Peripheral Neuropathy

Peripheral neuropathy is an umbrella term for nerve diseases that affect a specific subdivision of your nervous system. Many different conditions can cause peripheral neuropathy, which means a wide range of symptoms is also possible. Peripheral neuropathy can also affect different body parts, depending on how and why it happens.

What this name means

The term “peripheral” is from the Greek word that means “around.” “Peripheral” in this context means outside of or away from the “central” nervous system. The term neuropathy combines two words that trace their origins back to ancient Greek:

• Neuro-: From the Greek word “neuron,” meaning “nerve.”
• -pathy: From the Greek word “pathos,” meaning “affliction” or “condition.”

Your nervous system has two parts, the central nervous system and the peripheral nervous system. Your brain and spinal cord are the two components that make up your central nervous system. Your peripheral nervous system consists of all the other nerves in your body. It also includes nerves that travel from your spinal cord and brain to supply your face and the rest of your body.

Peripheral neuropathy can refer to any condition affecting your peripheral nerves. Healthcare providers often use the terms “neuropathy” and “polyneuropathy” (meaning “disease of many nerves”) interchangeably with “peripheral neuropathy.” Peripheral nerves are farthest from the central nervous system, and they often show the earliest and most severe effects of these conditions

Who does peripheral neuropathy affect?

Peripheral neuropathy can affect anyone, regardless of age, sex, race or ethnicity, personal circumstances, medical history, etc. However, some people are at greater risk for specific types of peripheral neuropathy (see below under Causes and Symptoms for more about this).

Peripheral neuropathy is also very common with some age-related diseases. That means the risk of developing peripheral neuropathy increases as you get older.

How common is this condition?

Peripheral neuropathy is common, partly because this term refers to so many conditions. About 2.4% of people globally have a form of peripheral neuropathy. Among people 45 and older, that percentage rises to between 5% and 7%.

How does this condition affect my body?

To understand how peripheral neuropathy affects your body, it helps to know a little about the structure of neurons, a key type of cell that makes up your nerves. Neurons send and relay signals through your nervous system using electrical and chemical signals. Each neuron consists of the following:

• Cell body: This is the main part of the cell.
• Axon: This is a long, arm-like part that extends outward from the cell body. At the end of the axon are several finger-like extensions where the electrical signal in the neuron becomes a chemical signal. These extensions, known as synapses, lead to nearby nerve cells.
• Dendrites: These are small branch-like extensions (their name comes from a Latin word that means “tree-like”) on the cell body. Dendrites are the receiving point for chemical signals from the synapses of other nearby neurons.
• Myelin: This is a thin layer composed of fatty chemical compounds. Myelin surrounds the axon of many neurons and acts as a protective covering.

Disease types

Peripheral neuropathy happens in two main ways:

• Demyelinating neuropathy: This happens when the myelin coating on the axon deteriorates or can’t form correctly. That affects the way signals travel through the neuron.
• Axonal degeneration: This causes the axon to deteriorate and die off. The longer a neuron is, the worse the effect. That’s why axonal degeneration conditions tend to involve your legs and feet, which are farthest from your spinal cord and rely on connections using longer axons. Axonal degeneration is the most common pattern seen with peripheral neuropathy.

How quickly does peripheral neuropathy develop?

How peripheral neuropathy develops, particularly the timeline of its progress, depends very much on what causes it. Injuries can cause it to develop instantaneously or within minutes or hours. Some toxic and inflammation-based forms of peripheral neuropathy may develop rapidly over days or weeks, while most other conditions take months, years or even decades to develop.