Central nervous system tumors are abnormal growths that develop in the brain and spinal cord. They may form in any of the tissues found inside the skull and vertebral column and they can be either malignant, which means cancerous, or benign, meaning non-cancerous. Most tumors develop in the cerebrum, the big, outer part of the brain concerned with thought, learning and speech. Young children are more likely to have a tumor in the cerebellum, which controls movement and balance. Central nervous system tumors in the spinal cord may develop inside or outside the cord's tough tissue covering, and those that are inside the covering may be inside or outside of the spinal cord itself.
More than 120 different types of central nervous system tumors exist and they are classified according to the types of cells they develop from or the location in which they arise. Tumors are graded from low to high grade, depending on how quickly they grow, with low-grade tumors progressing most slowly. Each tumor may give rise to different symptoms according to the part of the central nervous system (CNS) that is damaged by its growth. Most often, tumors develop in the cerebrum, which is divided into two hemispheres with a number of different areas, or lobes.
Central nervous system tumors arising in the brain's frontal lobes can cause symptoms of altered behavior and personality. Damage to frontal lobe nerve cells, or neurons, can also lead to problems with intellectual reasoning and speech. Coordination may be affected, causing walking difficulties. Tumors in the occipital lobes, which are concerned with vision, can lead to loss of one side of the field of view, and they can also affect how writing is processed by the brain. Temporal lobe tumors may cause seizures and problems with hearing and speech, while parietal lobe tumors may result in weakness on one side of the body.
When central nervous system tumors develop in the spinal cord, they are usually found lower than the neck. The symptoms they cause typically affect areas which lie at or below the level of the tumor. This means that a tumor in the lower back could lead to pain experienced in that area or in the legs. A tumor in the upper spine may give rise to chest pain, which could worsen when lying down. Central nervous system tumors are managed according to their type, position, size and grade, and treatments can include surgery, chemotherapy and radiotherapy.