Diagnosis
A child may be referred by a GP for neurological tests following symptoms including headaches, blurred vision, dizziness, vomiting or seizures. Emergency admittance to hospital may be necessary due to extreme symptoms, for example, severe vomiting/dehydration and/or confusion. A registrar/ paediatrician will carry out further test including neurological and optical tests. Neurological tests involve assessing the function of the brain and spinal cord. These tests can give a measurement of balance, strength and movement. Optical tests can identify increased pressure in the brain.
If an abnormality is found, or the doctor is still concerned, then the child will have a Computerized Tomography Scan (also called a CT or CAT scan) or a Magnetic Resonance Imaging Scan ( MRI). These are imaging tests and can show the location and size of the tumour. It can also show what effect the tumour has on other parts of the brain. The location of a tumour in the fourth ventricle and cerebellum and the physical appearance of the tumour can lead to a diagnosis of medulloblastoma. Confirmation of the diagnosis can only be given after the tumour has been surgically removed and following analysis of the tumour.
Magnetic Resonance Imaging Scan - MRI scan is used to give a clear picture of the brain itself. It will show exactly where the tumour is and the size of it. Often the MRI will include the spine or it may follow an initial MRI of the brain. This will show if there is spread of the tumour to the spine.
The scan is painless and takes about 30-45 minutes but unfortunately it is very noisy. Young children may find it frightening and may need to be sedated; occasionally, a general anaesthetic will be given. The child will have to stay very still as the pictures are taken. Earplugs/headphones can be given to help with the noise. The staff can talk to the child during the MRI to let them know what is happening. Some hospitals will allow a tape or CD of favourite music which they will play to help relaxation and to mask the noise.
The child will lie flat on the scanner bed and the bed will move slowly into the (large, ‘Polo Mint’ shaped) machine. Some children may find it a bit claustrophobic (it can help if the child is allowed to see the machine beforehand), also, it may be possible for a parent or carer to be in the room with the child.
Sometimes an injection will be given intravenously into the back of the child’s hand which consists of a contrast dye. This dye will give a clearer picture of the area of abnormal cells.
Computerized tomography scan (also called a CT or CAT scan) – This is a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images of the body. It is a lot quieter and does not take as long as an MRI scan. Again a contrast dye may be used as this gives a much clearer image. A parent/carer may be allowed into the CT room to give support to the child when they have the scan but will need to wear a special apron for protection from the x-rays.
Tumour staging
Following surgery/ biopsy, a diagnosis of medulloblastoma may be confirmed. The analysis of the tumour will also measure how far the tumour has spread beyond the original site.
- M0 - no evidence of metastasis
- M1 - Tumour cells found in cerebrospinal fluid
- M2 - Tumour beyond primary site but still in brain
- M3 - Tumour deposits or 'seeds' in spine area
- M4 - Tumour spread to areas outside the central nervous system
