Magnetic resonance imaging (MRI) is an imaging test that is usually painless and uses magnets, radio waves, and a computer to create detailed pictures of the inside of your body. MRI scans show organs and soft tissues clearly and can help tell healthy from unhealthy tissue in many cases.

MRI scans are often used to diagnose conditions that affect soft tissues and to monitor treatment.

MRI may be used to look at:

• The brain, spinal cord, and nerves
• Muscles, ligaments, and tendons
• Joints, such as the knee or shoulder

MRI does not use x-rays or other radiation. Because of this, it may be used when repeat imaging is needed.

MRI machines use powerful magnets. Metal objects or implants can interfere with the scan and may be unsafe.

Before your MRI, you will need to remove items such as:

• Jewelry and watches
• Hairpins
• Hearing aids

Before your MRI, tell your health care provider if you:

• Are pregnant
• Are breastfeeding, especially if you may receive contrast material (a substance that helps some parts of your body show up more clearly on the images)
• Feel anxious in enclosed spaces (claustrophobic)
• Have kidney problems
• Have metal in your body, such as bullets, shrapnel, or other metal fragments
• Have metal or electronic devices in your body, such as a pacemaker, artificial joint, or other implants
• Have tattoos or permanent makeup, since some darker inks may contain metal

You will usually change into a hospital gown. Sometimes before the test, you may receive contrast, which is usually given through a vein (intravenously or IV).

During the scan, you lie on a table that slides inside a large, tunnel-like machine. Some facilities use an open MRI machine, which is less enclosed. The machine makes loud noises as it takes pictures. You may be given earplugs or headphones.

The scan can take some time, depending on the part of your body being examined. You will need to stay very still during the scan.

After most MRI scans, you can return to normal activities right away. If you were given medicine to help you relax, someone will need to take you home.

A specialist called a radiologist reviews the images and shares them with your provider.

Your muscles help you move and help your body work. Different types of muscles have different jobs. There are many problems that can affect muscles. Muscle disorders can cause weakness, pain or even paralysis.

Causes of muscle disorders include:

• Injury or overuse, such as sprains or strains, cramps or tendinitis
• A genetic disorder, such as muscular dystrophy
• Some cancers
• Inflammation, such as myositis
• Diseases of nerves that affect muscles
• Infections
• Certain medicines

Sometimes the cause of muscle disorders is unknown.

Myasthenia gravis, sometimes called MG, is a chronic (long-lasting) disease that causes weakness in your voluntary muscles. The voluntary muscles are the ones that you can control. They include the muscles you use for:

• Eye and eyelid movement
• Facial expressions
• Chewing
• Talking
• Swallowing
• Breathing
• Moving your arms and legs

You can also have weakness in other muscles. This weakness gets worse with activity, and better with rest.

Myasthenia gravis is a type of autoimmune disease. In autoimmune diseases, your immune system attacks the healthy cells of your organs and tissues by mistake.

Myasthenia gravis is caused by an error in how nerve signals are sent to muscles. These signals get blocked at the nerve-muscle junction. This junction is the place where the nerve endings connect with the muscles they control.

Normally, this is how the signals work:

• The signals travel down a nerve that controls movement in the muscle
• The nerve endings release a substance called acetylcholine
• Acetylcholine binds to the muscle tissue at the nerve-muscle junction
• This causes the muscle to contract (move)

But in someone with myasthenia gravis, the body's own immune system makes antibodies that block the binding of acetylcholine to the muscle. This makes the muscles weaker.

The thymus gland, which is part of your immune system, may play a role in myasthenia gravis. Normally, your thymus gland is active and growing when you are a child. It makes white blood cells to fight infections. At puberty, it starts getting smaller and is replaced by fat. It is usually small by the time you are an adult. But in many adults with myasthenia gravis, the thymus gland stays large. And some people with myasthenia gravis can get thymomas, which are tumors of the thymus. The are usually benign (not cancer), but they can sometimes become cancerous.

Although myasthenia gravis can affect people of any age, it is most common in young adult women (under age 40) and older men (over age 60). It is usually not inherited (passed down in families).

Myasthenia gravis normally does not affect infants. But if you are pregnant and have myasthenia gravis it's possible to pass the antibodies to your fetus. The baby can then be born with neonatal myasthenia. This condition is usually temporary, and the symptoms typically go away within two to three months after birth.

