The symptoms of a low-grade or benign brain tumour depend on its size and where it is in the brain. Some slow-growing tumours may not cause symptoms at first.

When symptoms do occur, it is because the brain tumour is either putting pressure on the brain or preventing an area of the brain from functioning properly.

Increased pressure on the brain

If the tumour causes an increase in pressure inside the skull, it can lead to the following symptoms:

• epilepsy or fits, which can be either major seizures or twitching in one area of the body
• severe, persistent headache
• irritability, drowsiness, apathy or forgetfulness
• vomiting, which is sometimes sudden and for no apparent reason
• dizziness 
• partial loss of vision or hearing
• hallucinations
• personality changes, including abnormal and uncharacteristic behaviour

It is important to see a doctor if you develop a persistent and severe headache that does not have any obvious cause, especially if you also have unexpected vomiting.

Loss of brain function

Different areas of the brain control different functions, so any loss of brain function will depend on where the tumour is located. For example, a tumour affecting:

• the frontal lobe – may cause changes in personality, weakness in one side of the body and loss of smell
• the parietal lobe – may cause difficulty in speaking, understanding words, writing, reading, co-ordinating certain movements and there may also be numbness in one side of the body
• the occipital lobe – may cause loss of vision on one side
• the temporal lobe – may cause fits or blackouts, a sensation of strange smells and problems with speech and memory
• the cerebellum – may cause a loss of co-ordination, difficulty walking and speaking, flickering of the eyes, vomiting and a stiff neck
• the brain stem – may cause unsteadiness and difficulty walking, facial weakness, double vision and difficulty speaking and swallowing