Vasovagal Syncope, a fancy term for fainting

A number of conditions can cause fainting, including heart rhythm abnormalities, seizures, low blood sugar (hypoglycemia), and anemia. More common than these, however, is a relatively benign condition called vasovagal syncope, also known as the "common faint". Syncope [sing-kuh-pee] is themedical term for "blacking out" and vasovagal refers to the abnormal stimulation
of blood vessels by the vagus nerve.

What causes vasovagal syncope? One of the normal functions of the vagus nerve is to lower the heart rate. If excessive activation of the vagus nerve occurs, however, pooling of blood in the legs along with a sudden drop in blood pressure and heart rate can occur. Some of the reasons for this excessive activation include:

• Emotional stress
  
  
• Pain, such as having blood drawn
  
  
• Environmental factors, such as being in a hot, crowded setting
  
  
• Illness, especially when associated with dehydration
  
  
• Straining, as when having a bowel movement
  
  
• Visual stimuli, such as the sight of blood
  

The drop in blood pressure and heart rate temporarily causes decreased blood flow to the brain with subsequent loss of consciousness. Fortunately, the body is able to correct this temporary abnormality of the circulatory system and return blood pressure and blood flow to the brain in a matter of seconds. While the faint itself is usually not a sign of a serious disease, the consequences of fainting can be serious. Serious injuries can occur with falling and injuries to others could occur if fainting occurs while driving.

How is vasovagal syncope diagnosed? Since not all losses of consciousness are due to overstimulation of the vagus nerve, some amount of evaluation is usually required in order to distinguish between a benign type of syncope and a more serious cause. In many cases, the doctor can make the determination by asking questions about what occurred surrounding the event. Commonly, a person experiencing vasovagal syncope will remember experiencing certain symptoms prior to losing consciousness, such as being extremely hot, sweating, having ringing in the ears, feeling weak, and experiencing visual disturbances such as tunnel vision. When the specific cause is uncertain, special tests may be required, particularly if a serious cause, such as a heart rhythm disturbances or seizures are suspected. These tests could include:

• Blood tests, including a complete blood count to check for anemia and glucose
  tolerance test looking for evidence of hypoglycemia.
  
  
• Electroencephalogram (EEG), to look for abnormal brain wave activity if seizures
  are suspected.
  
  
• Holter monitor, which monitors the heart rhythm over a number of hours to look
  for disturbances.
  
  
• Exercise stress test and/or echocardiogram to look for heart conditions that could
  be responsible.Tilt-table testing, perhaps the most sensitive test to diagnose vasovagal syncope.
  

Special mention should be made of the tilt-table test in diagnosing this condition. During this test, subjects lie down on a table that can be moved from a horizontal to a vertical position. The heart rate and blood pressure are monitored while the bed is moved to a vertical position. Sometimes this is enough to produce the blood pooling and blood pressure drop that precipitates fainting. If not, a medication (isoproterenol) may be given through the vein that produces the abnormal reflex that causes vasovagal syncope.

Is there a treatment for vasovagal syncope? The best treatment is usually avoidance of the triggers that cause the episodes. For recurrent or severe spells, certain medications may be used including blood pressure drugs (e.g. metoprolol), antidepressants of the SSRI class (Paxil, Prozac, others), and blood vessel constrictors that are used to treat low blood pressure. Other "lifestyle" therapies include foot exercises, compression stockings, increasing dietary salt, and avoiding prolonged standing.

What should you do if you witness someone fainting? The appropriate steps to take for the fainting victim are:

• Check the person's airway and breathing. If necessary, call 911 and begin rescue breathing.
  
  
• Loosen tight clothing around the neck.
  
  
• Raise the person's feet above the level of the heart (about 12 inches).
  
  
• If the person has vomited, turn onto his or her side to prevent choking.
  
  
• Keep the person lying down for at least 10 - 15 minutes, preferably in a cool and quiet space. If this is not possible, sit the person forward with the head between the knees.

What is the prognosis for someone with vasovagal syncope? Brief periods of unconsciousness are generally harmless and do not necessarily indicate the presence of a serious medical problem. The main danger of fainting or vasovagal syncope is the risk of injury by falling while unconscious.

What is Listeria and who is at risk?

Listeria monocytogenes, or Listeria for short, is a bacterium that causes an infection called listeriosis. A recent outbreak of listeriosis, found to be due to contaminated cantaloupe, has placed Listeria in the news. Today's Health Tip describes the features of Listeria infections and discusses who is at particular risk for developing listeriosis.

