The aetiology of central nervous system tumours in children is not fully understood. It is estimated that certain genetic diseases may predispose to their occurrence (neurofibromatosis, tuberous sclerosis, Turcot syndrome). Studies also indicate a slightly higher incidence of this type of cancer in children undergoing irradiation for other reasons.

Tumours can localise anywhere in the central nervous system, so their clinical presentation can be very variable. The age of the child, the location, the rate of growth and, finally, the histological structure of the tumour itself are also important.

The most common tumours are those developing below the cerebellar tentorium, involving the cerebellum and the brainstem (approximately 50-55%).

The first symptoms are usually not very specific, so the mere change in the child's disposition should prompt parents to observe him closely. Disturbing signs can be a feeling of fatigue, reluctance to play, drowsiness, concentration and attention deficit disorders and strange behaviour of the child that did not occur before (aggression, anger or crying for no reason).

Some of the most characteristic symptoms found in CNS cancer include:

• headaches, especially in the morning,
• morning vomiting, often without accompanying nausea,
• visual acuity disturbances, most often described as "foggy vision",
• strabismus,
• nystagmus
• double vision,
• head tilting to one side,
• paresis and sensory disturbances,
• epileptic seizures,
• urinary and bowel disorders,
• hormonal disturbances (puberty or growth disorders),
• disturbances of consciousness and drowsiness,
• back and spine pain,
• gait disturbances.

As in the early stages of cancer the symptoms are very non-specific, the diagnosis is often made when the disease is highly advanced. Only 25% of cases are diagnosed during the first or second visit to the GP.

The mainstay of treatment for central nervous system tumours is surgery, so early detection is important to give the tumour a chance of complete removal. In advanced cases, complementary treatment in the form of radio- or chemotherapy may be necessary.