Sunday, July 27, 2008

Transcranial magnetic stimulation

Transcranial magnetic stimulation is an experimental procedure that uses magnetic fields to stimulate nerve cells in the brain in the hope of improving chronic depression symptoms. Transcranial magnetic stimulation is one of the newer types of brain stimulation methods designed to treat depression when standard treatment hasn't worked.

There are different ways to perform transcranial magnetic stimulation. But in general, a large electromagnetic coil is placed against your scalp near your forehead. The electromagnet creates painless electric currents that stimulate nerve cells in the region of your brain involved in mood regulation and depression.

Depression is usually a very treatable condition. Often, standard treatment with antidepressant medications, psychotherapy or electroconvulsive therapy can help improve even severe cases of depression.

But if standard depression treatment doesn't work, all hope isn't lost. Researchers are studying brain stimulation as the newest frontier in depression treatment. Transcranial magnetic stimulation is one form of brain stimulation being tested as a possible treatment option. This procedure is still experimental and hasn't been approved by the Food and Drug Administration as a depression treatment.

Because it's experimental, transcranial magnetic stimulation isn't recommended as a first treatment option for depression. It's used only as a research tool and is generally available in the United States only through clinical trials. In countries where transcranial magnetic stimulation has been formally approved to treat depression, it's typically used only for people with depression that hasn't improved with standard treatments or for those who may be considering electroconvulsive therapy but want an alternative.

People who have long-standing depression or depression that hasn't improved with standard treatments may be eligible to participate in a clinical trial of transcranial magnetic stimulation. Talk to your doctor to see if it may be a good option for you. Transcranial magnetic stimulation may also be used experimentally in other mental health disorders, such as post-traumatic stress disorder, obsessive-compulsive disorder and bipolar disorder.

Transcranial magnetic stimulation is the least invasive of the brain stimulation procedures used for depression. It requires no surgery or implantation of electrodes or nerve stimulators. While it's considered generally safe, it's not without some risks.

Common side effects
Common side effects and adverse health problems associated with transcranial magnetic stimulation include, but may not be limited to:

  • Headache
  • Scalp discomfort at the site of stimulation
  • Tingling, spasms or twitching of facial muscles
  • Lightheadedness
  • Discomfort from noise during treatment

Uncommon side effects
In rare cases, transcranial magnetic stimulation may also cause more serious side effects, including:

  • Seizure
  • Mania
  • Hearing problems

Because transcranial magnetic stimulation involves changes in brain function, unknown long-term adverse health effects are possible. Some studies have shown structural changes in the brain after transcranial magnetic stimulation. The significance of these changes isn't yet known. Also, the long-term effects of exposure to the strong electromagnetic fields involved remain unknown.

Because transcranial magnetic stimulation is experimental, it's generally available only through participation in clinical trials. Before having the procedure, you may need to have a medical evaluation to make sure it's safe for you and a good option in your case. You may need a full physical and psychiatric evaluation. But because transcranial magnetic stimulation isn't invasive, doesn't require anesthesia and can be performed in a doctor's office, little other preparation is needed.

Transcranial magnetic stimulation is usually done on an outpatient basis in a doctor's office or clinic that's running a clinical trial for the procedure. There are different ways to perform the procedure. Techniques may change as more is learned about the most effective ways to use transcranial magnetic stimulation.

In general during transcranial magnetic stimulation, an electromagnetic coil is placed against your scalp on an area near your forehead, often on the left side. To produce the stimulating pulses, the electromagnetic coil is switched off and on repeatedly, sometimes up to 10 times a second. This results in a tapping or clicking sound that usually lasts for a few seconds, followed by a pause. This process is repeated for the duration of the treatment session, which lasts about 30 to 40 minutes.

Although transcranial magnetic stimulation is generally painless, it may cause the muscles of your scalp or jaw to contract, which can be uncomfortable. Talk to your doctors about taking an over-the-counter pain reliever before the procedure if you're worried about discomfort. Also, wear earplugs during the procedure to reduce the risk of hearing problems.

It's not clear precisely how transcranial magnetic stimulation may help relieve symptoms of depression. Networks of brain regions may play a role in mood regulation. Stimulating the brain in these regions can change how the brain functions and may lead to mood improvement.

During transcranial magnetic stimulation, the magnetic pulses create painless electrical currents in your brain. These currents stimulate nerve cells in the region of your brain involved in mood regulation and depression. In some types of transcranial magnetic stimulation, brain activity is suppressed. In other types, brain activity is increased.

Researchers are still trying to determine the best dosage of stimulation and the best area of the brain to stimulate. The amount of stimulation can be changed depending on your symptoms and side effects.

Transcranial magnetic stimulation generally requires multiple treatment sessions. You may have the procedure every weekday for two weeks, for instance. After each treatment with transcranial magnetic stimulation, you can go about your normal daily activities.

If transcranial magnetic stimulation works, your depression symptoms will improve or go away completely. Improvement in your mood may last for days or weeks. Some research, however, shows a lack of dramatic improvement in depression symptoms. But as researchers learn more about different techniques, the number of stimulations required and the best sites on the brain to stimulate, the effectiveness of transcranial magnetic stimulation may improve over time.

