Updated: Sep 26, 2021
In the second part of this series, we look at the benign brain tumour known as meningioma as a reversible cause of dementia.
Meningiomas are common brain tumours and their incidence increases with age. They are mostly benign tumours that arise from the lining of the brain and tend to grow inwards inside the skull to compress the underlying brain tissue but separate from it. Sometimes they can grow to incredible sizes and their general slow rate of growth can hide their presence for a long time, although these tumours have been known to grow quite rapidly especially when they demonstrate more aggressive pathological features. When symptomatic they can cause headaches, seizures, speech or language disorders, visual changes, and when present in the frontal area of the brain patients can present with dementia.
Figure 1: MRI brain scan demonstrating a right frontal meningioma. Left/top: T1 weighted image with contrast, demonstrating a right frontal meningioma vividly contrast enhancing (bright white) arising from the membrane overlying the brain tissue. Right/bottom: T2 weighted image demonstrating significant amount of oedema or swelling in the right frontal lobe of the brain adjacent to the tumour. It is the swelling in particular that can produce many of the clinical symptoms associated with meningiomas, and this and the symptoms generally resolve once the tumour has been removed.
The frontal lobe of the brain is important for higher brain functioning, including memory, problem solving, planning and organising, emotions, attention, motivation, and some components of language. Most people are right hand dominant, and likewise in most people the left frontal lobe is particularly dominant for speech and higher cognitive function, although the right frontal lobe is also just as important in some aspects of higher function. When tumours grow in either frontal lobe any or all of these functions may be impaired, and this is particularly true with frontal meningiomas. One way to think of a meningioma is like a thumb pushing into a kitchen sponge, with the thumb being the tumour and the distorted sponge the adjacent brain; take your thumb away, and the sponge returns to mostly its normal shape again. More than this however, frontal meningiomas impair function not only by the mass effect of the tumour itself, but also by the development of swelling or “oedema” in the brain adjacent to the tumour at the interface. The good news is that once the meningioma is removed most or all of this functional loss improves significantly or completely resolves especially once the tumour is resected and the oedema resorbs. In some instances people have been in a high level care nursing home facility for many years prior to the diagnosis of a frontal meningioma; in one memorable case for me following removal of a large meningioma a woman was ultimately able to live independently with her family again, with her family telling me “you have given me my sister back!”.
Not all meningiomas need to be resected, in fact the vast majority of them are small, benign and completely asymptomatic, and it is very reasonable to simply observe them periodically with surveillance imaging alone considering their rate of growth is usually very slow and the chance of them needing surgical resection remains low in the patient’s lifetime. However, for meningiomas that are producing symptoms surgical resection via craniotomy remains the treatment of choice, and for benign meningiomas this frequently results in cure.
If you or a loved one have been diagnosed with a meningioma please ask your GP to refer you to see a Neurosurgeon for an opinion and for general management advice.