The symptoms of myasthenia gravis will depend on which muscles are affected. The symptoms often include:

• Weakness of the eye muscles
• Drooping of one or both eyelids
• Blurred or double vision
• Changes in facial expressions
• Trouble swallowing
• Shortness of breath
• Speech problems
• Weakness in the arms, hands, fingers, legs, and neck

Different people have different levels of muscle weakness. And the weakness can vary from day to day. Some days it might be mild, and other days it might be worse. Physical activity often makes the muscle weakness worse.

Some people with myasthenia gravis can get severe weakness that affects the muscles that control breathing. This is called a myasthenic crisis, and it is a life-threatening emergency.

There are many other conditions that can cause muscle weakness, so myasthenia gravis can be hard to diagnose. To find out if you have myasthenia gravis, your health care provider:

• Will ask about your medical history and symptoms
• Will do a physical exam, including a neurological exam
• Will likely order tests for myasthenia gravis, including:
  • Blood tests
  • Imaging tests
  • Electromyography (EMG) and nerve conduction studies

There is no cure for myasthenia gravis, but treatments that can improve muscle weakness and help with symptoms. They include:

• Anticholinesterase medicines, which can improve nerve-to-muscle messages and make muscles stronger.
• Immunosuppressive medicines, which are medicines that decrease your body's immune system responses. They can lower your body's production of abnormal antibodies.
• Monoclonal antibodies, which can also help decrease your body's immune system responses.
• Plasmapheresis (plasma exchange) and intravenous immunoglobulin, which are procedures to remove abnormal antibodies from your blood. They are usually used in severe cases. They can help with symptoms for a few weeks or months.
• Thymectomy, surgery to remove the thymus gland. It can reduce the symptoms of myasthenia gravis, possibly by rebalancing the immune system.

Lifestyle changes may be helpful for some people. The changes could include regular gentle exercise, getting enough rest, and eating healthy foods.

Some people with myasthenia gravis go into remission. This means that they do not have symptoms. The remission is usually temporary, but sometimes it can be permanent.

NIH: National Institute of Neurological Disorders and Stroke

Nausea is when you feel sick to your stomach, as if you are going to throw up. Vomiting is when you throw up.

Nausea and vomiting can be symptoms of many different conditions, including:

• Morning sickness during pregnancy
• Gastroenteritis (infection of your intestines) and other infections
• Migraines
• Motion sickness
• Food poisoning
• Medicines, including those for cancer chemotherapy
• GERD (reflux) and ulcers
• Intestinal obstruction

Nausea and vomiting are common. They are usually not serious. However, you should contact your health care provider immediately if you have:

• A reason to think that your vomiting is from poisoning
• Vomited for longer than 24 hours
• Blood in the vomit
• Severe abdominal pain
• Severe headache and stiff neck
• Signs of dehydration, such as dry mouth, infrequent urination or dark urine

Your health care provider will take your medical history, ask about your symptoms and do a physical exam. The provider will look for signs of dehydration. You may have some tests, including blood and urine tests. Women may also have a pregnancy test.

Treatments for nausea and vomiting depend on the cause. You may get treatment for the underlying problem. There are some medicines that can treatment nausea and vomiting. For severe cases of vomiting, you may need extra fluids through an IV (intravenous).

There are things that you can do to feel better:

• Get enough fluids, to avoid dehydration. If you are having trouble keeping liquids down, drink small amounts of clear liquids often.
• Eat bland foods; stay away from spicy, fatty, or salty foods
• Eat smaller meals more often
• Avoid strong smells, since they can sometimes trigger nausea and vomiting
• If you are pregnant and have morning sickness, eat crackers before you get out of bed in the morning

Neurofibromatosis is a genetic disorder of the nervous system. It mainly affects how nerve cells form and grow. It causes tumors to grow on nerves. You can get neurofibromatosis from your parents, or it can happen because of a mutation (change) in your genes. Once you have it, you can pass it along to your children. Usually the tumors are benign, but sometimes they can become cancerous.

There are three types of neurofibromatosis:

• Type 1 (NF1) causes skin changes and deformed bones. It usually starts in childhood. Sometimes the symptoms are present at birth.
• Type 2 (NF2) causes hearing loss, ringing in the ears, and poor balance. Symptoms often start in the teen years.
• Schwannomatosis causes intense pain. It is the rarest type.

Doctors diagnose the different types based on the symptoms. Genetic testing is also used to diagnose NF1 and NF2. There is no cure. Treatment can help control symptoms. Depending on the type of disease and how serious it is, treatment may include surgery to remove tumors, radiation therapy, and medicines.

NIH: National Institute of Neurological Disorders and Stroke