What is peripheral neuropathy?
Peripheral neuropathy refers to the many conditions that involve damage to the peripheral nervous system, the vast communication network that sends signals between the central nervous system (the brain and spinal cord) and all other parts of the body. Peripheral nerves send many types of sensory information to the central nervous system (CNS), such as a message that the feet are cold.
They also carry signals from the CNS to the rest of the body. Best known are the signals to the muscles that tell them to contract, which is how we move, but there are different types of signals that help control everything from our heart and blood vessels, digestion, urination, sexual function, to our bones and immune system. The peripheral nerves are like the cables that connect the different parts of a computer or connect the Internet. When they malfunction, complex functions can grind to a halt.
Nerve signaling in neuropathy is disrupted in three ways:
- Loss of signals normally sent (like a broken wire)
- Inappropriate signaling when there shouldn’t be any (like static on a telephone line)
- Errors that distort the messages being sent (like a wavy television picture)
Symptoms can range from mild to disabling and are rarely life-threatening.
The symptoms depend on the type of nerve fibers affected and the type and severity of the damage. Symptoms may develop over days, weeks, or years. In some cases, the symptoms improve on their own and may not require advanced care. Unlike nerve cells in the central nervous system, peripheral nerve cells continue to grow throughout life.
More than 20 million people in the United States have been estimated to have some form of peripheral neuropathy, but this figure may be significantly higher—not all people with symptoms of neuropathy are tested for the disease and tests currently don’t look for all forms of neuropathy. Neuropathy is often misdiagnosed due to its complex array of symptoms.
What are the symptoms of peripheral nerve damage?
Symptoms are related to the type of nerves affected.
- Motor nerve damage is most commonly associated with muscle weakness. Other symptoms include painful cramps, fasciculations (uncontrolled muscle twitching visible under the skin) and muscle shrinking.
- Sensory nerve damage causes various symptoms because sensory nerves have a broad range of functions.
- Damage to large sensory fibers harms the ability to feel vibrations and touch, especially in the hands and feet. You may feel as if you are wearing gloves and stockings even when you are not.