How does someone contract listeriosis? Listeria bacteria are found in soil and surface water, as well as in animals and humans who do not appear to be infected. Food can become contaminated when it is handled by an asymptomatic carrier or if it comes in contact with Listeria bacteria in fertilizer or animal waste. The great majority of people who develop listeroisis get it through contaminated foods. Foods that have most commonly been associated with Listeria contamination include processed meats (hot dogs, deli meats, etc.), cheeses (particularly those made with non-pasteurized milk), raw milk, and smoked seafood. Thus far, contamination of fresh produce has been uncommon. Infections that occur in pregnant women are particularly troubling since they can lead to miscarriage, stillbirth, premature delivery, or life-threatening infection of the newborn.

What are the symptoms of listeriosis? Most people that are infected have few or no symptoms. When symptoms are present, they are usually flu-like in nature, including fever, muscle aches, nausea and/or diarrhea. In severe instances, nervous system involvement including meningitis and brain abscesses can occur.

Who is at risk for developing listeriosis? In the United States, an estimated 1,600 persons become seriously ill with listeriosis each year. Some groups of people are at higher risk of becoming infected and developing complications than others. Those at increased risk include:

• Individuals with immune system weakness due to AIDS, cancer, or from taking immune-suppressing medications.
• Pregnant women, who are approximately 20 times more likely to contract listeriosis than other healthy adults
• People with chronic illness, such as diabetes, alcoholism, liver or kidney disease.
• Older individuals
• Newborns, particularly if their mother is infected at the time of delivery.

How is listeriosis diagnosed? The diagnosis is often suspected based on typical symptoms occurring during a Listeria outbreak. With the first cases of an outbreak, or when the diagnosis is uncertain, culturing the bacteria from the subject's blood or spinal fluid can be performed.

How can you reduce your risk for listeriosis? The Centers for Disease Control has offered the following suggestions for reducing your risk of developing listeriosis:

• Thoroughly cook raw food from animal sources, such as beef, pork, or poultry to a safe internal temperature.
• Rinse raw fruits and vegetables thoroughly under running tap water before eating (even if the peel is not eaten).
• Keep uncooked meats and poultry separate from vegetables and from cooked foods and ready-to-eat foods.
• Do not drink raw (unpasteurized) milk, and do not eat foods that have unpasteurized milk in them.
• Wash hands, knives, counter-tops, and cutting boards after handling and preparing uncooked foods.
• Consume perishable and ready-to-eat foods as soon as possible.

Persons at high risk, such as pregnant women and those with weakened immune systems, need to take additional precautions. These include avoiding soft cheeses (brie, feta, blue, etc.) unless made with pasteurized milk, refrigerated smoked seafood (which may be labeled as "nova-style," "lox," "kippered," "smoked," or "jerky), and refrigerated pâté or meat spreads from a deli or from the refrigerated section of a store. For more recommendations on keeping food safe, following this link to the CDC website.

What should you do if you've eaten food that could have been contaminated with Listeria? Even if the food contained Listeria, the risk of developing listeriosis is very small. No tests or treatment is necessary if symptoms do not occur after eating food suspected of being contaminated. If the person is in a high-risk group, the CDC recommends seeking medical attention if fever or signs of listeriosis develop within two months of eating the food.

Can Listeriosis be treated? In healthy individuals, Listeria bacteria are cleared by the body in about a week without requiring specific treatment. For high-risk patients with symptoms, antibiotics delivered through an intravenous line, are usually required. Ampicillin and Bactrim (trimethoprim-sulfamethoxazole) are two of the antibiotics that are typically used. Treatment with antibiotics is particularly important in pregnant women due to the risk to the fetus.

The recent outbreak of listeriosis tied to contaminated cantaloupe from Colorado has sickened a number of people and has even claimed lives. Fortunately, the source of the contamination appears to have been identified and new cases related to this outbreak are on the decline.

Common Food Allergies

Over 160 different foods have been identified that can cause allergic reactions in people. Of these, 90% are triggered by the following 8 foods:

1. Milk
   
   
2. Eggs
   
   
3. Peanuts
   
   
4. Tree nuts (such as almonds, cashews, walnuts, pine nuts)
   
   
5. Fish (such as bass, cod, flounder)
   
   
6. Shellfish
   
   
7. Soy
   
   
8. Wheat

Since 2006, the Federal Drug Administration (FDA) has required labeling to identify products that contain any of these 8 allergy-causing foods. Certain foods, however, including fresh produce, fresh meat, and certain oils are exempt from this requirement.

