Clarifying Terms Related to Senator Kennedy's Illness
I noticed that several of the reporters covering the recent news story about Senator Kennedy were using some brain terms (e.g., “stroke” and “seizure”) interchangeably. Because these terms are not synonyms, I’d like to provide some clarification and also briefly explain the Senator’s diagnosis.
A stroke is a disruption in the blood supply to the brain. A stroke can be caused by blockages to blood vessels (ischemic strokes), or when a blood vessel bursts (a hemorrhagic stroke). Individuals can experience one large stroke, or a series of smaller strokes, which are called Transient Ischemic Attacks (TIAs). The risk factors for stroke include age, family history, heart disease, uncontrolled diabetes, high blood pressure, and smoking. Common cognitive (thinking) effects of stroke include impaired memory, language difficulties, and paralysis, but depend on the part of the brain that is affected. For more information about stroke, please see our related topic center.
A seizure is a temporary abnormal electrical discharge by a group of neurons in the brain. This abnormal electrical activity can remain isolated to one small brain area, or can spread throughout the brain. Seizures can be caused by illness, brain damage, and/or abnormal growth and development. People who have repeated seizures across time are diagnosed with Epilepsy. Depending on the type and location of the seizure, a person will experience a loss of consciousness and/or attention and concentration, convulsions, and loss of bladder and bowel control. For more information about Epilepsy, please see our related topic center.
Senator Kennedy has been diagnosed with a malignant tumor. Tumors are masses of cells that grow and infiltrate the body. These masses of cells can be either benign (i.e., they will stop growing once they are removed via surgery) or malignant (i.e., cancerous, and will continue to grow and spread). Both benign and malignant tumors in the brain can cause impaired cognitive functioning, depending on their size and location. Individuals with malignant tumors (like Senator Kennedy) experience problems as the cell mass presses on and destroys healthy tissue in the brain, blocks the fluid that flows around and through the brain, and/or causes swelling due to accumulation of fluid. Malignant tumors can be treated by using chemotherapy (chemicals that destroy the cell mass), radiation (concentrated bursts of radiation that destroy the cell mass), and/or surgery. They are often lethal.
According to news reports, the Senator has a glioma, or a tumor composed of glial cells. Glial cells have several functions in the brain. They surround neurons, supplying them with nutrients and oxygen. They form myelin, which is a protective covering of neurons that speeds up the transmission of messages from one cell to another. Finally, glial cells help the body destroy germs that cause illness and remove dead neurons from the brain. Because glial cells serve so many important functions, this type of cancer is often hard to treat. Gliomas can cause a range of symptoms, such as seizures, headaches, and vomiting.
TIA and Stroke - Ty Callahan - Jul 2nd 2008
Thank you for clarifying some information that is often confusing regarding stroke, seizure, and the like. I would only add that transient ischemic attacks are not small strokes as described in the article. TIA's, by definition, are indeed transient and do not result in any tissue damage. Recovery is complete. Small strokes, on the other hand, are actual strokes that do result in residual damage to affected tissue. Recovery can be substantial, but is not complete. An important point about TIA's is that having these 'almost strokes' does seem to predict an increased likelihood of actual strokes in the future.