- Location of a meningioma is the most important factor in determining the outcome of treatment
- Common locations include
a. Convexity: this is the easiest type of meningioma to remove. I call this ‘trainee meningioma”. Removal is usually easy by first cutting off the blood supply to the tumour by cutting the dura around the tumour before removal. Computer localisation is useful to guide the skin and bone cut. It is not near or attached to important nerve or blood vessels.
b. Parasagittal meningioma: some of these tumours can grow to huge size before symptoms appear. The important issue with this type of tumour is sometimes it may involve a major vein of the brain, superior sagittal sinus. Small residual tumour inside the superior sagittal sinus may need post-operative radiotherapy.
c. Anterior cranial fossa: olfactory groove, tuberculum:
Olfactory groove meningioma is near the surface and therefore quite easily accessible. Nevertheless occasionally it may erode or invade the skull base bone making complete removal difficult. Small remnant tumour may be treated with Gamma Knife (a type of single dose computer guided radiotherapy).
Tuberculum meningioma often presents with visual problem. It may involve some arteries at the back of the tumour (anterior cerebral arteries) and surgeon needs to be very careful not to injure these arteries or else stroke may result. Most of the time it is possible to completely remove such tumours.
d. Middle fossa meningioma:
The bone called sphenoidal wing forms the boundary of the middle cranial fossa (middle part of the skull). Meningiomas arising from this region may be near the surface (lateral one third of sphenoidal wing), which makes it easy to remove. Or it may arise near the middle of the brain (medial one third of the sphenoidal wing) making it impossible to completely remove because of involvement of an important artery (internal carotid artery). When it arises in the middle of the brain involving the artery as well as important nerves and vein (cavernous sinus meningioma), surgery cannot be done but the tumour often can be treated with radiotherapy.
e. Posterior fossa meningioma:
Again, when the meningioma is near the surface, removal is not so risky. But when the meningioma is deep seated, like petroclival meningioma, surgery is risky but still do-able most of the time. Professor Ossama Al-Mefty stated in his book called “Meningiomas” stated that this type of meningioma is the most formidable of all meningiomas. He is one of the best neurosurgeon in the world and enthusiastic teacher from whom I learnt much.
Brain tumours can be divided into 2 groups:
1. Benign non-cancerous tumours
2. Cancerours tumours
1. Benign Non-Cancerous Tumours
Meningioma (10% of all brain tumours) (Figure 2):
This tumour grows on the covering of the brain (meninges). Usually it grows slowly but occasionally it can grow faster than expected. It may produce symptoms of
1) Headache. This type of headache sometimes occurs at night or early morning, waking the patient up. Coughing, sneezing and straining in toilet may aggregate the headache
2) Epilepsy. An epileptic fit may be the first symptom the patient experiences.
3) Neurological problems such as weakness, numbness of the arms or legs or blurred vision, depending on the location of the tumour. The patient may complain of walking difficulty.
INVESTIGATIONS
MRI scans is necessary to see the tumour clearly. For computer guided (stereotactic) surgery, a detailed (fine cut) is needed for the computer to reconstruct a 3-D model of the tumour.
Complete removal of the tumour gives long term cure (Testimonial 2, Ordinary complaints, Tan Pao Suang 54 year old Medan). Sometimes if the tumour has a lot of blood supply to the tumour (vascular), a pre-operative embolization of the tumour (injection of particles to block off the feeding arteries to the tumour) can make the surgery smoother and less risky.
Before surgery, often the patient needs to be started an anti-epileptic medication as epilepsy may occur after any brain surgery due to irritation of the brain due to the tumour or surgical manipulation. If there is brain swelling before surgery causing much pressure effect, steroid (dexamethasone) needs to be given to reduce the swelling first before surgery. With steroid, the patient’s symptoms often improve but this is not a permanent solution as steroid cannot reduce the tumour.
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