Some research suggests that transcranial magnetic stimulation is less effective in certain situations, including:

  • Older age
  • Presence of psychosis
  • Depression that has lasted four or more years

It's not yet known if transcranial magnetic stimulation can be used to treat depression for the long term, or whether you can have periodic maintenance treatments to prevent depression symptoms from returning.

Wednesday, July 02, 2008

Coronary bypass surgery

Coronary bypass surgery is a procedure to allow blood to flow to your heart muscle despite blocked arteries. Coronary bypass surgery uses a healthy blood vessel taken from your leg, arm, chest or abdomen and connects it to the other arteries in your heart so that blood is bypassed around the diseased or blocked area. After a coronary bypass surgery, normal blood flow is restored. Coronary bypass surgery is just one option to treat heart disease.

Just like all the other organs in your body, your heart needs blood and oxygen to do its job. Coronary arteries snake across the surface of your heart, delivering a constant supply of blood and oxygen to the heart muscle. When one or more of these arteries become narrowed or blocked, blood and oxygen are reduced and heart muscle is damaged. Coronary bypass surgery can minimize this damage.

Although they rarely occur, the most common complications of coronary bypass surgery are:

  • Bleeding
  • Heart rhythm irregularities (arrhythmias)
  • Kidney failure
  • Infections of the chest wound
  • Memory loss or troubles with thinking clearly, which often go away within six to 12 months
  • Stroke

Your risk of developing these complications depends on your health before the surgery. Talk to your doctor to get a better idea of the likelihood of experiencing these risks.

If you're having a scheduled coronary bypass surgery, your risk of death is usually low, but still depends on your overall health. The risk is higher if the operation is done as an emergency or if you have other significant medical conditions such as emphysema, kidney disease, diabetes or peripheral vascular disease.

During the procedure
Coronary bypass surgery generally takes between three and six hours and requires general anesthesia. On average, surgeons repair two to four coronary arteries. The number of bypasses required depends on the location and severity of blockages in your heart.

Most coronary bypass surgeries are done through a large incision in the chest while blood flow is diverted through a heart-lung machine (called on-pump coronary bypass surgery).

The surgeon makes an incision down the center of the chest, along the breastbone. The rib cage is spread open to expose the heart. After the chest is opened, the heart is temporarily stopped and a heart-lung machine takes over blood circulation to the body.

The surgeon takes a section of healthy blood vessel, often from inside the chest wall (the internal mammary artery) or from the lower leg, and attaches the ends above and below the blocked artery so that blood flow is diverted (bypassed) around the narrowed portion of the diseased artery.

There are other methods your surgeon may use if you're having coronary bypass surgery:

  • Off-pump or beating-heart surgery. This procedure allows surgery to be done on the still-beating heart using special equipment to stabilize or quiet the area of the heart the surgeon is working on. This type of surgery is challenging because the heart is still moving. Because of this, it's not an option for everyone. The long-term outcome of this type of procedure is not yet known, and there have been no proven benefits of this technique over standard coronary bypass using the heart-lung machine in the average patient.
  • Minimally invasive surgery. In this procedure, a surgeon performs coronary bypass through a smaller incision in the chest, often with the use of robotics and video imaging that help the surgeon operate in a small area. Variations of minimally invasive surgery may be called port-access or keyhole surgery.

Once you're anesthetized, a breathing tube is inserted through your mouth. This tube attaches to a ventilator, which breathes for you during and immediately after the surgery.

After the procedure
Coronary bypass surgery is a major operation. Expect to spend a day or two in the intensive care unit after coronary bypass surgery. Here, your heart, blood pressure, breathing and other vital signs will be continuously monitored. Your breathing tube will remain in your throat for a few hours after surgery, so you won't be able to speak. You can communicate with hand gestures and notes. The breathing tube will be removed as soon as you are awake and able to breathe on your own.

Barring any complications, you'll likely be discharged from the hospital within a week, although even after you've been released, you may find it difficult to perform everyday tasks, or even walk a short distance. If, after returning home, you experience any of the following signs or symptoms, call your doctor. They could be warning signs that your chest wound is infected:

  • A fever higher than 100.4 F (38 C)
  • Rapid heart rate
  • New or worsened pain around your chest wound
  • Reddening, bleeding, or other discharge from your chest wound

Expect a recovery period of about six to 12 weeks. In most cases, you can return to work, begin exercising, and resume sexual activity after six weeks, but make sure you have your doctor's OK before doing so.

After surgery, most people have improvement or complete relief of their symptoms and remain symptom-free for as long as 10 to 15 years. Over time, however, it's likely that other arteries or even the new graft used in the bypass will become clogged, requiring another bypass or angioplasty.

Although bypass surgery improves blood supply to the heart, it doesn't cure underlying coronary artery disease. Your results and long-term outcome will depend in part on following healthy lifestyle recommendations and taking your medication as directed. Healthy lifestyle recommendations include:

  • Stop smoking.
  • Follow a healthy-eating plan, such as the DASH diet.
  • Reduce cholesterol levels.
  • Maintain a healthy weight.
  • Control blood pressure.
  • Manage diabetes.
  • Exercise.