Medulloblastoma brain tumour. Colour 3-D computed tomography brain scan showing a medulloblastoma tumour (red). Image processing techniques have been used to cut away part of the skull. The blue structures are the fluid-filled ventricles in the centre of the brain. Medulloblastomas are malig- nant tumours that arise from the cerebellum of the brain that controls posture, balance and coordination. They are most common in children and tend to grow rapidly, spreading across the brain and spinal cord. Symptoms include headache, vomit- ing and clumsy gait. Treatment, which involves anticancer drugs, radiotherapy and surgery, often extends survival by five years or more.