Brain cancer involves the abnormal of brain cells. The cancer can originate in the neurons--the nerve cells located throughout the brain--or in the glia--populations of cells that work together to support neuron functioning. During cancer progression, the growth of the tumor can affect the surrounding tissue at the tumor periphery, as well as the brain as a whole. As a result, patients with brain cancer often develop physical symptoms associated with cancer progression.
Headaches
One physical effect of brain cancer, that begins early in cancer development, is the development of abnormal headaches. Headaches often occur due to an increase of pressure in the skull, called intracranial pressure. Tumor growth increases the mass of the brain, increasing the intracranial pressure by creating less room for healthy brain tissue. Cancer cell growth can also block the flow of cerebrospinal fluid within the brain, disrupting the flow of fluid out of the brain and increasing intracranial pressure due to fluid buildup. The Merck Manuals note that while most headaches are not the result of brain cancer, abnormally persistent or severe headaches may indicate brain tumor growth. Left untreated, the frequency of the cancer-related headaches will increase until the headache is constant, with no relief. Patients experiencing severe headaches should seek medical attention to address the source of the problem and investigate the possibility of brain cancer.
Visual Disturbances
Another possible physical effect of brain cancer is disruption of normal visual processing, leading to visual disturbances. Patients with brain cancers may suffer from tunnel vision or even blindness. Visual disturbances usually indicate the presence of a brain tumor in the occipital lobe of the brain, a region located at the back of the brain, according to the American Brain Tumor Association. Cancer growth in this region can damage the visual processing center of the brain, causing physical symptoms of blindness. The development of visual disturbances can indicate a more serious brain cancer, and requires immediate medical attention.
Lack of Muscle Control
Some brain cancer can cause the physical effective of muscle weakness and lack of muscle control. The frontal lobe of the brain, located at the anterior part of the skull, contains the nerve centers responsible for motor control. Neurons in the frontal lobe control voluntary muscle movement and speech, according to Harvard University. Damage to these nerve centers due to brain cancer growth can disrupt the brain's ability to communicate with the muscles of the body, leading to muscle weakness. Patients with brain cancer in the frontal lobe may also suffer from an abnormal gait, problems with fine muscle control or speech abnormalities.
