Audiometry

Functional testing of a person's hearing done by exposing each individual ear to various sounds in a soundproof room.

Autosomal dominant

Pattern of inheritance in which one half of an affected person's children are also affected without regards to sex of the child or parent. Autosomal refers to the fact that the genetic information for the disease lies on a non-sex chromosome. Dominant refers to the fact that only one piece of genetic information (out of the two which are received at conception) need be affected by the disease.

Cancer

An abnormal and uncontrolled growth of cells which invades the surrounding tissues, spreads to other parts of the body, and recurs and causes death if not completely treated.

Cataract

Clouding of the lens of the eye. If not treated, cataracts may cause blindness by blocking light rays from entering the eye.

Chromosome

String of genetic information carried by the cells of the body. Each person receives 22 non-sex chromosomes and 1 sex chromosome from each parent at conception. As the body grows, a complete set of these 46 chromosomes is replicated and placed in every cell of the body.

Ependymoma

Tumor which grows from cells which line the cavities of the brain and spinal cord.

Gamma Knife

Form of highly focused radiation therapy.

Gene

Individual piece of genetic information. Genes are strung like beads in a predefined order on the chromosomes. Since each person has two copies of each chromosome, one from each parent, they also have two copies of each gene.

Magnetic Resonance Imaging

Method of visualizing the internal structures of the body by exposing the tissues to magnetic fields and measuring their response. MRI produces highly detailed pictures of the anatomy of the body and is especially useful for visualizing the brain. MRI produces no functional information on the area scanned.

Meningioma

Tumor which grows from the cells which line the brain and spinal cord in protective sheets called meninges.

Radiation therapy

Form of treatment in which the tumor cells are exposed to controlled doses of X-ray irradiation. Although tumor cells are especially susceptible to irradiation, surrounding tissues will also be damaged. Radiation therapy rarely cures a tumor by itself, but may be a useful tool when used in conjunction with other forms of therapy, or when a patient can no longer tolerate other forms of therapy.

Schwannoma

Tumor which grows from cells which line the nerves of the body. These cells, called Schwann cells, not only protect the nerves but also provide them with the insulation they need to conduct electrical impulses to and from the brain.

Tinnitus

Ringing in the ears.

Tumor

An abnormal growth of cells. Tumors may be malignant, in which case they are called cancers, or nonmalignant. Non-malignant tumors do not aggressively invade surrounding tissues or spread to other parts of the body, but they may cause significant symptoms and even death depending on their location.