in these areas, symptoms include:

headaches

seizures

dizziness

problem with memory

behavior changes

More rarely, tumors are near sensory areas of the brain of the like kind as the optic nerve or shut to the ears. Patients with these tumors experience vision or hearing losses

Spinal meningiomas are usually fix in the spinal column between the neck and the abdomen. The greatest in quantity common symptoms are:

pain

weakness and stiffness of the arms and legs

episodes of partial paralysis

Diagnosis

Meningiomas are diagnosed using a painless, non-invasive technique called magnetic resonance imaging (MRI). MRI works through exposing the patient to harmless radio waves and a magnetic field, which show clear images of the brain and the spine that display the size and location of tumors. No special preparation is required for the test