Brain tumours are abnormal growths within the brain. There are many different types of brain tumour. They vary from benign tumours (e.g. meningiomas) to highly malignant (e.g. glioblastomas).
Often brain tumours do not have any symptoms, particularly when they are small. As they develop they present with focal neurological symptoms depending on the location of the lesion.
Brain tumours often present with symptoms and signs of raised intracranial pressure. As a tumour grows within the skull it takes up space. This leaves less space for the other contents of the skull (such as the CSF) to squeeze in to and leads to a rise in the pressure within the intracranial space.
TOM TIP: A common exam question asks the location of the lesion based on the neurology. A popular exam question describes a patient that has had an unusual change in personality and behaviour. This indicates a tumour in the frontal lobe. Remember that the frontal lobe is responsible for personality and higher-level decision making.
Raised Intracranial Pressure
Anything that takes up additional space within the skull will increase the pressure in the intracranial space. Raised intracranial pressure causes symptoms that can lead to a diagnosis of a brain tumour. Papilloedema is a key finding on fundoscopy in patients with raised intracranial pressure. This is a key component to examination in patients with headaches or other concerning features.
- Brain tumours
- Intracranial haemorrhage
- Idiopathic intracranial hypertension
- Abscesses or infection
Concerning features of a headache that should prompt further examination and investigation include:
- Worse on waking
- Worse on coughing, straining or bending forward
Other presenting features of raised intracranial pressure may be:
- Altered mental state
- Visual field defects
- Seizures (particularly focal)
- Unilateral ptosis
- Third and sixth nerve palsies
- Papilloedema (on fundoscopy)
Papilloedema is a swelling of the optic disc secondary to raised intracranial pressure. Papill- refers to a small rounded raised area (the optic disc) and -oedema refers to the swelling. The sheath around the optic nerve is connected with the subarachnoid space. Therefore it is possible for CSF under high pressure to flow into the optic nerve sheath. This increases the pressure around the optic nerve where it connects with the back of the eye at the optic disc, causing optic disc swelling. This can be seen on fundoscopy examination.
- Blurring of the optic disc margin
- Elevated optic disc (look for the way the retinal vessels flow across the disc to see the elevation)
- Loss of venous pulsation
- Engorged retinal veins
- Haemorrhages around optic disc
- Paton’s lines which are creases in the retina around the optic disc
TOM TIP: It can be tricky to learn to recognise papilloedema. When looking for elevation of the optic disc, look at the way the retinal vessels flow across the disc. Vessels are able to flow straight across a flat surface, whereas they will curve over a raised disc.
Types of Brain Tumour
The common cancers that metastasise to the brain are:
- Renal cell carcinoma
Gliomas are tumours of the glial cells in the brain or spinal cord. There are three types to remember (listed from most to least malignant):
- Astrocytoma (glioblastoma multiforme is the most common)
Gliomas are graded from 1-4. Grade 1 are most benign (possibly curable with surgery). Grade 4 are the most malignant (glioblastomas).
Meningiomas are tumours growing from the cells of the meninges in the brain and spinal cord. They are usually benign, however they take up space and this mass effect can lead to raised intracranial pressure and neurological symptoms.
Pituitary tumours tend to be benign. If they grow large enough they can press on the optic chiasm causing a specific visual field defect called a bitemporal hemianopia. This causes loss of the outer half of the visual fields in both eyes. They have the potential to cause hormone deficiencies (hypopituitarism) or to release excessive hormones leading to:
- Cushing’s disease
Acoustic Neuroma (AKA Vestibular Schwannoma)
Acoustic neuromas are tumours of the Schwann cells surrounding the auditory nerve that innervates the inner ear. They occur around the “cerebellopontine angle” and are sometimes referred to as cerebellopontine angle tumours. They are slow-growing but eventually grow large enough to produce symptoms and become dangerous.
Acoustic neuromas are usually unilateral. Bilateral acoustic neuromas are associated with neurofibromatosis type 2.
Classic symptoms of an acoustic neuroma are:
- Hearing loss
- Balance problems
They can also be associated with a facial nerve palsy.
Managing Brain Tumours
There is massive variation in brain tumours from completely benign to extremely malignant. Surgery is dependent on the grade and behaviour of the brain tumour.
Management options include:
- Palliative care
Treatment of Pituitary Tumours
- Trans-sphenoidal surgery
- Bromocriptine to block prolactin-secreting tumours
- Somatostatin analogues (e.g. ocreotide) to block growth hormone-secreting tumours
Last updated April 2019