Peripheral neuropathy is a condition in which one or more of your peripheral nerves are damaged.
Damaged nerves disrupt the messages sent between your peripheral and central nervous system. Symptoms of peripheral neuropathy are varied and depend on the kind of nerves damaged. This condition has many different causes. Treatment for peripheral neuropathy aims to address the underlying cause of the nerve damage and control symptoms. About 2 in 100 people are affected by peripheral neuropathy.
About the nervous system
The nervous system coordinates our voluntary and involuntary actions and sends signals between different parts of the body. Your nervous system is made up of the central nervous system and the peripheral nervous system.
The central nervous system (CNS) is responsible for interpreting sensory information and responding appropriately. It includes the brain and the spinal cord.
The peripheral nervous system (PNS) is the network of nerves that send information from the brain and spinal cord to the rest of the body, and then back to the brain and spinal cord. If your peripheral nerves are damaged, the information being sent back and forth can be mixed up or not delivered at all. The peripheral nerves are divided into 3 types of nerves.
Your ‘sensory’ nerves allow you to feel sensations such as cold, heat, pain, and pleasure. You ‘motor’ nerves communicate with your muscles and stimulate them to move. Your ‘autonomic’ nerves transport information to your organs. They control your unconscious bodily functions such as digestion, your heart rate, and breathing.
Symptoms of peripheral neuropathy
Neuropathy can affect only one or all three types of nerves (motor, autonomic and sensory). Your symptoms will therefore depend on which type of nerve is damaged, how many nerves are affected, and the locations of the affected nerves. Generally speaking, peripheral neuropathy can be divided into three types based on the type of nerve affected.
1. Sensory neuropathy, where the sensory nerves are damaged, can cause the following symptoms:
- Inability to feel pain
- Numbness and tingling
- Inability to notice changes in temperature
- Shooting pains
- Loss of coordination
The extremities (feet and hands) are usually affected first with this type of neuropathy. If the condition worsens, the symptoms will progressively move toward the body’s center.
2. Motor neuropathy, where the body’s motor nerves are damaged, can cause the following symptoms:
- Muscle weakness
- Muscle cramps and twitching
- Muscle paralysis
- Muscle wasting (due to disuse)
3. Autonomic neuropathy, where the autonomic nerves are damaged, can cause the following symptoms:
- Inability to endure heat (caused by a reduced ability to sweat)
- Incontinence of urine (caused by a loss of control over the bladder)
- Dizziness and fainting (caused by an inability to control blood pressure)
Causes
Diabetes: Uncontrolled diabetes is the most common cause of peripheral neuropathy. At least half of all people with long-term diabetes develop some type of neuropathy.
Certain Medications: Some medicines, especially those used to treat cancer and HIV, can cause damage to peripheral nerves.
Dietary Deficiencies: A lack of B vitamins can contribute to poor nerve health. Vitamin E and niacin are also important to maintain healthy nerves. Not having enough of these may cause peripheral neuropathy
Injuries/Trauma: There are some injuries that can put pressure on the nerves. These include injuries and traumas such as car accidents, sports injuries, or even spending too long in an unnatural position.
Infections: Some infections such as HIV, Lyme’s disease, and shingles can damage the peripheral nerves.
Other causes of peripheral nerve damage include certain cancers, consuming too much alcohol, certain hereditary diseases, chronic kidney disease, liver disease, some connective tissue disorders, and tumors.
Tests and Diagnosis
To determine if you need further tests for peripheral neuropathy, your doctor may ask you questions about: your symptoms, your health in general, history of neuropathy in your family, current medications, and intake of alcohol.
A physical exam focusing on signs of peripheral neuropathy such as muscle weakness and numbness will usually follow. Based on his/her findings, he/she may suggest some blood tests to look for possible underlying causes of nerve damage. For example, he/she may recommend a blood sugar test for diabetes, a kidney function test, or a test that looks for nutritional deficiencies such as vitamin B12.
If necessary, the doctor may then refer you to a neurologist for further examination. The neurologist will most likely suggest some further tests, depending on your medical history and symptoms.
Common tests include:
Electromyography:
This test examines your muscles’ electrical activity. This is examined by inserting a very thin needle with an attached electrode into a muscle. When you contract the muscle, for example, by bending your arm or leg, your muscle response will be monitored and recorded. In this way, the way the muscle responds when stimulated by nerves is measured. If you have peripheral neuropathy, the electrical activity in your muscles will be irregular.
Nerve conduction testing:
This test measures the speed that electrical signals go through the nerves through the placement of special electrodes on the skin. In patients with peripheral neuropathy, the speed is reduced.
A nerve biopsy:
For this test, a small part of your nerve is removed and then examined under a microscope for abnormalities.
A skin biopsy:
In this test, a sample is taken from any part of the skin, and then examined under a microscope. Particular attention is paid to the density of the nerve fibres in the piece of skin. In peripheral neuropathy, the peripheral nerves are not as dense.
Treatment
The treatment of peripheral neuropathy aims to treat any underlying condition, control symptoms of the condition, and allow you to live and function independently in your day-to-day life.
1. Treating underlying conditions:
The underlying cause or causes of peripheral neuropathy must be treated. If diabetes is the cause, blood sugar must be brought under control. If an injury or trauma is causing the condition, you may need physical therapy or surgery to relieve the pressure on the nerve. If you have a nutrient or vitamin deficiency, you may need to take supplements or change your diet. Each cause must be addressed and treated individually.
Controlling symptoms:
Symptoms vary from patient to patient, so treatments for symptoms depend a lot on the individual patient as well as the cause of the condition. Some treatments might include: medicines to manage pain, treat low blood pressure, help with digestive problems or help with bladder function.
Living normally and independently:
This condition can have a huge affect on your day-to-day activities and lifestyle. For example, if your leg muscles become weak it may become difficult to move and you may need crutches or a walking stick. Working with a physiotherapist can help you learn how to use these aids successfully. Physiotherapists may also be able to teach you exercises to rehabilitate weak muscles. An occupational therapist, on the other hand, can help you adapt your home and lifestyle based on your condition. For example, poor muscle control due to motor neuropathy can make falling or other injuries more likely. An occupational therapist will make recommendations about furniture placement and use in your home to reduce your likelihood of tripping, slipping, or falling.
Outlook
The outlook for peripheral neuropathy depends a lot on any underlying condition. Generally speaking, if the cause can be found and treated early on, recovery is likely. However, if the cause is not found or cannot be treated, or if the neuropathy is severe, the nerve damaged caused by this condition can be irreversible.