Meningioma refers to one oR many tumors that arise in very close contact to the meninges. The meninges are the membranous layers that cover the brain and spinal cord.
Symptoms of meningioma are produced via different mechanisms. By irritating the underlying cortex, they can cause seizures. Headaches, weakness, dysphasia, and apathy are some of the symptoms seen due to compression by the tumors. They may also produce symptoms relative to their position, e.g. a tumor in the foramen magnum will produce paraparesis and sphincteric trouble while one in the olfactory groove will produce symptoms like anosmia. If the meningiomas are located in the skull base, they may occlude the cerebral arteries and present as strokes or transient ischemic attacks. This is however rare .
The gold standard for treatment for treatment of a benign meningioma surgical resection. Medical care is only used for perioperative medication or when other methods of treatment have failed considerably. Corticosteroid use for example greatly decreases the morbidity and mortality associated with resection. Antiepileptic drugs are also used pre and postoperatively in supratentorial surgery .
The general principles in surgical resection of meningiomas are: remove all involved and hyperostotic bone if possible. The dura involved with the tumor as well as its rim that is tumor free should be resected and a duroplasty performed. If dura tails are seen on MRI, they should be removed even if they are not involved with the tumor.
Radiotherapy therapy is used as primary treatment for some unresectable tumors. It is also used as adjuvant therapy for incompletely resected tumor and recurrent tumors.
The size of the tumor may have a role to play in determining the outcome. Studies have revealed permanent cranial nerve deficits is seen in up to 45.5% of patients who have tumors greater than 3cm. In patients with tumors less than 3cm, only about 6% show permanent cranial nerve deficits. If the neoplasm extends into the lower jugular foramen, there could be deficit of the lower cranial nerves.
The prognosis is generally excellent in patients who have had their meningiomas completely resected. However, if the tumors are incompletely resected, multiple or malignant, there is an increased likelihood of recurrence .
The cause of these tumors have not been fully understood. They are believed to be familial but many cases have arisen randomly, arising sporadically. However, there appears to be an increased risk of developing meningioma in patients who have suffered brain injury or received radiation to the scalp. There is also an increased risk with heavy mobile phone use and with frequent dental x-rays .
Patients with neurofibromatosis type 2 also have an increased risk of developing meningioma. There are also genetic mutations that have been associated with meningioma .
In the United States, the annual frequency of symptomatic meningioma is 2 in 100000. It accounts for 20% of all primary intracranial tumors. In Africa, it is responsible for 30% of all intracranial tumors. The morbidity and mortality is difficult to assess but the 5-year survival rate is assumed to be around 73 – 94%. They have a higher prevalence in Africans and African-Americans than in Caucasians. It is more commonly found in women than in men with a male to female ratio of up to 1 : 2.8. The incidence of meningioma increases with age from as low as 0.12 in patients younger than 19 years to as high as 18.89 in patients older than 85 [4, 5].
These tumors may grow within the brain or within the spinal cord. They are widely thought to originate from the arachnoid cap cells which are in the arachnoid layer covering the external part of the brain. Most meningiomas are seen on the brain surface, either at the skull base or over the convexity of the brain. In rare occasions, the may have an intraosseous or intraventricular origin. Classifying meningiomas is problematic because arachnoid cells may exhibit both epithelial and mesenchymal features, and similar tumors may arise from other mesodermal structures.
The classification of all these tumors together is contentious. The current inclination is to separate tumors that are definitely meningiomas from other less well-defined or poorly defined neoplasms. It is however expected that with the advances in molecular biology, scientist will be able to identify the exact anomaly in a genome that is responsible for each specific tumor .
There are no known ways to prevent this condition. Avoidable risk factors like heavy mobile phone use should however be prevented as much as possible .
Meningiomas are typically benign in nature with only a few percentage turning malignant. They are also asymptomatic in many instances and some individuals carry them their whole life without realizing. They are usually found when investigation for other conditions or during an autopsy .
Definition: Meningioma is used to define any of many tumors that grow very close to the meninges. The meninges are the covering of the brain and spinal cord. They are usually benign and many people live and die without knowing that they have it.
Cause: It is believed to have a genetic link but some cases arise randomly. Factors that could increase chances of getting this condition and increased exposure to radiation like mobile phones and dental x-rays. Also, patients who have had a brain injury have an increased risk of developing this condition.
Symptoms: The symptoms are numerous and are determined by the location of the tumor and/or the effect it is having on the brain. They range from the milder headaches and weakness to severe symptoms like paraparesis and stroke.
Diagnosis: This is mainly by the use of imaging tests like x-rays, CT scans and MRI. Some of the sample of the tumor will also be sent to the lab for histology.
Treatment: The main treatment is mainly surgical removal of the tumor. Drug treatment may be used to reduce the operative risk and postoperative complications.