What are the symptoms of a food allergy? Allergic reactions to foods most commonly involve the skin, the digestive tract (stomach and intestines), or the respiratory system (throat and lungs). Skin symptoms include the development of hives, swelling (edema), and redness or flushing. Abdominal pain, nausea, vomiting, and diarrhea are the most common digestive tract symptoms. Respiratory symptoms include sneezing, wheezing, coughing, and runny eyes. The most severe allergic reaction to food is anaphylaxis, also known as anaphylactic shock. Anaphylaxis is a medical emergency that typically affects several areas of the body, including swelling in the throat that may be severe enough to block the airway, a rapid heart rate, and a severe drop in blood pressure. Each year in the U.S., anaphylaxis to food has been estimated to result in 30,000 emergency room visits, 2,000 hospitalizations, and 150 deaths.

Why do food allergies occur? In allergic individuals, certain proteins (allergens) in food are perceived by the body to be harmful. As a response to these allergens, the immune system produces antibodies to protect the body. These antibodies remain in the blood stream following the initial exposure and can recognize the offending protein if the same food is eaten again. Once reactivated, antibodies cause a special type of cell in the bloodstream known as mast cells to release chemicals, including histamine. Histamine is the primary chemical involved in producing allergic symptoms, such as runny nose, itchy eyes, rashes and hives, wheezing, and even anaphylactic shock.

Are all food allergies the same? The allergic features from exposure to different foods vary in many ways, including the specific symptoms produced and their severity, as well as the likelihood for them to become "outgrown". Often, these unique features can assist the doctor in determining the specific food allergen. Milk allergy is particularly common in children, with cow's milk being the usual cause. Milk rarely causes anaphylaxis, with the most common symptoms being gastrointestinal in nature (abdominal cramping, diarrhea, etc.). Eggs are another common allergen-causing food during childhood. Fortunately, most children eventually outgrow their egg allergy. Vaccines produced using eggs, such as the influenza vaccine present potential risks to people who have a severe allergy to eggs. Peanuts are legumes, and are thus biologically unrelated to tree nuts. Nevertheless, a number of people with tree nut allergies go on to develop allergy to peanuts also. It is possible for peanut allergy symptoms to occur with skin contact or from eating food that had been exposed to peanuts during their processing. Tree nuts include macadamia nuts, brazil nuts, cashews, almonds, walnuts, pecans, pistachios, hazelnuts, and pine nuts (pignoli or pinon). Tree nut allergies tend to be severe, and are strongly associated with anaphylaxis. Shellfish allergy can occur after eating crustaceans (crabs, lobster, crayfish, shrimp, etc.) or mollusks (clams, mussels, scallops, oysters, squid, etc.). In some people, shellfish allergy occurs with eating only one type of shellfish. Wheat allergy results from the production of antibodies to proteins found in wheat. In people with celiac disease, a specific wheat protein called "gluten" causes an abnormal immune system reaction in the small intestines.

How are food allergies diagnosed? The medical history is the most important diagnostic tool in diagnosing food allergy. A dietary diet, in which a record of the content of each meal is kept, along with any reactions that occurred, can also assist with making the diagnosis. If the medical history and diet information suggests a specific food allergy, specialized testing including allergy skin tests, blood tests, and/or a food challenge can be used to confirm the diagnosis.

How are food allergies treated? There are no medications currently available to treat food allergies. Once identified, the best treatment is to avoid the food that has caused a reaction. This often requires careful attention to the labeling, particularly with foods that do not obviously contain one of the common offenders. For example, pine nuts are a typical ingredient in pesto sauce, and eggs are included in a number of salad dressings. Medications are available for treating allergic reactions should they occur. The most commonly used medications are antihistamines (Benadryl, Allegra, Claritin, others). Inhalers used to treat asthma may also be helpful for people who wheeze during an allergic reaction. With severe reactions such as anaphylaxis, epinephrine, given by injection, can be life saving. People with a history of severe food allergies are advised to carry a self-injecting device loaded with epinephrine (e.g., Epi-pen) for use in the case of an unexpected reaction.