Emergency Neurological Conditions
Acute ischemic stroke (AIS)
Stroke is the leading cause of disability and is a major cause of death in the United States. Every year about 780,000 Americans suffer a stroke. In 2004, 150,074 people died from stroke. Acute ischemic stroke (AIS), is a subtype of stroke caused by a blockage of brain arteries. It is the most common subtype of stroke, accounting for 85% of cases. Common risk factors for AIS are hypertension, smoking, diabetes and high cholesterol. AIS can also be seen in the setting of heart disease, particularly in patients with rapid or irregular heartbeat and in patients with clotting disorders of the blood.
The primary symptom of AIS is the sudden loss of neurological function. Commonly patients will present with difficulty or inability to speak, loss of sensation or movement on one side of the body or a facial droop. Other symptoms may include sudden loss of vision, double vision, inability to walk or severe dizziness. Symptoms may occur suddenly and continue unchanged, may progress or may alternate between improvement and worsening. In some cases, symptoms may completely resolve, even though brain imaging will reveal that a stroke has indeed taken place.
AIS is a medical emergency and requires prompt medical attention. There is only a very limited time available for a physician to prevent a stroke from causing irreparable brain damage. Patients who arrive in a specially equipped ER can be treated with an intravenous “clot busting” medication called tissue plasminogen activator (t-PA). Patients presenting beyond 3 hours but in less than 8 hours may be candidates for a minimally invasive procedure in which physicians use a special device to travel to the site of the clogged brain artery and inject clot busting medicines or extract the clot. These procedures are referred to as stroke interventions. Only a small number of centers in the Los Angeles region offer this form of emergency therapy.
It is important to note that even though treatments are available for AIS, once a stroke has started the likelihood that it will result in disability is very high. Even with advanced therapies like those described above, only 15% to 20% of patients will emerge without significant disability. The reason for this is that the brain, unlike other organs in the body, is extremely vulnerable. While success with advanced therapy is only modest, the outcomes without advanced therapies are dismal, as most patients would be condemned to a permanent loss of brain function.
There are several causes of stroke. In 45% of cases, stroke is caused by a blockage in arteries either going to the brain or in the brain. 20% of the time, stroke is caused by clots in the heart, caused by a variety of conditions. Those clots may break off, traveling to the brain and causing a stroke. In 30% of cases, doctors may never discover the cause of stroke. Unusual causes, such as tearing of arteries, infection, clotting problems in the blood or migraines will lead to stroke in 5% of cases.
Treatment for AIS includes supportive care in a hospital unit specially trained and equipped to take care of stroke patients. As part of that care, the cause of stroke will be diagnosed and risk factors for a second stroke, like smoking, diabetes and high blood pressure will be addressed. Some patients with neurological impairment after a stroke will benefit from a therapy program designed to make patients independent again or to minimize the degree of assistance that a stroke survivor may require.
