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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

Retinal disorders are conditions that affect the retina, the thin light-sensitive tissue at the back of your eye. The retina senses light and sends signals to your brain so you can see.

Retinal disorders can cause blurred or distorted vision. Some can lead to vision loss or blindness.

The causes of retinal disorders vary. Aging is a common factor, but other things can raise your risk, such as if you:

• Smoke
• Have obesity
• Have health conditions like diabetes or high blood pressure
• Have had an eye injury or trauma
• Have a family history of retinal disorders

Some common retinal disorders include:

• Macular degeneration. Occurs when the macula (the center of the retina that helps you see fine details) breaks down. There are two types: wet and dry macular degeneration.
• Diabetic retinopathy. Occurs when diabetes damages small blood vessels in the retina, causing them to swell or leak.
• Retinal detachment. Occurs when the retina pulls away from the back of the eye. This is a medical emergency.
• Retinal tears. A hole or break in the retina caused when the gel-like substance inside your eye (the vitreous) pulls away.
• Retinoblastoma. A rare cancer of the retina that most often affects young children.
• Macular pucker. Scar tissue that forms on the macula and distorts vision.
• Macular hole. A small opening in the macula, often related to aging or injury. It can blur or distort central vision.
• Eye floaters. Small specks, cobwebs, or threads that drift across your vision. These are more common with aging.
• Retina pigmentosa. A group of inherited disorders (passed down through families) that slowly damage the retina and cause loss of night and side (peripheral) vision.

Symptoms can vary, but most retinal disorders affect your vision. Common symptoms include:

• Blurred or distorted vision
• Loss of central or side (peripheral) vision
• Flashes of light
• Seeing floating specks or cobwebs
• Trouble seeing at night
• Sudden vision loss (in severe cases)

Seek medical care right away if you notice flashes of light, sudden vision changes, or a sudden increase in eye floaters. These can be signs of a serious retinal problem.

Eye care providers check for retinal disorders with a dilated eye exam. Eye drops are used to widen your pupils so your provider can look at the retina for signs of damage.

They may also do other tests, such as:

• Optical coherence tomography (OCT) to take detailed pictures of the inside of your eye.
• Fluorescein angiography to check the blood vessels in your retina.
• Visual field tests to measure your side (peripheral) vision.

Some retinal disorders can be treated to slow or stop vision loss, and sometimes to restore vision. Treatment depends on the cause and severity. It may include:

• Laser therapy
• Medicine or eye injections
• Surgery
• Lifestyle management to control health conditions such as diabetes or high blood pressure

Not all retinal disorders can be prevented. Some are related to aging or genetics. But you can protect your eyes by:

• Wearing safety goggles or sunglasses
• Getting regular eye exams
• Making healthy lifestyle changes, such as:
  • Quitting smoking (or not starting)
  • Managing diabetes and blood pressure

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