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Nerves are like wires that carry messages back and forth between your brain and your body. Your peripheral nerves branch off from your brain and spinal cord and connect to all parts of your body, including your muscles and organs. Peripheral nerves carry messages from your brain that control your movement, breathing, heartbeat, digestion, and more. They also carry messages from your body to your brain, so you can feel things, such as pain, heat, and cold.

Peripheral nerve disorders happen when one or more peripheral nerves are damaged. Damaged nerves may not carry messages correctly, or they may not work at all. As a result, you may have pain, trouble walking, or a variety of other problems, depending on which nerves are involved.

Peripheral nerve disorders are very common. There are more than 100 different types.

Many things can damage nerves and lead to peripheral nerve disorders:

• Diabetes is the most common cause of peripheral nerve disorders. Most people with diabetes will develop diabetic nerve problems.
• Physical injury (trauma) that stretches, crushes, squeezes, cuts, or puts pressure on one or more nerves. Some examples of peripheral nerve disorders from physical injury include complex regional pain syndrome and brachial plexus injuries.
• Health conditions, including:
  • Certain cancers and their treatment (chemotherapy and radiation therapy).
  • Infections, such as HIV and Lyme disease.
  • Problems with blood or blood vessels.
  • Autoimmune diseases, such as rheumatoid arthritis and lupus.
  • Kidney or liver disease.
• Certain medicines.
• Contact with certain toxic substances, such as lead or mercury.
• Alcohol use disorder (AUD) and smoking.
• Vitamin imbalances, especially a lack of vitamin B12.
• Your genes, including changes in your genes or conditions that you inherit from your parents, such as Charcot-Marie-Tooth disease.

In certain cases, the cause of peripheral nerve disorder is not known.

The symptoms of peripheral nerve disorders depend on which nerves are affected, what is causing the damage, and how serious it is:

• Weak or aching muscles
• Problems with balance, walking, or using your arms and hands
• Cramps or twitching muscles
• Muscle shrinking

• Tingling, numbness, or pain often in the hands and feet
• Not being able to feel heat, cold, or pain, such as a cut on your foot
• Pain from even light touch

• A heartbeat that's too fast or too slow
• Trouble swallowing
• Sweating too much or too little
• Vomiting, diarrhea, or constipation
• Problems with urination or sexual function

Symptoms may range from mild to very strong. They may develop quickly over days or slowly over months and years. But they are rarely life-threatening.

To find out if you have a peripheral nerve disorder, your provider will:

• Ask about your medical history
• Ask about your family health history
• Do a physical exam
• Order tests, which may include:
  • Blood tests
  • Genetic tests
  • Nerve tests that measure:
    • Electrical activity in your nerves and muscles
    • How well your autonomic nerves are working
  • A biopsy of nerve or skin tissue
  • CT or MRI scan to see what may be pressing on your nerves

It's important to treat any conditions that are causing nerve damage. In certain cases, that will allow your nerves to heal over time.

Treatment for symptoms depends on the type of peripheral nerve disorder you have, where it is, and how severe. Treatment options include:

• Braces or splints
• Over-the-counter patches and skin creams
• Prescription medicines
• Non-drug pain management, such as electrical stimulation or relaxation therapy
• Surgery to relieve pressure on a nerve

You can help prevent peripheral nerve disorders by:

• Managing health conditions that may cause nerve damage, especially diabetes
• Preventing falls and accidents
• Avoiding toxic substances
• Being careful to avoid repeated motions and body positions that press on your nerves
• Eating a balanced diet, exercising, limiting alcohol, and not smoking

NIH: National Institute of Neurological Disorders and Stroke

Leukodystrophies are a group of rare genetic disorders that affect the central nervous system (CNS). The CNS is made up of your brain and spinal cord. Leukodystrophies damage the white matter of your CNS. The white matter includes:

• Nerve fibers, also called axons, which connect your nerve cells
• Myelin, a layer of proteins and fatty materials that covers and protects the nerve fibers. It also helps speed up signals between the nerve cells.

When the white matter is damaged, it can slow down or block the signals between nerve cells. This can cause many different symptoms, including trouble with movement, vision, hearing, and thinking.

There are over 50 types of leukodystrophies. Some types are present at birth, while others may not cause symptoms until a child becomes a toddler. A few types mainly affect adults. Most types get worse over time.

Leukodystrophies are caused by genetic changes. These changes are usually inherited, meaning that they are passed from parent to child.

The symptoms of leukodystrophies depend on the type; they can include a gradual loss of:

• Muscle tone
• balance and mobility
• Walking
• Speech
• Ability to eat
• Vision
• Hearing
• Behavior

There can also be other symptoms, such as:

• Learning disabilities
• bladder issues
• Breathing problems
• Developmental disabilities
• Muscle control disorders
• Seizures

Leukodystrophies can be hard to diagnose because there are so many different types which can have different symptoms. Your health care provider may use many tools to make a diagnosis:

• Physical and neurological exams
• A medical history, including asking about family history
• Imaging tests, such as an MRI or CT scan
• Genetic testing to look for genetic changes that could cause leukodystrophies
• Lab tests

There is no cure for leukodystrophies. Treatment focuses on relieving symptoms and providing support. It may include:

• Medicines to manage muscle tone, seizures, and spasticity (muscle stiffness)
• Physical, occupational, and speech therapies to improve mobility, function, and cognitive problems
• Nutritional therapy for eating and swallowing problems
• Educational and recreational programs

Stem cell or bone marrow transplantation can be helpful for a few types of leukodystrophy.

One type of leukodystrophy, CTX, is treatable if it is diagnosed early. It is treated with chenodeoxycholic acid (CDCA) replacement therapy.

NIH: National Institute of Neurological Disorders and Stroke

The retina is a layer of tissue in the back of your eye that senses light and sends images to your brain. In the center of this nerve tissue is the macula. It provides the sharp, central vision needed for reading, driving and seeing fine detail.

Retinal disorders affect this vital tissue. They can affect your vision, and some can be serious enough to cause blindness. Examples are:

• Macular degeneration - a disease that destroys your sharp, central vision
• Diabetic eye disease
• Retinal detachment - a medical emergency, when the retina is pulled away from the back of the eye
• Retinoblastoma - cancer of the retina. It is most common in young children.
• Macular pucker - scar tissue on the macula
• Macular hole - a small break in the macula that usually happens to people over 60
• Floaters - cobwebs or specks in your field of vision

NIH: National Eye Institute

Our senses of taste and smell give us great pleasure. Taste helps us enjoy food and beverages. Smell lets us enjoy the scents and fragrances like roses or coffee. Taste and smell also protect us, letting us know when food has gone bad or when there is a gas leak. They make us want to eat, ensuring we get the nutrition we need.

People with taste disorders may taste things that aren't there, may not be able to tell the difference in tastes, or can't taste at all. People with smell disorders may lose their sense of smell, or things may smell different. A smell they once enjoyed may now smell bad to them.

Many illnesses and injuries can cause taste and smell disorders, including colds and head injuries. Some drugs can also affect taste and smell. Most people lose some ability to taste and smell as they get older. Treatment varies, depending on the problem and its cause.

NIH: National Institute on Deafness and Other Communication Disorders