Brain Surgery

brain

The brain itself is made up of neural tissue (nerves, nerve tracts and nuclei) and glial cells (supporting cells that provide structural support and nutrients). Primary brain tumours most commonly arise from glial cells and these are intra-axial brain tumours. Primary brain tumours may also arise from the meninges (covering of the brain), pushing into the brain and these are called extra-axial brain tumours.

How do brain tumours present?

In general, brain tumours present in one of three ways.

  • Raised intra-cranial pressure: The brain is enclosed in a bony skull. Any growth within the skull cavity will increase the resting pressure inside the head. This may manifest itself with headaches, nausea/vomiting, or drowsiness/sleepiness. Raised intra-cranial pressure is an emergency situation as the brain is reliant on oxygen to survive and any drop in blood flow (and oxygen delivery) from raised pressure may result in brain damage.
  • Focal neurological deficit: Brain tumours growing in, or pressing on vital brain structures may result in stroke-like symptoms or focal neurological deficits. This may be transient, permanent or progressive. Tumours in deeper, more eloquent areas of the brain may cause focal neurological deficits at small sizes (less than 1cm) whilst tumours in less eloquent areas of the brain (frontal lobes) may grow to significant size before causing neurological deficits.
  • Seizures: Primary brain tumours may invade the surrounding neural tissue, or compress it and cause significant swelling of the brain. Either of these effects may result in abnormal firing of the nerve cells and cause seizures. These may be partial (no loss of consciousness) or generalised (with loss of consciousness).

How are brain tumours diagnosed?

Suspicious symptoms should be investigated with a CT scan of the head. This will demonstrate a brain tumour, however an MRI scan will be needed to further delineate the margins of the tumour and also to create a treatment plan for each individual. Occasionally an angiogram will be required pre-operatively to identify the blood supply of tumours and obliteration of this blood supply may be performed to minimise the risks of surgery.

Primary brain tumours

Gliomas

The most common primary brain tumour is a glioma. A glioma may be a low-grade astrocytoma, an anaplastic astrocytoma, or a glioblastoma multiforme depending on the aggressiveness of the cells. Treatment for these tumours include a combination of surgery, radiotherapy and chemotherapy.

Each treatment regime is individualised for the specific patient and tumour type. In general, surgery is required for biopsy and debulking (to reduce intra-cranial pressure). Higher grade gliomas (anaplastic astrocytomas and glioblastomas) will usually be given radiotherapy following maximal surgical debulking. Chemotherapy may be used at the same time for glioblastomas, or following a relapse with anaplastic astrocytomas. Treatment will be optimised and co-ordinated with the neuro-oncologist, radiation oncologist and neurosurgeon.

Meningiomas

A meningioma arises from the strong protective covering of the brain called the dura. The majority of meningiomas are benign however meningiomas grow locally and may cause symptoms from pressure effects on surrounding structures. A meningioma is slow growing. Just because a meningioma is found on CT does not mean it must be removed. It is reasonable to monitor a small meningioma with regular MRI scans annually to confirm it is not growing, particularly in older patients.