DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of stroke.
Alternative NamesAtrial Fibrillation; Transient Ischemic Attacks
An intriguing study in 2003 suggested that taking a single daily pill containing a number of heart- and circulatory protective agents could largely prevent heart attacks and stroke in nearly everyone over 55. It would contain the following:
The experts in the study believed this combination would reduce ischemic heart events by 88% and stroke by 80%. Only between 1% and 2% of the population would have to withdraw because of side effects. More research on this is certainly warranted.
Thrombolytics and Other Drugs for Initial Treatment of Ischemic Stroke
Intravenous Thrombolytics. Clot-busting, or thrombolytic, drugs break up existing blood clots. They are among the important treatments for heart attacks, and are now also being used for ischemic (not hemorrhagic) stroke. Their benefits for treating stroke patients appear to be more limited than for heart attacks, however, and only a minority of stroke patients is given these agents. More needs to be learned about the risks and benefits of thrombolytics for stroke.
The standard thrombolytic drugs are recombinant tissue plasminogen activators or rt-PAs. They include alteplase (Activase and reteplase (Retavase)). Both are similar in effectiveness, although reteplase is easier to administer. Others are under investigation.
The following steps are critical before administering these agents.
Thrombolytics carry a risk for hemorrhage and so may not be warranted for patients with existing risk factors for bleeding. They should not be used in patients who are experiencing seizures. The drug may be appropriate in more patients than previously thought, however, including older people, those with a history of stroke, and those with high blood pressure. More research is needed to confirm this.
Intra-Arterial Thrombolytics. Researchers are investigating thrombolytics injected directly into an artery in the brain. Early studies suggest this approach may allow effective treatment up to six hours after a stroke and improve recovery in more patients. The risk for bleeding and hemorrhagic stroke is significantly increased, however.
Fibrin-Depleting Agents.These drugs deplete the amount of fibrinogen in blood, which in turn reduces the "stickiness" in blood. Such agents include ancrod and batroxobin (Defibrase), which are derived from the venom of poisonous snakes. Some experts believe these agents might be a possible alternative to thrombolytics. Studies suggest they may modestly reduce the risks for death and disability if given early on. As with all anti-clotting agents, there is a higher risk for hemorrhage, but it appears to be slight.
Anti-Clotting Medications for Preventing a Recurring Stroke
Medications that prevent blood from coagulating or clotting are used to prevent a recurring or second stroke. They are generally either anti-platelet agents or anticoagulants. Specific anti-clotting agents may be warranted depending on risk factors.
Anti-Platelet Agents.Typically, an anti-platelet agent--most often aspirin--is initiated within 48 hours of an ischemic stroke and continued in low doses as maintenance. Studies suggest that antiplatelet therapy can reduce the risk for a second stroke by 25%.
Anticoagulants.Anticoagulants thin blood and may be useful under certain circumstances.
All anti-clotting drugs carry a risk for bleeding and a slightly increased risk for hemorrhagic stroke.
Drugs for Hemorrhagic Stroke
Calcium Channel Blockers. Early administration of calcium channel blockers, such as nimodipine (Nimotop), can improve functional outcome. One of the most common and serious dangers after a subarachnoid hemorrhagic stroke is spasm of the blood vessels near the ruptured site, which closes off oxygen to the brain. Calcium causes contraction of the smooth muscles of the blood vessels, and calcium channel blockers are drugs that relax the blood vessels. The drugs work best if it is administered within six hours of the stroke. Calcium channel blockers are not useful for ischemic stroke, although they can be used in combinations with blood pressure lowering agents to prevent them.
Antifibrinolytic Drugs. Drugs called antifibrinolytics (e.g., tranexamic acid, epsilon amino-caproic acid or an equivalent) are used to stop bleeding. They have been investigated for years for subarachnoid hemorrhagic stroke but, at this time, they do not appear to improve outlook.
Investigative Therapies to Protect or Restore Nerve Cells after a Stroke
Nerve-Protecting Agents. More than 50 medications have been studied in clinical trials aimed at slowing down or preventing the cascading process that destroys nerve cells after a stroke. Many investigative drugs are targeting the excitatory amino acids, such as glycine and glutamate, which are known to destroy nerve cells after a stroke. Although none to date have proven to have any significant benefits, some are showing promise. They include magnesium sulfate, citicoline, ebselen, piracetam, edaravone, albumin, and erythropoietin. In a 2002 study, for example, an analysis of studies using citicoline with the first 24 hours of a stroke suggested that it increased the probability of complete recovery by about 5%. Of particular interest are animal studies suggesting that sildenafil (Viagra) may have nerve-protecting properties and help recovery from a stroke.
Investigative Agents for Nerve Regeneration. It has been thought that when cells in the brain were destroyed, new ones could not grow to replace them. Scientists have now observed, however, that nerve regrowth (neurogenesis) can occur in the adult human brain. This exciting discovery opens the way for new agents that might in the future stimulate nerve growth and repair damage done by many neurologic diseases, including stroke. For example, a 2002 study reported nerve regeneration in animals whose brains were treated with the agent inosine. More research is underway.