Stroke is the No. 3 cause of death in the U.S. as of 2006, according to the Centers for Disease Control and Prevention, and an estimated 137,000 people die each year from stroke. A stroke can develop if an area in the brain does not receive enough blood and oxygen or if a blood vessel bursts, spilling the blood and oxygen instead of delivering it to the brain. There are several risk factors for strokes, but low sodium is not one of them.
Stroke
Ischemic stroke and hemorrhagic stroke are the two types of strokes. Approximately 87 percent of all strokes are ischemic strokes, while the other 13 percent are hemorrhagic strokes, notes Justin Zachariah, M.D., Assistant in Cardiology at Children's Hospital Boston in "Hurst's The Heart." The main risk factors for stroke include high blood pressure, age, Type 2 diabetes, smoking, atrial fibrillation and left ventricular hypertrophy. Atrial fibrillation is a disorder where the upper chamber of the heart, the atrium, has an irregular rhythm. In left ventricular hypertrophy, the lower left chamber of the heart, the ventricle, is too thick. A low sodium level in the bloodstream does not lead to strokes.
Ischemic Strokes
An ischemic stroke can develop if blood cannot reach an area of the brain because there is a clot in a blood vessel blocking the flow of blood. A clot may be the result of atherosclerosis, where cholesterol, fat, white blood cells and platelets accumulate inside a damaged artery and form a sticky area called a plaque. Pieces from the plaque can break off and the resultant clots can block the blood flow. Blood clots which have formed in the heart can travel to a blood vessel in the brain and block the blood flow. Certain heart diseases, including atrial fibrillation, can cause this.
Hemorrhagic Strokes
A low blood sodium level does not cause hemorrhagic strokes either. Hemorrhagic strokes include intracerebral hemorrhages and subarachnoid hemorrhages. Intracerebral hemorrhages are approximately three times as common as subarachnoid hemorrhages, per Dr. Zachariah in "Hurst's The Heart." They occur if an artery inside the brain gets weak and bursts, releasing blood into the brain. Hypertension can cause this type of hemorrhagic stroke, as well as certain brain tumors, abnormal blood vessels and drugs, especially cocaine. Subarachnoid hemorrhages are hemorrhages into the subarachnoid space, an area below the arachnoid layer of the membrane that covers the brain. It can be caused by the same disorders that cause an intracerebral hemorrhage.
Low Sodium and Strokes
A low amount of sodium in the bloodstream, called hyponatremia, does not cause any type of stroke. The normal range of sodium is 135 to 145 mEq/L. If your sodium level drops as low as 130 mEq/L, you may not have any symptoms. If your level continues to drop and falls as low as 110 mEq/L, but did so slowly over several months, you still may not feel any symptoms because the brain has had time to readjust. A rapid drop in sodium, however, can cause nausea, confusion, headaches, decreased reflexes, seizures, coma and death.
References
- Centers for Disease Control and Prevention: Stroke
- "Clinical Neurology"; Roger Simon, M.D., et al.; 2009
- "Handbook of Pathophysiology"; Elizabeth Corwin, MSN, Ph.D., FNP; 2000
- "Hurst's The Heart"; Valentin Fuster, M.D., Ph.D., Robert O'Rourke, M.D., et al.; 2008
- "Pocket Guide to Diagnostic Tests"; Diana Nicoll, M.D., Ph.D., et al.; 2007
- "Tintinalli's Emergency Medicine: A Comprehensive Study Guide"; Judith Tintinalli, M.D., et al.; 2004
