The brainstem is located below the main part of the brain (cortex) and joins to the top of the spinal cord. Within the brainstem there are 3 main structures, the Midbrain, the Pons and the Medulla oblongata.
See also brain stem animation
Tumours are graded according to their severity, from Grade 1 (least dangerous) to Grade 4 (most aggressive) and these different types can arise in any of the structures of the brain. Tumours can be focal, with discrete borders (typically less aggressive) or they may be diffuse (more dangerous).
About 20% of all brain tumours occur in the brainstem but they account for the majority of brain tumour deaths in children. Within the brainstem itself, 80% of tumours arise in the Pons region and they are most commonly high grade diffuse tumours. This type of tumour is known as a Diffuse, Intrinsic Pontine Glioma (DIPG) and carries the worst prognosis.
DIPG is a very cruel disease. Children experience an accumulation of symptoms, which commonly include some of the following:
- Turning in of one or both eyes (causing double vision)
- Slurring speech (or loss of)
- Progressive paralysis (typically on one side of the body)
- Locked-in state (a glazed look – they are conscious of their surroundings but are unable to move, talk or interact)
- Difficulty swallowing
- Respiratory and cardiac irregularities
A powerful steroid called Dexamethasone is usually given to reduce the pressure of cerebrospinal fluid in the brain caused by the tumour. This drug has side-effects, the most obvious is a dramatic increas in appetite causing large weight gain.
The mainstay of treatment is radiotherapy, which usually gives a transient improvement. Many chemotherapies have been tried but all have had no effect. Without treatment, the progression of DIPG is usually rapid. Median survival time with treatment is less than 1 year.